Fostex T50RP Incremental Mods and Measurements
I made incremental mods and measurements using a "virgin" set of current production T50RP's. The set I used has the non-textured, translucent white driver dampening "paper" and the darker color - smoother finished metal hangers. I measured each mod using Room Equalization Wizard (REW), my MacBook Pro soundcard, and a $50.00 DIY measurement kit comprised of a Phantom Power Supply and a Panasonic WM-61A Omnidirectional Electret microphone stuck in my ear. The following measurements should be compared and interpreted relative to one another, not to others' measurements such as another DIY measurement kit and state-of-the art measurement systems such as those used by Headroom, Tyll, and purrin.
Note: All information, photographs, and measurement graphs contained within this document are owned by me and represent my intellectual property. I have made this document available for anyone to use for DIY modification of their personal headphones. Use of any and all information, photographs, and measurement graphs in this document for publication, advertising, and profit is prohibited without my written consent.
Use of the tutorials, pictorials, guides, measurement graphs, and all information within this document are provided for DIY modification of your headphones. Use this document at your own risk. Please understand that your results and opinions may differ from mine due to variations in: materials used, implementation of mod components, audio equipment chains, music file type and resolution, hearing acuity, personal preferences, and tuning.
Simplified and Consolidated Tutorial and Pictorial for DBV #3, Preparing J&M Fiberglass, Preparing Rite Aid "First Aid Rolled Cotton," Cotton Ball Substitution, Grodan Rock Wool Mods, Tuning Rules of Thumb, and Repairing Stripped Cup Thread ---> Scroll down, past Graph #55 of this post.
"Pad Rolling" Comparisons of Fostex Stock Pads, HM5 Pads, FA-003 Pads, J$ Pads, Dog Pads, Alpha Pads, Shure Velour Pads, and Shure 840 Pads installed on an All Stock set of Fostex T20RP mk2 headphones --> Scroll to the bottom of this post.
"Naked Driver" Mod --> Scroll to the bottom of this post.
DIY Measurement Kit
A pictorial guide for making your own DIY measurement kit, REW links, REW Setup Pictorial, and more are located at the following link:
I encourage everyone to consider building and using a measurement kit. I find it indispensable for tuning. It's also interesting, easy to use, fast (6 seconds per measurement), and fun.
I mounted the mic in an Etymotic triflange ear tip using super glue. Next, I applied a ring of hot glue around the mic sitting on its perch at the IEM insertion hole. When making these measurements over two consecutive weekends, I made sure to use the same methodology to standardize the data as much as possible. I placed the mic in my ear at the same angle and depth on both measurement days. I did not remove the mic until all measurements were completed, each day. I SPL-matched the sweep level for each measurement. Various pads X mod(s) result in wide variability in sensitivity. Matching the sweep levels may not be necessary but I did so to control this variable.
I placed the headphones on my head based on my usual, most comfortable position whenever I use headphones. Considering the number of measurements and variables assessed, I made only 1 measurement for each. The baffles were secured to the cups with masking tape to avoid stripping the cup threads from multiple modding cycles done one at a time. I squeezed the baffle to the cup while taping and insured that all gaps and crevices were tightly sealed. Consider the data FWIW or a "snapshot" of each mod.
The small, sharp up/down "tics" in the SPL FR graphs and the very thin ridges in most of the waterfall plots are the result of "cable noise" from electromagnetic interference according to the REW Moderator.
The FR graphs don't tell us anything about the speed or decay of each mod. I included Waterfall Plots to show the speed and decay on the 'z' axis, back to front. Suffice to say that the T50RP is Fast. Decay is complete by 100 to 200 ms in most cases. The exception with some mods is low-level ringing below 30 Hz and at less than -20 to -30 dB. Bass and sub-bass are textured and fast. I cannot hear the ringing but maybe you can.
Anyone can download and use REW for free but please contribute (any amount) to support the site. You can use, view, and manipulate .mdat files without having to actually make any measurements of your own. Here's the link: http://www.hometheatershack.com/roomeq/
I uploaded the REW raw data (.mdat files) to Google Docs for all incremental measurements I made and listed, below. First, download and install REW and then download and save the .mdat files from Google Docs into your computer's 'Downloads' file. Next, open REW and click on 'Open', go to your 'Download' files, double click one of the two .mdat files, and the data files will load into REW.
The default graph format is SPL FR. Tabs across the top of the measurement window allow you to 'Generate' waterfall plots and spectrograms. You must adjust the SPL FR display to 'Zero' before Generating waterfalls and spectrograms. To do this, click the 'gear' icon at the top right of the measurement window, type in -155 in the offset window and then click 'Add to Data.' Go to the left side, vertical slider to pull the adjusted SPL FR graph down into the display window. Now, you can generate waterfalls and spectrograms along with decay and several other options, if interested.
In the "T50RP Mods Summary WIKI started by Ardilla, I have a WIKI entitled "BMF V8.1 Mods". One of the links in this group takes you to a Google Doc that explains more about how to use REW, including screen shots for clarity.
Within REW's measurement window, and after you've 'Opened' a .mdat data file, you can delete all but the particular graphs you want to overlay with one another by clicking the 'red X' you will see on the left side of the measurement window. Next, click 'All SPL', located at the top tool bar of the measurement window, to display your chosen graphs as an overlay. You can also change the resolution by clicking the '-' or '+' tabs at the top left of the SPL graph; i.e. 5 db or 10 dB. You can save this specific group of graphs by clicking 'Save All' at the top left of the window and naming it. When you're done comparing this set of measurements, close this file, after naming and saving it, by clicking the 'Remove All' tab and re-open the complete .mdat file to repeat the process for a different group of comparisons. For example, you can delete all but the 3 graphs for "Stock Left Acoustipack Lite, Newplast, and type of pad (840, Stock, and FA-003 pads)" for comparing and overlaying these 3 graphs. Do the same for any other combination of incremental measurements in one or both of the two sets of .mdat files I uploaded to Google Docs.
Here are the links for my Incremental Mods and Measurements REW .mdat files stored in Google Docs:
2. Main data set 1 .mdat data files for Incremental Mods and Measurements
3. Main data set 2 .mdat data files for Incremental Mods and Measurements
4. DBV #1 and #2 .mdat files:
5. Stock T50RP, T40RP mk2, T20RP mk2 measurements with Etymotic Foam and Triflange mounted microphones .mdat files:
6. DBV #2 with Taped on FA-003 Pads, T50RP Pads, and Inner Tube Modded FA-003 Pads .mdat files:
T50RP Incremental Mods and Measurements
Audio Measurement Chain
REW Generated Sweep > Calibrated MacBook Pro Soundcard > Glass Toslink > Dacmini with 1 Ohm Output Impedance Mod > Headphones > Calibrated Panasonic WM-61A Microphone > Calibrated Phantom Power Supply > MacBook Pro > REW Analysis
General Interpretive Guidelines for REW Measurement Graphs
1. Frequency Response Graph (FR): Zero dB horizontal x-axis is the baseline. The frequencies in Hertz (Hz) are shown at the bottom in logrithmic format. The vertical y-axis is Sound Pressure Level (SPL) in decibels (dB) which indicates how "loud" the headphones measure. Positive numbers indicate louder than baseline. Negative numbers indicate less loudness than baseline.
+/- 2 dB above or below the baseline is acceptable and you probably would not be able to hear a significant difference. An ideal FR "curve" would actually be a flat line at zero dB extending all the way across the graph from sub-bass on the far Left to high treble on the far Right.
FR graphs tell us nothing about resonances or ringing, speed of decay, impulse response, phase, or how the headphones will sound. You don't need to worry about any of these for now. Just understand that resonances, ringing, and slow decay speed are "Bad".... and, flat FR and fast decay are "Good."
2. Waterfall Graph: This is a 3D graph with 3 axes - SPL in dB on the vertical y-axis, Frequencies in Hz on the horizontal x-axis, and Decay Time on the Back to Front z-axis. Ideally, you want the x-axis to be as flat and uniform as possible across the top from left to right which indicates an even, or "flat" FR. The waterfall from the back of the z-axis and extending forward, toward you, should reach the floor and disappear within 200 ms, or less. The waterfall indicates the decay speed and whether or not there is ringing at particular frequencies shown as a ridge extending from the main waterfall that extends beyond 200 ms and is greater than -20 dB. Sharp dips or spikes are undesirable. Generally, you're more likely to perceive a spike than a dip. A "suckout" is a wider (x-axis) range of frequencies - 10 dB or more and can easily be "heard."
3. Spectrogram: This graph shows speed of decay, ringing/resonances, dips, spikes, and suckouts. The vertical y-axis indicates speed of decay in milliseconds and the horizontal x-axis marks frequencies from sub-bass to treble (Left to Right). The Color Scale on the right side of the graph indicates SPL from 0 = Red to - 40 = Blue.
Ideally, you want to see a wide beam of red with thin layers of yellow, green, and blue that extend uniformly from far Left to far Right. Green and Blue "Flames" indicate low level ringing that may be difficult to hear. Yellow and Red Flames are more likely heard. Upward "Bulges" indicate humps. "Squeezed" areas indicate dips. "Pinched off" areas are suckouts.
Use all three graphs to better understand headphones' performance and make more accurate predictions about how they might sound. Start by looking at the "All Stock T50RP" FR and Waterfall graphs. Notice the big hump in the middle and the slopes to either side, especially on the left side. This indicates a mid-centric headphone with weak bass and weak treble that "rolls off." There is a little peak at 1 kHz. It's fast with decay completed by 100 to 150 ms. What the graphs do not show, however, is the resonance and standing waves heard from Stock T50RP's and described throughout the main T50RP mod forum.
Fostex T50RP - All Stock Left Side: Current production with smooth finished metal hangers and non-textured, translucent white driver dampener
All Stock T50RP
Stock with sealed cup vents
Stock with sealed baffle port
Stock with sealed cup vents and sealed baffle port
Masking tape temporarily seals baffle to cup without risking stripping the cup threads. Shure 840 pads (Left) and FA-003 pads (Right-micmacmo's inner tube mod).
Stock with Shure 840 pads
Stock with Shure 840 pads and sealed cup vents
Stock with Shure 840 pads, sealed cup vents, and sealed baffle port
Stock with Shure 840 pads and sealed baffle port
Temporary Bass Port using electrical tape or masking tape on the outside of the cup vents. Once the mod is completed, the bass port is moved to the inside of the cup unless you prefer the flexibility of re-tuning, on the fly. Masking tape makes the job easier because you first apply a piece that covers all 4 cup vents and then use an X-acto knife to cut the precise size bass port you want. This masking tape bass port is 3x1 mm. To prevent the tape from separating at the corners (Not Shown in the photo, above), use an X-acto knife to remove the excess tape from where it overlaps onto the back of the cups and down the side walls flush with the cup vents. Once removed, smooth out and compress the tape flat onto the four cup vent slots. Use an X-acto knife to cut an opening over the center of one of the vent slots to make your modified bass port. Enlarge by 1 mm increments. If it's too wide, bass bloat will return. In this case, decrease the width of the bass port in 1 mm increments by placing a small piece of masking tape over part of the bass port already opened.
When you have determined the size of the bass port needed for your mod configuration, you can make a permanent one by duplicating and placing it over the cup vents on the inside. Cut a piece of masking tape to cover all the stock black cup felt overlaying the cup vents. Place the tape over the vent felt on the inside of the cup. Use shirt pins pushed through from the outside to mark the limits of the bass port width on the inside. Use the "pin markers" to trace a rectangular opening on the masking tape. Remove the tape but leave the pins in place. Cut out the rectangle from the masking tape, re-apply the tape onto the vent felt on the inside by using the pins as your guide, and remove the pins. Glue all the way around the masking tape so it will remain in place and not "leak" around the edges. The size of your bass ports from left to right may need to be different to balance the FR. In some cases, you may have, for example, a 3x1 mm bass port on one side and no bass port on the other side.
Stock with Shure 840 pads and 3 mm bass port
Grodan rock wool: 10x 60x70 mm with extra "fluff" around the rim. Thanks, JoelPearce and micmacmo.
Stock with Grodan Rock Wool and Shure 840 Pads
Stock with Grodan Rock Wool and Stock Pads
Stock with Grodan Rock Wool and FA-003 Pads
Note: micmacmo's Inner Tube Modded FA-003 Pads were used throughout these measurements.
"Unobtanium" Rite Aid Natural Absorbent Cotton - approximately 15 cm wide and 4 cm thick out of the box and easily separated to the desired thickness. Other types of cotton may work but will likely require altering the amount and thickness used.
Stock with Cotton and Shure 840 Pads
Stock with Cotton and Stock Pads
Stock with Cotton and FA-003 Pads
50x60x70 mm Johns Manville fiberglass - uncompressed
50x60x70 mm Johns Manville fiberglass compressed into cup with extra "fluff" around the rim. Note the rubber shock absorber caps showing through the fiberglass.
Stock with Fiberglass and Shure 840 Pads
Stock with Fiberglass and Stock Pads
Stock with Fiberglass and FA-003 Pads
1.5x35x35 mm Creatology Stiffened Craft Felt from Michaels' secured with strips of Transpore tape.
A better method uses 1.5x37x45 mm Creatology Stiffened Craft Felt secured by double sided tape strips cut to fit the outer edges of the driver grid. Thanks nick n.
Stock with 1.5x35x35 mm Stiffened Craft Felt over the driver and Shure 840 Pads
Stock with 1.5x35x35 mm Stiffened Craft Felt over the driver and Stock Pads
Stock with 1.5x35x35 mm Stiffened Craft Felt over driver and FA-003 Pads
12x35x35 mm open cell foam over the driver secured with Transpore tape.
Stock with Open Cell Foam over driver and Shure 840 Pads
Stock with Open Cell Foam over driver and Stock Pads
Stock with Open Cell Foam over driver and FA-003 Pads
4x35x35 mm 100% Wool Felt from Hobby Lobby, over the driver
Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and Shure 840 Pads
Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and Stock Pads
Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and FA-003 Pads
Acoustipack Lite and Self-Adhesive Felt in the cup floor. The Acoustipack is in the left and right "floor wells" and the self-adhesive felt is at the top and bottom of the center area, above and below the headband hanger compartment.
Stock with Acoustipack Lite and Felt in Cup Floors with Shure 840 Pads
Stock with Acoustipack Lite and Felt in Cup Floors with Stock Pads
Stock with Acoustipack Lite and Felt in Cup Floors with FA-003 Pads
20 grams of Newplast is less than 1 oz. 10 grams per side. Acoustipack Lite and self-adhesive felt in the cup. Newplast "Flush Mass Loaded" in the baffle compartments. A digital scale is not required. I used one to demonstrate just how little Newplast or plasticine is needed
Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and Shure 840 Pads
Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and Stock Pads
Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and FA-003 Pads
L2. This "Naked Driver" is associated with Graphs 33b, 33c, and 33d, Only. ALL preceding and subsequent graphs are based on modifications with the stock white driver dampening paper intact.
"Naked" Driver has had its stock white 'paper' removed, Acoustipack Lite and Felt in Cup Floors, and Newplast Flush Mass Loaded in the baffles. I do not recommend removing the stock white driver dampening "paper" from the back of the drivers. In my experience, this offers no benefits over keeping the stock white dampener intact.
Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, Shure 840 Pads
Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, and Stock Pads
Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, FA-003 Pads
1.5x35x35 mm Creatology Stiffened Craft Felt has been added to the back of the driver, directly over the stock white driver dampening paper.
Stock with Acoustipack Lite and Felt in Cup Floors, Newplast, Stiffened Craft Felt over the driver, and Shure 840 Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, and Stock Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, and FA-003 Pads
25x60x70 mm cotton has been notched to fit around the shock absorbers and jack, placed over Acoustipack Lite in cup. Cutting off the shock absorbers is not required. Removing the rubber shock absorber caps gives you a bit more room to work but this is also optional. If you remove them, save them in case you want to go back to stock.
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and Shure 840 Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and Stock Pads
Stock with Acoustipack LIte and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and FA-003 Pads
For DBV #2, cut 10x60x70 mm fiberglass, similarly notched for the shock absorbers, and place over 20x60x70 mm cotton. You may need more/less of each for your mod, determined by tuning
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and Shure 840 Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and Stock Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and FA-003 Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and Shure 840 Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and Stock Pads
Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and FA-003 Pads
This is the same FR Graph as the one just above but with 1/24 Smoothing. This is the only FR Graph in this measurement database with any Smoothing applied.
Additional Requested Pictures and Graphs
1. BMF DBV #1: With Shure 840 pads compared with Stock and FA-003 pads
2. My LCD2
DBV #1 and #2 Left Cup: 3x15 mm Paxmate "Ladder Rungs" over Acoustipack Lite in floor wells. 1.5x35x35 mm Creatology Stiffened Craft Felt over stock white driver dampener, Transpore overlay, and Newplast Flush Mass Loaded Baffle Compartments. Double Sided tape works best for securing stiff felt to the driver back for the permanent mod.
DBV#1 Left Cup: 20x60x70 mm (measured Uncompressed) Rite Aid Natural Absorbent Cotton with 10x60x70 mm (measured Compressed) Fiberglass overlaying Acoustipack Lite and Paxmate "Ladder Rungs." Baffle: Newplast Flush Mass Loaded baffle compartments, stiffened felt over stock white driver dampener and Transpore overlay. Note: Acid-free double sided tape applied to the driver grid perimeter works better than Transpore for securing the stiffened felt.
DBV #1 with Shure 840 Pads
Above: BMF DBV #1 with Shure 840 Pads - SPL FR Graph, Waterfall Plot, and Spectrogram
The "DBV" designation in the Notes section of these graphs is simply my way of keeping track of various mods I'm working on. This mod configuration is a variation of BMF V8.1 described with pictures in "The Fostex T50RP Mods Summary Links" WIKI started by Ardilla. This mod is fast and neutral with excellent bass extension, texture, and definition. Mids are properly placed, clear, and lush, particularly for vocals and acoustic music. Treble extension, detail, and shimmer are very good without fatigue. Imaging is precise, channel balance is perfect, and soundstage is wide for a closed 'phone.
Note: I inadvertently failed to list four important mod components in the Notes Section of my DBV graphs, above:
1. 3x1 mm bass ports over the black cup vent felt on the inside of the cups
2. Baffle ports are sealed with GE Silicone II
3. Dynamat (or FatMat) with self-adhesive felt overlay around the ear side of the drivers
4. Shure 840 pads
Note, also, that I typed in the wrong dimensions for the bass ports in the Notes section of these graphs. Instead of 2x2 mm bass ports for these DBV measurements, the actual bass ports are 3mm wide and ~1 mm high - and placed over the center of the lowest of the 4 cup vents.
I used a Dremel cutting tool to remove all 4 shock absorber posts inside each cup. This makes it easier to place the cotton and fiberglass overlay. I don't know if removing the shock absorbers improves the sound quality but it is possible because the cotton/fiberglass lays flatter and it's more uniformly distributed than when the shock absorbers remain in place. Removing the shock absorbers is not irreversible because they can be super glued back in place.
DBV #1 with T50RP Pads
Above: DBV #1 with T50RP Pads - SPL FR Graph, Waterfall Plot, and Spectrogram
DBV #1 with FA-003 Pads
Above: DBV #1 with FA-003 Pads - SPL FR Graph, Waterfall Plot, and Spectrogram
NOTE: All mod tutorials and pictorials have been moved to the bottom of this post (Post #1) along with tuning rules of thumb, repairing stripped cup threads, and making modified bass ports.
DBV #2 Left with Shure 840 Pads Compared to All Stock T50RP Left.
DBV #2 Left with Shure 840 Pads Compared to All Stock T50RP Left.
DBV #2 Left with Shure 840 Pads compared to All Stock T50RP Left.
DBV #2 Right with Shure 840 Pads compared to All Stock T50RP Right.
DBV #2 Right with Shure 840 Pads compared to All Stock T50RP.
DBV #2 Right with Shure 840 compared to All Stock T50RP Right.
DBV #2 Left with Stock Pads SPL FR
DBV #2 Left Stock Pads Waterfall Plot
DBV #2 Left Stock Pads Spectrogram
DBV #2 Right with Stock Pads SPL FR
DBV #2 Right with Stock Pads Waterfall Plot
DBV #2 Right with Stock Pads Spectrogram
DBV #2 Left with Inner Tube Modded FA-003 Pads SPL FR
DBV #2 Left with Inner Tube Modded FA-003 Pads Waterfall Plot
DBV #2 Left with Inner Tube Modded FA-003 Pads Spectrogram
DBV #2 Right with Inner Tube Modded FA-003 Pads SPL FR
DBV #2 Right with Inner Tube Modded FA-003 Pads Waterfall Plot
DBV #2 Right with Inner Tube Modded FA-003 Pads Spectrogram
DBV #2 Left with Taped on FA-003 Pads SPL FR
DBV #2 Left with Taped on FA-003 Pads Waterfall Plot
DBV #2 Left with Taped on FA-003 Pads Spectrogram
DBV #2 Right with Taped on FA-003 Pads SPL FR
DBV #2 Right with Taped on FA-003 Pads Waterfall
DBV #2 Right with Taped on FA-003 Pads Spectrogram
Triflange and Foam Tip Mounted Mic Comparisons
LCD2 v.1 Left: Triflange Mic compared with Foam Mic
LCD2 v.1 Left: Triflange Mic compared with Foam Mic
LCD2 v.1 Left: Triflange Mic compared with Foam Mic
Audeze's SPL FR Graph of my LCD2 v.1
All Stock T50RP, T40RP, & T20RP Measurements with Triflange and Foam Tip Mounted Mics
Stock T50RP - Triflange and Foam Tip Mounted Measurement Comparisons
T50RP Left: with Triflange Mic compared with Foam Mic
T50RP Left: Triflange Mic compared with Foam MIc
T50RP Left: Triflange Mic compared with Foam Mic
T50RP Right: Triflange Mic compared with Foam Mic
T50RP Right: Triflange Mic compared with Foam Mic
T50RP Right: Triflange Mic compared with Foam Mic
Stock T40RP compared to Stock T20RP with Foam Tip Mounted Mic
T40RP Left compared to T20RP Left using Foam Mic
T40RP Left compared to T20RP Left using Foam Mic
T40RP Left compared to T20RP Left using Foam Mic
T40RP Right compared to T20RP Right using Foam Mic
T40RP Right compared to T20RP Right using Foam Mic
T40RP Right compared to T20RP Right using Foam Mic
Note: All DIY measurements were made with the same methodology and measurement chain using a Triflange Mic unless stated otherwise below each graph.
For Your Consideration
Consider the graphs, select the various components you want to try, and build your mod. Here is where the real work begins --> tweaking, tuning, and testing one component change at a time to improve and "dial in" the sound you want. You can tweak: cotton thickness, fiberglass thickness if used, bass port size vs stock, modified baffle port size vs stock, Grodan Rock Wool thickness if used, pads used, Dynamat or FatMat vs without, additional acoustic foam in the cup and/or on the ear side of the driver, cotton vs fiberglass vs felt of different types and layers over the ear side of the drivers, omitting any of these components, and adding anything else you're interested in trying. You can literally tune for bass, midrange, or treble emphasis or go for neutral which is what I try to achieve. Be aware that changing one component will likely effect others in your design. Based on my experiments, "the total (SQ) is greater than the sum of its parts."
Remember that FR graphs provide only an idea of how a mod may sound relative to another mod configuration. You cannot rely on others' opinions and you cannot know how a mod configuration will sound until you build, tune, and test for yourself. A mod's perceived SQ may be better, or worse, than suggested by its FR graph. This may result from an interaction of variables including your equipment and audio chain, source and file type, your personal SQ preferences, your hearing acuity and psychoacoustic factors such as Placebo Effect, Selective Perception Bias, Expectation Bias (positive and negative), Confirmatory Bias, the ephemeral nature of auditory memory, and Cognitive Dissonance.
You must take anyone's mod and "make it your own."
Tweaking, or tuning, is key.
There are no "slam dunks."
Consider and compare these measurements relative to one another. Do not directly compare these measurements with someone else's measurements.
Submitted FWIW & YMMV.
Some Additional Mod Shots
Modified baffle port using masking tape. Glue around all 4 sides. Use a needle to pierce the center and enlarge to desired size. A smaller baffle port increases bass.
The white and yellow felt is Creatology Stiffened Craft Felt 1.5 mm thick. The black material is a piece of the ear side dust cover that was not glued down properly at the factory. Its "thickness" is ~ 0.2 mm. How much effect can it have on the SQ?
Dynamat (or FatMat) with self-adhesive felt overlay surrounds the driver. Note the notch for the baffle port which you can leave open, completely close, or modify the size.
1.5x37x45 mm stiffened craft felt held in place with double-adhesive tape around the outer perimeter of the driver grid. 22x28 mm Transpore overlays yellow felt for better treble. Try different sizes. DBV #2 uses 45x27 mm Transpore but you may need to use less for your mod. 8 grams of Newplast in the baffle compartments. Acoustipack Lite in L/R floor wells, adhesive felt on top and bottom of the central area, and Paxmate strips 90 degrees across Acoustipack Lite.
Re-flow soldering method makes soldering tiny wires to tiny terminals easy-er. Instructions are provided in the link at the top of this post.
Panasonic WM-61A in an Etymotic foam tip.
NOTE: Etymotic Foam IEM ear tip Increases sub-bass measurements by ~ 2 dB and Decreases treble (9 kHz to 10 kHz) measurements by ~ 5 dB. Adjust graphs accordingly.
Panasonic WM-61A mic in Etymotic Triflange ear tip(micmacmo)
NOTE: Etymotic Triflange ear tip with a surrounding bead of hot glue Decreases sub-bass measurements by ~ 2 dB and Increases treble (9 kHz to 10 kHz) measurements by ~ 5 dB. Adjust graphs accordingly.
Phantom Power Supply: 2 caps, 2 resistors, 2 jacks, 1 9-volt battery snap, a PCB from Radio Shack, and some wire.
Original idea and design by symphonic; Design revision by wdahm519.
Top View of the Phantom Power Supply
Phantom Power Supply circuits mounted in tea tins
Wired mic, Ety foam tips, and extra Panasonic WM-61A microphones
Old driver dampener
New driver dampener
Old and New Driver Dampening Paper
T20RP Clear Mesh over the cup vents lets the light from my work table shine through.
T20RP: No screw compartment cover. Clear mesh dampener over cup vents shows work table light shining through.
Note the blue light shining through and showing unwanted ventilation around the jack, central screw compartment, and at the top where the wire enters the cup.
Johns Manville fiberglass from Lowe's
Aleene's "Fabric Fusion" peel & stick tape holds stretched pads on the cups and works great. It is semi-permanent but will pull loose from the cups, if necessary. It remains on the pad flap and may require another layer before re-installing onto the cups. Do not place this tape over the white thread around the pad flaps. Position the pad against the baffle and roll it over.
It works great as shown, above. The application on the left works best for sealing very stretched pad flaps. The application on the right works well and allows for easier removal should you decide to remove the pads.
Aleene's "Fabric Fusion" protective covering has been removed. Press it firmly onto the pad flap, then use your fingernail or tip of an X-acto knife to get it started and it peels right off.
Stretched-out Shure 840 pads now securely mounted with Aleene's "Fabric Fusion" double sided tape.
Sources for Modding Materials and Current Prices (July 2012)
Grodan Rock Wool Get the slab or the 4x4x3 inch cubes (6-pack) Without holes. ~ $12.00 to $16.00. Also: Dynamat, FatMat, Silverstone Acoustic Foam (Similar to Paxmate Plus).
Fiberglass: Johns Manville (JM) yellow fiberglass at Lowes or Owens-Corning (O-C) pink fiberglass at Home Depot. Each comes in a small roll 2x16x48 inches for ~ $5.00. I used JM Fiberglass, which is more resilient than O-C fiberglass, for all Incremental Mods and Measurements. Also: 3/4" Masking Tape, Super Glue, mini screwdrivers, etc.
Transpore Tape labeled: "3M clear flexible plastic tape" and available at most drug stores. A 3/4" width roll in a dispenser is more convenient for ~ $5.00. A 1" width roll is cheaper for ~ $3.00.
3/4" Masking Tape: Anywhere for ~ $2.00.
Stiff Craft Felt for ~ $1.00 per 8.5x11 inch sheet. Also: Acid-free double sided tape, 3/4" masking tape, plasticine, rubber cement (Acid-free), X-axto knife, Super Glue for repairing stripped cup threads, Hot Glue, Limp Felt, Self-adhesive Felt, etc.
100% Wool Felt: Hobby Lobby for ~ $4.00. Density is Not uniform. May be available at fabric stores.
Paxmate Plus for ~ $17.00.
Newplast Scroll down. ~ $21 for one, 500 gram bar includes shipping to USA. Cheaper per bar if you order 3 bars.
Shure 840 Pads Currently for ~ $15.50 per pair.
Fischer FA-003 pads Ask for Billy for ~ $25.00 per pair.
If you can find it, get Rite Aid "Natural Absorbent Cotton" that comes in a roll for ~ $5.00 which is what I used for all Incremental Mods and Measurements. Alternatives that may work include "Rite Aid First Aid Rolled Cotton" for ~ $5.00, "London Drugs Absorbent Cotton Roll" for ~ CAD $6.95, and "U.S. Cotton Absorbent Cotton Roll" 2-pack for ~ $12.00, each weighing one pound. Cotton makeup remover pads and ordinary cotton balls pulled lengthwise may also work but not as well as rolls of cotton, in my experience.
Available in stores and online November 2012.
Rite Aid "First Aid Rolled Cotton" when properly prepared works similarly compared to "Natural Absorbent Cotton."
Preparing "First Aid Rolled Cotton" for Effective Dampening:
1. Separate the roll of dense cotton into 40 individual layers.
2. Divide into 2 parts of 15 layers, each. 15 layers = approximately 2 cm thick.
3. Cut 15 layers to fit the cups = 2x7x7 cm.
4. Cut 1x7x7 cm fiberglass and place over the top of the cotton.
This is my initial DBV #3 build with "First Aid Rolled Cotton" followed by tuning one or more of the following variables (individually) to achieve the desired frequency response:
* add/remove cotton
* add/remove fiberglass
* tweak the size and number of holes in the stiff felt over the rear driver grids
* tweak the size of the paper treble reflectors
I thought it would be interesting to measure the effects of different pads on FR of an All Stock set of Fostex headphones. This should provide clues about the performance of various pads without making any other mods. I did not have an All Stock T50RP on hand so I used an All Stock T20RP mk2 for some pad rolling experiments. Pads measured included: Fischer FA-003 Pad taped onto the baffle, Fischer FA-003 Pad with 'micmacmo' Inner Tube Flap Mod, Shure Velour Pad, J$ Pad, MrSpeakers Dog Pad, MrSpeakers Alpha Pad, Shure 840 Pad, and Stock Fostex Pad.
I used a recently built and calibrated phantom power supply and mic. The new mic was mounted on an Etymotic Triflange Ear Tip in the same manner as the mic used for "Incremental Mods and Measurements." I placed the mic in my ear at the same depth and angle (as close as possible) as I did for the "Incremental Mods and Measurements." I did not remove or change the position of the mic during measurements. The T20RP mk2 was placed on my head in the same position for each pads' measurement. Clamping force was constant across all measurements.
EDIT: I adjusted the "Check Levels" setting within REW to -15dB for the Left Channel of the All Stock T20RP mk2 with a Stock Fostex Pad. I did not change the volume pot setting of my CEntrance Dacmini for any of the other 7 pads. Each pad has its own "efficiency factor" based upon its materials, dimensions, and construction. The "Notes" section for each graph indicates the SPL for each pad relative to the Stock Fostex Pad baseline of -15 dB. The SPL ranged from -15 dB (loudest) for the Stock Fostex Pad to -20.1 dB (least loudest) for the Shure Velour Pad. I matched the "amplitude" of all graphs referenced to the Stock Fostex Pad by adding the difference between each pads' REW "Check Levels" measurement and the Fostex Pad -15 dB baseline. For example, before generating graphs, I added +1.7 dB to the taped on Fischer FA-003 pad measurement and +5.1 dB to the Shure Velour pad measurement.
Top Row: Fischer FA-003 Pad, Fischer FA-003 Pad with micmacmo inner tube flap mod, Shure Velour Pad, J$ Pad.
Bottom Row: MrSpeakers Dog Pad, MrSpeaker Alpha Pad, Shure 840 Pad, Stock Fostex Pad.
NOTE: As pointed out by micmacmo, the pleather of the Fischer pads (top row, 1st and 2nd pads) is different. The first one is a Fischer FA-003 pad with soft pleather all around and inside the ear hole. The second one may actually be an HM5 pad; its pleather is stiffer all around and inside the ear hole.
Taped on Fishcer FA-003 Pad. All others mounted with the pads' flaps.
Stock Fostex Pad on Stock T20RP mk2
FA-003 Pad taped on Stock T20RP mk2
FA-003 Pad with inner tube flap mod on Stock T20RP mk2
J$ Pad on Stock T20RP mk2
MrSpeakers Alpha Pad on Stock T20RP mk2
MrSpeakers Dog Pad on Stock T20RP mk2
Shure Velour Pad on Stock T20RP mk2
Shure 840 Pad on Stock T20RP mk2
Implementing What I Have Learned: DBV #1, DBV #2, DBV #3, Grodan Rock Wool, and Naked Driver Mod Tutorials and Pictures
Every Mod Is Different - Even When Built By The Same Person
***** DBV #1 - A Variant of BMF V8.1 ***
1. Seal the jack and wire entry points with GE Silicone II. Cover the jack hole with tape to prevent silicone from oozing into the jack.
2. Optional: Remove all four shock absorber posts using a Dremel cutting tool. Cut flush with the bottom of the cup and save the posts in case you want to super glue them back in place to return to stock form. Be careful to not cut the driver wires and headband hanger screw compartment.
3. Construct a 3x1 mm modified bass port centered over the lowest of the four cup vents. Cover all other cup vents and the remainder of the lowest vent, to either side of the modified bass port, with tape applied directly over the stock black cup vent on the inside. Seal the edges of the tape with glue. Alternatively, use masking tape on the outside of the cup vents during the tuning process. This makes it easier to try different sizes of modified bass ports vs fully open vs fully closed cup vents.
4. Install 20x70 mm Acoustipack Lite in the left and right cup floor "wells" trimmed to conform to the curvature of the cups.
5. Install 3x10 mm Paxmate "Logs" over Acoustipack Lite as shown in the picture, above.
6. Install self-adhesive felt on the top and bottom areas of the central column, above the headband hanger screw compartment and below the stock black cup vent felt.
7. Install 10 grams of Newplast or plasticine Flush Mass Loaded in the baffle compartments.
8. Cut a 40x40 mm square of Creatology Stiffened Craft Felt and apply directly over the stock white driver dampener on the back of the drivers. Use strips of tape, double-sided tape, or glue to hold it in place.
9. Cut and apply a Transpore tape square of the desired size centered over the stiffened craft felt.
10. Measure (Uncompressed) and cut a 20x60x70 mm block of Rite Aid Natural Absorbent Cotton (or equivalent) placed and compressed in the cup. Snip the four corners to conform to the curvature of the cups. Snip all four sides to clear the shock absorbers (if not removed) so the cotton will lay flat in the cups.
11. Measure (Compressed) and cut a 10x60x70 mm block of fiberglass with corners and sides similarly snipped and place directly over the cotton. Optional: Add additional pieces of "fluff" around edges.
12. Use an X-acto knife or Dremel to remove the dust cover and its adhesive from around the ear side of the driver down to bare plastic.
13. Cut a ring of Dynamat or FatMat and apply to the bare baffle plastic. Use a triple A battery as a rolling pin to compress the butyl substrate firmly to the baffle. Cut a notch to expose the baffle port.
14. Cut and notch a ring of self-adhesive felt to overlay the Dynamat or FatMat.
15. Shure 840 pads.
16. Tune, measure, and tweak to achieve your desired sound quality.
17. Seal the baffle ports and cup-to-baffle rims with tape (temporary) or GE Silicone II.
***** DBV #2 mod tweaks that are different than DBV #1 *****
1. Transpore over the stiff craft felt covering the back of the drivers measures 45x27 mm (length x width with length oriented in a North-South position ---> see BMF V8.1 pictures) instead of 22x28 mm Transpore used in DBV #1.
2. There are No modified bass ports in DBV #2. The stock black cup vent felt remains in place inside the cups, over the cup vents. The outside of the vents remain uncovered. (DBV #1 uses a modified bass port measuring 3x1 mm as described, above.)
3. The baffle ports are sealed in DBV #2. (Only one baffle port is sealed in DBV #1.) Be aware, however, that your mod may sound better with baffle ports Open so try it both ways.
4. All the other mod components are the same.
DBV #2 used to be my Current favorite mod configuration. Now, I prefer DBV #3...see, below. Sub-bass and bass are deep, musical, and textured. Bass does not bleed into the midrange or mask the treble range. Midrange is clear, lush, and properly placed. Treble extension and clarity are improved over DBV #1. Imaging is very good. These headphones are Fast.
Note: Treble can be significantly extended by placing the Transpore Under the stiff craft felt. If you want even more treble, substitute paper from a glossy magazine cover in place of Transpore. Using a piece of non-porous paper the same size as the Transpore in this mod delivers more treble but may reduce sub-bass quantity. I find that magazine paper ranging from 20x20 mm (or 25x23 mm oriented East-West, size determined based upon the rest of the configuration) centered over the back of the driver's stock white dampener offers the best FR from bottom to top.
Below, are side by side comparisons of modified and stock headphones. I've made 3 sets of DBV #2's. Each one differed slightly from one another for baffle ports opened vs. closed, amount/thickness of cotton and fiberglass, and amount of Transpore tape or size of magazine paper Under stiffened craft felt. Approximately 20 modding cycles, or individual tweaks, were required to achieve these measured results but the first build sounds awesome.
DBV #3 Cotton + Fiberglass Mod Notes
DBV #1 with DBV #2 changes + 20x20 mm glossy magazine paper treble reflector taped over the center driver grid/stock white dampening material And Under the 40x40 mm stiffened craft felt Over the back of the driver = DBV #3. Tweak the amount of cotton, fiberglass, and size of paper under stiff craft felt to get the sound quality you want.
Rules of Thumb: Generally, more cotton/fiberglass, larger paper treble reflector, and baffle ports open = more treble, less bass. Going the other way generally = less treble, more bass. Reducing the size of the cup vents by making a modified bass port (i.e. 3 mm width of one of the four cup vent slots open and the rest sealed = less bass, more treble.
Good news: Rite Aid First Aid Rolled Cotton and London Drugs Absorbent Cotton Roll work almost as well as Rite Aid Natural Absorbent Cotton which is difficult to find. For Rite Aid First Aid Rolled Cotton, cut two 7x7 cm blocks, snip the corners, cut slits for to accomodate the four shock absorber posts, and then tease or pull the compressed layers apart to make it more fluffy. For London Drugs Absorbent Cotton Roll, cut and snip in the same manner; no teasing or pulling required. See below for links.
***** Simplified and Consolidated Tutorial for DBV #3 *****
Note: The stock white driver dampening paper and stock black felt over the inside of the cup vents are your modding "friends." Do not remove them for this mod configuration. Instead, work with them for great sound.
1. Seal the open area around and under the jack in the left cup with GE Silicone II. Cover the jack hole with tape to prevent silicone from oozing into the jack. Make sure it does not ooze around sides of the jack because this could interfere with seating the plug.
2. Install 19x70 mm Acoustipack Lite in the left and right cup floor "wells" trimmed to conform to the curvature of the cups. Use 19x55 mm in the left floor well of the left cup next to the jack.
3. Install 3x15 mm Paxmate (or Silverstone) "Ladder Rungs" over Acoustipack Lite laid at 90 degrees; 3 or 4 above and below the side shock absorber posts.
4. Install self-adhesive felt (from Michael's) on the top and bottom areas of the central column, above the headband hanger screw compartment and below the stock black cup vent felt. Do not cover the stock black cup vent felt with self-adhesive felt.
5. Install 10 grams of Newplast (or non-drying plasticine) Flush Mass Loaded in the baffle compartments. Compressing the plasticine into the rear baffle compartments and flush with the top = 9 to 10 grams per baffle.
6. Use a dime as a template and cut 18 mm disks of shiny magazine cover paper (or thin card stock) and secure one to the back of each driver directly on the center grid of the stock white driver paper. Use 2x10 mm strips of 3M Removable double-sided Scrapbooking tape (from Michael's) applied to two sides of the center grid square. This serves as a treble reflector.
Alternatively, cut a 20 mm square of for each driver instead of disks.
Or, use a 27x52 mm strip of Transpore tape oriented North-South UNDER stiff craft felt with South at the bottom of the driver next to the solder points. Place the Transpore on the underside of the stiff craft felt, not on the stock white driver paper.
7. Cut a 45x52 mm square of Creatology Stiffened Craft Felt and apply directly over the stock white driver dampener on the back of the drivers, covering the treble reflector. To secure the stiff craft felt over the driver, use 6x45 mm strips of 3M Scotch Removable double-sided Scrapbooking tape, cut lengthwise from the roll, and apply to the wider North and South edges of the driver. Apply 3x52 mm strips of double-sided tape to the narrower East and West sides of the driver, overlapping the ends of the N-S strips. Make sure the double sided tape does not cover any of the grid spaces along their edges. See Tuning Tips, below, for "Bass Boost Holes."
8. Separate and cut ~ 20x60x70 mm of J&M Fiberglass (from Lowes). Snip the corners to fit the curvature of the cups. Cut 10 to 15 mm slits aligned with the 4 shock absorber posts so the fiberglass will lay flat in the cup floors. Firmly compress it against your work surface. It should retain the compressed thickness and measure ~ 10 mm thick after compressing. Add or remove fiberglass layers to achieve this thickness. Finished weight ~ 0.7 to 1.0 grams.
Preparing J&M Fiberglass
a. Measure and cut a 7x7 cm block from a roll of J&M fiberglass, 2 inches thick.
b. Divide into thirds.
c. Remove layers until you have equal blocks ~ 2 cm uncompressed.
d. Optional: Weigh each block. 0.9 to 1.2 grams is about right.
e. Remove/add tiny amounts to the blocks until weights/thicknesses are equal.
f. Compress each block, firmly. It should not "decompress."
g. Measure thickness of each, after compressing. You want ~ 1 cm, or slightly less, thickness after compressing.
h. Once you've confirmed equal weights and dimensions, snip the corners and slit the sides like you did with the cotton.
i. Weigh each block and record in your "Modding Registry." 0.7 to 1.0 grams finished weight is about right after snipping the corners to fit the cup curvature.
Alternatively, omit the fiberglass and increase the Uncompressed cotton thickness by 5 to 10 mm OR omit the cotton and increase the fiberglass Compressed thickness by 10 to 20 mm. That said, I think the combination of cotton and fiberglass works best, most of the time.
9. Measure and cut ~ 20x60x70 mm of Rite Aid Natural Absorbent Cotton (or equivalent). Snip the four corners to conform to the curvature of the cups. Cut 10 to 15 mm slits aligned with all four sides to clear the shock absorbers so the cotton will lay flat over the fiberglass.
Note: Rite Aid Natural Absorbent Cotton is no longer available. Rite Aid First Aid Rolled Cotton is an effective substitute IF properly prepared. Here's how:
Preparing Rite Aid "First Aid Rolled Cotton” For The Best Sound Quality
a. Measure and cut a 7 x 15 cm block from the First Aid Rolled Cotton roll. The roll is 15 cm wide so just measure and mark 7 cm Length from the roll and cut with very sharp scissors. It's easier to cut if you first divide the full thickness into two or three parts.
b. Begin by carefully separating a single, VERY thin layer of 7 x 15 cm cotton and it peels right off. This is 1 of 40 layers from a "full thickness" of Rite Aid First Aid Rolled Cotton. Often, 2 or 3 layers come off as one thicker layer. You may think you have one layer, but you don't. Separate each VERY thin layer.
c. Lay the first layer on your work surface and peel off another layer.
d. Lay alternating layers "face up", "face down", "face up", "face down", etc. Also, alternate turning, or flipping, every other single layer, end to end. This makes the stack more uniform. You'll see why/how as you do it. This photo shows 1/2 prepared and 1/2 not yet prepared.
e. Stack 15 layers = approximately 2 cm thick, uncompressed.
f. Trim the edges evenly, all the way around, for a neat 2x7x14 cm block of fluffy cotton. Divide this in half. Use your ruler to measure your "cutting point" by placing your scissors at the middle of one long side. Don't cut yet. Hold your scissors in place and measure each side to make sure you actually have the center point. Now cut straight across. You now have two, 2x7x7 cm blocks almost ready for your initial build. The photo, below, shows one 2x7x7 cm block weighed Before trimming the corners.
g. Snip the corners of each cotton block to fit the curvature of the cups. Cut ~ twice as much from the corner that will be placed next to the jack, as shown in the photo, below.
h. Mark and cut slits aligned with the four shock absorber posts so the coton will lay flat in the cup floor.
i. Optional: Weigh each block using a digital scale that comes with a calibration weight. You can see the model I use and bought from Amazon for $20.00. Add or remove individual layers of cotton from one or the other 2x7x7 cm block of cotton to obtain equal weights. This will help insure L-R Channel Balance. Weigh and record the weight and dimensions of each cotton block = ~ 1.7 grams
Preferred Installation: Place the 2x7x7 cotton blocks in the cup floors. Place the fiberglass over the cotton like "Dmitry's DBV #2 Mod" shown in Graphs #59 - #61, below.
10. Shure 840 pads.
Installing Shure 840 pads: Turn the flaps inside out. Place the pad against the baffle and fold the top of the flap over the cup at the 12 and 1 o’clock positions and hold in place. Fold over the flap on the left side from 12 o'clock to the 7 o’clock position and hold that spot in place. Still holding the 1 o’clock and 7 o’clock positions in place, continue to fold the flap over the right side of the cup, working your way down while holding in place each segment as you progress. Now that you have the flap folded over the cup and holding the 5 o’clock and 7 o’clock positions in place, finish turning the flap over the bottom of the cup.
11. Tune and tweak to achieve your desired sound quality.
***** Simplified and Consolidated Pictorial for DBV #3 *****
Just opened. Be careful with the wires attached to the solder connections. When closing, be sure the wires are not pinched between the cup and baffle rim.
The Good Stuff - Now Extinct - is on the left. The one on the right works great with preparation. See preparation instructions, above.
"Good cotton" separates easily to your desired thickness and is pleasingly "Fluffy." Start with 20x70x70 mm block and snip corners to fit the curvature of the cups. Rite Aid Natural Absorbent Cotton layers are very fine and uniform. Compress it and it pops back up. Other types of cotton I've tried have dense, non-uniform layering. They don't compress and are not as "springy" as Rite Aid Natural Absorbent Cotton. If you find some, buy it because it's hard to come by. Rite Aid First Aid Rolled Cotton works as a very good substitute, if you pull the dense layers apart as describe, above. London Drugs Absorbent Cotton and U.S. Absorbent cotton Roll may also work if similarly prepared. Note: These 3 types of cotton are too dense and matted to use right off the roll.
J&M Fiberglass from Lowes.
19x70 mm Acoustipack Lite, Paxmate Plus, OR Silverstone in the side floor wells except 19x55 mm in the left side of the left cup. Self-adhesive felt on the central floor Above the center compartment and Below the stock black cup vent felt at the bottom.
Newplast has been Flush Mass Loaded into the rear baffle compartments. 19x55 mm Acoustipack Lite (or similar acoustic foam) on the left side of the left cup floor next to the jack.
Left Photo: Double sided tape around perimeter of the driver has had its protective top removed. It will secure 45x52 mm stiff craft felt. Double sided tape strips in the center with protective covering not yet removed will secure the treble reflector.
Right Photo: 18 mm treble reflector is my "default" size for initial builds. 44x52 mm stiff craft felt goes over this treble reflector/back of the driver. Make it larger for more treble. Make it smaller for less treble. Fiberglass over cotton in the cup.
Left Photo: 20x20 mm treble reflector over stock white driver paper. Preferred: Use an 18 mm disk. Try different sizes, if needed.
Right Photo: 3x15 mm Silverstone "ladder rungs" set at 90 degrees over Acoustipack in cup floor wells. Self-adhesive felt above the central screw compartment and Below (Not covering) the stock black cup vent felt.
Acoustipack Lite with 3x15 mm Paxmate Plus “Ladder Rungs” 40x40 mm stiff craft felt (left photo) over stock white driver paper and treble reflector in the left photo. The photo on the right shows a better method using 45x52 mm stiff craft felt over stock white driver paper and treble reflector. Note 3 mm holes in the stiff felt overlaying the center of the 4 corner grids on the back of the driver which serve as "Bass Boost Holes."
Optional: Punch holes in the stiff craft felt over various driver grid spaces for More bass. More/Larger holes = more bass. Note another method of making a treble reflector, shown in the photo on the right. I used a 27 mm (width) strip of Transpore tape 52 mm in length and centered it onto the stiff felt. Holes were punched to increase bass. The stiff felt will be turned with Transpore "face down." Double sided tape holds the stiff felt in place. Try different Transpore widths or "coverage" patterns. The "half-circle" holes around the sides add nothing to the sound quality but are punched so the stiff felt lays flat against the back of the driver.
Left Photo: Fiberglass cut and notched to fit around all 4 shock absorber posts and compressed into cup floors. Cotton ready to go over fiberglass. You can try it with cotton in cup floors and fiberglass over the cotton (Preferred). Use double-sided tape around driver perimeter and under the 45x52 mm stiff craft felt, instead of Transpore tape, for a "cleaner" build.
Right Photo: This is a better method. Cotton (~ 20x60x70 mm; 1.75 g.) trimmed to fit curvature of the cups and notched to fit around the shock absorbers was placed in the cup over Acoustipack Lite and Silverstone "ladder rungs." The fiberglass (~ 10x60x70 mm; ~ 0.7 to 1.0 g.), similarly trimmed and notched will go over the cotton. Stiff felt with holes is secured by double sided tape. There's an 18 mm disk of glossy magazine paper under the stiff felt and centered over the driver grid. Newplast "flush mass loaded" in the baffle compartments.
Cotton over fiberglass, both notched for the 4 shock absorber posts and corners trimmed to fit the curvature of the cups. Holes punched in stiff craft felt for more bass - This is optional and generally not necessary unless you want more bass. Newplast Flush Mass Loaded baffles. There is no need to fill the tiny oval compartments around the driver.
Acoustipack Lite in cup floor wells, 3x10 mm Paxmate "Ladder Rungs" at 90 degrees over Acoustipack LIte, and self-adhesive felt at top and bottom of the cup central floor area. 2.5 mm holes punched over the center of all grid spaces=Even more bass. Newplast in the baffles. Note the empty "square" at the bottom to receive the Jack in the left cup.
Cotton: ~ 2x7x7 cm (Measured Uncompressed)
FG: ~ 1x6x7 cm (Measured Compressed)
Note: These measurements are your starting points. You must tune each cup to achieve the sound quality you like best. You may need a little more or a little less cotton and/or fiberglass in the cups and the amount may differ slightly from one side to the other. Use a calibrated digital scale for easier L-R Channel balancing.
1.7 g Cotton over 0.7 g Fiberglass with slits to accomodate the 4 shock absorber posts. 40x40 mm stiff craft felt with 2.5 mm holes over center of all grid spaces. Note: 45x52 mm stiff felt is preferred.
*****DBV #3 Update: Modding Made (A Little) Easier (March 15, 2013)*****
Recently, I misplaced my last box of Rite Aid "Natural Absorbent Cotton." As described above, Rite Aid "First Aid Rolled Cotton" performs similarly but requires "preparation."
Over 1 year ago, mrspeakers posted a modification to his Rastapants Mod using cotton balls. I tried different brands, sizes, and numbers of cotton balls in whatever mod iteration I was working on at the time (Not DBV #3). Cotton balls did not work with that older mod so I kept looking for materials and happened to get good results with "Natural Absorbent Cotton." Several months ago, Rite Aid discontinued "Natural Absorbent Cotton."
Fast forward...I've been searching for an easier application than the preparation necessary when using "First Aid Rolled Cotton." I came across several boxes of Rite Aid "First Aid" cotton balls and decided to give them a try with DBV #3.
I opened up one of my DBV #3's and removed the prepared cotton and prepared fiberglass. I placed 6 "First Aid" cotton balls, right out of the box and with No preparation in two columns, in the cup floors. I did not use any fiberglass. Everything else remained the same as described in my DBV #3 Pictorial/Tutorial. I closed them up and took a listen. The results? Cotton balls work, And they work really well with DBV #3 mod - with no preparation.
I have not yet tried teasing them apart (a little vs a lot). I have not tried altering the number of cotton balls + fiberglass. It is possible that doing so will further improve their performance. If you try this, please post your results.
6 unprepared cotton balls weigh 1.8 grams which is similar to the weight of "Natural Absorbent Cotton." Prepared "First Aid Rolled Cotton" weighs about the same.
6 Rite Aid "First Aid" cotton balls = Unprepared/un-teased
****** BMF Rock Wool Mod - Improved (May 2013) *****
Do Not remove the stock white driver damping material that covers the back of the drivers. Doing so creates "Naked Drivers" that significantly change the sound quality for the worse. The driver diaphragm excursion becomes too great because it is under-damped. The result is Boomy Bass Bloat that muffles the midrange frequencies and overwhelms the treble frequencies. The "fix" requires a different mod configuration --> "Naked Driver Mod" described at the end of this Post # 1 (with links to photos and graphs).
1. Apply hot glue or GE Silicone II to seal the jack as shown, previously. Do not allow oozing around the sides that could impede the stock cable locking mechanism or block the jack opening.
2. Cut 2x7 cm Paxmate Plus(Silverstone or Acoustipack Lite) acoustic foam, trim the ends to fit the curvature of the cups, notch for the side shock absorber posts, and place in the cup floor wells; 2x5.5 cm goes in the left cup on the jack side. (See photos in "Simplified and Consolidated Pictorial for DBV #3", below) Cut and place acoustic foam above the central compartment and below the stock black cup vent felt. Make sure the black cup vent felt remains in place and uncovered unless you decide to make a modified bass port during the tuning process.
For T40RP mk2: Remove and save the plastic rectangles that cover the inside of the cup vents. Glue a rectangle of felt over the opening.
For T20RP mk2: Glue a rectangle of felt over the stock clear mesh. Place a piece of masking tape over the open central compartment.
Note: 18 months ago, I tested the effects of completely filling the cups (floors and walls) using a single layer vs a "crosshatch" configuration using strips of Paxmate in 3 layers. The results were equivocal. I also tried encircling the ear side of the drivers with Paxmate Plus: 1 layer, 2 layers, and 2 layers on the back half but only 1 layer on the front half with mixed results. I tried the same with the present Grodan Rock Wool mod. I decided to omit Paxmate on the cup walls but use a single layer around the ear side of the driver which seems to improve clarity. Perhaps this reduces ear side reflections off cup walls and your head.
3. Custom cut Paxmate Plus (or Silverstone) pieces and install in the baffle compartments. Alternatively, install Newplast (or plasticine) flush mass loaded in the baffle compartments. Yes, I know. They have different functions. Use what you have or try both to determine which works better for you.
4. Buy Grodan Stone Wool (their new name for Rock Wool) in 3-inch or 4-inch cubes Without the "planting" holes. The "slabs" I bought are not the same density as the cubes. The cubes work much better. They are easier to cut and keep their shape better than the slabs. Use a Sharp Serrated knife, preferably with a cutting guide. I use a bread knife that works great. It cuts cleanly with very little crumbling. Cut a slice of Grodan your desired thickness. Make sure the slice the same thickness, throughout. Cut the slice to your desired dimensions (width x length).
I've tried all the following dimensions: 1.3 x4x4, 1x4x4 cm, 1.3x5x5 cm, 1x5x5 cm, 0.7x4x4 cm, 0.7x5x5 cm, 1x5x7 cm, and 1.3x5x7 cm. Each performs similarly but offers different "flavors" and ratios of Bass:Treble. Smaller/Thinner = More Bass/Less Treble. Larger/Thicker = Less Bass/More Treble. IMO using my "ears and gears," 1x4x4 cm and 1.3x5x7 cm "slices" work best. The best will be determined by each DIY'er during tuning.
5. Cut gauze the necessary width x length needed to "wrap" your Grodan slices. If you use 1x4x4 cm (Default Configuration) or 1x5x5 cm squares, snip off the corners just enough for the corners to fit inside the 4 shock absorber posts. This creates a Diamond shape. Wrap with gauze and use Transpore or Micropore tape as if wrapping a gift for a friend. Snip off the excess gauze at the corners. Turn the "Grodan Diamond" so each of its 4 snipped corners align with a shock absorber and position it in the cup. Gently adjust the snipped corners so they do not cover the shock absorber rubber caps.
If you use 1.3x5x7 cm slices, you need to cut holes for the top and bottom shock absorbers. Use a drinking straw for a cleanly cut hole. Snip the corners to fit the curvature of the cups and to clear the jack. Wrap with gauze and tape. Cut openings in the gauze (on both sides) so the top and bottom shock absorbers can go all the way through the "Grodan Block." Cut a diagonal slit at the top right side of the "Grodan Block" for the driver wire. This will prevent strain on the diaphragm solder pads.
6. Position the baffle/driver over the cup and make sure your driver wires are correctly positioned. Lower the baffle/driver onto the cup and compress with even pressure on the back of the cup and ear side of the baffle. You will feel and hear the rock wool compressing - this is normal. Secure in place with masking tape for quick tuning cycles or use the 4 screws.
7. Make a template and cut a ring of Paxmate for the flat area on the ear side of the baffle. Cut an opening 40x40 mm to match the driver opening with an extra 2 mm width x length. Cut a notch for the ear side baffle port. Rub your finger along the driver perimeter to expose the outline of the driver under the super thin dust cover. Use a silver or white marker and trace the edges of the driver. This makes it easier to position the Paxmate Ring and ensure you do not accidentally cover any of the driver opening.
Alternatively, cut 4 strips of Paxmate ~ 2 cm wide to make a "picture frame" around the ear side of the driver. This is an easier method.
8. You can use any pads you like but this configuration was tuned only for Shure 840 pads. Using other pads may require tuning tweaks to the other components to achieve the sound you like.
9. This mod configuration does not need a modified bass port unless you want Less bass/Tighter bass. See above, near the top of this post, for a description of how to make a temporary and permanent modified bass port.
10. The baffle port remains open in this configuration unless you want More bass and More lower treble. In this case, seal the baffle port with masking tape for a temporary fix. For a permanent fix, use hot glue or silicone. Hot glue is more easily removed if you use only a small amount.
11. This mod configuration does not need Dynamat (or FatMat) with self-adhesive felt overlay around the driver on the ear side of the baffle. This optional component, however, may help reduce vibration-induced distortion. If used, remove the very thin dust cover material from the baffle around the driver and remember to cut a 4x4 mm opening from the Dynamat (or FatMat) to expose the baffle port.
12. There is no need to remove the dust cover directly over the driver because it's Very thin. Measurements showed No improvement in treble response after removing the dust cover over the driver. YMMV. For more treble, damp more and/or add a square of magazine paper over the drivers' center grid space.
13. Tuning: Your "Initial Build" may sound "just right" to you and require no tuning, at all. If you want more or less bass and treble, tweak the thickness, width, and length of Rock Wool. You could also try a 4 mm wide modified bass port, treble reflectors, stiff felt over the back of the driver, or snipping off more at the bottom to expose some/all of the cup vents. Try your build with the baffle port open vs. closed. Try different pads. Make only one tweak at a time to assess its results.
Personally, with my preferences and audio chain, I like the SQ best after adding an 18 mm stiff/thin card stock treble reflector Under a 45x52 mm rectangle of stiffened craft felt secured to the back of the drivers with double sided tape and, if modding T20RP mk2 or T40RP mk2, with a rectangle of stiffened felt over the inside cup vents (first remove the plastic rectangle over the inside of the T40RP mk2 cup vents).
***** BMF Grodan Rock Wool Mod Pictorial (May 2013) *****
1. A 4-inch cube of Grodan Rock Wool Without a planting hole in the center of the opposite side.
2. Serrated bread knife with adjustable width guide.
1x10x10 cm slice of Grodan Rock Wool.
3. A 1x4x4 cm Grodan Rock Wool "Diamond."
Use a drinking straw to "drill" a hole in the center. This optional and adds a bit more bass.
4. Optional center hole "drilled" with a drinking straw and a straw segment 1/2 as long as the Grodan thickness. In this picture, the Grodan "Diamonds" are 1x4x4 cm with corners snipped off to fit inside the 4 shock absorbers. The other one has been wrapped in gauze, taped with Transpore, and excess gauze has been snipped off and ready for installation.
5. Wrapping Grodan Rock Wool with gauze.
6. A 1x4x4 cm Grodan Rock Wool "Diamond" wrapped, taped, snipped, and ready to install.
7. Cup: Paxmate Plus in floor wells and 1x4x4 cm Grodan Rock Wool. Paxmate not yet installed at top center of the cup floor.
Baffle: Paxmate Plus custom fit pieces fill the baffle compartments. Optional: Use Newplast, instead. Stock white driver damping material in place.
8. Cup: Grodan "Diamond" has more snipped off at the bottom to expose 2 of 4 cup vents to increase bass.
Note that for this T20RP mk2, there is a single layer of craft felt over the stock clear mesh that covers the internal cup vents. This is optional = a little more damping for a bit more bass control
Baffle: Paxmate Plus instead of Newplast.
9. Ear side of Baffle: Paxmate around driver with 4x4 cm opening. Note the white marker outline of the driver edges. Masking tape secures baffle to cup for quick turn-around during tuning.
*** Tuning Rules of Thumb ***
This configuration may sound "just right" to you and require no tuning at all. If you decide to tune, make only one tuning tweak at a time to assess its effect on the sound quality. Understand that very small changes in mod components can result in significant changes in sound quality - for better or worse.
a. If you want more or less bass and treble, tweak the amount and size of Fiberglass, Cotton, and Treble Reflectors. Generally: More/Larger/Thicker = more treble, less bass. Less/Smaller/Thinner = more bass, less treble.
b. Try your build with the baffle port open vs. closed. Open = less bass. Closed = more upper bass and a bit more lower treble. Making a modified baffle port (ear side of baffle) with masking tape and needle may assist with fine-tuning.
c. Punch 2.5 mm holes in the stiff craft felt using a hole punch similar to the ones sold at Michael's. More/Larger holes = more bass.
d. If bass is too boomy and bloats the midrange, you can fine tune it by making a modified bass port as described, above, in the DBV #1 Tutorial. Covering more of the cup vents/decreasing the size of the modified bass port reduces bass quantity and should improve bass quality and speed.
e. If treble is too "hot," add some cotton or fiberglass over the ear side of the driver, under the Shure 840 pads, to tone it down.
f. Adding cotton, foam, or other materials under the pad cushions may increase sound stage and/or angle the pads but at the expense of bass quantity.
Here are some additional tuning tweaks that work for me:
g. Thicker stiff felt (or two layers/partial layers) = Less Bass, More Treble. Thinner felt = opposite effect.
h. Smaller Treble Reflectors = Less Treble. Larger = opposite effect. My default size for DBV #3 is 18 mm disks installed over the center of the driver (covering the center grid).
i. Greater cotton thickness = Less Bass, More Treble. Thinner thickness = opposite effect.
j. Fiberglass = Less Bass, More Treble. No Fiberglass = opposite effect.
k. Stock cup vents = More Bass. Cover some or all with tape = Less Bass.
l. Stock baffle port open = Less Bass. Closed with tape on ear side of baffle = More Bass and lower treble.
m. Buy some 3/4" masking tape. Cut 4 segments to go all the way around the cup/baffle rim. Use masking tape to seal baffles to rims during tuning. This prevents stripping the cup threads. Put the small screws in a medicine bottle for safekeeping. Here's how to apply the tape for best tuning: Position the baffle onto the cup. Adjust so it fits properly. Compress the back of the cup and the ear side of the baffle with one hand while you start taping. Put the tape aligned with the edge of the cup. Fold the tape over onto the ear side of the baffle (the rounded area). Repeat with tape slightly over-lapping as you work your way around. Done. Use fresh tape for each tuning tweak. You can expect a little more bass once you seal the baffles to the cups with the 4 screws.
n. Buy some GE Silicone II. Apply a bead around the cup/baffle rim.
o. Buy some Aleene's Fabric Fusion double-sided tape. Use it as described in Incremental Mods and Measurements. This semi-permanent and will give you a good seal and prevent the Shure 840 pads from slipping off. Use this Only after you are satisfied with your tuning.
p. DBV #3 is tuned specifically for Shure 840 pads. You can use other pads but all bets are off with regard to sound quality. You can stuff cotton or tissue under the pads but at the expense of bass: see Incremental Mods and Measurements.
q. Fine Tune and reduce Bass Quantity with a Modified Bass Port at the cup vents = 3 mm opening of just one of the four cup vent slots and covering the other three completely with electrical tape over the inside stock cup vent dampening material. This is described in Incremental Mods and Measurements.
r. Increase Bass by reducing the internal dampening materials.
s. Increase Bass by punching holes in the stiff felt overlaying some of driver grids. My default for DBV #3 is “No holes” for flater FR and 3mm holes in the stiff felt overlaying the 4 corner grids for slight “bass boost.” Try holes of different sizes for more or less bass.
*** Repairing Stripped Cup Threads ***
There is a solution for repairing your cup threads. You need a 2 mm (1/16) drill bit and liquid super glue; super glue gel will not work.
4 x 1.5 mm Modified Bass Port over inside cup vent felt.
External view of 4 x 1.5 mm Modified Bass Port. The Stock black cup vent felt has been removed from the vents. Once installed, the Modified Bass Port will not show because it will be installed behind (over) the cup vent felt on the inside.
"Naked Driver" Mod
"Naked Drivers" have had their stock white damping material removed from the back of the drivers. Naked Drivers are too under-damped so bass is excessive, out of control, and so bloated it messes up the mids and covers up the treble frequencies. I posted the "Naked Driver" config, with graphs, that worked best for me in Post # 244 of this thread. I had to use two layers of stiffened craft felt without any holes to make the drivers behave. This mod configuration measures and performs very close to DBV #3. Here's the configuration:
Initial Build Steps:
1. 2 layers of Michael's Craft Store stiffened craft felt, each measuring 45x52x1.5mm, notched for clearance of all 8 driver mounting screw heads, stacked, and secured with 3M Removable double-sided craft felt.
2. 20x25 rectangular thin card stock treble reflector centered over the back of the driver and secured under the stiffened craft felt with thin strips of 3M double-sided tape.
3. 1x7x7.5 cm compressed J&M fiberglass = 1.3 grams.
4. 1.5x7x7.5 cm Rite Aid Natural Absorbent Cotton = 1.4 grams, under the fiberglass. As a substitute, use "Prepared" layers of Rite Aid First Aid Rolled Cotton 2x7x7.5 cm = 1.8 grams OR 4 to 6 Rite Aid First Aid cotton balls as described near the bottom in Post #1 of this thread.
5. Acoustipack Lite (or Paxmate or Silverstone) 2x7 cm trimmed to fit the side cup floor "wells."
6. Newplast (or non-drying plasticine) flush loaded baffle compartments = 9 grams of Newplast.
7. Stock cup vent felt intact.
8. Stock Open baffle ports.
9. Shure 840 pads.
"There are many paths leading to the same destination."
DIY Measurement Acknowledgements
All the credit goes to 'symphonic' and Room Equalization Wizard (REW) for bringing DIY measurements to the masses.
Developments, innovations, and contributions have been made over the course of the past 8 months by micmacmo, Arleus, wdahm519, Ardilla, Cortlendt, geetarman, nick n, and wje - all active on the T50RP modding thread.
Edited by bluemonkeyflyer - 5/15/13 at 8:50am