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post #4156 of 10678

As good as these sound (modded), they do seem a bit unbalanced, left always feels stronger in presence. It could well be from unbalanced modding, reducing the amount of cotton stuffing under the left ear pad did seem to even them out a little.

 

Anybody experienced unbalanced L/R?

 

I think a recable is in order, might have to buy a second pair and do a full blown ultimate one time mod.


Edited by HDMan - 10/22/11 at 1:13am
post #4157 of 10678
Quote:
Originally Posted by HDMan View Post

As good as these sound (modded), they do seem a bit unbalanced, left always feels stronger in presence. It could well be from unbalanced modding, reducing the amount of cotton stuffing under the left ear pad did seem to even them out a little.

 

Anybody experienced unbalanced L/R?

 

I think a recable is in order, might have to buy a second pair and do a full blown ultimate one time mod.


Yup...but it's not the cable.

 

post #4158 of 10678
Care to enlighten us what it could be then LFF
post #4159 of 10678
Quote:
Originally Posted by leeperry View Post

I've been lent a vanilla NFB-12(w/o the oversampling jumpers) by our local A-GD importer, it was really nothing to write home to Mummy about...it prolly needed a few weeks of burn-in, though ^^


I am not a fan of Audio GD.  I too have heard the DACPort sound as good as $800 worth of their gear.

 

post #4160 of 10678

Quote:
Originally Posted by HDMan View Post

Anybody experienced unbalanced L/R?

 

 

I have. It was due, in part, to product variability. Plasticine in this case.

 

I'd mass loaded one driver with blue plasticine and the other with white. Because I used the same volume of material in both sides (just flush to the top of the cavities in the baffles), I thought I was doing it right. So when I noticed a slight imbalance, I thought it was due to poor driver matching or what looked like a colder solder joint on one of the drivers. Then I Super Mass Loaded the baffle (a trademarked BMF mod :) ) and made the plasticine colours symmetrical, mirroring the same pattern on both baffles. The problem largely disappeared. So now I'm thinking that the white plasticine was damping differently than the blue. 

 

There's still some differences between the channels, though. When I switch the left and right cables between my amp and DAC, Art Blakey's opening drum work on A Night in Tunisia, for example, sounds splashier when directed to the right channel and slightly recessed coming from the left. But it's a difference in sound quality/texture, not so much volume. 

post #4161 of 10678

My first pair became unbalanced while modifying it, because without noticing it, there was a little plasticine touching the back of the 1/4" female jack connector. I keep that pair hoping that a spare female jack connector will solve the problem, because cleaning the plasticine and applying deoxit wasn't enough.

 

With that experience, I was more careful with my second pair and it's 100% balanced.

post #4162 of 10678

I believe all your questions have been answered before.  Look back in the thread or perhaps someone who remembers the answers can let you know.

post #4163 of 10678

BMF #6 v1 and v2 photos and comparisons:

 

Fostex BMF5,6v1,6v2.jpg

 

Before standardizing mods - From L --> R: 

 

BMF #4 with Transpore:  Replace the stock white driver felt with 2 layers of 3M Clear Flexible Tape (Transpore), 1 layer of Paxmate Plus in the cups, baffles Super Mass Loaded with plasticine, the rest is stock.

 

BMF #6 v1:  Dynamat Xtreme in the cups on each side of the central section containing the main screw chamber, 1 layer of Paxmate Plus in the cups, baffles Super Mass Loaded with plasticine, 1 layer of Dynamat surrounding the drivers on the ear side of the baffle, 2 layers of aluminum tape over the ear side Dynamat, cotton gauze under ear pads for tuning bass/treble ratio, the rest is stock.

 

BMF #6 v2:  Identical to #6 v1 except 1 layer of AcoustiPack Lite in the cups and a second layer of Dynamat Xtreme surrounding the drivers on the ear side.

 

 

Fostex BMF 3M Transpore x 2 layers.jpg

 

BMF #4:  2 layers of 3M Transpore tape in place of the stock white driver felt, Super Mass Loaded, and 1 layer of Paxmate Plus in the cups. The piece of Paxmate on top of the central screw compartment has not yet been removed.  The rest is stock. 2 layers of 3M Transpore sounds very similar to the stock white driver felt.  To me, this combination of mods is easy and provides very good results. I experimented with 3 sets of mods after removing the stock driver felt. For me, removing the driver felt offers no benefits and takes extra time to get the sound just right.  This set of mods with the white driver felt intact (and no 3M Transpore tape, of course) offers the best bang for the buck.

 

To be extra clear, there are many other mod set-ups that others have made and love. You will not know which is right for you unless you try them and decided for yourself.

 

 

 

Fostex BMF #6 v1.jpg

 

BMF #6 v1: 1 strip of Dynamat Xtreme in the cups on both sides of the central section, 1 layer of Dynamat Xtreme surrounding the drivers on the ear side of the baffles, adhesive-backed craft felt over the ear side Dynamat, 1 layer of  Paxmate Plus in the cups, Super Mass Loaded with plasticine, stock white driver felt (re-applied after a previous mod with stiff felt over the drivers), stock black bass port felt in place, central screw compartment is not covered with Paxmate, stock ear pads, cotton gauze rope under back half of each ear pad for lifting and tuning, stock cable.

 

 

 

Fostex BMF #6 v2 SML.jpg

 

BMF #6 v2:  1 strip of Dynamat Xtreme in the cups on both sides of the central section, 1 layer of AcoustiPack Lite in the cups over the Dynamat (instead of Paxmate Plus), central screw compartment is not covered with AcoustiPack, 2 layers of Dynamat Xtreme surrounding the drivers, adhesive-backed black craft felt over the ear side Dynamat, super mass loading with plasticine, stock white driver felt intact, stock black bass port felt intact, stock cable, stock ear pads, and cotton gauze rope under the back half of the ear pads for lifting and tuning. If I were doing it all over and making only one set, I would not put Dynamat in the cups and use only 1 layer of Dynamat surrounding the drivers for less weight. I would use acoustic foam that is available: Paxmate Plus, AcoustiPack Lite, or Silverstone.

Quote:
Originally Posted by bluemonkeyflyer View Post

BMF 6 v2:

 

I received my shipment of AcoustiPack Lite (thanks AnotherNoob for the link) and wanted to compare it with Paxmate Plus.  

 

EDIT: The photos, below, are of BMF #5. BMF #6 is described in post 3952 at the following link: http://www.head-fi.org/t/452404/just-listened-to-some-fostex-t50rps-today-wow/3945   BMF #6 has 1 layer of Dynamat Xtreme on the ear side of the baffles but it is the same as BMF #5, internally.

 

     CAUTION: Be very careful when removing reflex dots from the white driver felt (or paper). Furniture bumpers from the same package vary in their adhesive strength. I made a small tear in the white driver felt when removing one of the bumpers despite being careful and using my X-acto knife to slowly lift the edges and prise it off.  Luckily, it was no bigger than the end of a ball point pen and located over one of the grid lines instead of one of the openings.  I was able to use a bit of glue to make the repair.

 

Procedures for  BMF 6 v2:

 

 1.  Place Dynamat Xtreme on both sides of the central section inside the cups. Make sure the Dynamat is pressed down firmly and fully attached to the plastic cups.

 

 2.  Apply AcoustiPack Lite over cup Dynamat, cup walls, and the 1" square at the top, opposite the bass ports. Make sure it's pressed down firmly and fully attached to the Dynamat and plastic cups. Leave the central screw compartment uncovered. If you have too much treble, you can later tune it down by covering the central screw compartment with AcoustiPack Lite;. You may be able to "dial in" the treble by covering some or all the central screw compartment.

 

 3.  Leave the  white driver felt in place.

 

 4.  Leave the black bass port felt in place and otherwise uncovered for your first test. You can later tune the bass by covering some or all of the bass port vents to suit your preferences. I like them uncovered except for the stock black felt over the bass vents, inside the cups.

 

 5.  Leave the dust cover over the drivers in place. I previously chiseled off the dust cover surrounding the ear side of the drivers. Some have found removing the dust cover from the ear side of the drivers increases treble and detail.  I did not.

 

 6.  Leave the baffle equalization vents open.

 

 7.  Super mass load the back side of the baffles with plasticine. Do not fill the main baffle equalization vent and the other three semi-open baffle vents with plasticine. 

 

8. Apply 2 layers of Dynamat Xtreme surrounding the drivers on the ear side of the baffles. 

 

9. Apply two layers of aluminum duct tape over the second layer of Dynamat.  Note: Here's a handy method for applying this tape - cut to length, position across adjoining sections of Dynamat, and slice away the tape with an X-acto knife by following the curvature of the Dynamat.

 

10. With ear pad removed, make a stencil of the baffle by positioning a clear sheet of overhead projector acetate over the ear side of the baffle. Looking through the acetate, outline the inner oval and the driver square using a magic marker pen. Cut it out and use the acetate stencil to make a stencil of stiff cardboard stock.  Use the cardboard stencil to mark the back and cut out the adhesive-backed black felt, then apply over the Dynamat. Notch an opening for the baffle equalization vents.

 

11. Make cotton gauze "ropes" and place one under the back half of each ear pad. It's a good idea to first tape the back half of each ear pad to the cup to prevent the ear pad from coming off. This is a temporary measure while testing. A semi-permanent solution is to use double-sided tape under the ear pads. SQ can be tuned by varying the length and diameter of the gauze ropes.

 

EDIT: As others have reported, simply lifting the back half of the ear pads may improve SQ and soundstage.  You may be able to reap benefits by tuning the ear pads with gauze, cotton balls, or fiberfill; changing the amount and size of "rope lifters", going only half way around, or differentially lift all the way around the ear pads. 

 

12. Test and tune to suit yourself.

 

 

Comparison Phones - Identical to BMF 6 v2 except for the following:

 

1. One layer of Dynamat surrounding the drivers.

2. Paxmate Plus instead of AcoustiPack Lite.

 

Results:

 

Careful A/B comparisons were made with SPL matching, lossless files, MacBook Pro, and glass toslink to Dacmini DAC and amp. I really like BMF 6 v1 but BMF 6 v2 has a bit more detail, better vocal clarity, more treble sparkle with air and without harshness, and cleaner bass.  These comparisons are not as specific as my previous comparisons because there are at least 2 variables involved instead of 1.  The noticeable SQ differences of BMF 6 v2 may be due to AcoustiPack Lite, a second layer of Dynamat surrounding the drivers on the ear side of the baffles, an unknown/uncontrolled "Factor X", or the synergy of 2 or all 3. I suspect that the main factor, however, is the different acoustic foams used --> Paxmate Plus vs AcoustiPack Lite. 

 

Edit:  After more extended listening comparisons, I would not say #6 v2 is necessarily better than #6 v1. Instead, v1 and v2 offer different "flavors."  #6 v2 sounds crisper while #6 v1 sounds warmer. These differences are slight but noticeable. v2 is heavier than v1. "Pad lifting" is the easiest reversible mod to make. Changing the amount and the placement of padding under the ear pads makes a remarkable difference in bass quantity/quality and treble sparkle. 

 

 

Note: AcoustiPack Lite and Paxmate Plus are each 4 mm thick and about the same in terms of ease of application.  The difference is that AcoustiPack is heavier due to the constrained layer and purportedly has better sound absorption. Perhaps it soaks up more reflections, reduces standing waves, and further limits the amount of dirty waves sent back through the drivers to your ears?

 

I have some different materials on the way for more experiments. I'll post the results whether favorable or not.

 

 

 

 

 

 

 

 

 



 


Edited by bluemonkeyflyer - 10/22/11 at 12:19pm
post #4164 of 10678

Originally Posted by bluemonkeyflyer View Post

 

Fostex BMF5,6v1,6v2.jpg

 

Oooh, AcoustiPack looks sexy...me want! Don't you think you went a bit over the top w/ the clay? it seems to go as high as the top of the driver? Doesn't that restrict the air flow within the cups too much? And you don't like the idea of not leaving a single piece of black plastic visible within the cups and adding clay in all the surrounding parts of the cups/baffles that are in contact w/ each other?


Originally Posted by Anaxilus View Post

 

I am not a fan of Audio GD.  I too have heard the DACPort sound as good as $800 worth of their gear.


Well, the NFB-12 is uber cheap...but no opamps, so if you get bored of its THD'ness you're SOL. The DACPort runs an AK4396 off a Class A biased OPA1612, not my fav. sounding chip either. Ah well, I'm a major nitpicker when it comes to sources anyway [:xxantoinexx]

post #4165 of 10678

Originally Posted by kkl10 View Post

I still would like to get some answers to the three main questions


If you wanna talk to the godfather of damping clays, try this forum: http://audioqualia.freeforums.org/index.php

 

the owner made some very light 0.8 damping factor homebrew putty, but it's not available for sale yet and at this stage he doesn't seem to be able to send samples either: http://audioqualia.freeforums.org/post71.html#p71

 

anyway, newplast reaches 0.635 and is dead cheap: http://qualia.webs.com/newdampingfactors.htm

 

tungsten is 0.725, spendy and very heavy, blutack 0.166 and plasticine 0.304...so major bang for bucks here.


Edited by leeperry - 10/22/11 at 4:09pm
post #4166 of 10678
Quote:
Originally Posted by Anaxilus View Post

I am not a fan of Audio GD.  I too have heard the DACPort sound as good as $800 worth of their gear.

 



Amp only, not any of the DAC's.

post #4167 of 10678

^I sold my AudioGD C2C because I want a more tube like sound :P --- and a smaller footprint amp.

post #4168 of 10678

higher damping factor the better right? has anyone tried newplast instead of plasticine?
 

Quote:
Originally Posted by leeperry View Post

If you wanna talk to the godfather of damping clays, try this forum: http://audioqualia.freeforums.org/index.php

 

the owner made some very light 0.8 damping factor homebrew putty, but it's not available for sale yet and at this stage he doesn't seem to be able to send samples either: http://audioqualia.freeforums.org/post71.html#p71

 

anyway, newplast reaches 0.635 and is dead cheap: http://qualia.webs.com/newdampingfactors.htm

 

tungsten is 0.725, spendy and very heavy, blutack 0.166 and plasticine 0.304...so major bang for bucks here.


 

 

post #4169 of 10678

Good call.

 

I mentioned the weight issue.  It's a heavy issue. With all the plasticine, foam, and Dynamat these are too heavy to be comfortable for more than 15 minutes. So, I took #6 v2 apart, removed the Dynamat in the cups, the side pieces of AcoustiPack Lite, and about 1/2 of the plasticine...yes, you can have too much of a good thing.  I left plasticine in place from the edge of the driver perimeter sloped down to the baffle rim.  Re-installed AcoustiPack Lite to the bottom of the cups and over the 1" square in the central section opposite the intact bass port felt. Comparing in retrospect, the bass was not quite right probably due to some congestion from over-damping. The SQ is improved and the weight is no longer a  big problem.  Tomorrow I will remove 1 of the 2 layers of Dynamat around the drivers on the ear side which will further lighten them.  

 

There have been several mods I really like and some not at all.  Many are not better than the others, just different from one another. Still having fun with this.
 

Quote:
Originally Posted by leeperry View Post

 

 Don't you think you went a bit over the top w/ the clay? it seems to go as high as the top of the driver? Doesn't that restrict the air flow within the cups too much? And you don't like the idea of not leaving a single piece of black plastic visible within the cups and adding clay in all the surrounding parts of the cups/baffles that are in contact w/ each other?

 

 

 

post #4170 of 10678
Quote:
Originally Posted by firgoe View Post

higher damping factor the better right? has anyone tried newplast instead of plasticine? 

 

 


It's actually possible to overdamp...

 

(for simplicity sake we will just consider vibations due to a single impulse)

 

Underdamping means it will oscillate, with the amplitude shrinking over time and eventually settling to zero. Critically damped means it does not oscillate and reaches zero relatively quickly. Overdamped also means it does not oscillate, but takes longer to reach zero.

 

Sometimes in audio, underdamping may be desired. This is because while there is still oscillation, the initial return to zero is faster than the critically damped config, and the size of the subsequent oscillations may be insignificant.

 

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