[unispeed]

I added some stuff to the post before this one about sympathetic vibrations and how they MIGHT be affecting the frequency drops measured by @csglinux in his graph. Sympathetic vibrations are a guitar builders biggest fear, and usually, the better the wood, the more prevalent they are. The way you combat them is either use a softer material or have more mass (thick guitar necks).

Using a filter in a metal tube might be causing some higher frequencies to lose energy by vibrating the tube itself instead of the eardrum, effectively canceling each other out.

I guess these pictures kinda explain why I like my mids intact, lol. Guitars need to growl and sound thick, not be some instrument in the background due to a highly scooped FR curve! The midrange is where all your ambiance is. Sometimes people tend to concentrate on the high sparkly details but forget that a lot of the songs feeling is lost by a steep V or U sound signature. lol I know this is a headphones thread but here are a couple of shameless pictures of my baby... I cant speak of building guitars (okay, I only built 2.. and that was enough!) without posting a couple of pictures:

 

[unispeed]

@csglinux lol, you must be getting sick of me tagging you in posts but I found some evidence that might help answer why your frequency response shifted to the left when you were trying Knowles filters.

Here is a table from Sonion showing the effect of nozzle diameter on the high frequencies. The orange line represents a 2.5mm inside diameter nozle... its has a resonant peak in the neighborhood of 8,000 Hz. The purple line represents a 1.6mm inside diameter nozzle (basically the stock filter..stock is 1.78mm). .. it has a resonant peak in the neighborhood of 10,000 Hz.

Earlier I was assuming that this might be due to cancellation of frequencies but with this new evidence I have to reconsider some of my assumptions. At this point I would say that too large of a tubing diameter is the biggest culprit for that 8000 Hz shift in the frequency response and perhaps, tubing material also plays a role.

This reopens the possibility of using Knowles filters in the SE846 without messing up the frequency response we have all come to expect from these IEMs. Stock inside diameter however must be respected if one does not want shifts in the resonant peaks. It would seems that Shure had a very clear reason for choosing 1.78mm as the diameter of the plastic tube. Its a bit of a sweet spot.

To truly improve upon something one must understand why it was designed that way and what components should not be altered. My conclusion is that the stock Shure filter tube cannot be removed. Any improvements that are to be had will be had altering the inner components of that insert. Removal of that tube altogether will almost certainly be a downgrade.

 

[unispeed]

A short but extremely informative read on tuning balanced armatures. Interestingly, they also make filters and instead of having metal housings they use plastic. I thought Sonion was a European company but their balanced armatures are made in China. The electronics coming out of China keep getting better and better for sure!

https://www.sonion.com/wp-content/uploads/Documentation_Designing_Earphones-1.pdf

 

[csglinux]

Very interesting stuff @unispeed (BTW, nice guitar-making skills buddy!)

That Sonion brochure shows how switching out their dampers (all of them being left in the same position) does nothing but dissipate acoustic energy. I presume it all ends up as heat through frictional losses in the damper material. The interesting aspect of the trishd mod and the variants that you've been trying is that keeping the same filter (or foam) but shifting it up and down the tube primarily seems to redistribute the energy, i.e., you have a fixed amount of acoustic energy supplied by the driver(s), and the FR curve is playing whack-a-mole with us - i.e., you push it down in one place and it pops up somewhere else. That makes for all sorts of fun and games with modding

Looking forward to hearing the results of your damper experiments and whether those smaller sized dampers will fit in the filter tube without some kind of major surgery.

 

[unispeed]

Very interesting stuff @unispeed (BTW, nice guitar-making skills buddy!)

That Sonion brochure shows how switching out their dampers (all of them being left in the same position) does nothing but dissipate acoustic energy. I presume it all ends up as heat through frictional losses in the damper material. The interesting aspect of the trishd mod and the variants that you've been trying is that keeping the same filter (or foam) but shifting it up and down the tube primarily seems to redistribute the energy, i.e., you have a fixed amount of acoustic energy supplied by the driver(s), and the FR curve is playing whack-a-mole with us - i.e., you push it down in one place and it pops up somewhere else. That makes for all sorts of fun and games with modding

Looking forward to hearing the results of your damper experiments and whether those smaller sized dampers will fit in the filter tube without some kind of major surgery.

Thanks, Guitars and Tube amps were an extremely time consuming hobby of mine a few years back, lol.

The Sonion approach is also to place the filter as far away from the BA as possible without running the risk of earwax clogging it, so as to be able to user a more freeflowing filter. This is a much different approach from Knowles who in their documentation encourages a tuning of the filter position. They also use anything above 1500 of resistance as Low Pass filters but my guess is that this approach only works in a custom IEM where each BA has its own tube all the way to the end. One interesting note on the coupler they use to obtain their measurements. They have a disclaimer right in that pdf stating that measurements above 8000Hz suffer from decreased accuracy. I would suspect that a company like Sonion has access to some of the very best measuring equipment so if they are disclaiming the accuracy of their equipment above a certain frequency, it makes me wonder about the accuracy of consumer level equipment above that frequency. Then again, I know very little about sonic measuring equipment, it was just a passing thought when I saw their disclaimer.

 

[csglinux]

I would slightly reword the part about 711 couplers not being "accurate" above 8 kHz. The issue is that the transfer impedance is a function of insertion depth and relative distance from driver to eardrum (or mic). This is a separate issue from that of driver resonances, but it's still an integral part of what you hear.

There are "hi-res" couplers that define their own closer tolerances on the transfer impedance beyond 10 kHz (some sample measurements here: https://www.head-fi.org/threads/ety...and-your-couplers.908512/page-6#post-15122517), but this is just another ear canal model that arguably isn't any more "accurate". It may have other benefits for designers, but no coupler can guarantee to match what any individual would hear. The problem isn't really the coupler, it's human variance. We are really the source of what's inaccurate above 8 kHz

 

[unispeed]

"GREEN FILTER" (Originally created by @Quadfather)

&​

"THICK GREEN" (My design and current preference)

Even if you've tried Knowles filters in the past, they sound very different configured this way!

• @Quadfather a couple years ago very quietly created the green filter by disassembling a 2mm Knowles green and using the cloth inside to replace the stock filter element in the Shure inserts. In so doing he not only fixed the weak bass response that came from using Knowles filters in the traditional way but also unknowingly fixed a left-ward shift in resonant peaks that has kept many (including me) from trying them in the first place.

• I stumbled upon the green filter using a slightly different approach... While everyone was ordering the 2mm green filters, I decided to go with the smaller size hoping it would be a direct fitment for the stock Shure tubes ... and it basically was...and then I found out that the 1.78mm filters were the same as the 2mm, they were just missing the metal barrell.. . And there may be a size that even better fits the stock Shure inserts (scroll down to post 206 for more details on that). The end result was the same though an excellent filter that only a handful of people have experienced.

Here is the extremely high tech tool I had to manufacture to install them (not really, just a tooth pick... I just chopped off the points in different spots...2 tools in one). I used one side for slightly enlarging the entrance to the filter and the other side for putting the filter in. Finally I went back to the other side (larger side) to slide the filter in until it hits the plastic ridge. The back side of a 1/16" bit should work also. These filters are ever so slightly bigger than the tube but easily slide in and the friction keeps them in place... and for those who are wondering, yes they seal and yes they stay put, just like the stock ones.

A few observations so far:

1. When you first put them in they tend to want to spring back out...just be patient, and keep gently pushing them in. That springiness that's working against you on installation will be working for you when they are in place.
2. Turn off any ceiling fans if you have them in the room...just do it.
3. Also shown in the image is the original filter insert. This one came out of a white filter and is somewhat brown in color.

30 MIN LATER UPDATE: I like what I hear!

Now I just gotta hope @csglinux recreates it so I can see one of those pretty FR graphs he posts. hahaha (eartips are comply P series, the long ones).

2 HOURS LATER UPDATE: I'm pretty sure at this point that they are superior to my last mod "Unispeed Mod for White Filters". They are just very clear. Bass is very present and clear even at low volumes, in fact I find I am listening to tracks at a slightly lower volume due to the clarity in the bass. Highs are very clear, maybe slightly too clear.

24 HOURS LATER UPDATE I prefer it a hair warmer but am afraid that the red filter might be too warm... so on to part 2 of this mod...


Second part of the mod "THICK GREEN".
Drum kicks will make you . Highs are still all there but slightly more natural. This is definitely a more "fun" and "growly" sound signature (energetic music, hard rock, metal, hip-hop). The standalone green is more "analytical" and "surgical" (nylon string guitar, ochrestra, classical piano, string quartets).

1. Steal a foam piece from a BLUE filter
2. With a razor blade, cut that foam piece in half (The length and the diameter should be about the same)
3. Place it at the depth indicated by the bolt and nut tool (I wonder what this would cost if it had a Shure part number...if a plastic tube is worth $20, a metal bolt and 2 nuts gotta be worth at least $30 ) Set depth with everything installed. Notice that depth is about where the hosebarb ridge is. Deeper for more treble.

 

[EastOne]

This looks really interesting! I tried the mod you suggested 30th May and thoroughly enjoyed it, though I ended up coming back to my Green Knowles filter because I felt it had slightly brighter a sound and perhaps a tiny bit more bass - when using the Jackomik needle mod, bass tends to roll off slightly and a slight brightness coupled with the venting adds a really immersive aspect, which pushed me back.

Interestingly from your photos, the green filters you bought are simply the filter cloth from inside the larger diameter Knowles dampers we've been using here, there's a post where someone removed theirs and pushed in the Knowles inners for a similar effect, though I didn't see any reason to do this over just using the knowles dampers and a clear inner tube, I think I'm going to revisit this and mod my stock tubes to your Green Filters, I anticipate the sound I've been searching for between the green Knowles stock and the modded black tube you suggested on the 30th is probably what you've proposed in the above post.

I'm very eager to get home tonight and test it!


I've added a few photos of the Jackomik mod I've used here, I bought some silicon hose from amazon with internal diameter 3mm and outer diameter of 5mm, added a small drop of epoxy (Araldite clear, though superglue would work too, I prefer the epoxy) and then the needle tube, of measurements 0.3mm ID and 0.5mm OD. Finally as per Jackomik's design I added a piece of heat shrink to further secure it in place. Finally a standard bore earphone tip is used, though when funds permit I want to try out the standard Symbio MandarinES

The specific internal diameter of the metal tube results in a good ratio of the surface area to opening and lets less sound from outside in, when compared to larger diameter tubes. If using a darker filter like the Knowles Red, Black Stock etc, you can add more than one tube and I've found this to be better than adding a larger tube resulting in a larger vent area but maintaining your vent area to surface area of metal ratio, which gives the airy upper notes and preserves bass. I can't fully express the difference in spaciousness, it gives me chills occasionally at how clearly it images wide, expansive space compared to stock.

A good side effect of this mod is that I've not experienced fatigue as I used to, and can have my earphones playing music all day (9 hours) without feeling any ill effects, I'd attribute this to the venting releasing pressure and stopping the oscillating static pressure provoking the acoustic reflex mechanism that creates a feedback loop.

It's basically the same effect as this concept https://www.nsf.gov/news/news_summ.jsp?cntn_id=119406

 

[unispeed]

@EastOne This is interesting. You're basically venting your ear canal and on purpose breaking the seal slightly but in a controlled fashion. I can see where this would result in longer listening sessions due to confort.

I have a few questions about your setup:

• Do you have a 2mm Knowles green filter sitting in a piece of silicon tubing?
• If so, does the silicon tubing run the entire length of the nozzle or is it just a short section that just holds the filter in place?
• Where about in the nozzle are you placing your green filter?

I ask because there is research from Sonion that shows that as nozzle diameter increases resonant peaks shift left-wise. And both Sonion and Knowles publish in their literature that as a filter moves away from the balanced armature it becomes more efficient and basically more powerful. Knowles goes one step further and specifies that as a filter moves away from the BA it also affects a larger part of the FR curve.

My reason for going with the Green filter was from the comments of people on this very thread (first few pages) saying the Brown filter was the sweet spot. But Since my intent was on placing a Knowles filter in the stock position (closer to the BA) I had to move to the next step up from Brown. A brown filter in this position would likely be too piercing. Basically, a Green (1500 resistance) filter placed in the stock position would be the same as say a Brown filter (1000 resistance) placed where most were placing them some time ago, slightly further away, while still retaining the "tuned inside diameter" (cause decreased sounds like a downgrade) of the original Shure filter inserts.

I am actually a bit curious as to what a red filter would sound like so close to the BA. The problem is that I don't see a red filter manufactured in a 1.78mm diameter . Then again, if it really is true that the smaller diameter ones are just the larger ones without their housings, well, that opens that option as well.

 

[EastOne]

@EastOne This is interesting. You're basically venting your ear canal and on purpose breaking the seal slightly but in a controlled fashion. I can see where this would result in longer listening sessions due to confort.

I have a few questions about your setup:

• Do you have a 2mm Knowles green filter sitting in a piece of silicon tubing?
• If so, does the silicon tubing run the entire length of the nozzle or is it just a short section that just holds the filter in place?
• Where about in the nozzle are you placing your green filter?

I ask because there is research from Sonion that shows that as nozzle diameter increases resonant peaks shift left-wise. And both Sonion and Knowles publish in their literature that as a filter moves away from the balanced armature it becomes more efficient and basically more powerful. Knowles goes one step further and specifies that as a filter moves away from the BA it also affects a larger part of the FR curve.

My reason for going with the Green filter was from the comments of people on this very thread (first few pages) saying the Brown filter was the sweet spot. But Since my intent was on placing a Knowles filter in the stock position (closer to the BA) I had to move to the next step up from Brown. A brown filter in this position would likely be too piercing. Basically, a Green (1500 resistance) filter placed in the stock position would be the same as say a Brown filter (1000 resistance) placed where most were placing them some time ago, slightly further away, while still retaining the "tuned inside diameter" (cause decreased sounds like a downgrade) of the original Shure filter inserts.

I am actually a bit curious as to what a red filter would sound like so close to the BA. The problem is that I don't see a red filter manufactured in a 1.78mm diameter . Then again, if it really is true that the smaller diameter ones are just the larger ones without their housings, well, that opens that option as well.

Yes, exactly that. The initial intention was to see if controlled venting produced a similar sound difference between open and closed back headphones and I believe that this was the case, although I only have my own subjective perception to measure this with. I'd imagine using an even smaller tube (I recall diameters of 0.1mm available) would result in pressure release without the change to soundstage. Depending on where in the world you are, I could offer the inserts assembled if you'd like to try, you'd just need to find a standard earphone tip to suit, a tip internal fit diameter of 4mm is ldeal as it fits snugly around the heatshrink and doesn't come loose.

To answer your questions.

• I don't use silicon tubing internally, I've got the 2mm filter in a piece of heatshrink to increase the diameter, and then with some mastic (blutack) to fill the gaps. I only use the blutack because the internal fitting is somewhat different to what I expected, and it's not perfectly round, so there was some space to fill.
• The heat shrink is only the length of the filter, so it's exposed metal down the tube.
• It's far back as you have indicated, I have tried oriented with the filter material closest to my ear and closest to the driver, and found that it produced a sound closer to the white stock filter if it was oriented closest to the driver ie. filtering less and ending up too piercing. This is similar to your hypothesis behind the use of green filters, I think. I'd anticipate based on this conversation that I'd prefer the red Knowles within the stock inserts if this is true

I have a set of calipers at home so I will try and measure the diameter of the filter cloth alone when I try and replicate your most recent mod, but they're only graduated to the mm so it may be unclear, though if it fits into the standard housing in the same orientation as stock then I'd assume they are the same.

 

[unispeed]

For anyone attempting this mod, I have just a small disclaimer. I ordered from mouser the 1.78mm size thinking that there were only 2 sizes available. The reality is that there are 2.08mm, 1.78mm, 1.37mm, and 1.12 mm. Based on my experience with installation of the 1.78mm diameter filter, I would say that its a hair too big. Keep in mind that I used a blunt toothpick to widen slightly the entrance of the filter. The result was a VERY tight-fighting green filter. So if anyone buys these filters I would suggest to buy the 1.78mm size and the 1.37mm size. They are not that expensive and you may find that the smaller size is a more precise fit for the Shure inserts.

• 1.78MM Knowles Green (buy at least 2) https://www.mouser.com/ProductDetail/Knowles/BF-3038-000?qs=sGAEpiMZZMuTkJYgZlQcScTJ90lUAd4Z1GtUs/Z31iE=
• 1.37mm Knowles Green (buy at least 2) https://www.mouser.com/ProductDetail/Knowles/BF-3039-000?qs=sGAEpiMZZMuTkJYgZlQcScTJ90lUAd4ZFVr9MDEj0Bw=

My suggestion when installing these. Use a toothpick but cut the points off... or, use the back side of a 1/16" drill bit. Either way works. For pushing them out go from the other side with a paper clip and simply push them out. ...these are cheap mods but they make appreciable differences in what you hear.

 

[unispeed]

Yes, exactly that. The initial intention was to see if controlled venting produced a similar sound difference between open and closed back headphones and I believe that this was the case, although I only have my own subjective perception to measure this with. I'd imagine using an even smaller tube (I recall diameters of 0.1mm available) would result in pressure release without the change to soundstage. Depending on where in the world you are, I could offer the inserts assembled if you'd like to try, you'd just need to find a standard earphone tip to suit, a tip internal fit diameter of 4mm is ldeal as it fits snugly around the heatshrink and doesn't come loose.

To answer your questions.

• I don't use silicon tubing internally, I've got the 2mm filter in a piece of heatshrink to increase the diameter, and then with some mastic (blutack) to fill the gaps. I only use the blutack because the internal fitting is somewhat different to what I expected, and it's not perfectly round, so there was some space to fill.
• The heat shrink is only the length of the filter, so it's exposed metal down the tube.
• It's far back as you have indicated, I have tried oriented with the filter material closest to my ear and closest to the driver, and found that it produced a sound closer to the white stock filter if it was oriented closest to the driver ie. filtering less and ending up too piercing. This is similar to your hypothesis behind the use of green filters, I think. I'd anticipate based on this conversation that I'd prefer the red Knowles within the stock inserts if this is true

I have a set of calipers at home so I will try and measure the diameter of the filter cloth alone when I try and replicate your most recent mod, but they're only graduated to the mm so it may be unclear, though if it fits into the standard housing in the same orientation as stock then I'd assume they are the same.

Ok, in light of of what you just told me, please scroll up to post 197 and take a look at the correlation between nozzle diameter and frequency response. In your configuration you've introduced 2 significant variables (Larger tubing diameter and a more resonant tubing material) both of which greatly affect what you hear.

 

[EastOne]

So by swapping from the raw metal tube to the Stock Filters with modified filter material, I'd be reducing nozzle diameter whilst using a less resonant tubing material, so the net effect is that with the same colour filter I would get a less bright sound if all else remains the same as I understood your posts, this would mean based on my preferences, I'd be looking for a step down from the Green at 1500ohms to the Red at 1000ohms to compensate, right?

edit: err, hang on, I mean brown at 1000 ohms not red, in both this and the previous post.

 

[unispeed]

So by swapping from the raw metal tube to the Stock Filters with modified filter material, I'd be reducing nozzle diameter whilst using a less resonant tubing material, so the net effect is that with the same colour filter I would get a less bright sound if all else remains the same as I understood your posts, this would mean based on my preferences, I'd be looking for a step down from the Green at 1500ohms to the Red at 1000ohms to compensate, right?

Your first statement is correct. By removing the filter you've made the nozzle bigger and more resonant due to the material. From researching what the likes of 64 audio are doing currently, they are working to get rid of sound tubes altogether in their 3000 dollar IEMs due to tube resonance. Going from a plastic tube to a metal tube would only increase its resonance. That's why I asked if you were using silicone, as it would be even softer than plastic and therefore less resonant.

I dont know if this is a correct analogy but it might be compared to a recording studio and its use of dampening material on the walls vs being inside an all metal room with nothing else in it besides you and the speaker. Where would you prefer to listen to music? There are probably echoes that are being produced ( I say probably because its an assumption) in the metal tube that are being absorbed by the plastic material. But an even bigger factor is the shift in your resonant peaks when using a larger inside diameter. That's what I was trying to point out with that graph. Look at the orange line and compare it to the purple line. Do you see what is happening at 8000, 9000, and 10000 Hz? The end result is an even faster drop off of high frequencies when using too big of an inside diameter and an accentuation of some of the frequencies around 8000Hz. That is the reason why many walked away from the Knowles filters originally. But the real cuplrit was not the filter, it was the change in nozzle diameter that went along with changing over to Knowles filters.

To answer your last question...well, not necessarily. The change to a smaller diameter and less resonant material does not necessarily mean that the sound has gotten any darker. Keep in mind that there is a faster dropoff of High frequencies above 10000 hz when using a metal tube with the larger diameter. Finally, keep in mind that Red is darker than green. Red is 2500 ohms. Green is 1500, and brown is 1000.

My suggestion. Green is a good base to build on. If you find that it is still too bright fine tuning of high frequencies can be done with a single piece of foam from the stock blue filter.

Now here is a final thought for consideration and this may be new to a few here. The SE846 keeps the acoustics internally and externally of the balanced armatures separate up until the end of the nozzle. The filter tube seals the outlet of the armatures and it does not communicate with the space outside the armature (inside the IEM shell). Instead, the air from outside the armatures is vented to the side of the filter tube and into your ear, but it stays separate from the sound all the way to the end of the nozzle...Meaning if you are removing the stock filter, you are making one single chamber of the inner and outer parts of the balanced armatures. In the speaker world this would be similar to a speaker mounted to a plank of plywood (acoustics from front of and back of the speaker mixing) whereas the stock way is more similar to a speaker mounted inside a box (inside acoustics separate from outside acoustics) .

Now, there is something that is a compromise between the 2... the open back speaker. This is the style of enclosure used in the SE846. They are separating inner and outer spaces up to a certain point (the end of the nozzle) at which point they mix inside your ear.

Here is a picture showing the vent I am talking about. The vent is circled in red. So technically if there was a pinsize hole anywhere in the outer plastic housing you would be venting your ear canal to atmosphere.. As of now you're venting to the space inside the outer plastic housing, which I think is sealed.

 

[EastOne]

The vent tube I have aligned parallel to the earphone tube and terminatesoutside of the threaded connection entirely, so it’s venting parallel to the earphone tube from canal to atmosphere, but in the configuration I had, damper and heat shrink, it would also have been venting the entirety of the speaker box configuration due to not using the sealing arrangement of the Shure filter insets

From about 15 minutes with the green filters in a stock Shure filter inset, the sound is noticeably different, and for the better - this is definitely the sound I was after the entire time.
I’d need more listening time with them to be sure, but the 8-10k peak was very very offputting and I’ve only just noticed it from its absence, and I tried a number of combinations of knowles damper, diameter or total number of metal vent tubes etc to remedy this previously but returning the internal arrangement to stock state, and then using a knowledge damper purely for the filter effect is definitely the way to go.

As far as size goes, my callipers aren’t useful for a measurement, but inserting them into the filter inset was a very tight squeeze, so I think it’s reasonable to assume they are the same size as what you had ordered.