[JadeEast]

I'd suspect that if you've made a "head laser" there's too much reflection off the damping. The foam can act more like a spring for the main damping. The tape could just be too much. The orto-tweeters that were on the market had no rear perforations on the back side.... That said, the only Fostex I've had experience with are the T20 and the version of that pulled into the Concept one. And I stole the drives from the T20 to replace a blown trace on the Concept. They were both good and pleasant, but I never quite got teased with the feeling that "there was some hidden potential" I was going to recover/uncover/reveal as compared to some other cans. I like them but never really put much effort into tuning. I wouldn't be surprised if once optimized they could be very good. But finding the sweet spot might be harder as I think there's been the least efforts overall into the T10 and T20 for the number of them out there vs other vintage cans.

 

[nick n]

See if you can try this arrangement.
= https://www.head-fi.org/threads/orthodynamic-roundup.111193/post-13995265
SCROLL DOWN 2 POSTS FOR IMAGE, and further along for some thoughts by others as well

It may cost a tiny bit for a 3 x 3 inch piece of Sorbothane, but results are well worth it.
Very transformative and nothing else I tried got similar results.
I do have yet to trial some of that fo.Q damping tape, I do have the TA-32 and TA102 thicknesses but it is uber pricy and the T10 here is already tweaked..
I don't care what gets used so long as results are audible and an improvement.
I am not a materials snob = If I can find something better I will use it and switch at the drop of a hat.
So far trial with fo.Q Damping Tape on a dynamic has a slightly different characteristic effect than sorbothane ( yet to try fo.Q on an ortho )

There were a couple others here who also did this to a T10 with happy results, or at least something extremely similar.
It's nice to get feedback on things.
Best thing to do is let that driver fly free without being stifled directly at the rear face of it.
Give it some room to breath or at least use a material that can breathe a bit while reflecting just enough of the sound back to boost these black nameplate ones.

= It is the Sorb itself that will give the main charateristic results so you can't really duplicate that with other stuff.


One other thing to consider is something leeperry always mentions, and that is the age and/or condition of the older copper in their cables.
Some things do benefit from a new cable install.
Perhaps as a final tweak. Or leave as-is it may be just fine.

Hope this helps in some way.
Don't get frustrated, it is all supposed to be fun ( I think )

~Nick


P.S.

@JadeEast is right about the amount of first aid papertape ( commonly referred to as micropore in here ).
It is too close, and is reflecting too much back.
When I was stupidly obsessing over a T50RP Mk2 mod even a tiny shift around of a shaped piece of that tape , or adding a small square extra tended to affect the sound.
I trialled so many tuning pads with variations of that papertape / micropore I nearly went nuts.
Luckily it is now much improved compared to the last posted mod scheme, some real bass now.
Long story short the stuff does affect things noticably when on backside of a porous, direct damper pad like you have there and I also used.

( hear that @waynes world ? Better send yours down for the update or else...)

 

[Philimon]

I appreciate the information everyone. Ive ordered some sheets of open cell foam in various densities ranging frok 2-15lbs as a start. Do you(s) have a favorite source for sorbothane and arctic brand quilt batting? In the past Ive liked to use damplifier pro from second skin audio (like dynamat but a bit stronger), sorbothane is more effective? O.O

Unforunately Ive already sent the T10 to @dBel84 . dBel attempted to fix my YHD-1 (rip). I wanted to repay him for his free help and T10 is a fav of his.

Dont worry about me though - I have another Fostex coming thanks to @VanHai :

 

[GREQ]

I've always suspected the T10 driver is limited by the semi-closed cups, since the KH-83 sounds a lot better with less tuning due to the almost fully-open cup design.
As far as we know, there are also 2 versions of the T10 driver, one being more linear than the other, so it could also be that KH-83s have these more linear T10 drivers.
I havn't done a driver swap to find out.

 

[Philimon]

YH-1

Setting mod baseline (besides stock). Seated driver with butyl. Will replace with sorbothane in future. Removed all damping.

Not bad just like YH-2. Relaxed warm sound. About as clear sounding as YH-2 stock (good condition, smooth chamfered hole magnet). And a lot more clear than my previous YH-2 which was in poor condition and I think had the common driver version (sintered, would need to go back and look at pics to verify). The big drivers do give a bigger soundstage, but most importanly bass sounds more enveloping. Not sure if ear pad hole size is the same, but the pads are larger overall which should make getting measurements easier. Unfortunately my headband adjuster is broken. A rubberband holds it in place but I can see the adjuster already coming completely apart as I set for head time then EARS time. I will need to source another HP/YH-1. Please let me know if you have one for sale or for lend.

T30 and some new mod materials should arrive this weekend.
Next, the YH-1 will get the basic treatment, felt and foam. Please see other site for measurements unless I get requests to add some here.

BTW there is barely enough room for connection tab when driver is seated center. Has to go just off center in order to fit. I hope I dont accidentally smoosh, might have to move more off center for safety.

 

[Philimon]

Yamaha YH-5M for sale on local CL

 

[Philimon]

RE: sorb, sorbothane

Higher or lower duro? And is it naturally sticky, or do I need an adhesived version?

 

[JadeEast]

I'd go with the self adhesive stuff. Unless you were just going to use it a situation where you could compress it in place.
More utility with adhesive stuff I'd think. My guess would be someone else who takes notes on the ideal Duro.
My brain says I used 70D... I've no notes and I'm suspicious if that's true or not.
I do like the stuff, my completely subjective take is that the judicious use of it helps clean up things and allows for less damping.

1K for the Yammy headbrace is a silly price. They've gone for under $200 in Japan in the last few years.

 

[Philimon]

This is an easily available and cheap foam: makeup pad. High density, high bounce. Even though I was warned against micropore I used it to hold foam in place and maintain seal (I had bought a box of this stuff thinking it was going to get used a lot for ortho mods). This was too much damping. Removing the sealing tape would help and I bet the foam is thick enough to compress itself in place. Will try without tape next. Thanks @spoony for the tip.

I wonder which is better: a uniform damping along entire driver, or an uneven and vented damping. Coupled open foam (like above) vs semi-coupled open foam (tape removed and foam sitting loosely with some gaps particularly around wiring).

Does too high of density foam reflect?

 

[Philimon]

Foam factory has a lot of specs for their foams including density and airflow. I only chose by density and chose a variety from 2-15lbs. Guess I'll later look for foams of same density but different airflow ratings to test.

 

[Philimon]

I think airflow is probably most pertinent in this application (damping by limiting airflow). I've been choosing based on density because I assumed it's directly correlated to airflow. But I see how you could have two densities that have different airflow based on the construction of the foam. Just like how you have open-foam and closed-foam, maybe one is semi-closed, etc. I'll look at what I ordered already and get some stuff with different airflows. Density I guess would be important to absorption? That would make sense. Everything for resonance control is dense, and I've seen melamine foam advertised for upper frequency control like 10kHz.

 

[Philimon]

I included the products under open-foam that included airflow ratings.

As reference, "speaker" foam looks like speaker grill foam.

edit: Mcmaster Carr has a wider selection but no airflow specs. Maybe I wasn't looking in the right places at Factory Foam.
edit2: The differences in specs arent huge here except for a couple. I'll check again to see if there were sections I missed. Mcmaster Carr has some wild options. I must've not seen everything at factory foam.
Edit3: another spec called ppi (pores per square inch) probably important

 

[Philimon]

I did a quick search and couldnt find information on how sorb compared to common damplifier/dynamat. I read somewhere that sorb>butyl. Butyl is what damplifier uses in its goo layer followed up by the metal layer. Another thing I found confusing was that on sorb website they chart sorb’s resonance damping frequencies at different compressions. So, does sorb need to be compressed? I ordered some sorb in Duro 70 to try since I ran out of damplifier pro anyway.

 

[nick n]

EDITED THIS POST

If you have a hole punch ( I use a new leather belt hole punch that has multiple size holes ), you can play around with placing multiple breathing holes at strategic locations over a magnet area in that memory foam pad.
Best part about this is if you decide to refill some holes again during a trial, and your hole punch was sharp, the little plugs will temporarily fit back in the holes until you find a scheme you like.
Or decide if it is worth it or not.

At least the mem-foam makeup pads are cheap at a local Dollar Store here.

This can help strike a balance between letting the driver breathe more and also damping.



One other option, I just picked up some Mr Clean Magic Eraser, and it now comes in thinner sheets so easy to stack and try various amounts of that too.
Same size as the blocks but sliced already to perfect even thicknesses.
Slicing that up the old way never managed to get it even
Pretty sure @Hutnicks had mentioned being happy using that stuff in various mod schemes.
Maybe it was someone else
Again , this is cheap stuff and commonly found.
And proven use in damping.



***Saw the above post.
Some reported using Sorbothane compressed, but I never bothered to.
Maybe if the stuff gets done when the baffle is screwed down correctly sure... to ensure even compression.
otherwise how to tell and keep it compressed.
There is a dedicated Sorbothane thread in here if you want to go crazy. lol
I only posted a couple times in there, I know what it does for my needs.

I started out using 30d then 30D and 50D.

There is no constrained goop layer like dynamat/fatmat/damplifer etc.
It is like a rubbery solid type stuff.


*** While I remember, try not to put any Dynamat-type stuff near driver vent holes, as depending on ambient temperatures ( and headphones inside can heat up during use from body heat ) the goop slowly creeps out from under the constrained ( is that the term?) metal layer edges and can weep around a bit.
I had a headphone slowly lose it's tuned vent holes over time from this.
It drove me nuts since the sound changed slowly over time until I noticed.
Plus one could ruin a nice driver.
I only use Dynamat/Fatmat for mounting drivers to baffles here these days.

Sorry to blab.

 

[JadeEast]

@Philimon my suspicion on the foams, based on the chart, is that density is weight for sample size. Probably relates somewhat to resilience or spring. Unsure about absorption but makes sense it would impact wave length. For CFM I'm somewhat familiar with it from my work life. But that's with clothes and fabric... not foams and filter mediums. 3 isn't that much flow. A coffee filter layer is something like 50-75 CFM. Often people will use a breath test on a fabric. Put it up to the mouth and breath as a relative test.

One wild card would be the impact of compression on the CFM, absorbing and reflective properties of foams. My suspicion would be that with both foams and fabric there's a goldilocks point. The point where there's enough pressure to be stable but not enough to impact things negatively. My gut feeling is that felted and fiber based matetrials will have a more stable characteristics under compression due to the longer fibres used.

There is one potential filter material with a stable CFM that is now more widely accessible. The melt blown layer inside of any 3 layer surgical mask is a spray laminated filter and should probably be in the range of 30-40 CFM. Almost everyone has some lying around and could be a source.