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Investigation into possible mods for the Stax SR-404


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With two layers of felt (one more dense then the other) on the back of the drivers there is some improvement but the midrange peak still shines through. :-\ I'll have to find some suitable foam tomorrow and I'll also try to damp the phones next to the ear.

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With two layers of felt (one more dense then the other) on the back of the drivers there is some improvement but the midrange peak still shines through. :-\ I'll have to find some suitable foam tomorrow and I'll also try to damp the phones next to the ear.

be careful, or you'll have people demanding that you sell them your new SP-404 :) :)

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I love a good DIY project, and I love to save money. Now I won't have to buy an O2, right? :D

These aren't going to beat a SR-007 anytime soon. The Lambdas will always be more forward but if the midrange peak can be contained then that makes the phones a good choice for their given price range.

be careful, or you'll have people demanding that you sell them your new SP-404 :) :)

...wouldn't be the first time. :rolleyes: These will be sold though as the only use I would have for a Lambda is for testing amps and I already have two other sets for that. :P

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It turns out I was onto something by damping the front of the drivers and not just the back. I went out and bought a bunch of different cleaning cloths today and placed the thinnest one (made of paper-like material and almost see through) underneath the pads which has flattened the peak a bit and made it less noticeable and made it more recording dependent. The bass is also a bit overblown but very tuneful and responsive so I can live with that compromise. I will have to try a lot of materials though to see how far I can push this and if the damping in the back is even necessary.

What makes all damping on the front of the drivers quite a bit easier are the new Lambda pads with the cloth dust cover. The old pads had the foam sown in on the sides but the new ones have "pocket" underneath the pads where the cloth cover is put. That is mounted on a disk so you can easily remove it from the pads. Good move Stax. :)

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I don't think so, no. You can try asking KuboTen or Yama's though. The new pads come in a swanky box now with instructions and everything (though very Engrish at times). I must say I preferred the plastic bag with a label on it... :D

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I've been listening to the SR-404's for a few hours now with two layers of this paper-like material on the front of the drivers and tow different layers of felt on the back and there is no more midrange hump. ;D In it's place is a strange "thwack" coloration but it's rare and not overwhelming in any way. This does point to me having gone too far with the damping so I'll try some different materials and see if they work better. The bass has suffered though and lacks both extension and depth so I have to find a way to increase its depth.

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The sr-202's are glue, not sticky tape. That might explain why

the 202's sound a bit different than the 404's, along with the smaller cable.

The highs are less aggressive.

My experience with woodies and damping on Senn's was that it's hard

to find a medium. Anything that helps one end of the spectrum really

screws up the other end.

I did not glue the driver to the front mounting plate. I used sticky tape.

I looks like the only way to really improve the newer series Stax is an

enclosure change, or a change in driver contruction.

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I wouldn't be too quick to write off the old Lambda chassis... :) I've removed the back damping now and just have the front damping and I quite like them this way. They are more forward then they should be (next to no hump though) and the bass has this "lighter then air" feel to it but the extension and speed have returned. Next I'll try some minimal damping to the back of the drivers and see how they respond but I could live with the phones as they are now.

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Wow, nice work on getting rid of the SR-404's midrange coloration. I guess I don't have to tell you that this coloration drove me insane while I still had the phones.

The driver is attached with double-sided sticky tape? Good God. I don't know much about headphone design but that strikes me as awfully lazy construction. Won't this make the housing pretty much useless at dissipating excess energy regardless of what the housing is made of? I can't believe that mounting the drivers properly would drive up the cost or manufacturing time that much, at least in comparison to the sonic benefits. Stax's standards and QC have slipped enormously...

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The drivers have always been attached by double sided tape (or rather adhesive sheets) but now Stax have gone green and the new stuff just isn't as good as the one they have always used. I've opened up my fair share of Lambdas and Sigmas and I've never seen any of the old models "creep" like this. The other change is also the second layer of double sided adhesive which isn't helping matters.

I've not managed to spend nearly enough time with the SR-404 tonight but I did try a few different materials underneath the pads and nothing compares to this "fiber paper" that I'm using. I've also switched to just one layer of felt on the back of the drivers and I'm just going to let them stay like this for a while. That really is the best way for me to evaluate anything as any small issues eat at me as time goes on. :P

Btw. If anybody has a SR-303/404 and wants to try this layer of paper between the front of the drivers and the ears, just PM and I'll send you some. It's always nice to get a second opinion. It's better though that you have the new type of earpads since the is easier to fit the paper that way but the old ones should work as well.

Edited by spritzer
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Ok, here are some pics. This material is very hard to photograph but these should give you an idea what it is.

img1980p.th.jpg

img1975.th.jpg

img1974u.th.jpg

It is rather similar to the Tork fiber towels I used to damp my Koss SFI ortho. I bought from Europris which is a nordic budget store and it is branded "EFFEKT, CHIFF'ON Kluter".

As for installing it on the older type of pads, it is possible to put it on top of the foam but you will likely damage it and there isn't much overlap to hold the paper in place. You will also get some mild reflections if you do not damp the back as well with some felt.

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The LNS would need something totally different to give them a bit more "life" so these mods only apply to the SR-404 (and SR-303 since they are nearly identical). I'll also try them on a set of SR-202's which I will get soon and hopefully the Limited Edition SR-404.

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The LNS would need something totally different to give them a bit more "life" so these mods only apply to the SR-404 (and SR-303 since they are nearly identical). I'll also try them on a set of SR-202's which I will get soon and hopefully the Limited Edition SR-404.

LNS are perfect, they don't need no stinking life :P

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Sure they do. :indra: They will sound rather different given what pads they have and the old LNS pads are horrible, ghastly things.

I have new Lambda Pro pads on my pair, I also have SR-404 pads and kinda feel stupid ripping off perfectly good Lambda Pro pads to replace them with SR-404. Will they sound better with SR-404 pads? Somehow I doubt that.

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The sound will change given the different properties of the materials but if you are happy with the sound then don't rip off the new pads. Both of my old LNS's still had the old stock pads which were in good condition but the material is very thin and can only have hurt the sound (like the Fostex pads).

To bring us back on topic, I'm gluing the drivers permanently to the baffles now and I've also finished making new damping sheets for the earpads and fitted them in place. I'm documenting it with pics (though I keep forgetting to snap at the right moments :palm:) and if all goes well I should post them early on Saturday. The only thing I've yet to make up my mind about is to whether I should fix the felt damping layer to the back of the drivers or mount it inside the housing. There isn't a lot of difference but allowing the drivers access to some "fresh" air can't hurt and that's how I've done all the testing until now.

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Would this paper mod work on a Lambda Signature? Is should right?

Could you post a pic of that paper thingy please? Thanks.

Speaking of Lambda Sigs, I've stuck some tissue paper into my pair :P I still don't think they suit me, but at least they don't sound like drillbits in my ears.

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The Lambda Sigs have never struck me as being shrill so there might be something else at play here. I'm very sensitive to exaggerated HF response and even with my sole use of silver wire they have never presented like that. That's about 10-15 sets in total so have you checked that the set still has the stock drivers? There are plenty of them out there with SR-404 drivers...

I've just rebuilt the phones after permanently gluing the drivers to the baffle and it seems that I may have to revisit my damping. :-\ The bass is much more even but there appears to be more treble energy as well which I'd like to tame. I'm taking this with a grain of salt as I'm way too tired for any coherent thinking. It's 6pm here now and I've been working since 4am so I'm slightly loosing it... :D

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I am way too tired but I managed to bring back most of the sound that I had before I stripped the phones down. It turns out that I had mounted the dustcovers for the earpads the wrong way around so they pushed the drivers away from my ears just a bit. :palm: I may have only been a couple of millimeters but that was enough to add some etch to the midrange.

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