Jump to content

The Headcase Stax thread


thrice

Recommended Posts

They just slid on. It is certainly easier then to install the same pads on a SR-007... :P

p1000919r.th.jpg

p1000917h.th.jpg

The comfort is excellent but it might alter the sound too much for your liking. They also fart now.

Damn I love my new fiber connection for uploading pics. Going from 1mbit to 65mbits is quite a step...

Link to comment
Share on other sites

Well the port should always be there, it was there on the Mk1 as well:

Had a real panic yesterday. Took the SR007's apart to do the blu-tak port mod. Got them back together and plugged them into the T2 - bad distortion on RHC. Serious panic sets in.

Turned out to be a dead 2SJ79 that was causing one output to be at -250V. Just blew coincidentally with the blu-tak mod. The astonishing thing is that with a dead driver transistor for the grounded grid output EL34, the damned amp was still working - all that happened was that the output clipped and distorted - and of course the headphone diaphragm was biassed one way.

J79 replaced and all is sweetness and light again.

Link to comment
Share on other sites

It is very fast indeed. I'm getting about 7.5MB/sec for torrent downloading and it isn't maxed out... :D

If you change the pads, do go for the Mk2 earpads. I for one wouldn't go back to the Mk1's even though I have quite a few sets.

I have DSL, and the upload speed sucks (maybe ~40KB/sec for torrent uploads). When I do a large torrent download, I have to upload for days to keep my upload/download ratio high....

Unfortunately, I have 2 pairs of new SR-007 earpads, and 0 pairs of SR-007 Mk2 earpads. :(

Link to comment
Share on other sites

Had a real panic yesterday. Took the SR007's apart to do the blu-tak port mod. Got them back together and plugged them into the T2 - bad distortion on RHC. Serious panic sets in.

Turned out to be a dead 2SJ79 that was causing one output to be at -250V. Just blew coincidentally with the blu-tak mod. The astonishing thing is that with a dead driver transistor for the grounded grid output EL34, the damned amp was still working - all that happened was that the output clipped and distorted - and of course the headphone diaphragm was biassed one way.

J79 replaced and all is sweetness and light again.

I just hate it when stuff like this happens. What the hell did I just DO!!! :o

So how do you like them after the port mod?

Link to comment
Share on other sites

It is very fast indeed. I'm getting about 7.5MB/sec for torrent downloading and it isn't maxed out... :D

If you change the pads, do go for the Mk2 earpads. I for one wouldn't go back to the Mk1's even though I have quite a few sets.

I have a pair of mk1 pads on my Smegma Pro, and a sealed spare set I could try on my SR-5 gold edition, but I'm not convinced I want any change in sound by using them. I was saving them for when I wear out the pads on my O2 mk1, but it seems that you recommend the mk2 pads when that happens.

Link to comment
Share on other sites

Had a real panic yesterday. Took the SR007's apart to do the blu-tak port mod. Got them back together and plugged them into the T2 - bad distortion on RHC. Serious panic sets in.

Turned out to be a dead 2SJ79 that was causing one output to be at -250V. Just blew coincidentally with the blu-tak mod. The astonishing thing is that with a dead driver transistor for the grounded grid output EL34, the damned amp was still working - all that happened was that the output clipped and distorted - and of course the headphone diaphragm was biassed one way.

J79 replaced and all is sweetness and light again.

That's what I call hardcore man, not only does it go fubar, you calmly figure out the problem and fix it. Hats off to you, good sir.

Link to comment
Share on other sites

I just hate it when stuff like this happens. What the hell did I just DO!!! :o

So how do you like them after the port mod?

Much more solid and tactile low and mid bass. Kick drum really kicks now. But it goes beyond that - the whole voice thing sounds cleaner in some way too. Maybe there is a helmholtz thing going on between the large void between the ear and the diaphragm, and the little (leaky) void that colours the midrange in some way.

Edited by Craig Sawyers
Link to comment
Share on other sites

I did some tests yesterday of this thing (the large one):

p1000926.th.jpg

A bit of back story first, this is the Mk2 version of my TinyTransformer which gives you the ability to use Stax sets with pretty much any good headphone amp and being completely self contained so no external PSU. Now the small one uses transformers pulled from a Philips N6325 with a virtual center tap and a rather crude self biasing circuit. Now this one works but the transformers are tiny and the ratio is too low. Wanting to keep this as cheap as possible I went to the local store but they had no suitable audio transformers but plenty of cheap power transformers. I picked some suitable units and clobbered it together a few months ago. The only thing I heard was distortion so I though "bloody things can't handle the FR range needed" so I just put it on a shelf.

Fast forward to last week and I took the small transformer with me on my weekly mini-meet with Stuart to mess with him a little bit. I plugged my iphone into his Grado RA-1 and the small transformer into that, which in turn was driving the SR-507. With the RA-1 at max volume the sound was loud enough, with plenty of bass and sounded bloody good. This peeked my interest in the large one again so I opened it up and I saw immediately what was wrong, I had forgotten to solder one of the diodes in the multiplier so no wonder it didn't work... :unsure:

A quick test on my Cmoy showed that it did indeed work but yesterday it was pretty much stunning from a Shanling A80 integrated amp. The headphone output on that one is taken from the main amps and fed through resistors so plenty of power on tap. Much louder than the small box and no distortion I could detect. Not bad for about 35$ in parts... :) So here is how this works:

p1000920l.th.jpg

The large transformers are for the audio with virtual center taps, The input is via the black wires on the left and the output is via the black and purple wires on the right. These go directly to the Stax socket but they are also connected to the small transformer on the right. That one steps up the audio signal (which is just AC) even further and then feeds the bias supply. The bias supply is fitted with a 150V transient suppressor (so that the input voltage will never be higher than 150V) and then fed through a voltage quadrupler to give a ~600V bias. The goal here is to always have enough voltage on tap for the bias supply so you don't experience diminished output during quiet passages. Here is a better picture of the bias supply:

p1000922.th.jpg

I'm going to build one more of these with proper audio transformers and if that works ok, design a PCB for it. This is the perfect tool to mess with people at meets... :D

Much more solid and tactile low and mid bass. Kick drum really kicks now. But it goes beyond that - the whole voice thing sounds cleaner in some way too. Maybe there is a helmholtz thing going on between the large void between the ear and the diaphragm, and the little (leaky) void that colours the midrange in some way.

I think it is a combination of raising the height of the earpads and the port that creates that midrange coloration. Does your SR-007Mk2 have a serial number that starts with SZ3?

Edited by spritzer
Link to comment
Share on other sites

I think it is a combination of raising the height of the earpads and the port that creates that midrange coloration. Does your SR-007Mk2 have a serial number that starts with SZ3?

Yes - SZ3-1487. What is the relevance of that? And what am I missing with earpad height?

Yeah - I know you're going to say it is already in this thread somewhere :)

Link to comment
Share on other sites

Yes - SZ3-1487. What is the relevance of that? And what am I missing with earpad height?

Yeah - I know you're going to say it is already in this thread somewhere :)

There was this theory floating around that these sets already had the ports closed but I take it that it isn't true. What Stax might have done is alter the spring inside the earpads to have them sit closer to the drivers and they protruded quite a bit on the first sets.

Link to comment
Share on other sites

There was this theory floating around that these sets already had the ports closed but I take it that it isn't true. What Stax might have done is alter the spring inside the earpads to have them sit closer to the drivers and they protruded quite a bit on the first sets.

No - they are precisely the same as in your photos - absolutely no closure of the vent. Now, courtesy of your blu-tak idea, they have exactly the same sound as the Lambdas when you push the cans closer to your ears (what you describe as squeak/fart).

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.