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The Headcase Stax thread

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On ‎12‎/‎6‎/‎2019 at 11:53 PM, justin said:

joamat, did you ever check out trying the adapter I came up with for EL34 and 20B in the same amp? 

Well, I did start with a layout of a regulator board with some smd parts. A sop-4 ssr for relay…

2084587448_topadapter.thumb.JPG.119daa110aa99f39a4974773a71f8ce4.JPG         2101239869_bottomadapter.thumb.JPG.82d713e8fbfc68c4b6e74cc03780cfbd.JPG
… but it all stalled. The to-220 regulator probably needs a heat sink and the layout has to reworked – it's just an early draft. But so far I stick with the EML V20B to EL34 adapters I have.


Maybe you should make your idea of adapter public here on Head-Case. I think it’s a very elegant way to make it possible to use either EML tubes or EL34.

Edited by JoaMat

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sure, here's the schematic again. the way it works is the relays flip when you plug in the 20B. because there should always be a time delay on the high voltage and I'd hope nobody is hot swapping the tubes it should be completely safe

 

 

20b-or-el34.jpg

Edited by justin
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On 12/7/2019 at 1:57 PM, gomo said:

Hi,

Has anyone tried Ether flow angled pads for SR-007 and how is it compared to EP-007?

 

Terrible match IMHO. Also the Ether Voce pads.

The best pads I came across for the 007 were the 009 pads.

Actually they proved to be the best for all my headphones. I love those pads - especially after I removed the white reinforcing layer from the internal foam. Same mod works great for the 007 pads as well. Best generally usable ear pads in the industry IMHO (not counting special ones like Focal or Sony or Phenomenon). I have dozens of obsolete pads from other makers that I collected over time, but the 007 and 009 pads stand out. So if anything, I'd move *for* them, not away from them :).

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48 minutes ago, zolkis said:

Terrible match IMHO. Also the Ether Voce pads.

The best pads I came across for the 007 were the 009 pads.

Actually they proved to be the best for all my headphones. I love those pads - especially after I removed the white reinforcing layer from the internal foam. Same mod works great for the 007 pads as well. Best generally usable ear pads in the industry IMHO (not counting special ones like Focal or Sony or Phenomenon). I have dozens of obsolete pads from other makers that I collected over time, but the 007 and 009 pads stand out. So if anything, I'd move *for* them, not away from them :).

There are a few other pads that allegedly work with the 007, like Kennerton Audio's ECL-01 and ECL-02, and ZMF pads (I know someone using ZMF auteur pads on a pair of 007s). Have you tried any of these pads?

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So here I was modding a SRM-006tS to a CCS and noticed this: 

staxftw.thumb.jpg.f5ca518835fdd34ade086401980b019b.jpg

That is the R+ output and notice the 3 lines coming off it, one going to the feedback, one going to the output resistor and one... going to the other side of the output resistor...  ;) 

One has to wonder just how many of these they have shipped like this? 

In other news, it was fun converting an original T1 and and this one at the same time.  30 years apart and almost exactly the same...

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On 12/13/2019 at 1:00 PM, zolkis said:

Terrible match IMHO. Also the Ether Voce pads.

The best pads I came across for the 007 were the 009 pads.

Actually they proved to be the best for all my headphones. I love those pads - especially after I removed the white reinforcing layer from the internal foam. Same mod works great for the 007 pads as well. Best generally usable ear pads in the industry IMHO (not counting special ones like Focal or Sony or Phenomenon). I have dozens of obsolete pads from other makers that I collected over time, but the 007 and 009 pads stand out. So if anything, I'd move *for* them, not away from them :).

I second Zolkis findings. Have followed his instructions, first modded original 007 pads then 009 pads and no way back. In  2 words - increased immediacy.

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I don't suppose anyone who tried the 007 with 009 pads experiment has a headphone measurement rig so we could take a look at the resulting FRs? Doesn't have to be perfect, just (moderately) consistent in measurements so the differences are meaningful.

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I recently bought a pair of SR-Lambda NB headphones on ebay and they're missing the wool dampening behind the driver. I've tried searching here and on HF, but I can't seem to find a good source for this stuff. Does anyone know where I can get some replacement wool? Or something that replicates the effect of the original foam?

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I recently bought this for my own SR-Lambda. Your country's stax distributor should be able to get it for you at a reasonable price (about 20 dollars if I remember right). Stax still has stock of it.

16 hours ago, ilikebananafudge said:

I recently bought a pair of SR-Lambda NB headphones on ebay and they're missing the wool dampening behind the driver. I've tried searching here and on HF, but I can't seem to find a good source for this stuff. Does anyone know where I can get some replacement wool? Or something that replicates the effect of the original foam?

 

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I don't have a ton to add to this thread, but I wanted to let you guys know how much I appreciate the wealth of information available here.
I haven't posted anything, but I've been lurking and working on my own stuff behind the scenes for some time. I helped another user off audiokarma by fixing his dead Superex pep-74 adapter, and I bought Spritzer's Stanton Isophase Mk3 wayy back, which had a bunch of issues that I was able to identify and repair (there are more to tackle, but I haven't bothered spending the cash on them yet). They sit proudly on top of my amplifier. Couldn't have done it without you guys, you're all legends.

Next project is a set of realistic HP-100, unknown whether they work or not. Wish me luck!

Question for anyone that knows how this works- I know the stax SB units piggyback off the output of an amplifier to create the bias voltage, and as I understand it the SRD units do something similar... What exactly does the mains cable do? If mains voltage is stepped down to create the bias voltage (which is how I thought these worked), then why does the audio input need to be amplified?

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Inside the Stax SRD unit, there are a pair of step up transformers for audio signal and a step up voltage circuit for the bias voltage.

The audio signal needs to be amplified a lot for it to be played on the electrostatic headphones.  Many of electrostatic amps can swing the audio signal to over +/- 400V.  The bias voltage for electrostatic headphones also needs to be stepped up from the main AC voltage.  For Stax headphones, the bias voltage is 580V.  So, the amplified audio signal together with this bias voltage of 580V can actually be more than 1KV. ;)

 

 

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With the SB boxes there is a third transformer inside the unit which taps off the HV side of the audio units and further steps up the voltage.  That is then fed into a voltage limited voltage multiplier which generates the bias voltage. 

With the AC units they feed directly into the bias supply multiplier which isn't very safe these days. 

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Hmm okay, that seems like a huge amount of voltage swing for just the audio signal- I had no idea that I was dropping a kilovolt of power near both sides of my head. Spooky :D
Even spookier that the Isophase have metal grilles on both sides that are connected to ground, and I can feel little bits of static if I touch both ears to the bare metal. Probably some caps need replacing...
It's actually a wonder that the self biasing adapters can step things up enough to work from just the speaker taps. Amazing.

It's not very safe these days because amplifiers are rated much higher than in the era that srd6/7 were being built? Or some other reason?

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2 hours ago, Hifilutin said:

I had no idea that I was dropping a kilovolt of power near both sides of my head.

Power is not measured in volts.

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1 minute ago, dsavitsk said:

Power is not measured in volts.

I had no idea I was dropping a kilovolt and a small amount of current near both sides of my head!

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On 2/7/2020 at 5:09 PM, Hifilutin said:

I had no idea I was dropping a kilovolt and a small amount of current near both sides of my head!

Just for perspective, every time you walk across a carpet on a dry day, and touch your hand to a doorknob getting a little electric shock you are discharging a kilovolt or two of static electricity.

.

Edited by JimL
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Left to right: 404, L700 and 507 Sigma 

The one with 404 driver is more laid back and has more colouring while the 507 one has the best transparancy . But the L700 sigma is the best with a very full bodied mid bass and excellent 3D- imaging and soundstage I have never heard of in any other headphones.

Love all three of them 

AFB4CFF3-6009-4BDB-BF57-D6C846664119.jpeg

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I posted a repair diary of Omega as a new post under Headphone section :

 

I think its relevant so I will leave a link here.😄

 

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Are there any velour pads out there for any Stax sets that people have tried? Ideally in Lambda or Omega style.

I realized recently that I am still using my janky Lambda Novas that I repaired myself back in college because I had no money. I want to finally upgrade but I do have an issue with leather pads in hot weather. I found a few options searching around but I want to know if anyone has tried any.

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I suppose if I am spending that much on Stax, what is the cost of a nice set of earpads compared to that.

Especially since it looks like they can do that blended leather/velour style that is on my Fostex.

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