The Headcase Stax thread

[spritzer]

They claim 450V but who knows what the drivers will actually handle. 

[shipsupt]

I had a chance to listen to KS with its tube amp earlier this week. The overall sound wasn't that bad, but I didn't quite like its bass. There's bass but it's different from Stax or mine DIY phones. It's rather difficult for me to describe it. But, I think the open area at the back side of the drivers is not enough or there is too much damping material. The bass just doesn't sound as "open".

I also don't like its headband. It's just too small for my head.

 

There are several issues with the Kingsounds, but I agree that something is wrong with the damping and area behind the drivers. 

[DefQon]

Checking in again on the repair on my SRM-1.

 

Received the class N jfets from UTSource, desoldered both the old ones, diode tested the lot to get a balanced pair.

 

Soldered her in and voila, it's singing sweet tunes to me again.

 

Measured all voltage points and the sc1828's have gone up an extra 30vdc but measure consistently throughout the circuit.

 

Next step rebuild bias section.

 

@spritzer what resistor/diode did you use in your voltage divider to drop 600 b+ to pro bias mark?

[spritzer]

To drop the 20V use a 13.5K series resistor, a 390K to ground after that and then the 5M ballast resistor. 

[DefQon]

Thanks for that. I'd use that as guide to work out how much needed to drop 70v. Is 600v for a pro-bias Stax bad in the long term?

[spritzer]

No, makes very little difference. 

[nopants]

Has anyone tried both colors of the ep007 earpads? I was wondering if the brown ones might be softer like the older version- the black ones are very firm. This seems to be both a blessing and a curse as I can seat the drivers farther away from my ear but it seems to negatively affect the efficacy of the seal (slightly).

[spritzer]

Aren't the brown pads just the same stuff as they sold for the Mk1?  If they come in a nice EP-007 box then it is something different but otherwise it's just the same old pads. 

[nopants]

I've never actually bought pads straight from stax so I wasn't sure, thanks for clearing it up. 

[Dusty Chalk]

Can't you just soften them up, mafia style?  With a bat?

[spritzer]

I prefer to use a hammer but yeah, that is possible.  The problem with the Mk1 pads was the foam as it just didn't last long enough.  It would get too soft and then the pads were useless.  My Mk2 pads are fine after 5 years now though so a proper improvement for one from Stax. 

[Sherwood]

I prefer to use a hammer 

 

The Icelandic mafia is halfway there.  The fury of Thor gets folks to pay up, but the accounting of Kaupthing still leaves the enterprise a little wanting.  Here's to Gudjonsson 2014 shaking things up in the Althing.

[complin]

New electrostatic amp from Poland

Eurydice – Stereophonic tube amp dedicated to electrostatic high-class headphones

 

• Works with headphones:
  STAX PRO  (580V bias polar.)
  Sennheiser HE 90 (Orpheus) (500 V bias polar.)
• Transmission band: 5 Hz-55 khz
• Inputs: 2 switched RCA (XLR for special order)
• Output voltage: 800V ss
• Used tubes: 6SL7 (ECC 83 for special order), PL 841, 5W4.
• Input sensitivity: 500 mV
• THD unlinear distortions: <0,5% dla 100V ss,   <5% dla 800V ss
• Signal to noise ratio: 86 dB
• Input impedance: 50 kohm
• Maximal power consumption: 140 W
• Weight: 12 kg.
• Dimensions: 31 x 34 x 21cm (Width/Depth/Height)
• EUR 2.338,05
• http://en.dubieltubeamps.pl/102/eurydice-stereophonic-tube-amp-dedicated-to-electrostatic-high-class-headphones/

 

• 
•  

Edited August 17, 2013 by complin

[Torpedo]

5% distortion at 800V ss... What's ss? other way to name rms, or perhaps saddle to saddle as in peak to peak? Either way, considering the SNR is 86dB it doesn't seem that marvelous. It looks classy though.

[spritzer]

Check out post 8317... 

 

The SS is stator to stator so pretty much p-p.  That thing has to be pretty much the same circuit as the M-20 and I posted it some pages back.  Not a bad circuit but 2400€?   Ehhh... no....

[Torpedo]

lol, thanks Birgir, I'm sorry I can't remember all the knowledge this thread provides. My fault for not searching it, though to be honest, I thought it was some bogus parameter, one of those which too many makers love to claim. Is it really possible to measure the ss voltage directly at the headphone?

[spritzer]

My post reference was aimed at complin and not you.    Now what we really could need at some good new Stax amps. 

 

The p-p figure is easy to determine based on the plate voltage and the tube parameters (Rp mostly) but that said, it doesn't really tell the whole story.  Most of these amps can't be adjusted for max voltage swing for the particular tubes installed so it can be a ways off. 

 

Speaking of whacky Stax amps... I've been cooking up a plan for a while now to make a tiny one.  Just got some boxes and they are 150x90x45mm (D, W, H) and I'm going to try and cram an Egmont in there...  Transformer and tubes on top but the rest has to be crammed in there.  XLR's are too big so this has to be RCA only...  

[nopants]

this isnt constructive at all but i really dig the look of the all black o2

[Dusty Chalk]

That goes without saying.

[n_maher]

[Voltron]

this isnt constructive at all but i really dig the look of the all black o2

 

Look, that brncao guy doesn't need to read about stuff like this, so keep on topic and keep the thread organized!

[nopants]

Actually I was going to ask if stax stocked things like replacement head assemblies so I could black it up...then I realized it would probably cost 40% of a mk1 pair through dealers. But my mk1's don't sound dark enough, so I don't see a better way to achieve this

[deepak]

Actually I was going to ask if stax stocked things like replacement head assemblies so I could black it up...then I realized it would probably cost 40% of a mk1 pair through dealers. But my mk1's don't sound dark enough, so I don't see a better way to achieve this

You can buy the MK2 black parts like headband unit, but they say SR-007MK2 on the top of the leather part of the headband. Sorta like putting a Fiat badge on a 911

 

And the cable would still be brown.

[spritzer]

This should be here, Kingsound M-10 internals:

 

http://gilmore.chem.northwestern.edu/dsc_0425.jpg

http://gilmore.chem.northwestern.edu/dsc_0426.jpg

http://gilmore.chem.northwestern.edu/dsc_0427.jpg

 

Hello Stax SRA-12S/SRM-1 Mk1 clone done very badly.  B+ 588V and with a very stupid bass boost circuit.  Again the PCB is supposed to act as a heatsink, not the best idea in the world. 

[GeorgeP]

You can buy the MK2 black parts like headband unit, but they say SR-007MK2 on the top of the leather part of the headband. Sorta like putting a Fiat badge on a 911

 

And the cable would still be brown.

 

You can still get the black MK1 headpad without 007 MK2 markings from Stax USA for the BL model but you have to ask for it.

 

And yes, the cable would still be brown.