The Stax Thread III

[wink]

Quoteier paolo

 This afternoon, on the wings of the happiness of the success with my SRM-600, I have set also the gain on my SRM-323s. Despite te procedure is the same, I would have expected to reach zero dc and offset easily. Wrong! I only could set 150-200 mV (balance or offset, do not remember) and the other to zero for both channels. The pots are different from the tube unit and they work better, but I cannot reach zero.

These aren't like for dynamic headphones. 
 
Anything below 1 Volt is perfectly fine.

 

[Pier Paolo]

Yes, I know, but I thought that the solid state would have been easier than the tubes one.

 

[wink]

The problem with offset in a dynamic system is the offset voltage causes dc current to flow through the headphone's voice coil which can burn it out.
 
With an electrostatic earpiece, the offset will not damaget the transducer, because it is effectively a capacitor which charges up and discharges.
i.e. no voice coil to burn out.

 

[davidsh]

So why bother with it in the first place?

 

[Pier Paolo]

Because of the distortion when dc balance and offset are too high

 

[kevin gilmore]

Actually if the offset is too high the headphone bias can
End up too high and this will damage the headphones.

The gain of the amp is high enough to make accurate dc zero
A tough setting with 1 turn pots.

All my newest stuff has a servo for this reason.

 

[Pier Paolo]

Please kevin, define "too high".

 

[kevin gilmore]

30 volts negative to ground is approaching too high.
 
Which is why when the plate resistors open up, the
voltage can sink to -300 pretty easily making the
bias 880v. Not a good thing.

 

[Ali-Pacha]

  I'd grab those but they are a bit on the high side considering you can get a Lambda NB with an adaptor for around the same price.

Same thing for me...and I have a SR-5 headband in perfect shape 

 
Ali

 

[Pier Paolo]

Thanks Kevin, that was exactly my 600 situation.

 

[shipsupt]

  Keep both the amps unless you find a 717 and mod it then use that to replace the 323S. 

 
What 717 mods would you recommend?

 

[DefQon]

Forgot to add the 727 in that sentence. The 717 is probably the best amp out of the lot if you're driving anything up to the O2's which does a fine job. I'm not sure which amp it was but it can be modded to a near identical KGSS, antonyfist can chime in on this extensive mod.

 

[tdogzthmn]

I'm really happy with the performance of my SRD-7/SB paired with my 2W SET amp.  It is incredibly detailed and clear but the sound is silky smooth.  Reminded me of the Sennheiser HE-6 + Cavalli Audio Liquid lightning combo I herd at the Bay Area meet up last year.  The gain is not that extended as other dedicated STAX amps but I find it easily reaches a satisfactory volume with the music I play.  For being a relatively cheap component the SRD-7/SB is very satisfying to use.

 

[DefQon]

  I'm really happy with the performance of my SRD-7/SB paired with my 2W SET amp.  It is incredibly detailed and clear but the sound is silky smooth.  Reminded me of the Sennheiser HE-6 + Cavalli Audio Liquid lightning combo I herd at the Bay Area meet up last year.  The gain is not that extended as other dedicated STAX amps but I find it easily reaches a satisfactory volume with the music I play.  For being a relatively cheap component the SRD-7/SB is very satisfying to use.

You mean HE-60?

 

[bbest]

Hi guys!

I have STAX 507 and custom amp. Not so long ago, one of headphone sounds too quiet compared to normal one. I disassambled "problemed" headphone and wiped with alcohol staters. May be they became clean from fat and dust. Sound after that became more louder. But it still had some artifactes - too meager sound. And now surfaced one more bug: "problemed" heaadphone has white nois. This noise head in silent pauses and even when all headphones disonnected from amp! (noise head 10-15 secs). So I have some questions:
1) Why this noise sounds in "problemed" headphone? Why headphone could sound quietly?
2) How could I clean membrane of STAX - alcohol, acetone or something like that?