The Stax Thread III

[Pier Paolo]

i know, but there is. -70 V. If I unplug the amp it goes to zero.

 

[georgep]

Weird. The voltage should at least rapidly decline once you switch the power off.... Can you post a photo of how you are measuring as well as tell us which pots you are adjusting to affect balance and offset. Also, was this unit modified in any way by a previous owner?

 

[Pier Paolo]

The unit is a 600ltd. I measure with a multimeter in VDC at the right scale. I read the dc balance for left channel at pins 1 (+) and 5(-) and right channel at pins 3 and 4 (clockwise starting from NOON. I measure offset at positive pin of each channel and negative at ground on the rear panel. I rotate the balance pot for dc balance and the offset pot for offset for each channel. The unit is not modified at all.

 

[georgep]

I am not familar with that model, but understand that Stax normally has the pots labelled backwards - so "balance" would adjust offset and "offset" would adjust balance. Spritzer would be able to confirm this. Still puzzled by your -70v though....

 

[Pier Paolo]

Ah, I forgot to mention that the sound was distorted as soon as the volume pass the 5 mark (12)

 

[georgep]

" at pins 3 and 4"

Sorry, you mean pins 2 and 4? I think based on your numbering, that pin 3 is bias, not output.

Also, why were you adjusting the unit to start with - did it have the distortion before you started adjusting?

 

[Pier Paolo]

Yes, 2 and 4 and yes it was distorted after half volume

 

[DefQon]

ECC99 tubes gone bad? Pop the cover off and see if anything is burnt or out of the norm, including the solder tracers underneath the board as well for any shorts. AC voltage input set to correct matching country AC.

 

[kevin gilmore]

A number of these units had bad plate resistors.

Measure the resistance with the power off for at least 30 minutes.

 

[tdogzthmn]

I have a modded SRM-600 Limited and think it sounds wonderful.  Some shots of the interior.
 

 

 

 

[eric65]

Hello everyone,
 
Always, for information.
 
SRM T2 amp listening seems to be improving "hot".
 
 
 
 

 

 

 

 

 
Here an direct comparison for SRM T2 Vs SRM 727 on 009 and an indirect comparison for SRM T2, Vs SRM 727 Vs RKV-WEE on 009 (with not shunted and shunted Wee transformers)
 
See links (in french)
(you can use google translator)
 
http://www.homecinema-fr.com/forum/post177810847.html#p177810847
 
http://www.homecinema-fr.com/forum/post177811772.html#p177811772
 
PS : It used SRM T2 is currently for sale in France
 
http://www.casques-headphones.com/les-bonnes-affaires/381-stax-srm-t2.html#

 

[Pier Paolo]

Thank You all.
Kevin, I will check everything. Do you have a schematic, please? I have got a 600 schematic but I would prefere the 600ltd one to be sure.

 

[kevin gilmore]

no difference between the two as far as I know. will look later.

 

[Dafo]

I preferred the 202 off my Xh, 212 and the 252 from the 207 package than my 323S. The LP and 404 was nice off the 323S. Not a bad amp I must say.

Why do you prefer the 252 to the 323s?

 

[Pier Paolo]

Ok, tonight, home from work, I will check.
TKS again