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Vintage Stax repair and maintenance - Page 5

post #61 of 165

Hi everybody,

 

I'm new here but am pretty sure I'm supposed to say this here:

Some time ago I bought an amp and speakers from an old man who didn't hear well anymore, but I didn't come here to talk about that.

The fact is that with this purchase he gave me as a present an old pair of SR-40 (with its SRD-4) because those didn't worked well anymore, the right side was clearly quieter than the left one and if I tried to balance the volume (through my amp) to equalize both sides the right side's quality went off and everything sounded fried, so I quickly gave up, connecting back my speakers to the amp. At this time I had my speakers connected to the SRD-4 for a while and don't remember of anything not working correctly aside from the headphones (but my memory's sometime terrible).

 

This was more than a year ago now, and recently decided to give these headphones another shot, so I connected the SRD-4 to my amp (the same one) and my speakers, this time the right side did not emit any sound, and when turned on loudspeaker mode my right speaker do not do anything as well. So in the end I've got headphones with only the left side producing music (and with a pretty good quality at that) when the SRD-4 is turned on earspeaker mode and only my right speaker working when the SRD-4 is on loudspeaker mode.

 

I apologize if this post does not belong here, thank you for reading this and I hope to get answers from you.

post #62 of 165

Since no one bothered answering I will give it a shot.

 

SR-40's have electret transducers which have a fixed bias charge rather than a true electrostatic transducer requiring bias charge from the amp or energiser off speaker taps of an integrated amp.

 

You're pretty much out of luck as you can't fix the right drivers due to the pre-fixed bias, which is a downside as electrets can lose it's charge over time..

post #63 of 165

An electret will in fact not loose its charge with time.  What happens is the same phenomenon as with "normal" electrostatics, a charge sits on the diaphragm and thus lowers the sensitivity.  No way to get to the diaphragm though so removing it is all but impossible. 

post #64 of 165

Good to learn something everyday. :o

 

I had a few SR-40/30's that had massive imbalance problems leaving me no choice to sell them off for cheap parts or disposed. 

post #65 of 165
Quote:
Originally Posted by spritzer View Post
 

An electret will in fact not loose its charge with time.  What happens is the same phenomenon as with "normal" electrostatics, a charge sits on the diaphragm and thus lowers the sensitivity.  No way to get to the diaphragm though so removing it is all but impossible. 

 

Does this mean that it's not good to leave electrostats (not electrostets) unused for any amount of time?  I've assembled a few vintage pairs and generally keep them in rotation, but will the charge sitting on usued electrostats lower the sensitivity permanently?  And the same phenonemon on newer stats, i.e. 007 and 009? Thank you for the advice.

post #66 of 165
No, not really. There is no way to predict this behavior.
post #67 of 165
Quote:
Originally Posted by spritzer View Post

No, not really. There is no way to predict this behavior.

 

Thank you, Spritzer.  As always a big help.

post #68 of 165

Subscribed

post #69 of 165

I opened up my SRD-4 out of curiosity & found a very simple circuit: a pair of big ceramic caps (Murata  P T H     BD4R7M) and a pair of fairly rude looking wirewound ceramic resistors (5W 27ohm.)  Does anybody know what value the Murata has?  I'm thinking the ease of upgrade would be quick fun, if nothing else.  My 40's sound good, but an inadvertant yank on the cables introduced an intermitant open circuit.  The bass is definitely weak.  Has anyone played with this?  I get nothing from my Murata search online.  Thanks!

post #70 of 165

That Murata part is a thermistor, not a capacitor.  No meaningful benefits from upgrading it unless they are broken. 

post #71 of 165

Dear Forum!  Does anyone here encountered with this product ( CPY/ECP phono cartridge and it's transformer ) of STAX?

post #72 of 165

I've never bought one as the odds aren't good that these are still working 100% and well... I don't like vinyl.  :o  It's a neat system though but let down by the preamp. 

post #73 of 165
yes I own one, have not used it in over 35 years. Was very good in its
Time. Battery is a problem
post #74 of 165

Hello,

 

I have here a vintage Stax SRD-X Professional amp with the Stax 12V 400mA power supply. The amp works well with normal bias phones but with pro phones it works only well about that two minutes then the sound gradually fades to become inaudible.

 

Where is the problem and how can i fix them?

 

Thanks!

post #75 of 165

Oh, ok, because there is a set up for sale now at the Bay that has some shortcomings those can be repaired. I am using an old Shure ED95 stylus that I've found great, so don't know if it is worth the upgrade of course after a successful renovation.


Edited by Nemeske88 - 11/3/13 at 1:18pm
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