[Knijsterbek]

Quote:

I have a chance to get this spritzer restored srm-1 mkII PP.  According to the description, it seems to be no problem to be re-wired to 110V for US voltage.  I have PM spritzer but got not reply yet.  Can anyone here familiar with it may confirm that there is no problem to do so?  And maybe kindly point me to the links (i remember reading it somewhere in the past) to re-wire it for 110V.
 
Thanks a lot!

This is what I found on the net:
 
[size=10pt]Here is the correct wiring:[/size]
[size=10pt]100v:
Gray+White
White wire from the  ACplug+Brown+Green

117v:
Gray+White
White wire from the AC plug+Blue+Purple

240v:
Blue+White wire from the AC plug
Purple+Gray[/size]
[size=10pt]Should work for all Stax amps. [/size]
 
Pic of the wiring:
 
 
 
Good luck.
 

 

[dukja]

Thank you all who helped and provided the links.   I hope that Stax did not cut the wires of the transformer in SRM-1 (series-C) so the conversion should be straightforward.  Is it the case?
 
And it seems that I need to re-bias and balance the amp after converting it to 110V, right?  (Oops! getting more complicated...)
 
Quote:

This is what I found on the net:
 
[size=10pt]Here is the correct wiring:[/size]
 
[size=10pt]100v:
Gray+White
White wire from the  ACplug+Brown+Green

117v:
Gray+White
White wire from the AC plug+Blue+Purple

240v:
Blue+White wire from the AC plug
Purple+Gray[/size]
 
[size=10pt]Should work for all Stax amps. [/size]
 
 
Pic of the wiring:
 
 
 
Good luck.
 

 

 

[Knijsterbek]

Mine is C4245 and has all the wires.
Re-bias is always a good idea. Adjust balance and offset for 0V DC. Repeat measurements a few times.
Remember that the power supply is not regulated, so your measurements will change as mains voltage changes.
Also, the bias fluctuates heavy with the actual temperature of the amp. Let it heat up until it is stable and measure before/while you lift the top off. In my experience, the moment you remove the top, especially offset starts to drift.
I try to monitor how much it has drifted until I actually turn the pot and try to correct for that, so that when the top is on and the temp is stable again, the setting stabilizes around zero.
After that, start enjoying!

 

[dukja]

Just finish reading all links.  One more question about rewiring the transformer to 110V.  So I just need to solder
 
Gray to White wire
White wire from AC to Blue and Purple
 
And I should NOT need to solder those wire to the "back panel" with 2x6 holes, right?
(I imagine those were for the user's convenience to change voltage but is not disabled by Stax.)
 
Thanks for the confirmation.
 
Is there any way to test before firing up and potentially damage anything?

 

[Knijsterbek]

Quote:

Just finish reading all links.  One more question about rewiring the transformer to 110V.  So I just need to solder
 
Gray to White wire
White wire from AC to Blue and Purple
 
And I should NOT need to solder those wire to the "back panel" with 2x6 holes, right?
(I imagine those were for the user's convenience to change voltage but is not disabled by Stax.)

Wiring is correct.
The back panel was meant for the versions that were shipped with a plug to change the mains voltage in a more comfortable way...

.
If you don't use the plug, you don't need the back panel.
But: be carefull and convince yourself that the connections you make by pulling wires off the back panel and soldering them together are properly isolated!
 
 
Quote:

 
Is there any way to test before firing up and potentially damage anything?

With a variac, you could slowly turm up the mains voltage and check secondary voltages.
 
 

 

[dukja]

Thanks for the confirmation.
 
And I assumed a signal generator may be used to generate 60Hz a few volt signal for input and check the secondary side (the RED wire in your diagram?).  What is the voltage should I expect (step-up or -down ratio)?
 
Thanks!
 
Quote:

With a variac, you could slowly turm up the mains voltage and check secondary voltages.

Originally Posted by Knijsterbek /img/forum/go_quote.gif

 
 
 

 

 

[Leonardo Drummond]

Quote:

I'd just recap the unit and do the opamp upgrade for the EAD stuff.  The rest of those mods don't seem very important unless you want balanced.

 


Quote:

Depends on which vintage DAC you're talking about, but I think in most cases yes, they can outperform new DACs for similar money. Check out Computerparts' vintage DAC thread for much more in depth opinions on some of the great classic DACs. 
 
Rather than upgrade your iMac, consider adding an ART Legato USB > S/Pdif converter. That should provide a huge improvement over toslink straight from the computer, and it should handily beat the PS3's digital out as well. It only does 16/44, but with a vintage R2R DAC that's all you can use anyway.
 

Thanks again guys, I really appreciate your help!

 

 

[Knijsterbek]

Quote:

Thanks for the confirmation.
 
And I assumed a signal generator may be used to generate 60Hz a few volt signal for input and check the secondary side (the RED wire in your diagram?).  What is the voltage should I expect (step-up or -down ratio)?
 
Thanks!
 

In mine, which is wired for 240V, with AC mains of 230V, I measure 39V between the red secundairies and 480V between the yellow secundaries.
So red would be step down and yellow would be step up.
 
Here is the schematic whee you can also see the details of the transformer wiring.
 

 

[dukja]

Thanks a lot for the schematic.  Is there pdf or image file floating around?  It is nice that you even have a paper copy but it is a little bit hard to read the details...
 
And the transformer shown on the new image has different secondary?
 
I think that I am ready to get the amp. 

 
Quote:

In mine, which is wired for 240V, with AC mains of 230V, I measure 39V between the red secundairies and 480V between the yellow secundaries.
So red would be step down and yellow would be step up.
 
Here is the schematic whee you can also see the details of the transformer wiring.

 

 

[Knijsterbek]

This is all I got. It was once posted by Spritzer, so we would have to thank him....
If you save the jpeg and open it in a viewer it is a rather large file and easy to read.
 
The previous transformer wiring pic is from a valve amp (6.3V heater supply secundairy).
Bottom line: primary wiring is the same, secondairy can vary between different amps.
 
Good luck with the amp. I still have to find the time to modify mine to balanced...

 

[dukja]

Got it.  The original file is much nicer.  It is precious.  Thanks to spritzer!
 
You probably read the info about modding it to balance at other place.  The difficulty seem to get the 4-gang pot.  Or try alternative approach? 
 
Thanks a lot for helping out during spritzer's absence.
 
Quote:

This is all I got. It was once posted by Spritzer, so we would have to thank him....
If you save the jpeg and open it in a viewer it is a rather large file and easy to read.
 
The previous transformer wiring pic is from a valve amp (6.3V heater supply secundairy).
Bottom line: primary wiring is the same, secondairy can vary between different amps.
 
Good luck with the amp. I still have to find the time to modify mine to balanced...

 

 

[shipsupt]

Well, I didn't expect my first post to the "high-end" forum to be after a just over 300 dollar purchase.... but here I am. As luck would have it another Head-Fi member was struck with upgraditis which gave me the chance to pick up his SR-202/SRM 252A combo and give electrostatics a try. Don't let out the secret, but these sound great, especially considering the cost! I have to say that since they arrived I can't seem to get them off my head, I'm enjoying them that much. Last night I was just letting the tunes come randomly from iTunes, not cherry picking, and an Elvis Costello song cued up (I Want You) and I had one of those moments in this hobby where you just get floored. It was that good.

I guess the down side is that I've entered another arena where the slope can get quite slippery.... I'm sure my Stax journey does not end here, but for now I'm really glad that I took a chance to see what all the hype is about.

That's it really, just wanted to post up because I'm having fun enjoying music with some new kit, and let others know that entry into the high-end doesn't need to come with a huge price tag. Keep an eye out for these entry level deals, they really are worth a try.

 

[livewire]

Surprisingly good, arent they? You got a great deal. You are at slippery slope - tier #1.
 
The slope looks like this: $500 - $1k - $2K - $4K - $11K - $30K<----ridiculous!!!
You may leapfrog as your wallet sees fit.
 
I'm currently at the third tier.
I want to be at the fifth = BHSE + SR-009.
Time to win the lottery or sell off a kid....

 

[Hammerzeit]

Dang! Only over $300!? That's a great deal. Livewire I'd go with the latter hahaha. Only one more month before I have enough for a deposit on the bhse with the rk50 1-2 years...to go...

 

[livewire]

Hey - it's only time and money.
But then so much can happen during that waiting period,
Stay the course, the rewards will be worth it!