[edstrelow]

Stax has not made any transformers for their electrostatic phones for many years, going totally over to amplifiers.  I myself have not had a transformer to run Stax phones in over 20 years having also gone totally over to amps..  But I obtained a low bias Stax SRD6 mains-operated transformer a little while back when I got an SR5 phone and finally got around to comparing the sound from the transformer versus an amp,  mostly on an SRM1Mk2.    
 
Whereas the low bias Sigma has a marked high frequency roll-off on the amp ,  I was immediately struck by the fact that the Sigma seemed to have a better tonal balance with the transformer.  I am not sure why this would be.  The amp I used to drive the transformer was an inexpensive  Sherwood rated at 100 watts/channel, normally used to run speakers in the bedroom. While no world beater  it was an improvement over the last amp I used in this setup.  I suppose it's possible that the bias is out of spec either in the SRM1 or the SRD6.
 
However putting the Sigmas back into the SRM1 amp,  I was struck by the fact that I was hearing much more detail and ambience. 
 
Comparing my other low bias phones on these set-ups, I did not hear any advantge in tonal balance with the SRXMk3  or SR5 using the transformer.  Possibly because the Sigma is so inefficient compared to these other phones, it needs a  big power amp to bring it alive and that's what i am hearing.
 
Some users seem quite happy with their transformers but on balance I did not think that using this  transformer was the way for me.   But I wonder how a high bias transformer would sound.  Would you get the same trade-off of balance vs detail and ambience? Also, would  the benefits of a higher quality power amplifier could be heard through a transformer?

 

[John Buchanan]

Ed,
I've been using the Spritzer pro board in a SRD-7 mains powered unit driven by a Studer power amp and it sounds very good, with more apparent oomph than the SRM-Monitor.

 

[edstrelow]

I take it you are running the Sigma/404 this way.  Did you run the 007 from this set-up and if so what did you think of it?

 

[John Buchanan]

Got the SRD-7 after selling the SR-007, so never tried it, Ed. Yes, the Sigma/404 is being run through the SRD-7.

 

[Clarkmc2]

I am currently using a modified SRD-7 with my SR-007Mk2. I previously used an SRM-007tII. The SRD-7 has a Spritzer board and I rewired the box to run the signal direct to the transformers and from there to the socket. One socket is normal bias, the other pro.
 
The SRD-7 driving the O2s is perhaps a touch "slower" than the Stax amp driving directly, but the fidelity is otherwise a significant improvement to my ears. The main factor is surly that I have one of the best amps in the world powering the SRD-7. Not a fair comparison at all. Even set to triode, my little Grommes PHI-26 has power to spare. It has a distortion free MU Stage preamp and plenty of iron for a small amp. Like everyone says, give the Omegas lots of high quality power and the issues disappear.
 
The bottom line is, if you have an amp way better than the dedicated stat amp you have, give the modified box a chance.
 
..............................

 

[n3rdling]

Dedicated amps by far.  The transformer solutions have always sounded like a compromise to me: detail loss, unrealistic dynamics, and higher distortion.  Might as well use dynamic headphones.  This is with multiple different power amps driving the transformer boxes.

 

[Pyriel0]

I am not doubting you this is an honest question. Have you only heard the stax transformer boxes or any customs? I have been toying with the idea of trying stax but I would buy the x75 plitron electrostatic step up transformers to use with my amp. I have wondered for a long time if a high end power amp+high end transformers is as good as a high end stat amp but I don't recall coming across any comparisons.

 

[Clarkmc2]

Spritzer had his high end home brew box at CanJam 2010. I listened to it for a long time but had no stat amps present to compare with. Perhaps someone there had an opportunity to compare directly.
 
I did compare it to my modified /7 box and I have to say there was not much difference between them, subtle I would say. But of course at this level it is about subtleties. The direct wiring and the board may be the most important upgrades. It did sound great! They were being powered by a Grommes PHI-26 into a FirstWatt F2JFET, so the amplification was up to the task.

 

[edstrelow]

What about the Woo Audio Wee transformer? I have heard some good reports.  I don't think that the power amp I have available is good enough to do it justice.

 

[warp08]

Dedicated, by far.  RSA A-10/O2Mk1 combo with some rolled tubes works best for me.  It also works quite nicely with the HE60, so it's worth the investment for me.

 

[dave650]

The original question is a no brainer for me.
I started my electrostat life with an old NAD receiver plugged into an SRD7 and SR5s, and it hummed and was terrible, even though I could tell the SR5s are quite good.
Switch over to a T1 and better Lambdas and havent looked back.

 

[John Buchanan]

The SRD 7 does hum with some amplifiers and not others. No hum with the Studer, some hum with the Audio Research.

 

[dave650]

Yeh I blamed the NAD.
Whenever I go to plan a visit with you I get another bunch of shows up north to do.
Im stuck in Port Hedland all my life.

 

[FrankCooter]

Definite lack of detail and increased distortion when the SRD-7 is compared to a dedicated amp. That said, one wonders what a really high end transformer coupled to a top notch speaker amp would sound like. I haven't measured one, but the SRD-7 transformers look mighty small for their intended purpose. A smaller step-up ratio would also help . The transformer's tonal quality reflects the amplifier behind it. Something like a big 845 DHT amp might put a little extra fullness and body in the midrange that some might find a welcome addition to most electrostatic rigs. After hearing a 300B driven SRD-7, I was intriqued enough to order a pair of high end transformers. If you like a DHT sound signature, it's something worth exploring.
 

 

[TimJo]

I was wondering that myself, and hoping this thread would shed some light. 
 
I've been toying with the idea of getting some HE-6's, and some folks are saying they do best with a higher quality speaker amp. So that got me thinking about transformers, so I could either power the HE-6's directly, or my SR-404LE's using some nice transformers. 
 
Hmmm...