Quote:

spritzer said:

It may function and play music but unless it's been completely rebuilt then it doesn't work perfectly.  All the ES-1 and ES-2 amps have the same problems, single filament supply which is grounded and the tubes really don't like that with -450V on the cathode, the G3 isn't connected on the output tubes which causes some interesting issues, the bias supplies aren't even close to what they should be and the offset adjustment doesn't work so the amp is always stuck at -110V.  Then we can add to that the fun option such as a digital voltmeter to adjust the amp (doesn't work and causes a bunch of issues), the digital volume control which is a huge kit from China which often didn't fit the boxes very well and called for some interesting wiring. 
 
The whole myth that the SP amps were once good and then deteriorated simply isn't true.  The first ES-1 amp was just as fubar as the last ones.  The ones with the most custom stuff are the worst though and any that were sent in for repair Mikhail often stole parts from and substituted with some very cheap crap. 

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That's just too sad.
 
Neil

sad but true. and if you bought some of the tube adapters  (2c51, 3d21 and 12az7 among others) you are
in for even more grief. The biggest issue is still the filament to cathode voltage at the output stage which
causes all the trouble. Since there were 2 seperate windings from the transformer, mikhail could have
fixed this from day one. But he would have needed more wires than the 2 speakon jacks were able to
supply. Turns out there is an 8 pin speakon connector that would have fit the existing chassis hole.
 
So far i'm 35 hours into my rebuild project, the amp is almost done, waiting for a few more parts.
http://gilmore.chem.northwestern.edu/myesx30.jpg

What is even worse is that other manufacturers are just as clueless as Mikhail and there are amps with this exact same problem on sale now. 

Singlepower amps are now what Satan uses for his music.

spritzer said:

What is even worse is that other manufacturers are just as clueless as Mikhail and there are amps with this exact same problem on sale now. 

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Someone told me about this (THANK YOU, WHO KNOW WHO YOU ARE).

I'm very disappointed with the designer. At least they seem to keep up with their orders though .

Kevin, that amp re-build is coming along AWESOME!

Summary of mikhail esx failures
 
1) filament to cathode voltage on the output tubes. known to the stax mafia when the first one blew up.
biggest cause of rather dramatic failures.
 
1a) identical umbilical cables that sometimes cross, and sometimes don't depending on which unit,
and hooking the cables up wrong blows up parts.
 
2) not enough gain requiring messing with seperate attenuators to get the balance right, and it drifts
with time.
 
3) unregulated power supply that runs 400v caps at more than 450v
 
4) output tubes actually biased at -110v which when combined with the 450v actual power supply voltage
does get close to the right bias for the headphones, but limits total voltage swing to 1000 vppss.
 
5) G3 on the output tubes never wired to anything. This one is new, just found it, and then checked
all previous amps, and mikhail left G3 floating. For true pentodes like the 6ca7, this is a really bad idea.
Also causes changes in sound quality with tubes and over time.
 
6) tube adapters that are not symmetric, and not labeled and do wierd things when put on the wrong side.
This one is also new
 
7) xlr connectors with the locking pins forcibly removed doing damage to the connectors.
 
8) cheap ultra junk ceramic sockets from god knows where that rust and crack when you try to
unsolder them.
 
9) power transformers that make absolutely no sense whatsoever. Enough power to run 10 amplifiers
(highly unusual for mikhail) but all the wrong voltages.
 
10) expensive coupling caps (audio note and similar things) not rated for the >600 volts required.
 
11) digital step attenuator.  Don't get me started on this one, what a waste of $600 in parts.
 
12) digital voltmeter. Even worse, and besides which it could not measure the output bias, which
was not adjustable anyway. The prestage bias, is really set once and forget it.
 
13) preamp output. OH my god you gotta be kidding. And what a waste of blackgate capacitors.
 
14) input switching with -30db of crosstalk.
 
stay tuned, i may find more fail once i get to the rest of the power supply.

Boy, does this thread bring back some bilious memories.
 
If there is any justice in this world, Mikhail is stuck in the eternal elevator with naught but the the crazy frog song on endless loop.

WOW... I haven't been around HF in 5-6 years.  I come back, looking for an amp upgrade for my RS1, HF1, HD580 and Koss A250 and I read this thread.  How sad, I remember how much I enjoyed the PPX3 slam I demo'd all my cans with.  I remember meeting Mikhail, chatting with him briefly and shaking his hand at a bigger meet.
 
Hope you all get this resolved.

My MPX3 still looks good and sounds good, although the resale value is zip. I no longer run it in "high power" mode and have found a tube set I prefer that shouldn't cause it any stress. It's a shame the way this all turned out.
 
- augustwest

I've had the "killer" at a few HD 800 owner homes and they really liked it. The TS 5998 do a great job adding bass weight. I think those that have a good running unit just shut up and kept them because they did sound so good. What else are ya gonna do with em? I think of all the black gate caps when these things were trashed.

Quote:

happy camper said:

I've had the "killer" at a few HD 800 owner homes and they really liked it. The TS 5998 do a great job adding bass weight. I think those that have a good running unit just shut up and kept them because they did sound so good. What else are ya gonna do with em? I think of all the black gate caps when these things were trashed.

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My heavily upgraded SDS continues to sound mighty fine after all these years.  It continues to sound better than any dynamic amplifiers that I throw at it including my Gilmore Reference Balanced (an equivalent the the mighty Headamp GS-X), Zana Deux, and Woo 5.  I wish Mikhail will do right to his customers.  By now he should have plenty of funds to pay them back given that he made plenty of money from his tube listings on ebay under "Suprabuyer".

im owed 10k to this day

My MPX3 still looks good and sounds good, although the resale value is zip. I no longer run it in "high power" mode
and have found a tube set I prefer that shouldn't cause it any stress. It's a shame the way this all turned out
    What is " high power"  mode?
    I recently acquired the MPX3 and is now using it with the HD800 without any problem and the HD800 is singing
beautifully with no problem with its bass at all.  I plan to use it with the R10 's and may consider the 5687's  will there
be any precaution that I should consider?

"hi power" mode is actually higher voltage mode, and you definitely do not want to run it this way,