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ress4278 1st April 2009 03:30 AM

Threshold 400 a
My amp is in CA. w/ Jon Soderbergh, (Vintage Amp Repair) awaiting a final diagnosis. I've hesitated to say something but I have to warn people. There is a man named Ken Ealy (Easly maybe) who stated he had some ideas about repairing/upgrading the amp. He retrofitted a bunch of stuff into the amp that Jon is now trying to undo to make it work. The thing came back to me twice from Ken after two repair attempts. It cost me $360.00 in parts and labor, (not including the shipping) and the damn thing oscillates so badly it is unusable. I would think twice before sending Ken any repairs, at least.on this amp.

anatech 1st April 2009 03:41 AM

Hi ress4278,
Sorry to hear about that.

The problem you are having with "hack upgrades" is a common one all over the place. I get a steady stream of the same thing for repair.

I'm going to bet that Jon is not happy about this. It means more total money for him, but he will lose money on the job. That's the normal way these go. It certainly never makes me happy when I see a customer that has been taken.

I wouldn't send this technician any more work for anything. Nothing. He should have refunded you at least all the labour, assuming he didn't mark up the parts too high. If that is also the case, some of the parts as well.

The fact that he dove in and changed things right off the cuff, and they didn't work, says volumes. The questions are, if the amp was oscillating, why didn't he catch that before shipping it out?? Why didn't he test the amps to at least meet it's specifications? That should have showed this problem as well. Why didn't he run the amplifier for some time before releasing it?

I am suspicious that he may not have the required test equipment. I also suspect he doesn't really know that much, but he is probably very proud.


Heiney9 2nd April 2009 05:57 PM

Is this the guy?

Thought about sending him and Acurus pre-amp.......but maybe not.

anatech 2nd April 2009 10:16 PM


Seems scary and not a little arrogant! I didn't see the kind of test equipment that would allow proper testing either.

I read he removes the output inductors in amplifiers (!!!!!). Believe me when I say that manufacturers would not install them if they were not a critical part.

I honestly do not think he understands how amplifiers actually work. It seems to be more a collection of "upgrades" done by non-technical people. I wonder how many of his victims are out there, possibly oscillating themselves to death. BTW, simply removing that output inductor is enough to allow the amplifier to become unstable and oscillate.


m2003br 3rd April 2009 10:35 PM

Happily the 400A donīt have output coils in your native condition:D

anatech 4th April 2009 12:32 AM

Hi m2003br,

Happily the 400A donīt have output coils in your native condition
True. The 400A does not.

However, I was responding to a comment on his site where he stated that he actually removes the existing coil on amplifiers (not specified as it is a general case). This is in fact a reckless and completely irresponsible thing to do. I stand by my statements.

Why not have a look at his site and let us know if you agree with his policies and methods?


m2003br 4th April 2009 01:35 AM

Hi Chris,
It's not my intention to go against your oppinion. my only purpose is to comment about the amp of "ress4278" which have escaped from being stripped, because it already don't have an output coil.
I'm not a fan of mods in classic gear, and my own 400A is nearly 100% original, and have a very good sound, a kind of spectral cleanness not so often seen and a very good bass too.
My believing is: leave the classics untouched and only making "upgrades" im my own projects.


anatech 4th April 2009 02:03 AM

Hi Marcos,
I just wanted to make this clear to casual observers. I was not upset at all.

So, have you had a look at what this fellow does? You really have to have a look. There are many out there like him.


I'm not a fan of mods in classic gear
Nor am I, unless you are correcting a very real design problem that does cause issues with reliability. Then do the minimal.


My believing is: leave the classics untouched and only making "upgrades" im my own projects.
We think the same way. I can't tell you how happy I am every time I find another person that has respect for older equipment and engineers.

The one thing I will do to a classic piece is to match the transistors where the design assumes that is the case. If you have not done so in your amp, try it. The sound quality will improve again. Replace all the non-NP0/C0G ceramic capacitors with these types if you want to stay true to the original appearance. Another big improvement if you haven't done so.


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