[kschac]

I wanted to post a belated note of thanks to Roger Modjeski for help WAY above and beyond the call of any normal manufacturer.  About two weeks ago, I fired up my RM200, which I hadn't used in about two months (I tend to use my cooler-running McCormack DNA500 in the hotter months).  I noticed severe clipping in one channel and then could not get a bias reading from one of the power tubes.  I should mention that I did not buy the RM200 new.  I bought a one year old unit off Audiogon about a year ago.

I decided to call Roger -- on a Saturday afternoon -- thinking I would just leave a message on his voice mail.  Well, Roger picked up the phone and proceeded to spend a good 90 minutes on the phone with me, walking an electronic near-idiot (me) ever-so-patiently through a series of very logical steps designed to determine if the problem was a power tube (it wasn't), a fuse (no, not that either) or maybe a driver tube (the likely culprit, by process of elimination).  By the end of the marathon call, the problem had actually blossomed a bit - I was now getting no bias from two of the four tube sockets.  We decided it was best to order a new pair of driver tubes and see if that would rectify things.

Since I had been away on business most of the last 2 weeks, I finally was able to install the new tubes I purchased from RAM Labs last night.  At first, things looked bad -- more distortion in one channel -- and I was ready to call poor Roger again. I left to watch the World Series and returned to see that half of my equipment had shut itself off.  I recycled my PS Audio Power Plant and brought the equipment to life again, wondering what caused it to shut off.  Then I noticed the tubes in the RM200 were cold, which was weird since it had been on a while. Then - the flash of insight.  Could it be that the RM200 was plugged into the Power Plant by accident? Sure enough, that was it.  The amp draws way too much power for the Power Plant, which resulted in the shut off and, I think, the anomalies I had experienced.  I felt pretty stupid, but at least I knew what was going on.

After some power cord swapping, I had reconfigured the RM200 to draw current from the wall, and everything was better.  The amp sounded great and everything was back to normal.

Anyway, this is  a long-winded thank you to Roger for his extraordinary patience that Saturday afternoon with someone who, as I told Roger, had not even bought the amp new (and an apology for making him think his amp was misbehaving).  Amazing customer service from Music Reference.

Thanks again, Roger.

[Roger A. Modjeski]

Thanks for the posting. We had a good conversation as I recall.

To all who are interested here is what I think about power conditioning:

I do not recommend power conditioners for any of my designs as I have gone to considerable effort to make them extremely line tolerant. All my preamps have very tight voltage regulation. All my power amps have excellent bias stability. There is no need to condition the power in any way. There is no need for fancy power cords. Dedicated lines are nice but usually not needed unless your audio outlets are shared with some large appliances.

The internal resistances of my power transformers are minimized so as to provide high peak currents when needed. Powerline filters and conditioners add resistance and thus limit these high peak currents. It's very hard to get a power transformer primary down to two ohms so let's not add any unwanted ohms to that. It defeats the purpose doesn't it?

I also doubt any of the power re-generators can provide 10-15 amps of peak current. I would be happy to hear whether they can or can't.

Roger