DIYbanter - View Single Post

isw

In article ,
wrote:

I want to build a tube power amp for my stereo. Tubes have always had
the best sound. Actually two amps, one for each channel. First off,
what tubes can I use in Push-Pull Parallel to achieve at least 1000
watts RMS per channel. I want real power. Not peak to peak, but true
RMS.

Secondly, where can I obtain the output transformers, or will I
have to have them custom made, and where?

When I was much younger I had two amps that used 4 6L6 tubes in
push-pull parallel and I was able to achieve about 120 watts per
channel. The sound was great, but 6L6 tubes have their limits on
power, and tend to be noisy (at least the old ones did, as I had to
shock mount the amps to prevent feedback thru the tubes.

Going with 1000 watts, I will need much more control and tubes that
can handle the abuse. In reality, I'd like to go for 2500 or even
5000 watts per channel, but I doubt any tubes can handle that.

It used to be done all the time. While in college, I babysat an RCA
BTA-50F1 (almost the last of the plate-modulated 50 kilowatt AM
transmitters). The modulator delivered a cool 25,000 watts of tolerably
clean audio. The transmitter was on the second floor; the entire first
floor was the plenum for the blowers.

I suggest you look for a couple of old AM broadcast transmitters, and
extract the modulation transformers and audio circuits, for a good
starting place.

Then, I suggest that you learn exactly what the performance differences
are between tube and solid state amplifiers. Pay special attention to
what those output transformers do to the frequency and phase response.

Prepare to rewire your listening room, too, because if you don't,
there's no way you're getting a kilowatt -- much less a stereo pair of
kilowatts -- of output from a tube amp connected to a normal outlet.
With a switchmode solid-state job and special attention to efficiency,
maybe.

Isaac