• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

The end of tubes?

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An SS kilowatt amplifier is way complicated, while a kilowatt tube amp is quite simple.

You-must-be-joking :rolleyes:

This is a 1000W tube amplifier.

const9g.jpg


It is way larger than it looks in a picture, those are not KT88 or similar but 813, now scale your mental image up by 3X or 4X

const9f.jpg


Don´t worry, supply "only" runs at 2500V DC .... just what the Doctor ordered for a homemade:

An externally hosted image should be here but it was not working when we last tested it.
 
You-must-be-joking :rolleyes:

I didn't say it was smaller, I said it was simpler. My 300 watt is about the size of a small microwave oven, The PS is inside a large microwave oven cabinet.
But way simple, with P to P wiring, and components that even my fat fingers can handle. ;)

2.5kv for 4 813s? I'm feeding one 813 at that, and when I decide to add a tube, I'll feed the pair with about 4kv. But I'll need two more diodes for a bridge.
 
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I'm feeding one 813 at that, and when I decide to add a tube, I'll feed the pair with about 4kv.

And they won't like it. Max continuous plate voltage rating is 2250 volts, intermittent ham radio service shows 2500 volts. The most I have heard of on 813's was just under 3KV and that was in an RF amplifier.

4KV in an audio amp would require an "impossible" OPT. You would need a P-P load impedance of 25,000 ohms or more and it would need to be insulated for about 10 KV.......can't get that at Walmart. I'm guessing the guy who built that 1000 watt guitar amp used 4 813's to get his load impedance down to under 10K and then wound the transformer himself.

My 1KW amp will use TV sweep tubes on less than 700 volts. The load impedance will be 1250 ohms for each of the 500 watt channels. Not necessarily a simple design, but a whole lot easier and safer than wiring up old sparky (the electric chair) in the listening room.
 
People often say that "X technology will be gone in the next five years". How many times have they said "The desktop PC will be gone in the next five years", yet here we are. The reality is, manufacturers don't stop manufacturing a product if people want it. And just because something is "theoretically better" or more practical does not mean that everyone will want to use that.

At the same time, we have all heard "In five years time we will all be using tablets for everything". Yet tablets really aren't much more prevalent now than they were a few years ago.

And let's be honest, the 9-year-old boy inside all of us desires things that glow in the dark, are moderately dangerous and extremely inefficient.

And that's the reason that 2A3s and enormous Cadillacs are still made. No they don't make sense, but people love them.
 
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