Neutral header on OPTs
rec.audio.tubes

I dont actually know where the Velleman K4000 trannies came from, Tom. But a good guess would be Antrim Transformers, in Northern Ireland. They are winders to just about everyone capable of defining a proper spec and who want a fair number of units. Quite a few of the famous European brand names have no windery of their own, only the Antrim works.

What are you going to build in the case instead? Those trannies were designed for 3x EL34, so theres nothing commonplace about them. And the case is a nice piece of polished stainless, but there isnt space for big film caps in the bellypan, and even the plain painted steel bits are pretty substantial, so as little metalwork as a few extra holes will be a pain. (Listen to Mr Soft Ali speak!)

I still have mine in a box in a store, just in case I ever want to put subs back in my system, or my son wants a proper big tube amp.

Do you remember the primary impedance of the OPT?

For the rest of you, Tom and I are discussing an early incarnation of the bestselling kit amp in the world, the Velleman K4040. I dont know what the procise configuration is now, but the K4000 was a PPP EL34 Class A/B with 18W in Class A and 96W in Class B into 8ohms. That was on the spec. Mine actually put out 101W at the spec input of 0V775 and could be substantially overdriven without adverse effects. It was like Jekyll and Hyde, a delicate enough amp into sensitive speakers but a monster when driving big bass bins. I loved it for being a lot of amp for a really very reasonable price. It cost about 500 quid when the best EL34 tube kit of the day, the Audio Innovations Classic 25, intended for an entirely different sort of owner and application (a purist EL34 PP amp, 25W strictly in Class A1), was 700 quid. The Chinese seem to me even today to be hard put to match Vellemans price, if you consider quality for quality.

Andre Jute

Tom Schlangen wrote:

Hello Andre,

just out of curiosity, if I remember correctly, you
once had a very favourable article/review on the
Velleman K4000 on your old homepage, so you might
know what origin these toroid OPTs are from?

I tried to get the answer from Velleman already
(I have a very early K4000 in my living room,
and my aim is to replace it with a completely
homebrew amp) but they only wrote something like
"made to Velleman specs" without getting any more
precise.

Tom

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