Nice valve amp with 8 x KT88…would you like one of these?


David Davis

This is in the process of being built now. it is basically a Williamson but updated and improved using modern components. Copies would be between £4,000 and £5,000. And you’d have to have it without the Avro-Lancaster-T1154 meters, as I only have one more,

It uses 4 x KT88 in each output stage. But lesser copies could be built using 6L6 output valves, for about £2,000.

I designed the entire transformer set of four myself, and they were specially wound to order by a good maker in England. An identical set would cost about £1,000 of the total price, like a Bentley or an Aston Martin. You could have lesser ones of course, which would work perfectly well, like a Peugeot, for less than £500 of it.

The specifications are as follows:-

(1) Two channels, VERY conservatively rated at 50Watts RMS per channel.

(2) Total Harmonic distortion <0.7% between 30Hz and 30KHz.

(3) Outputs to speakers 4, 8 or 16 ohms.

(4) 40-volts DC aux power supply for preamp using valves or transistors.

(5) variable or removable neg-feedback.

(6) Front-panel meters from recycled Lancaster bombers (you will not be able to have any more of this pattern as this was the last pair I owned, but others could be subbed.)

(7) Optional high-voltage-delay for valves (heaters on first).

Those of you who knnow about audio/HiFi and valves also know that there is a certain indefinable something about the valve sound. Yes of course transistor amps are perfectly faithful to the signal and in some ways even more reliable and  responsive, but …. it’s not like that entirely. Valve stuff just, well, sounds better to the human ear.

If you would like a Williamson, get in touch. I am happy to make it entirely to your order, and will quote bespoke accordingly. In a recession, Libertarians have got to do what they have got to do.

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6 responses to “Nice valve amp with 8 x KT88…would you like one of these?

  1. Pingback: Cloth-eared git « The Landed Underclass

  2. Steven Northwood

    Well it looks fantastic David. You know, there’s surely loads of money to be made making things like that, especially in the right circles, people who kit out venues like pubs and so on, they love stuff like that. I’ve never heard one of those things play, but I seem to remember James May doing a programme about those valve thingys, and how they were a revolutionary invention at the time. Alas, I’m more of a transistor man myself. :-)

  3. Steven, it won’t “be” any “better”, in scientifically measurable terms, than your average 19-inch-rack-transistor-silver-box, from the good people at Pioneer, Trio-Kenwood etc.

    It will look beautiful in his big house though, and the sound will reverberate stunningly.

    However, although I _know_ that the output of a modern push-pull-MOSFET amp is as near absolutely faithful in its bandwidth as can be realistically achieved, it is true, even to me subjectively, that valve amps do sound somewhat “different”. It’s probably the distortion they introduce, mainly via the output transformers, which are unavoidable as imperdance-matchers between the valves and the speakers.

    I’ve thought of using instead 20 valves per channel, in parallel in the output, and connecting the speaker in series with the 20 anode(s). But I think that’s overkill, and he’d have to turn down his central heating to compensate.

  4. Pingback: Valve amp coming along nicely « The Libertarian Alliance: BLOG

  5. Mr Krishna Murthy

    Hi David,

    I’ve seen the video and am interested in hearing or reading a review when you finish making it.

    I am quite keen on Amplifiers based on the KT88.

    Please could you get in touch so we can communicate on your amp.

    Regards

    Krishna Murthy

  6. Certainly Krishna. I aim to actually test it out in the next few days as I have nearly finished the PA stages.