• 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.

Which diy valve amp without valve sound?


please recommend me a very good and simple to diy valve (integrated) amp with excellent sound (and preferably point to point wiring).

I am a huge Naim fan and only once tried valves: since SE triode was recommended to me as the only and real truth (I knew that such thing doesn't exist) I tried a KR audio integrated amp called VA350i with incredible big T100 valves and a very clean sound, but after 1,5 years returned to Naim, preferring even the smallest integrated to the KR: the Naim sounded dirty in comparison, but much more involving. And it never stopped annoying me that the KR made a kind of "ringing" sound, especially noticable in solo piano recordings, that sounded as if there was an empty wine glas standing somewhere on the piano and adding some strange harmonics which made the piano sound wrong, although I was really impressed how the KR removed all the fuzzyness, untidyness and smokyness I was used to. Don't get me wrong: some bigger Naim amps do sound exceptionally clear and open, but in my memory even the 500 (at that time non-DR) series sounded "dirty" in comparison to the KR...

I learned that this must be the famous valve sound so many rave about. But I thought I didn't like that ringing. Of course after I went back to Naim (now building my own clones) I missed that clear sound of the KRs and never forgot how open they sounded...

So is it possible to get all of this but without that ringing or whatever it's called?


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That ringing you complain of may have several causes--2nd order harmonics (high in SE tube amps), or the output transformer hitting its high-frequency limits and causing a ringing or hardness in the sound--or, literally, the tubes themselves acting microphonic and producing a "feedback" effect from the speakers.

To answer your question, yes, there are clean-sounding, non-ringing DIY amps out there. I would steer you toward a push-pull amplifier for the cleaner harmonics, more power and better bandwidth (especially for piano!!!).

Elekit makes a push-pull kit that is very popular. Also Tubes4HiFi sells kits for classic Dynaco amplifiers. It's hard to go wrong with those. The ST35 is a classic, a very nice 15wpc.

I'm a big proponent of the classic Williamson amplifier, which first appeared in the late '40s and was extremely popular with DIYers through the 1950s, when it was superceded by other designs offering more power. Typically they are 12wpc (triode) or 24wpc (ultralinear). The original Williamson was an "all triode" design (using triode-wired KT66s) and IMO it's very hard to beat for bandwidth, beauty of tone and naturalness of reproduction. Instruments and voices sound "right." The tricky thing about a Williamson is that the output transformer has to be very good, and you have to design the feedback network carefully or they can oscillate--another thing that eventually caused them to fall from favor.

I recently commissioned a PCB for the classic Williamson from a fellow forum member. It's a 6" x 8" board that holds everything except the transformers, the rectifier, the first capacitor and the balancing pot for the output tubes. The power trannies and chokes are available from Hammond, and the recommended output transformer is a copy of the marvelous Peerless S-265-Q output transformer made by Heyboer. I'm contemplating a "kit" but that involves a huge amount of planning and investment and I'm not there yet ;-). I built a prototype, which you can see below. The cost was about the same as the Elekit or Dynaco kits, around $1200-1500 for a pair of monoblocks. That may seem like a lot but these do not sound like DIY amps. They have authority and terrific frequency response, and they are VERY stable. Most importantly, they get piano right. ;-) If you can get a good simulation of Horowitz at Carnegie Hall, you're doing pretty well.

There's also a version of the Williamson with Edcor transformers that a fellow DIYer designed, and which could be easily implemented with this board. It would be a bit cheaper. But they Heyboer Peerless copies have been evaluated by a well-known expert over at Audiokarma and he gave them a big thumbs up for performance.


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What are your loudspeaker models?

Does anybody remember the McIntosh solid state amplifier that used an output transformer?
If you do, did it have the same problems that jpk73 is mentioning?
I never noticed that when I listened to that McIntosh amp (I was auditioning some loudspeakers with that particular amplifier).

Unlike WhiteDragon, I am not convinced that the output transformer is always the cause of the problem . . .
even if the speaker impedance versus frequency is like a washboard.

Some single ended tube amplifiers, and some push pull tube amplifiers deal very well with the loudspeaker impedance variations.
Your Mileage May Vary

Just my opinions and experience
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Most of the times the "ringing sound" is due to vibrations. Tubes are prone to sing if the amp is not isolated and typically the resonances happen in the 200-2000 KHz range. Sometimes people like such colarations but for me they are not welcome. Isolating a component means no spikes! Spikes are couplers....
It’s also possible the “ringing” is actually power supply ripple induced. You can get IM products between the signal and the supply ripple (ie, 120 Hz offset tones) which are quite obvious on piano. And electric guitar - and can be intentional in that case. The hum itself can be nulled out in a push pull stage but the IM products can’t be if they are present. Amps with big caps and/or choke filtering and regulated screens tend not to do this. Cheaping out with really small supply caps (or bad ones that need replacement after 70 years) and you get this phenomenon.
Some great ideas here.

FWIW I've just finished a Pete Millett Mighty Midget 6T10 amplifier and it was fairly simple, is the most quiet valve amp I've ever heard and has a very clean, studio sound on efficient full range speakers.


I should have mentioned Pete's site. He has a number of tried-and-true push-pull designs for DIYers, and sells various PCBs on eBay.
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Thanks for all the input! The ringing was with Harbeth 30.1 speakers - I have also other speakers but didn't try them with the KR because I knew the 30.1s well and never heard them ring with solid state amps.

I know some people like harmonics, but I don't want the amp to add anything to the signal that a trained ear can detect - be it pleasant or not...