• 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 Micro-amp







With D 120mm x H 130mm x W 185mm and 4.5kg, this is probably one of the most compact stereo tube amplifier ever... ;)

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Dang, I assumed it is a production amp because of the plates front and back!!! Who made those for you?

Well yes @djn... Often my builds are considered as regular production, and/or criticized by jealousy by those "Experts" who know everything without ever having learned anything except what they have taken from others - you see what I mean, I guess ;)... No way : no production nor commercial activity, only DIY amateur work.

If you are interested :

I design the plates myself (vector file) and have them engraved locally :


It is nice and looks nice.
Indeed because of the paint it looks like a 50ties product.
I thought El 95 instead of 85 but the seem the same.

Thanks @stevenrotterdam !

A member on another forum named that style "RetroCool"... :cool::cool::cool:




Yes, the EL95 and the EL85 are similar tubes. In fact, the EL85/6BN5 can be considered as a Noval 9-pin close version of the EL95/6DL5. The EL95 was stricly AF operation, while the EL85 was also RF and VF, notably in TV equipment.

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Thank you Guys ! :)

I built the Micro-Amp - first : because I had most of the convenient parts on hand, OK ? - as a miniature challenge that prooves that TUBE circuits doesn't mean or imply BIG / COMPLICATED / ODD / SPECIAL, etc...

Yes, as far as possible, I always try to build compact tube amps and preamps, but there are limits, you guess it ! For a complete, fully operational, "conventional" tube amp, I don't think that I can't go very smaller without compromising usable output power or reliabilty.

I tested the Micro-Amp left powered on for a complete day : no issue, no overheating, enough loudness and punch provided... Surpisingly little in relation to its size !

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