Originally Posted By: Planobilly
A failure...lol

What I wanted to do was to design a two channel amp that could be switched with a foot switch. One channel would sound like a Fender Vibroverb and the other like a 100 watt Soldano.


Sounds similar to my Rivera Knucklehead - one channel can do Fender Blackface (with a pull knob for Tweed) and the other does Marshall-style crunch (with a pull knob for boost that gets quite hairy). It has fewer gain stages than a Soldano might have, but probably would sound pretty close. Anyway, keep at it, hopefully you'll get it working!



Originally Posted By: VideoTrack
Quote:
2. single low voltage supply. 9 volt battery would be great.
(with bipolar op amp supplies, one often ends up with too many darn components. and yes i know bout the 5 buckie mic pre.)
4. maybe useing a low voltage cheap "new technology tube" or a couple of germanium transistors

Sadly, 2 and 4 don't mix. A 9 volt battery isn't going to reliably give the 100volt+ HV that the anode requires of a vacuum tube, and supply the heater current. Germanium transistors? I would have thought that at the very least, a low noise analog op-amp with feedback set for the right gain would have been a much more effective option. But just my 2 cents.


I agree, 2 and 4 won't mix without "too many darn components". From a 9v, you'd need a voltage booster to be able to drive a tube, or even an op-amp, and this style of voltage booster would add noise to the circuit. Even with a Nutube, it requires 17ma of heater current alone, and would flatten a 9v battery in half a day or less. AA's would be better, or 18650's.

Germanium transistors are most often not low noise. They're sensitive to temperature in regards to noise output. Any germanium transistor available these days is going to be "new old stock" at best, or used and half dead at worst.

Low noise analog op-amp, sounds like a perfect application for the 5 buck preamp. Still requires more than 9 volts though.

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