• 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.

Recommendations on a simple design?

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Re: Not a triode?

Positron said:
"If you want the sound of a triode, why not use a triode! (unless of course you have lots of NOS EL34s lying around )"

An EL34, 6550 or KT88 can easily be wired as a triode, Shifty. Don't want any bad info getting out there.

Hi Steve,

I agree, a triode wired pent can sound very good depending on how you implement it.

In another thread recently, there was some discussion about 6550 PP load impedances. If I'm not asking for your trade secrets what do you suggest? I've been using 6k and 11k5 with some success at about 380V B+, 80 - 90mA/tube, cathode biassed, but suspect something in the middle might be the best but don't have suitable OPTs to try. Opinions?
 
PP load

Hi Brett.

I haven't gone quite that high with my loads (in PP) as I targeted for pretty good output power (for the consumer market) at reasonable plate voltages and nice idle currents, (thus reasonable plate dissapation), and still run class A by the classic definition. And also good frequency response.

I was able to use an OPT rated for double of what my amps are rated, to keep the distortion of the OPT down too.

You are definitely right Brett; it depends on how one impliments these tubes (6550, KT88s etc). Design is of utmost importance, but the rewards are gratifying.
 
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