• 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.

Tube Amp Design Resources


2019-09-21 9:01 pm
Hi All,

I'm looking for some good resources about designing tube amps. My knowledge is extremely spotty right now. I understand some concepts, but others still baffle me.

I can take an existing schematic and build something without electrocuting myself. That's all well and good. But one of the main things I'm struggling with is how component values are selected. For example: given a simple 12AX7 two-stage preamp, how and why are resistor and capacitor values selected? And how to calculate new values for a different desired results?

I don't always want to use stock schematics. I also have some tubes I would like to experiment with that I'm having a hard time locating stock schematics. I have also read some of the older posts here that recommend certain books. I just want to make sure that if I buy any more books, they will cover those concepts well enough that I could take (for example) a 12AX7 and a 6V6 and design the entire circuit for a single-ended amp myself. Not simply copying a stock schematic.

Thanks in advance!
Melrin's website has sufficient for an entry foray into designing it yourself. His hifi pre-amp book is a "next steps" into the relevant design considerations including the math involved in selecting passive components.

For power amps, the current definitive modern texts are Morgan Jones's two tomes in their various incarnations.

If you want to go the full hog, the venerable radiotron designers handbook 4th edition will keep you asleep for hours, possibly months. The math alone is enough to turn all but the most dedicated engineer into a firm believer in paint by numbers, but the prose is delightfully 1940's and should be read in the tones of a Noel Coward production. RDH4 as its commonly known is available in the education sticky area of this forum.
All of the above with the added recommendation to also check out the "Designing Valve Amplifiers" books by Morgan Jones. eBooks are available as well as print, although I find the print editions are a bit pricy. 3rd and or 4th edition I have on hand- if you buy just one I would say start with the 3rd edition. You can also find previews on google books and other resources.

The RCA Resistance coupled amplifier charts are handy if you want quick values to knock something together with a known tube, also a quick sort-of cross reference for small signal stuff-

Tubebooks.org is a fantastic resource for older books that are had to find-
tubebooks.org - Vintage info from the age of vacuum tubes

Once you understand the basics you can pretty easily take a datasheet and work something up based on your needs., then, to check your work check against contemporary circuitry you'll see some similar older stuff to verify that you aren't nuts :)
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