Tube Circuit Gain Calculator

Tubes || AX84 version || RC-22/mu version || RC-22/gm version
This calculator is based on a standard gain equation from Circuit Analysis of a Legendary Tube Amplifier: The Fender Bassman 5F6-A, Second Edition by Richard Kuehnel. (A simplified form for a fully bypassed cathode resistor appears in many versions of the RCA Receiving Tube Manual).

                                      tube gain x plate load resistor
Circuit gain = -----------------------------------------------------------------------------
               plate load resistor + plate resistance + ((tube gain + 1) * cathode resistor)

Values may be any standard form (68400 or 68.4K, 1M or 1000000, etc.) Check the "Use comma for decimal point" box if you use a comma to designate a decimal point (i.e., opposite the way it's done in the USA). You may leave the cathode resistor as 0 if it is fully bypassed. If you aren't sure if it's fully bypassed, add a cap value and pick a frequency to compute the gain for. If you have cathode resistor and cap values and leave the frequency blank, it will default to 1kHz.

Tubes || AX84 version || RC-22/mu version || RC-22/gm version
Tube Circuit Gain Calculator version 2.0 Copyright 2007 by Miles O'Neal, Round Rock, TX.

Miles O'Neal <meo@XYZZY.rru.com> [remove the "XYZZY." to make things work!] c/o RNN / 1705 Oak Forest Dr / Round Rock, TX / 78681-1514

	Use comma for decimal point
Plate resistance :	from tube manual or spec sheet
Plate load resistor :	value of resistor between plate and power supply
Tube gain :	tube's gain (amplification) factor (a.k.a., mu)
Cathode resistor :	value of cathode resistor
Cathode cap[s] :	value of cathode bypass cap[s]-- multiple values allowed, separated by spaces
Frequency :	matters only with bypass cap; if you use this, try at least extreme values you care about. For guitar, this would be 60 and 6000. Unused if multiple bypass cap values are present.