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Re: Preamp Tubes? - Who, What, When, Where, Why, and How?
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Originally Posted by MartyStrat54
... Here again Josh is but another example of what I've told you and that is not every Marshall player wants or needs a 12AX7 in V1. Here we have a 12AT7 being used. (He probably would have liked the worn out Tung-Sol 12AX7's that I sent back! They probably had a gain of 45 to 60.)
The 12AX7 and the 12BZ7 both have a gain of 100. However, when placed into an actual circuit (with resistors) the gain drops some. However, since the 12BZ7 has half the resistance value of a 12AX7, it provides more gain in the actual circuit.
Some other tubes with lower gains are the:
1.5751 with a gain factor of 70. This tube can really kick butt in some amps.
2.12AZ7 with a gain factor of 60. Rare, hard to find tube.
3.12AY7 with a gain factor of 40. Difficult to find. Works well in Fenders...
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In general, is it better to start with a lower gain tube (say a 12AY7... which I actually used to have one, but it went bye bye when I sold my Valve Junior) in V1, then gradually increase the gain factor of the tube by using a 12AZ7 (for example) in V2, then a 12AX7 or 12BZ7 in V3, and round out v4 w/ a nice balance 12AX7? Or is better to start high and decrease the gain factor with each following tube (i.e. the reverse of the layout I just mentioned)? Or does it matter? 
Last edited by joshuaaewallen; 04-04-2009 at 02:14 PM.
Reason: poor spelling
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