The preamps I'm using now are a nice fit for what I want especially from clean to midgain tones. The CV4024 has a gain factor of 60 compared to a 12AX7 at 100. It made the gain more articulate and didn't neuter the gain of the amp by any means. The AC5's just sound good and the LPS makes a great PI.
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.
There are a whole bunch of tubes that have gains of 17 to 37, but they were never used that much in medium/high gain applications. There are also a whole bunch of tubes that are out of stock, very difficult to find and were superior to a 12AX7. Some of these tubes go for $100 to $250 "each."
Another topic I have stated before is, "Marshall has found a way to make their amps sound good using the currently available tubes."
We have the option to find old tubes and swap them out for the stock ones. This may go on for another four or five years, but after that, all that we will have is the JJ's, New Sensor and Chinese tubes. At least we know that our amps sound decent with them. And hey, maybe in four years or so, these current tube manufacturers will make a better product that will rival a 1959 RCA Black Plate 12AX7. Hey, maybe they will make a copy of a 59 RCA Black Plate? Wouldn't that be sweet?
The future of our sounds all depends on the companies that are making tubes now. I would like to see them step up on quality control and improved designs.
Marty