12AU7 in Express...

[hairyandy]

I have two old Mullard 12AU7s and I thought that I'd try one in the PI of my Express clone to see how drastically it reduces the massive amount of gain that it has. So I did and it reduced the gain quite a bit. Where before it was REALLY gainy at about 10-11 o'clock, now it seems to have more headroom and breaks up really nice at about 12-1 o'clock.

So then I tried the other one in V1 and it's cleaner still, getting into pretty high gain territory at about 3 o'clock. Also, and maybe I'm imagining this part, it seems to like pedals a lot more this way, I assume because of the increased headroom. I tried my old 80's Rat in front of it and it was amazing, way better than it was with all 12AX7s and lots more gain. Before I didn't need the Rat because there was so much gain but now I can use it more like I used to use my old Bassmans. Maybe this defeats the purpose of the Wreck "ethos" of just using the guitar volume knob and the amp, but for those that need to use pedals for certain sounds it's kinda cool. The "cleaner" sounds are still amazing and harmonically rich and can get into AC/DC territory if you have it around 12:00 and really lay into it.

I just thought I'd share my experiment for the day.

Andy

[geetarpicker]

On one track on my CD I wanted a clean country tone with a tele through my original '89 Express. I went with 12AY7s in V1 and V2 and it drastically cut the gain. That's another tube worth trying.

[rfgordon]

I use 12AU7 and 12AY7 tubes a lot, and have turned a lot of other players on to them, too. When most folks want to drop gain, they tend to reach for the 12AT7 first, but it draws so much current it sometimes (depending on the amp) yields odd results, since it can pull other voltages down.

I like the 12AU7 for it's sweet tone. Since there's not much demand for that tube, NOS/Vintage ones can be had fairly cheaply.

Another one to try, depending on the application, is the 12DW7, which has the A side of a 12AU7 and the B side of a 12AX7. This one can be really nice in the reverb recovery spot of a Blackface amp, as it can result in a more useful range on the reverb control, without sacrificing gain in the mixer stage that follows.

[stoo]

Yet another to try is the 5751. 30% less gain but same "characteristics" as the ax7
Stew

[joe6v6]

Yea - nice to see others arnt afarid to experiment with diffrent pre-amp tubes. Some would say its blasphmous to do so but I say what ever works for you is what needs to be done. I like the 5751 in V1 and also a 7247 (12dw7) which like someone mentioned is half an ax7 and half an au7 ,,,

JOE

[novosibir]

I like the 5751 in V1 and...

... which not seldom also does its job great in the PI stage.

Larry

[zendragon63]

Interesting; so by using a 12AU7 (or 12AY7) you reduce the gain through to the two power tubes so they won't get to the point of saturation (distortion)? Just the V1B, V2A and the 12AU7 will reach the desired level of saturation?