12au7 in V1 & V2 in a Rocket?

[GEN DAWG]

Title is wrong: it's an express, not a rocket. Sorry.


Hi -- Just scored my first Express build, and my first impression was "great amp, waaaaaaay too much gain for me.". So I swapped 12au7's for V1 and V2, and it is now more to my liking. My question: I'm not doing anything that will screw up the amp, am I?

By the way, I am told that this Rocket was built by forum member Fusionbear. Right on, buddy. My first Wreck clone, and it balls. Clips to come....

[M Fowler]

No problem, you can also use 5751 or 12AY7 as well. You can use a 12AT7 in V3 phase inverter postion too.

Or lower the 220k plate resistor of V1 to 100k for less gain and less early breakup.

[GEN DAWG]

No problem, you can also use 5751 or 12AY7 as well. You can use a 12AT7 in V3 phase inverter postion too.

Or lower the 220k plate resistor of V1 to 100k for less gain and less early breakup.

Thank you. I'm limiting myself to tube swapping at this point, since I truly suck with a solder iron.

[rp]

I think 12AU7's and 12AT7's subbed where they don't belong (ie in place of 12AX7's) sound like poo, people like it 'cause their looking for lower gain and they sure get it. I think the appropriate subs, 12AY7 and 5751, lower the gain without doing too much damage to the sound. Yes, you see 12AT7s and 12AU7s in PIs but in amps designed around them, try subbing a 12AT7 for a PI meant to have a 12AX7 and then check what happens to the PI's plate voltage. I leave the PI alone and roll V1 and V2.

If you need lower gain than the tubes mentioned you need to tweak or get an other amp. Honestly, the Rocket has no more gain than an AC30TB - a vintage hotty but not that rad an amp. Can't say without knowing your style but if you're not used old school tube amps you might be mistaking dynamics with gain. Play with it some more, get to know it, before tweaking. Use the guitar volume too.

Are you used to MV amps? Maybe add an MV to give you more control?

[GEN DAWG]

I think 12AU7's and 12AT7's subbed where they don't belong (ie in place of 12AX7's) sound like poo, people like it 'cause their looking for lower gain and they sure get it. I think the appropriate subs, 12AY7 and 5751, lower the gain without doing too much damage to the sound. Yes, you see 12AT7s and 12AU7s in PIs but in amps designed around them, try subbing a 12AT7 for a PI meant to have a 12AX7 and then check what happens to the PI's plate voltage. I leave the PI alone and roll V1 and V2.

If you need lower gain than the tubes mentioned you need to tweak or get an other amp. Honestly, the Rocket has no more gain than an AC30TB - a vintage hotty but not that rad an amp. Can't say without knowing your style but if you're not used old school tube amps you might be mistaking dynamics with gain. Play with it some more, get to know it, before tweaking. Use the guitar volume too.



Are you used to MV amps? Maybe add an MV to give you more control?

Thanks for the suggestions on other tube substitutions. I will fiddle around until I get this Express build dialed to my liking. I am considering options like MV, although I prefer NMV amps for feel.

A little about me: I have been playing about 30 years, have gigged a good bit, and have owned a large number of excellent tube amps. I play mostly with my fingers and frequently adjust my volume knob. What I haven't done much is play high-gain amps in general and wrecks in particular. So this is a learning process for me. Thanks.