What to do with hybrid amp husk?

[johnnyreece]

Good day, folks!

I've been given a non-functioning amp head. It's a Randall V2, and it seems there's a problem with the channel switching, but someone else has been into it before me, and I don't really care to make it what it was...What I *do* have is an amp that was formerly a three channel, 400 watt head. It has three 12ax7 and one 12at7. Any thoughts on what this could be turned into? I thought about maybe making it a bass amp. The iron is HEAVY! I'm mostly interested in getting something interesting, but not too complicated crammed in this. Mostly just want to get it buttoned up and out the door, as I already have *my* bass amp, and have no need for a 400 watt guitar amp. I appreciate any thoughts!

[Stevem]

I am scratching my head here making sense of your need for posting this at all!

If your in love with your current bass amp and have no need for another, then why the need to do anything with that Randall, and if you can’t resist the need to as you say “ do something with it” why does it have to be interesting as you say?

You don’t need our approval to do anything with it you want and you have not directly asked for any suggestions no less!

Doing something interesting with it for some folks might be flipping the chassis upside down , making it water proof and planting Flowers in it!

[johnnyreece]

I'm scratching my head at your post, as well...I asked simply for some thoughts on what could be built with a platform of 4 preamp tubes and 400w worth of power amp.

The reason to do something with it is, as it sits, it's an extremely large, heavy paperweight. I would like to make it something that is maybe a tad more useful. That, and I like to tinker with things. I appreciate you taking the time to comment. However, your statement that I have "not directly asked for any suggestions" is a bit off base, as I'm pretty sure I said, "Any thoughts on what this could be turned into?" I'm wide open to suggestions. I gave a brief summary of the current setup, so that an educated guess about what it *could* be could be made. I'm sorry if I implied anything different. I've also never mated a tube preamp to a SS power amp, so I was hoping to get some thoughts on that as well.

Actually...I would prefer a moderator just delete this now. I think I've got a new flower pot...

[Phil_S]

A brief search suggests that a schematic will be hard to find. It would help a great deal to see a picture or two of the chassis along with info about the transformers. As you might expect, I'm thinking along the lines of making it into an all tube amp. It would be helpful to know if the iron will support that.

[johnnyreece]

I've had trouble finding info on it. It's closely related to the T2, which I've been able to find some info on. I even emailed Randall to see if I could get info, but it's been months, and nothing but crickets. My SS knowledge is even more limited than my tube knowledge, so I don't understand all of what's going on, but I've got a T2 schematic. There's some info about voltages, but no PT ratings. I suppose I could add a small OT and make like a 2w amp, but (and I can't stress this enough) it would be HEAVY for a 2w...If there's a way to squeeze a tube power section in, I'd be all for it. Thanks for taking a look.

[thetragichero]

gut the preamp and channel switch and build something with the tubes that doesn't rely on power tube distortion for its signature sound? i'd think either something really clean or a really dirty metal amp that might benefit from a (likely) tight solid state output stage. could still have channel switching if that's your thang

[johnnyreece]

gut the preamp and channel switch and build something with the tubes that doesn't rely on power tube distortion for its signature sound? i'd think either something really clean or a really dirty metal amp that might benefit from a (likely) tight solid state output stage. could still have channel switching if that's your thang

You're kinda reading my mind here. It's also why I was possibly thinking bass amp, like maybe a single channel Ampeg SVT-type thing with SS power amp. I don't know. I'm sure there are a world of possibilities, I'm just not up on SS, nor how to mate a tube preamp to it.

[thetragichero]

there are plenty of svt amps (svt3, svt4, etc) that marry a tube preamp to a solid state power amp. i would use the original Randall schematic as a reference. my guess is that the 12au7 is the phase inverter. take note of any voltage dividers in the preamp meant to bring the signal down. build in such a way that it'll be easy to tweak those voltage dividers if the svt preamp signal is too large or small (turret board would be better than pcb for this)

[thetragichero]

hopefully the pcb is designed in such a way that you can cut the preamp section out to make room for the new one?

[johnnyreece]

Thanks for the ideas. I'm thinking of doing something stupid, like try Merlin's ultra high gain preamp. Why not?