Which tube balanced preamp good for modding?

Hi Allen, We're not aware of anyone doing that so far, but of course if they were they likely would not be talking to us about it. We've seen maybe two examples where someone tried to use your Super Reg circuit in the MP-1 power supply, but unfortunately they were botched so badly that they needed repair.

We use a proprietary high voltage monolithic regulator that is very quiet and does not require a lot of headroom, so its tricky to install something after that fact and actually have it be better.

Pedrillo, my advice is try doing some mods on something cheaper like an old Dyna PAS-3 or the like first. I would start out by replacing the filter caps in the unit first, and test all the tubes. Then give it a good solid listen- maybe for a couple of weeks. After that time then you can go ahead and modify it. That way you will know what the changes did. The PAS-3 is a good place to start because there are so many mod articles around for it, and parts are easy.

You'll know when you are making good progress because it will sound a lot better, and because you will be wondering, after changing everything in it, if you shouldn't just go ahead and design and build a new chassis for it as well :)

A number of very keen enthusiasts have taken the Atma-Sphere balanced preaamp and modified it with circuit sections from my RTP3C/D circuit with great results.

You can find the schematic of the RTP3D on my site and info on the mods on the Atma-Sphere forum.

Regards, Allen

www.vacuumstate.com

Most of the balanced tube pre-amps that I know of are already "top of the line" or nearly so. Changing out some capacitors will change the sound, as will changing the tubes. Changing the resistor package to Caddocks, for example, will be costly, even if you do the work yourself ($1000, or so) and will quiet the "noise floor" a bit. One that you may want to look at for not a lot of money that you can modify is the Audio Experience balanced line stage (I think they make 2 models). The BAT's, AR's, Atma-Spheres, and other balanced line stages are already "tricked out to some degree" but may benefit from noise dampening treatments, power filtration, power cords, etc. I'd recommend that you get one, see how it sounds, and then figure out specifically what you might want to change.