2 2 channel preamps

antichef

pornk rock
GAS hit hard today, and I bought 2 different 2 channel preamps - a Great River MP-2NV at GS (it's on its way) and, at a local pawn shop (for just over 1/10 of the price of the GR :) ) an Aphex 207.

I've got the 207 now - it was dirty, so I cleaned it up - haven't tried it out yet. I opened it up - pretty simple and sound looking construction for the most part - it's got a (single, for 2 channels?) 12AT7 that can't be doing much - there are two Burr Brown OPA2134s that I bet are doing most of the gain work. I hope I get a chance to try it soon - this weekend won't work, though.

I may get out the soldering iron and socket those 2134 chips so I can try some alternatives. If I do that, I'll start a thread in DIY and try and provide samples.

Can't wait until the Great River gets here! It will be safe from my soldering iron :D
 
Leave the 2134s, not worth swapping those. Well, maybe the input stage--try 2227 for lower noise.

The 12AT7 will be doing what it's doing, the trouble is it can clip the following 2134 stage. I think that's the major limitation of these sorts of boxes. What they ought to do is stick a transformer on the plate of the tube, that would do a couple of things: you could crank DC to a reasonable level even with starved plate, but you'd have the usual AC gain. Plus you get step-down into the opamp so you can push the tube without clipping the opamp.

Man . . . that's actually not a half bad idea . . .
 
Leave the 2134s, not worth swapping those. Well, maybe the input stage--try 2227 for lower noise.

The 12AT7 will be doing what it's doing, the trouble is it can clip the following 2134 stage. I think that's the major limitation of these sorts of boxes. What they ought to do is stick a transformer on the plate of the tube, that would do a couple of things: you could crank DC to a reasonable level even with starved plate, but you'd have the usual AC gain. Plus you get step-down into the opamp so you can push the tube without clipping the opamp.

Man . . . that's actually not a half bad idea . . .

Make it so. Theres a lot of Aphex 107 and 207 pres out there and they arent bad from the gitgo.....If its a simple and effective mod, you've got yet another career path........
 
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