Neve 438/440 substitution query

[soundguy]

I already know the answer is "try it and see" but thought Id pose this for the experts.

Im building a 5x2 mixer out of 33114 EQs. Starting to think about the make up amps on a passive mix bus. I was going to use 3415's for this but am considering something different. First off, Id like to see if the make up amps could be transformerless inputs. Second, Id like to see if I can basically copy the block of the 3415 but instead of using 438's on the input use a 440 instead. Ideally, Id like to have the mix buss feeding 2 440's in series into an output transformer. Im thinking of using 440's simply because I have a few extra, no other reason.

Is there an obvious reason why this WOULDNT work on paper?

also, can a 440 drive an output transformer wired 50 ohm primary 600 ohm secondary into 600 ohms?

thanks!!

dave

 

[Family Hoof]

soundguy,

I see no reason for this not to work. The 338 and 340 amps are identical, except that the 440 has a push-pull pair tacked on the output to drive a transformer. Since they're designed to drive a 70:600 output trafo, I can't see why 50:600 would be a problem. It's just going to run 20% hotter, no? I know BAE and maybe a few others have wired up these amps with 150:600 ohm output trafos available from Jensen and the like with no problems. I would look into that option myself.

[EDIT] Just noticed the part about two amps in series. If I were to do this, I would remove the AB output pair from one of them, effectively making it a 338, get most of your voltage gain there, then put a fader on its output and have the wiper feed the other 340 which would run closer to (or at) unity gain and drive the trafo with it's output pair intact.