INPUT OR OUTPUT TRANSFORMERS FOR PASSIVE SUMMING AMP??

[kingmonkey]

Hi all

I am building a passive summing amp, but want to get a little transformer sound in there as my make up gain mic pre is really clean.

Is it better to put the transfomer as in input or at the end of the chain as an output?

Any suggestions as to what might be nice to use? I was thinking sowter or Cinemag?

Was looking for a api or neve kind of sound?

Many thanks in advance

Darren

 

[ruffrecords]

Inputs and outputs are presumably line level so the signal level in the transformer would be about the same. You only need one transformer per output if you fit it at the output but one per input if fitted at the input so I guess from the economic standpoint the output would be better.

Cheers

Ian

 

[Meathands]

Seems like 1:1 inputs would be cool so you could choose how hard to hit them, have them on every channel, and isolate the input grounds (if indeed that would help anything). But, as the "Poor Man" himself duly points out, that's the pricier route.

 

[toddgw]

Darren,
First...  my answer assumes that you will only be using two transformers in your summing mixer and they will be inserted between the summing buses and the mic pre's. 

It's important that the transformer you select should match the input impedance of your mic pre.  a mic splitter type would be where i would look first.  Also if you're looking for a particular sound from your summer, then you should design it using the basic topology of the circuit that you wish to emulate.  I say this because the transformer will add a bit of a 'sound' but of the two sounds you mention (api and neve) only the neve uses a transformer at the input of it's summing amps. API used an inverting input of an opamp, which requires no gain makeup due to the virtual ground node at the opamp's input. 

nonetheless...  both the sowter and cinemag are excellent transformers and either one would work nicely, just keep in mind that one of the objects in building a good transformer, is to color the sound as little as possible. 

 

[CJ]

not much color from a 1:1 unless you find a way to hit it hard,

you could jack up the gain from 1:10 and then bring it back down with a 10:1,
use two transformers, cinemag on the input, sowter on the output,

your goal is to have the heaviest chassis on the block, and therefore the heaviest sound, right?

don't tell me this is to mix down country western,

if i hear red solo cup one more time im gonna blow chunks,