Leek said:
If the input transformer has the least effect on the signal using an IC like the THAT1250 balanced line receiver seems a more practical approach.
The input transformer has the BIGGEST effect in these vintage circuits. Without it, the noise performance will be dire.
THAT 1250 is a
line receiver. It is a
terrible mike preamp .. like your early 5532 efforts.
... OPA134, NE5532, LME49710, Analog Design OP27 and TL075's. I do have a build based around the THAT1250 balanced input stage, Transistors and LME49710 preamp stage and the output transformer that I recently bought. But, I'm still trying to decide what to do with everything.
If you'd bothered to read my LNprimer in Yahoo MicBuilders, you'd see you FIRST DEFINE WHAT YOU WANT TO DO. Then you work out how to do it with what you have available.
... a good mid range, color which I can get from the n*** style output transformer. Which adds color and is known to be one of the biggest parts of the n*** sound.
This is BS
IC's like the OPA134 and etc are known for the BB sound which is sort of laid back and has a good "bitey" mid-range.
This is pure liquid BS.
Kingston had an excellent thread on what is REALLY important.
opamps and local decoupling of rails, some questions
http://www.groupdiy.com/index.php?topic=37307.80
Many true gurus chime in. It proves how OPA rolling takes a VERY poor second place to correct earthing, layout & decoupling. It’s a long thread but read the whole thing from #41 to find pearls of wisdom.
Any tips in which way to take this Ricardo?
You still haven't specified what you want to do except some vague stuff about 'colour'.
And I can't find any specs on your Neve transformers.
But if you want a Mike Preamp with a vintage distortion profile to work with your Digi 002, I'd use my circuit with the Neve input transformer. Should be in the ball-park ... if not quite as good as my Sowter/Lundahl/Jensen recommendations.
I'm more wary of the Neve output transformer. I'd use your Crimson as this has a 'known' distortion profile which fits in with the circuit, the Digi 002 levels .. what you want. 'Some' spec is better than the Neve 'no spec.'
Or just leave the output unbalanced. If the preamp is within a metre or so of your Digi 002, it should be OK. The transformer(s) add(s) mainly 3rd harmonic while my circuit is mainly 2nd.
PN2907 can probably replace BC557C in this circuit.
There's loads of
other stuff that's important for a good Mike Preamp ... like Layout, Earthing, Decoupling. Some of it is in Kingston's thread and there's more in my MicBuilders LNprimer.