Racking Harrison TV-3 micpres

[Ziga]

Hi,

I've came across some old Harrison TV-3 console parts, among them a couple of mic pre cards. I'm thinking about adding output transformers, but I'm not sure about what kind would be best, regarding impedances. My guess would be a 600:600, but how would it come together with the RC filters before it? Any help or tips would be appreciated

Schematic

 

[Ziga]

Anyone...?

 

[abechap024]

Just strap it on the End! 600:600 done probably increase the 100uf to 470uf. Also consider putting a buffer in there, in order to drive the output transformer properly. But try it! If there is an excessive distorted or grainy sound, a buffer will probably help that output chip drive the transformer. Is there any other circuitry on the board? if so there probably is a buffer lying around you could use.

 

[Ziga]

I've tried it with a Pikatron RÜP 219/1M (data @ http://audio.kubarth.com/rundfunk/index.cgi) and it sounded ok, but I don't want to get any surprises after I order (and pay for) 4 output trafos for this project. The cards I got are micpre modules only, so if will get any distortion i will have to build my own buffers. I'ill try to get my hand on a 600:600 trafo and test it out, if it plays OK thats it