Mic Pre Conversion - Wiring Record and Repro Cards in Series - Invonics Model 375

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fixproaudio

Active member
Joined
Jun 9, 2022
Messages
26
Location
Long Beach, CA
Got this rad invonics model 375 on Reverb and would love to use the record card as a gain stage and drive it into the repro card.

Service manual attached - my board revision does not have T2 at the start of the repro card input it just goes straight to Q1.

I would like to grab the signal post R48 right after the last gain stage after the record card amplification and send it to the input of the repro card. Im assuming a impedance conversion here would be required (wish my model had the repro input transformer) so are there any other alternatives? I don't want to blow the output stage of the record card.


All the best,

Jon
 

Attachments

  • Service Manulal.pdf
    12.3 MB · Views: 1
I think you really need to consider the headroom of each "gain block". The repro card probably won't have much headroom if being fed from a line output. If you have a scope and signal generator figuring out headroom and levels shouldn't be that big of a deal, I wouldn't worry about hurting it.
 
I 100% agree with you on this. I have been just playing around with the record card and am incredibly impressed with the headroom if I calibrate the input back a little bit.

Also, distortion never hurt any one did it?

Thanks
 
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