| dsavitsk |
I am working on a balanced preamp based on this schematic
For the input, I picked up a pair of Cinemag CMLI-15/15 transformers. I'd like to accept both single ended and balanced inputs, but this being my first endeavor into balanced circuits I am not sure of how to connect everything up.
Is it reasonable for balanced input to connect the + and - inputs to the two sides of the primary, and for single ended input to connect the input signal to where the balanced + connects and the input ground to where the balanced - connects? This leaves the balanced ground, but I gather this is often ignored anyway. |
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| David Davenport |
I am confused about how your question is formed so I’ll tell you how I do it. Refer to figure 3 on http://www.raleighaudio.com/active_output.htm
It’s incredibly simple: For balanced input, connect the + signal to the + input and – signal to the – input. For single ended input, connect the signal to the + input and ground to the – input. Switch both sides through your source select switch so you switch +/- for balanced input and +/ground for single ended input.
Dave |
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| dsavitsk |
| Thanks Dave. That is what I was trying to say in my own convoluted way. It seemed right, but I wanted to be sure I wasn't missing something. |
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| David Davenport |
Okay good, I thought so but I wasn't sure.
One more thing: use the chassis ground for the single ended ground. Don’t use the internal circuit ground.
Dave |
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| fredriksweden |
Hello Mr.
For balanced signal use + (hot), - (cold) and ground.
On a XLR (Cannon) connector Pin 1 is ground, Pin 2 +(hot) and Pin 3 - (cold).
For unbalanced use: (line signal) you have to solder - and ground together otherwise you lose 30 dB of the signal.
So the RCA connector would be: center tap + shield - and ground.
I have the experience the sound isvery dependant on what transformer you use.
In my opinion the best line-trafos ever made was the German Studer (fitted in their two-track reel to reel models), the German Haufe transformers (fitted in Neumann mics etc.), the Swedish Lundahl trafo model SR501 (specially designed for National Swedish Broadcast); and the German Dynacord trafos (fitted in amplifiers like the Eminent and MV-46).
Cheers Fredrik |
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