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Preamps: RCA unbalanced in, XLR balanced out?

REK2575

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If a Preamp has both RCA and XLR inputs and outputs, does that mean you can input an unbalanced signal via RCA connection and output a balanced signal via XLR connection to a power amp? Or is that not necessarily a given?

Specifically i'm looking at the Rotel RC-1572 MkII preamp (https://www.crutchfield.com/p_440C15722B/Rotel-RC-1572-MKII-Black.html?tp=75886). My Topping E30 DAC only has unbalanced analog out. But would this preamp convert the signal received via RCA to balanced if it was connected to power amp via XLR cables?
 
D

Deleted member 46664

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Let me answer that like this ... If you can't, get a refund.

A properly designed piece of kit will have its balanced to single ended conversion right at the inputs ... internally it will be a single ended device... then just before it's outputs it will convert back to balanced signals. Thus, you should have balanced outputs no matter which inputs you are using. Most of the time, the RCA and Balanced outputs are both active at the same time.
 
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REK2575

REK2575

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Thank you for the response. So, if I were to set things up as described:

DAC --rca out--> Preamp --xlr out --> power amp

and it works -- i.e. simply, music is playing from my speakers! -- then the preamp necessarily converted the unbalanced signal (from DAC) to a balanced signal.

I suppose the confirmation that it was *not* outputting a balanced signal would be: no music playing, because the preamp would need a balanced in via XLR in order to output a balanced signal to power amp via XLR. Is that correct?
 
D

Deleted member 46664

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Thank you for the response. So, if I were to set things up as described:

DAC --rca out--> Preamp --xlr out --> power amp

and it works -- i.e. simply, music is playing from my speakers! -- then the preamp necessarily converted the unbalanced signal (from DAC) to a balanced signal.

For the end user the best confirmation is that it works as expected. And yes you should expect that to work.

I suppose the confirmation that it was *not* outputting a balanced signal would be: no music playing, because the preamp would need a balanced in via XLR in order to output a balanced signal to power amp via XLR. Is that correct?

No music or music at a somewhat lower level.

Balanced audio is about eliminating noise from cables. It is not a whole new kind of audio.

This is how a properly designed pre-amp (or other device) handles Balanced Audio...

topology.png


Immediately at the inputs it is converted to a single ended (unbalanced) signal for the device to process. The point of doing it there is to make sure that any noise on the input cable does not make it into the internals of the device.

Internally the device is unbalanced, no different than any other device ( a pre-amp, in your case).

Then once the signal passes through tone controls, volume, balance, whatever it is converted back to a balanced output right before the external connector. This enables noise cancellation at the other end of the output cable.

Typically the RCA connections are patched in at the output of the balanced input (first triangle) and the input to the balanced output (last triangle).

So yes... hearing music is almost certainly success.
 
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