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Gain into my preamp from DAC

I am using a Bryston BDA-1 DAC into a Jolida Fusion Tube preamp. The output of the DAC is 4.6V via 'fully differential balanced' (Bryston terminology) XLR and 2.3V via unbalanced RCA. I understand that this is to be expected. Both DAC outputs can be used simultaneously, however I geberally use the XLRs to the Preamp and the RCAs to a headphone amp.. 

When I compare output volume between the XLR and RCA inputs of the preamp there is no difference. I would have expected 6dB greater gain via XLR . I understand that the preamp is not balanced.

Please elucidate as to this finding. Thank in advance.


mesch
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almarg
9,670 posts
 
Thanks for the nice words, Mesch.

As an FYI, a commonly seen example of a preamp (or integrated amp or power amp) having a single-ended internal signal path while providing 6 db of additional gain for an XLR input compared to the gain provided for an RCA input, would be a solid state design which utilizes an "op amp" ("operational amplifier") integrated circuit configured to differentially receive the balanced pair of input signals while providing a single-ended output. That kind of an input circuit can be configured to provide 6 db of gain, zero db of gain, or any other desired gain within a wide range of limits, simply by changing the value of two resistors.

Best regards,
-- Al

mesch OP
3,484 posts
 
Thanks once again Al. I am going to call Jolida and ask how the XLR input is configured. 
mesch OP
3,484 posts
 
After talking to Jolida, Al's second descriptor for what accounts for my gain issue best fits. There is no conversion stage (op amp?) on the Jolida's XLR input. 

I now think I might be better off using the Brystons RCA outputs connected to the RCA inputs on the Jolida. I will need a 0.5M pair of Audioquest Columbia interconnects to make this comparison. Once found I will do this and report back.
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