# BFD RCA to TRS vs XLR input levels different



## floydo (Feb 10, 2008)

I just received a BFD and built a Processor to BFD RCA to XLR cable and noticed the input levels to the BFD were very low (bypass switch blinking and operating level button on back pushed in). So using an RCA to RCA cable with phone (two conductor adapter) connection to check if there was a problem, the levels from the PreProcessor were much as expected, more than twice the level of the XLR, and the experiment repeated in both channels of the BFD. The XLR cable is Belden 1505 (basically RG59) and the pin 1 ground and 3 cold are bridged per the not on page 19 of the BFD manual. One would think the line levels should be the same, but has anyone had this experience? 

I have not tried breaking the pin 1 shield connection to see if that makes a difference. Wierd.
My solution will be to eliminate the phone adapter later and go to the RCA to TRS cable as did mississippi with his $10 solution, and per other comments in the forum.


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## brucek (Apr 11, 2006)

> One would think the line levels should be the same


The connectors (TRS and XLR) share the same differential amplifier, so there should be no difference in using either jack on the BFD. The shorting of the minus (-) input to ground of the differential amp raises the gain by 6dB to account for the unbalanced usage. 

In fact, the 'quasi-balanced' configuration you reference that mississippi used is fine for reducing hum (if it's a problem), but suffers from not engaging the 6dB gain function.

If you aren't experiencing any hum problems, I would probably just use the RCA to TS plug, since that seems to work fine in your case.

brucek


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## floydo (Feb 10, 2008)

Thanks, the TS plug solution works fine and that answers the riddle  It is funny, having been involved with stage, studios and high fidelity there is this subconscious resistance to a mic plug over XLR...
No hum with this 1124 bought from ..sounds!


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