2. amps-preamps
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Mixing XLR and RCA outputs when biamping?

I’m about to introduce two new (to me) amps into my 2-channel system, and wondered about how to hook them up.

 

The amps are refurbished Adcom GFA555s1, and I plan to bi-wire them vertically.  My preamp (NAD C658) has both XLR and RCA outputs,  and it appears they output simultaneously.    However, the amps are RCA input only (no XLR input).          It would seem I have a couple of options:

 

1. use the RCA output of the preamp, and split each signal to feed both channels of each amp.    
 

2. Use both XLR and RCA outputs, with the two left channels going to the left speaker amp.

 

Would the voltage/sound level be the same for situation 2?    I was thinking running the left XLR into the low freq on the left speaker, and the right XLR not the low freq of the right speaker.

 

this is probably a dumb idea and I should split the RCA signal.

 

 

 

 

chessie
erik_squires
16,436 posts
 

Well if you were considering doing more work, those are good speakers to take semi-active.  Using a 2-way active crossover, and by passing the woofer low pass and mid high pass can increase your dynamic range and give you some powerful EQ capabilities.

erik_squires
16,436 posts
 

Also, didn't these speakers come with an "alignment filter" of some sort?  You can do away with it if you go fully active.  Replace the bass EQ in the filter box and use the DSP instead.

chessie OP
23 posts
 

There is/was an "alignment filter" but I don't have one.   I have looked for one but they are apparently made of solid gold.    How does one introduce an active crossover?   I assume there is some hardware to add somewhere.

12many
288 posts
 

I vertically bi-amp my speakers and found it to be a nice improvement.  I had BJC make a XLR cable that splits the signal from one XLR connector at the pre-amp output to two signal paths that run to the amplifier, each run is terminated with an XLR connector.  Works great.  You would not want to mix XLR and RCE.  

avanti1960
1,520 posts
 

@chessie

alignment filter is the crossover network between woofer, midrange and tweeter. you would need 3 amps to run fully active and a good working knowledge of appropriate crossover frequencies, slopes and level matching the drivers as well as if there was an impedance flattener, notch filter, baffle step compensation and roll off filter. not for the uninitiated.

run the amps as you have planned using a splitter off one set of outputs. you should enjoy the difference assuming the adcoms are up to snuff.

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