Don't think my preamp likes feeding signal to two seperate places.


Just discovered that my system sounded noticeably better when I disconnected the interconnects that feed my subwoofer crossover unit.  Simply having them connected, micro detail diminishes. Treble gets a little less extended. Is this what is meant as an impedance mismatch? It's obviously affecting the fidelity arriving to the main stereo amp.  Now I'm stuck with having better bass or better micro detail and sounstaging. Is there  anything I can do? I'm bummed out. The main stereo amp is fed by balanced out from the pre. The subwoofer crossover unit is fed by rca out from the pre. It seems like the preamp doesn't like feeding two things at once. This is a really upsetting discovery. It's not a huge difference, but noticable to me.  Now the system sounds absolutely incredible, but now I don't have any sub bass. 


ARC  LS 17 preamp-----main out rca to paradigm x30 sub crossover------adcom GFA555se (as subwoofer Amp)
 
Main output XLR to ARC  DS450

is this a limitation to the ARC ls17 circuitry? Would the preamps up the range not have this phenomenon? I know it's not arcs hi end model, but I wouldn't expect this from a unit at this price range. I wouldn't think I would have to have this compromise. 

Any thoughts?

audiolover718

Showing 3 responses by atmasphere

An additional problem is that the RCA is in parallel with the balanced output on the ARC preamp. This means that as soon as the RCA connection is used, the output of the balanced connection is no longer really balanced. There's a lot here that is pointing to the preamp as the bottleneck.
Many subs can operate off of the output of the amplifier terminals. You might contact the manufacturer and see if this is the case for your model.
Does the crossover have outputs for the mids and highs? If so, even if they are single-ended, this would be worth trying.

Some of the ARC amplifiers that have allegedly balanced differential inputs really don't do well with single-ended inputs (which indicates a radically  poor Common Mode Rejection Ratio spec). This is so profound with some of them that if operated single ended they have lower power and much higher distortion. But if your amp is not one of those types this would be worth trying.

(FWIW our amps behave the same whether the balanced or single-ended input is used.)