2 REL Strata Subs and Mono amps

Connection of the red and yellow wires to the red output terminal of the amp is fine. Connection of the black wire to the black output terminal of the amp is fine if the amp does not have balanced outputs, and is not bridged.

If the amp has balanced outputs or is bridged, the black output terminal will have a full-amplitude audio signal on it, equal but inverted with respect to the signal that is on the red terminal. If a path exists between the circuit ground of the sub and the circuit ground of the amp, the result of connecting to the black terminal in that situation would be that the signal on that terminal will be shorted to ground, possibly damaging the amp. Whether or not such a path will exist depends on the internal grounding configuration of the two components. If both components have their circuit ground and chassis ground connected together, for instance, that path would exist via the AC safety ground wiring in their power cords, and the house wiring (or internal wiring in a power strip or conditioner, if one is being used) that interconnects the respective outlets.

If the amps are balanced or bridged, connecting the black wire to a chassis screw should be safe to try, and may or may not work acceptably depending on the grounding scheme of the amp. If hum or other issues result, and the amp has an unused RCA input connector, an approach that would definitely work is to solder the black wire to the ground sleeve connection point of an RCA plug, leaving the center pin connected to nothing, and inserting that plug into the unused connector. Similarly, if there is an unused XLR input connector, connecting the black wire to XLR pin 1, using a mating XLR connector instead of an RCA plug, would also be a good approach.

Regards,
-- Al

Rel has the correct wiring for Neutrik plugs on their website I think (or in the manuals) as I found 'em for making my own REL cables...in any case, once you figure out which wire is going to the negative speaker post, I imagine you only need one positive lead per mono amp, as otherwise a single REL sub combines those signals anyway to utilize both channels. I also suggest the "angled" Neutrik plugs as they allow easier placement close to walls...I love those damn Neutriks.

Zormi
My amp is a CJ LP 70S.
Almarg is absolutely correct that the wiring scheme of red+ yellow in the neutrik speaker wires tied to the +(red) terminal of the amp's speaker binding posts and the black to the -(black) speaker post is the way to go in respect of an unbalanced amp. For a balanced /bridged amp check with REL. If I remember the G1 manual covers all scenarios. The input impedance of the G1 is in excess of a 1k ohms and amp damage is not likely.
The G1 is an amazing sub.
Njoy

Huh..

Primare A32 is fully balanced design, as emphasized on their website, so it seems that I will have to look elsewhere. Safety is of course the most important issue, at least for me..

Thank you all for very insightful set of opinions.

12-29-12: Wolf_garcia
I imagine you only need one positive lead per mono amp, as otherwise a single REL sub combines those signals anyway to utilize both channels.

If the amps are not balanced or bridged, I suspect that results in most cases would be similar or identical regardless of which output terminal the yellow wire is connected to. If it is connected to the black terminal, the internal circuitry of the sub will see a signal level that is 6 db less than if it were connected to the red terminal. The level control on the sub would be increased to compensate for that.

If the amp is particularly low powered, it would suggest the likelihood that it would be preferable to connect both wires to the red terminal, resulting in a higher level after the two inputs are summed together. If the amp is particularly high powered, it would perhaps suggest the possibility that connecting the yellow wire to the black terminal would be preferable. Although it is possible that it would make no difference in both of those cases.

HOWEVER, if the amps are bridged or balanced, connecting the red and yellow wires to opposite colored terminals would result in essentially no sound from the sub, because since the two signals are inverted relative to each other, they would cancel when summed together in the sub.

12-29-12: Sunnyboy1956
For a balanced /bridged amp check with REL. If I remember the G1 manual covers all scenarios. The input impedance of the G1 is in excess of a 1k ohms and amp damage is not likely.

Input impedance has no relevance to the damage possibility I described earlier. Input impedance refers to the impedance seen "looking into" the inputs of the sub from the red and yellow wires (i.e., the signal inputs), and has nothing to do with the impedance between the black (ground) wire and the sub's internal ground, which can be presumed to be a direct (zero ohm) connection. In the scenario I described in my previous post that might result in damage (depending on how the grounds are handled in the specific designs), the signal on the black output terminal of the bridged or balanced amp would be shorted to ground through essentially zero ohms.

12-29-12: Zormi
Huh..

Primare A32 is fully balanced design, as emphasized on their website, so it seems that I will have to look elsewhere. Safety is of course the most important issue, at least for me..

Not sure what you mean by "look elsewhere." My previous post described three possible approaches that are applicable to your situation, starting with trying a connection of the black wire to a chassis screw or other ground point on the amp.

Regards,
-- Al