2. speakers
  3. 156099-139155

How to connect monoblocks to a single REL sub with ONE RCA input

I just purchased two Quicksilver 60w Monoblock amplifiers and a LineStage Preamp by QS.
To connect this REL 328, normally one uses connect their Speakon cable (Red, Yellow, Black ends that connect to Right+, Left+, and Ground) or a SINGLE "low-level" RCA in. But this preamp doesn’t have a single sub out.

REL’s advice is to buy a second sub and attach one sub to each monoblock. Well, maybe I’ll do that, but in the meantime, I’d like to be able to hook up what I have.

Should I orient the amps so that the speaker terminals are close enough together to attach the strands of the Speakon cables? I have been warned by REL not to hook up high level to monoblocks because it will create a ground problem.

An alternative is that I get a Y cable that will bring two RCA outputs from my Preamp into the single RCA input on the REL?

Or is there another alternative?

Advice appreciated. (But please try not to tell me to just buy a second sub.)
hilde45
hilde45's avatar
hilde45 OP
5,445 posts
 
@pjr801 — the reason is because the standard advice for this REL is to connect it to the main speaker terminals on a normal (non-monoblock) amp. I am trying to follow that advice from REL but adapting it to monoblocks.

@almarg Thanks! I feel confident about these purchases.

So, before I ordered the preamp, I had Mike wire the "Tape Out" as a *second* main out. Right now, the preamp's MAIN OUT goes to each monoblock and the other (TAPE OUT -- now a second main out) is free. Does that fact change your advice? (I don't know why the main speakers would become mono by doing this, but that's just from lack of general understanding about how these are wired.)

Depending on what you say to the above question, I'll try the monoblock connection approach you suggest — and just listen for a hum. I'll also contact REL. It would be shame if I couldn't use the sub.



imhififan's avatar
imhififan
2,231 posts
 
Or is there another alternative?
You can connect your preamp  second main out to a 
Stereo to mono signal converter
and connect one of the converter mono output to the REL 328 low level input. This converter utilizes an independent 1:1 ratio audio transformer for each channel, which also function as a ground loop isolator.

https://www.ebay.com/itm/MCM-CUSTOM-AUDIO-50-20795-Stereo-to-Mono-Signal-Converter-/164155969190?_tr...

hilde45's avatar
hilde45 OP
5,445 posts
 
Thanks imhififan -- I'll definitely keep that in mind if the high level input solution won't work. 
lak's avatar
lak
4,751 posts
 
Best video's I've seen that are extremely informative:https://rel.net/how-to-connect-my-rel/

almarg's avatar
almarg
9,670 posts
 
...  the preamp's MAIN OUT goes to each monoblock and the other (TAPE OUT -- now a second main out) is free. Does that fact change your advice?

No, it doesn't affect my comment.  Presumably the change that was made disconnected the two tape out connectors from the internal circuit points to which they are ordinarily connected, and connected them instead to the main out connectors (or to corresponding internal circuit points).  So if you were to connect a y-adapter to the two tape out connectors, to create a mono signal for the sub by shorting the signals on the two tape out connectors together, you would also be shorting the signals on the main out connectors together.  Thus an identical summed-to-mono signal would be provided to both monoblocks.

@imhififan 's suggestions are almost invariably excellent, and from what I can tell from the somewhat limited descriptions shown at the links he provided it looks like the device he suggested should work fine.

Best regards,
-- Al


More to discover