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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
5,448 posts
 
@jl35 Got you. And that makes me feel good! Since I just got these amps, I will have a chance to live with the setup for a while and see how itis.

@daveyf That's a really interesting point -- two smaller subs. I read somewhere not to go smaller than a 10 inch woofer. I wonder if that's for any and all subs or for just one. And I don't blame REL for their advice -- it does seem optimal for sound and that's what they're known for. It is helpful to have some "escape hatch" for that person who wants/can afford *one* good sub rather than *two* lesser subs.

daveyf's avatar
daveyf
3,086 posts
 
@hilde45  I have two (2) REL T5i's in my system. They are more than enough for my small room. I believe that two 8" drivers ( in the two T5i) are more surface area than one 10" driver. IME, the room size is the real factor as to how many subs and the size of each...not 10" driver or bigger, etc. 
hilde45's avatar
hilde45 OP
5,448 posts
 
Thanks, daveyf. I can't remember where I read that it should be at least 10, but my space is only about 500 sq feet so I bet your setup would work well. I'm sure we could start a shooting match over in "Speakers" if we tried...let's not.
ieales's avatar
ieales
1,201 posts
 
@ hilde45
you should NEVER use the high level output. Especially on a tube amp.
Their use is strictly lofi. No professional installation uses anything like them. No matter what anyone says, they cannot produce accurate bass. Especially on a REL328 with no phase control. It's actually a polarity control.

See  http://ielogical.com/assets/SubTerrBlues/TubeAmpSpkrV.png and read  http://www.ielogical.com/Audio/SubTerrBlues.php and https://www.soundoctor.com/whitepapers/subs.htm

What you plan to do will be  H U G E  compromise over what is correct.
hilde45's avatar
hilde45 OP
5,448 posts
 
@ieales I appreciate your input and will look at the links. There are now a lot of different opinions out there. The amp mfr says it’s fine. REL prefers high level to their own sub if there are two subs. Otherwise, they say low level but have no answer as to how to sum the stereo signal to mono. Others on this thread say both.

Can you clarify what you meant by "Their" when you said:

you should NEVER use the high level output. Especially on a tube amp. Their use is strictly lofi.
Thanks.
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