2. amps-preamps
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Differential Monoblocks with twin REL subs

Hi, I would appreciate any advice to avoid damaging my amps. I have a pair of Magneplanar MG 2.6R speakers which I use with a Primare 928 pre and a couple of Primare 928 Monoblock power amps. I am now looking for a little more bass depth and so have bought a pair of 2nd hand REL Q50 subwoofers. I now realise that I am not sure how to connect them without risking damage to the monoblocks.

The issue is, I think that the monoblocks are fully balanced (differential) amps, and so unlike most amps, the
-ve terminal is likely to be live, and connecting the REL Neutrick black ground lead as normal to the -ve terminal would short the amp.

So my questions are:

1. Would my best bet be to connect both yellow & red Neutrik leads from my left sub to teh +ve terminal on my left monoblock, nothing attached to the -ve terminal, and teh black ground wire attached to a ground point on the amp's chassis? Same for the right sub & monoblock. Would this be safe?

OR because the amp is deifferential would I be losing out on some of the signal by not using the -ve terminal?

2. In which case should I connect the yellow live Neutrik lead to +ve, the red live Neutrik lead of -ve on the same monoblock, and the black ground lead to a ground point on the chassis? Would this be safe?

3. And finally, if the amp isn't really differential (I don't have the manual, would either of the above options be likely to cause any damage?

I hadn't really thought this through properly before buying the subs, so any help greatly appreciated before I take the plunge and set them up.

mackh
mackh

Showing 1 response by chipbyrd

chipbyrd
17 posts
 
Hello,

The following is a response I received from REL:

Chip,
Connecting a pair of RELs to a balanced amp in stereo is only a little different form the standard REL connection scheme. Your subs should have come included with the REL High Level cable. That cable consists of three wires, Black, Yellow, and Red. The Red and Yellow are positive leads and eth Black wire is your ground lead. You need to pair the Red and Yellow wires from the first sub to a single positive binding post (right side). The Red and Yellow wires from the second sub will be paired together on the other positive binding post (left side). Both Black wires need to be attached to a dedicated ground post or chassis screw. You cannot connect the Black wires to a negative binding post because there is enough current on the negative side of a balanced amp to potentially damage eth ground circuit on the RELs.       

Paul Greene
Service Department Manager
SUMIKO | 2431 Fifth St | Berkeley, CA 94710
ph 510.843.4500 | fax 510.843.7120
www.sumikoaudio.net
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