Proper way to hook up a REL Sub

[tdelahanty]

Originally Posted by junker

Unfortunately not. The MC452 is fully-balanced.

Yours does have the Autoformer though.

Don't see how balancing would matter however... Balancing in and of itself primarily reduces noise.

No low-level input on that sub? Is it amplified??

A fully balanced amp does not have a ground connection at the speaker binding-posts, so the sub gnd terminal will float. Amps that are not fully balanced have the black speaker binding-post at gnd, therefore the sub will see a proper gnd.

[junker]

Originally Posted by Rick U

That's it! I'm ordering the 452!

[j3brow]

Originally Posted by tdelahanty

A fully balanced amp does not have a ground connection at the speaker binding-posts, so the sub gnd terminal will float. Amps that are not fully balanced have the black speaker binding-post at gnd, therefore the sub will see a proper gnd.

So what does it mean if the sub gnd terminal will float? What is the consequence? Hum?

[cougit25]

Originally Posted by Still-One

Make sure you check with McIntosh to connect a REL sub with Speakon cables properly. When they connected the REL G1 to my 1.2ks one of the wires was connected to a screw in the chassis and not one of the speaker taps. The learned here can explain why, something to do with the design of certain Mac amps.

I agree 100%. I had an REL some years ago and the connection scheme was different because my MC402 is a fully balanced amp. My memory of that scheme escapes me now.

[j3brow]

Originally Posted by cougit25

I agree 100%. I had an REL some years ago and the connection scheme was different because my MC402 is a fully balanced amp. My memory of that scheme escapes me now.

I am really interested in this topic. I have had REL subs hooked up in the conventional REL manner to McIntosh amps for 5 yrs now -- 1st MC402 and now MC501s. I don't have hum. Never have. Am I losing subwoofer performance?? I don't really know my exact wiring scheme now -- I am using aftermarket Signal Cable brand REL custom cables with the standard 3 wires per sub reduced to the typical 2 leads, black and red (I think the yellow and black combine to black, dunno). Each sub is hooked up to its dedicated channel (501) via the 4 ohm +/- taps that are supplying my Sophia 3 speakers.

[tdelahanty]

Originally Posted by j3brow

So what does it mean if the sub gnd terminal will float? What is the consequence? Hum?

Float, floating gnd means there is no connection to gnd , you need a hard (zero ohms) connection to gnd to avoid hum.

[jfray]

Originally Posted by edward3132

It depends if your amplifier is truly fully balanced or not.

From the manual:

For differential (i.e. fully balanced) amplifiers using one REL, simply use
the standard connecting scheme with the exception of connecting the black
wire to chassis ground (i.e. a metal bolt or screw, preferably not painted or
anodized, on the chassis of the power amp or receiver), not to a negative
speaker terminal,, and then connecting into the HIGH LEVEL INPUT on the
REL. Please contact your dealer should there be any questions concerning
this or any other hookup procedure.

+1 This is the correct way.

[Rick U]

I received a reply from McIntosh. Basically, the REL speaker level connections are okay on the MC302 and not okay on the MC452 because the 452 is not a common grounded amp. Chuck recommended using line level but the magic of the REL sub is in it's speaker level connection. This is a curve ball because I ordered the 452. I also hooked up the sub to the 302 and the synergy was stunning. Do I cancel the 452?

[j3brow]

Originally Posted by Rick U

I received a reply from McIntosh. Basically, the REL speaker level connections are okay on the MC302 and not okay on the MC452 because the 452 is not a common grounded amp. Chuck recommended using line level but the magic of the REL sub is in it's speaker level connection. This is a curve ball because I ordered the 452. I also hooked up the sub to the 302 and the synergy was stunning. Do I cancel the 452?

Rick,

No way should you cancel the Mc452. It's a beautiful beast and should be a worthy step up over the 302. And don't get rid of the REL either. Just hook it up as the manual states. I am assuming that Chuck was able to tell you which chassis screw could serve as a ground??? For what it's worth, this thread has informed me that I have had my single REL B3, then single B2, then stereo B2's hooked up incorrectly for 5 years now with 1st MC402 and now MC501s both of which are quad balanced designs. I also hooked the RELs up to stereo and monoblock Mc2102s. I have not suffered any deleterious effects that I know of. I don't have any audible hum. Guess I have been lucky. Did Chuck say if hooking up the REL could be harmful to the amp????

Jason

[Rick U]

Chuck did not discuss using a grounding screw. I believe that was in the REL manual. I might be wrong.

Jason do you still have the 452 w/ REL?