Proper way to hook up a REL Sub

[Rick U]

How do you connect the common black wire to an RCA plug? Is the center part of the RCA negative or positive?

[tdelahanty]

Originally Posted by Rick U

How do you connect the common black wire to an RCA plug? Is the center part of the RCA negative or positive?

The center post is "hot", the taller post which appears to be part of the side or main body is the ground post and strain-relief

[Msegal]

I am late to the party but I am grafting two REL G1's onto my Focal Scalas. I plan to drive them with my monoblock MC275LE's. REL prefers to drive off the amplifiers directly to maintain the same sonic signature. I am hoping the 150Kohm impedance of the G1 will be benign enough to prevent any bass loss. I also expect the filter network to reduce the work the amplifier has to do.

Am I making correct assumptions?
Should I have concerns regarding the tube amp driving the G1's?
Any other thoughts or experiences are appreciated.
Thanks in advance.

Mike S.

[tdelahanty]

Originally Posted by Msegal

I am late to the party but I am grafting two REL G1's onto my Focal Scalas. I plan to drive them with my monoblock MC275LE's. REL prefers to drive off the amplifiers directly to maintain the same sonic signature. I am hoping the 150Kohm impedance of the G1 will be benign enough to prevent any bass loss. I also expect the filter network to reduce the work the amplifier has to do.

Am I making correct assumptions?
Should I have concerns regarding the tube amp driving the G1's?
Any other thoughts or experiences are appreciated.
Thanks in advance.

Mike S.

You're almost there !!!. The high Z of the R1 will not pose any problem. However the R1's filter network (cross-over) will not reduce the bass load on your amp, it only sets the hi-cutoff of the sub. REL intends the amp to run full-range and the sub to augment "sub-bass". I recommend setting the R1 no higher than 40hz.

[Msegal]

Originally Posted by tdelahanty

You're almost there !!!. The high Z of the R1 will not pose any problem. However the R1's filter network (cross-over) will not reduce the bass load on your amp, it only sets the hi-cutoff of the sub. REL intends the amp to run full-range and the sub to augment "sub-bass". I recommend setting the R1 no higher than 40hz.

Thanks for the advice.
The Sumiko rep should be showing up next week to tune it in.

[cougit25]

It would seem to me that since a fully balanced amp has a floating ground and I connected the load from the REL sub across the chassis ground and a hot terminal of the amplifier... I would be in effect eliminating the floating ground. However, I am not sure if the high impedance of the REL sub makes this a non-issue.

[Rick U]

From REL re using RCA as ground.

That is not recommended for Balanced or Differential amps. You can damage both the REL and the amp by attaching the black ground wire in the REL cable to any negative terminal on a fully Balanced amplifier, including an unused RCA. You should look for another ground source. If you have another nearby appliance like a preamp with a chassis screw or dedicated ground post, that would work.

[j3brow]

Originally Posted by Rick U

From REL re using RCA as ground.
That is not recommended for Balanced or Differential amps. You can damage both the REL and the amp by attaching the black ground wire in the REL cable to any negative terminal on a fully Balanced amplifier, including an unused RCA. You should look for another ground source. If you have another nearby appliance like a preamp with a chassis screw or dedicated ground post, that would work.

Thank you Rick!!! Kinda scary to hear I could damage my Mc amps and REL subs by running my subs without a proper ground. I would of never known my subs were incorrectly hooked up without this thread. Seems simple enough --- hook up red, black, yellow wires. I haven't read manual since I first ran REL with my unbalanced Musical Fidelity amp. I had NO CLUE a balanced amp meant a floating ground. I do now. Thanks guys.

Big thanks to Rick for following up his conversation with Sumiko. I have a grounding post on my Mc C2300 preamp that I suppose will suffice. If memory is correct, it is grounding post for phono

I'm gonna ditch my 'custom' REL Signal Cable brand connections and use the standard issue Speakon connection. The sound improvement was very very modest if any at all anyhow.

Jason

[tdelahanty]

Originally Posted by cougit25

It would seem to me that since a fully balanced amp has a floating ground and I connected the load from the REL sub across the chassis ground and a hot terminal of the amplifier... I would be in effect eliminating the floating ground. However, I am not sure if the high impedance of the REL sub makes this a non-issue.

Bingo, the REL's high input Z is the key, NO HARM WILL BE DONE !!!

[tdelahanty]

Originally Posted by Rick U

From REL re using RCA as ground.
That is not recommended for Balanced or Differential amps. You can damage both the REL and the amp by attaching the black ground wire in the REL cable to any negative terminal on a fully Balanced amplifier, including an unused RCA. You should look for another ground source. If you have another nearby appliance like a preamp with a chassis screw or dedicated ground post, that would work.

This statement is nonsense !!! A ground on a preamp will be carried to the power amp by your interconnect cables, if all components have a three wire power cord then all chassis are at earth ground potential. The output-stage of the power-amp is above ground (floating), the load (speaker) is connected between the two sections of the output stage.

Both my Levinson amps, 335 & 383 are fully balanced. The ground wire from the REL is connected to a rca input ground. They have functioned perfectly for years without damage.