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New Rel Carbon Special Sub “Roars” when there is no signal!

I’ve been breaking in my new Rel Carbon special subs (I have a pair) and one of them started having an issue after about 12 hours of playing them (quite loud).

Just recently the left sub makes an absolute roaring sound when the music signal stops, or when I turn the volume all the way down.  It starts as a quiet rumble but VERY quickly builds to an absolute massive roar.  Was worried about damage but it seems fine provided a music signal is playing.  The issue did not happen until just recently. Now, when I simply turn on the sub, even with the Amp in standby mode, the roar starts building and I have to shut off the sub really, really quickly.

I have my Rel’s connected to my Gryphon Diablo 300, using Rel Bassline Blue high level cables, using Rel’s directions for connecting a balanced differential amp which I’m told the Diablo 300 is.  I have each sub’s high level cable connected to the amp with each cable’s yellow and red lead connected to the red speaker output, and both black ground leads connected to my Diablo 300’s ground terminal.

There is one thing different about each sub right now - the sub without any issue is connected to the wall to a dedicated 20A circuit.  The sub that just recently developed the issue is connected to a shared 15A household outlet - temporary until I acquire longer power cords. I have half a mind to plug the “working” sub to the shared household AC circuit to see if the problem is limited to that line but I’m a bit scared of damaging something.

My Diablo 300 amp is connected to a Torus RM 20 that is plugged into another dedicated 20A outlet….

Any guidance would be appreciated!

 

 

 

nyev
holmz's avatar
holmz
2,328 posts
 

Send that one back or contact the MFR

mofojo
2,167 posts
 

+1. Shouldn’t need a dedicated outlet to function properly although you could try it pretty easily. 

bimmerman2's avatar
bimmerman2
79 posts
 

REL hookup to a balanced differential amp use the yellow and red together only, the black is unused. That's how they are attached to my differential monoblocks. 

nyev OP
1,019 posts
 

@bimmerman2 Talked to Rel today, yes you can have the black wire floating (you should tape it with electrical tape to avoid it accidentally coming in contact with the chassis and causing a short.

if you have a ground stud on your balanced differential amp (NOT the negative speaker terminal as that would be disastrous, you can also connect it to that. Rel recommended doing so to me on the phone today, but it’s not necessary if you don’t have any problems with ground hum.

Back to my issue, after much diagnostic troubleshooting this evening I found the problem. Turns out the position of my left sub is in close proximity to a wireless device ( I think it is a router) in the suite below, despite the thick soundproof flooring. When I move the sub either forward or backwards the noise changes to a low and constant hum. Move it far enough and it goes away entirely.

My next step is to see if Rel thinks it is worth it to source some inexpensive EMI shielding material. My thought is I can lay 1m x 1m of it (or more) it on the floor l, and then put a small rug over it so it doesn’t look bad, and the Rel can then sit on top of the rug. Not sure how effective that mesh EMI shielding is but I think it’s worth a shot.

I’ll talk to Rel tomorrow again to see if they think this is worth trying.  I’m just really glad I didn’t have to send back a defective unit and have a replacement shipped.  My wife was afraid that sound was going to break the houses windows and now the kids are absolutely terrified of my subs.  Rel, you are not helping with my popularity in my house! :)

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