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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

Showing 2 responses by audiorusty

audiorusty
267 posts
 

Sounds like you were experiencing acoustical feedback. Having the issue diminish or disappear all together when you moved the sub is an indicator that you were able to disrupt the phase relationship between the subs output and input and since you lowered low pass filter setting the offending signal is more than likely above that setting and no longer being reproduced by the sub.

audiorusty
267 posts
 

I totally agree. If it is acoustic feedback and I believe that it is, it is the most bizarre case I have ever come across.

My guess is that the high level speaker cable is the culprit. I’m guessing that since it is a speaker level connection, REL is using speaker cable for the connector. Speaker cable by design is unshielded. I believe you also mentioned that there is a router in close proximity to the offending sub.  My guess is that the router or something near it is emitting a low level signal that the high level connector cable is picking up, sending it to the subs input and so on. The solution could be as simple as raising the high level connector cable off the floor or by using the low level inputs.

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