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REL subs with Rowland Amplifiers

I'm having issues connecting my REL Carbon limited subwoofer to my Jeff Rowland 625 S2 amplifier via the high-level input. I connected my sub according to REL's instructions...yellow lead to positive on one channel, red lead to positive on the other channel, and floating the black wire(ground). I get minimum output when connected according to the instructions. When I use the low level input, the output is sufficient and the sub sounds great. Per my conversation with Jeff Rowland I need to ground the black wire by loosening a screw on the amplifier and connecting the black wire, but if it isn't properly grounded I may damage my amplifier. Is there anyone that owns a REL with Jeff Rowland 625 S2 amplifier or other balanced differential amplifier? If so, how do you connect your REL via the high-level input. Is there an easier way to ground the wire than unscrewing the screw on my amplifier. I just don't want to unscrew the screw and prefer another method of grounding the sub.   
ricred1
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almarg
9,670 posts
 
daveyf,
You are correct my Signal cable has the red and yellow cables together and each cable has a Speakon end at the sub and a red/yellow connector and a black connector ( at the amp end).

OK, thanks to you both for pointing that out. I see no problem as far as that goes, then, given that each cable is just connecting a single sub to a single amp channel.

Al,
I’m assuming if the Signal Cable is picking up EMI from something nearby to cause the hum, adding an external ground screw on my amplifier won’t eliminate the hum?

I suspect that chances are it will eliminate the hum, although I can’t be totally certain about that. But I suspect that even if something nearby is inducing hum in the Signal Cables, providing a better ground path between the subs and the amp (i.e., one that does not involve the AC safety ground wiring) would eliminate susceptibility to that hum. And the fact that connecting the LFE cable does eliminate hum when the Signal Cable Speakon is used would seem to provide confidence in that expectation.

Best regards,
-- Al


ricred1 OP
2,043 posts
 
After talking to Jeff Rowland via email today I decided to continue to use the low-level input of my RELs with RCA cables. My only question now is how much of a difference subwoofer cables make? I'm going to call my local dealer for a home audition of Audioquest's Wolf subwoofer cable to compare against Audioquest's Boxer and Wireworld's Equinox.


On a side-note, I just have to say what a class act Mr. Jeff Rowland is and he provides outstanding customer service.
ricred1 OP
2,043 posts
 
Based on the recommendation of a fellow Audiogon member I purchased Aurelex SubDude-HT subwoofer isolation platforms to put under my REL subs. In my opinion it’s a relatively inexpensive way to improve the overall sound of a system with subs...money well spent.
ricred1 OP
2,043 posts
 
Changed from REL Carbon Limiteds to dual REL G1 mkII. I'm going to compare the high-level connection to the low-level connection to see which one I prefer. 
ricred1 OP
2,043 posts
 
I don't know why, but with the G1 mkII there's a big difference between using the high-level and low-level connections. My wife and I prefer the high-level because it sounds more natural. The orher difference is the REL Carbon Limited's sounds better when placed on  the inside of the speakers.  The G1s sound better behind and to the outside of the speakers...much more open. 
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