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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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daveyf
2,871 posts
 
 @ricred1  I’m not so sure that the compatibility issue with REL subs and balanced differential amps isn’t well documented. There are quite a few posts on this forum and others about the issue. REL themselves now has a helpful video on their web site about hook up protocol. 
I run dual REL subs with my Jadis mono blocks, there were also some issues to hooking up those as well. I ended up having two connector cables custom made by Signal cable. Took me months to get the blend correct, and last night I noticed that my left subwoofer seems to put out a lot less output than my right...not sure why this is the case, but more experimenting to find out what’s going on. Sometimes these subs can be a royal PITA. 
ricred1 OP
2,021 posts
 
daveyf and almarg PM sent
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almarg
9,670 posts
 
PM answered.

Best regards,
-- Al

ricred1 OP
2,021 posts
 
Although I'm frustrated with the inability to at least try the high-level input, I ordered a second REL Carbon limited that I should have on Monday. The addition of a single REL has increased my enjoyment of my 2-channel system; so I figure dual subs will be better. I reached out to REL again today in hopes that someone can provide a simple way to use the high-level input without damaging my amplifier or sub. Hopefully someone from REL will contact me tomorrow. 
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daveyf
2,871 posts
 
In the past whenever I have contacted REL, i have done so via e.mail. They have always responded fairly quickly to all of my inquiries and questions.

The addition of another REL should give you a nice boost in SQ, albeit with a lot more set up time involved and experimentation in positioning, x-over, and volume settings in order to get the blend to be invisible. It took me almost two months to get it right...and I am still making very minor adjustments even now!! Two subs are more than twice as difficult to dial in than just one...BUT the effort will be worth it.
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