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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
ricred1 OP
1,981 posts
 
davefy,
If you read my post dated 9-21-2019, "I have been corresponding with Justin Magana who is REL’s Chief Engineer. Based on his advice I twisted the red and yellow wires together and connected my REL via the high-level input. The black wire is floated. It worked! I have plenty of output from the sub and absolutely zero hum." PLEASE NOTE NO RCA CABLE WAS CONNECTED AND IT DIDN'T SOUND GOOD TO MY EARS. I clearly have listened to the high-level connection with the supply REL speakon cables. 

"The red to right positive, the yellow to left positive and the black to either negative connector." PER MY CONVERSATION WITH ROWLAND AND REL CONNECTING ANY LEAD TO THE NEGATIVE CONNECTOR  WILL DAMAGE MY AMP, SUB, OR BOTH.

I have two options:
1) use the low-level input connected via RCA cables
2) send my amplifier to Rowland and have him add an external ground screw that will enable me to safely connect to the high-level input
daveyf's avatar
daveyf
2,835 posts
 
Richard,
Clearly the best ( and maybe the only way) to hook-up the sub to your particular amp is to have Jeff install a ground connector ( like he did for me). This is a sure fire way to success. 
Since you like the low level connection, maybe sending to Jeff isn't going to be worth it....with all of the hassle that will involve.
ricred1 OP
1,981 posts
 
davefy,
"I did notice that Richard turned down the low level connection...BUT I believe that the connection to the low level bypasses the connection to the high level once the RCA ic is connected to the preamp/sub. Since he had sound, I would suspect that the sub may have been out of the system blend and the mains were being solely listened to." 

I DON'T KNOW HOW TO MAKE MYSELF ANY CLEARER. IT WAS NOT, I REPEAT NOT CONNECTED TO THE LOW-LEVEL INPUT. BOTH REL SUBS WERE CONNECTED TO THE LFE INPUT, PER REL THAT ESTABLISHES A GROUND CONNECTION FOR THE SUBS. CONNECTING TO THE LFE INPUT DOESN'T BYPASS ANYTHING; IT'S USED  AS A WAY TO GROUND THE SUBS TO PREVENT HUM. I WAS LISTENING TO THE HIGH-LEVEL INPUT PERIOD.
ricred1 OP
1,981 posts
 
Al,
Is there a logical reason why when both subs are connected through the high-level input with the REL supplied speakon cable no hum is audible,  but when  I use the Signal speakon cables the hum is clearly audible?  This is with no RCA cable  connected to the RELs LFE inputs and into my preamps outputs. Of course connecting RCA cables to the LFE inputs and my preamp's output eliminates the hum when the REL supplied speakon cables or Signal speakon cables are used. 
daveyf's avatar
daveyf
2,835 posts
 
Richard, were you or were you not connecting your RCA ic to your preamp from your REL at the low level connection (LFE connection)? Because if you were, you are now activating your low level connect ( pushing signal as well as establishing a ground), I do NOT believe you can have both a high level and a low level at the same time...as I was told that if you do this, the low level takes precedence.
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