REL subs with Rowland Amplifiers

For sake of comparison, if the high-level connection is a 100 for sound, what is the low-level connection, 80, 90, 95?

Your guess is as good as mine on that question, Richard. As I’m sure you’ve seen, REL recommends using speaker-level connections where possible, their rationale being that the signals received by the sub and the main speakers will then both reflect the sonics of the power amp. Although over the years I’ve seen at least one or two members here having extensive experience with subs express disagreement with that philosophy.

Personally I don’t use a sub, and I have no particular opinion concerning that rationale. And in any event I would expect the degree of difference that would occur between the two connection approaches to be significantly system dependent. The more accurate/neutral the amplifier’s sonics are, the less difference there would presumably be between the two approaches.  Assuming, that is, that the preamp is capable of driving the relatively low input impedance that most subs have at line-level without issue, while simultaneously driving the power amp.

Best regards,
-- Al

I own a JR model 8T. I had the same type of issues as you. Having contacted REL, I was told to hook up the system essentially the same way, yellow on the positive left, red on the positive right and the black to the negative ( neutral) of the red channel. This seemed to be ok. However, after I had my amp modded by Jeff, I asked him about this and he suggested that we add a ground connection at the chassis of the amp...which he did. I now utilize the ground connection for black, and the red to right, yellow to left. You might want to send your amp back to Jeff for him to do the same thing. Not sure I would want to loosen a screw of the chassis as Jeff suggests. Nonetheless, I think Almarg's advice is also correct.

I'm just so surprised that the compatibility problem between REL and Jeff Rowland amplifiers and other balanced differential amplifiers isn't well documented.

lalitk,
Thanks so much for your assistance.

daveyf,
" Not sure I would want to loosen a screw of the chassis as Jeff suggests." I know it sounds trivial to some, but I couldn't agree more and I'm not going to loosen any screw. I may contact Jeff Rowland and ask about adding a ground connection on the chassis. 

 @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. 

daveyf and almarg PM sent