REL subs with Rowland Amplifiers

Hi Richard,

I suspect the reason floating the ground wire doesn’t work in this case is that the inputs of your amp are transformer coupled, so a ground path is not established between the sub and the amp via the preamp, since the preamp’s ground is isolated from the amp’s ground via those transformers. If the grounds of the amp and preamp were not isolated, as is usually the case with most other designs, a ground path having reasonably low impedance would be established between the sub and the amp via the preamp-to-amp interconnections in combination with the AC safety ground wiring of the preamp and the sub.

For the same reason connecting the black wire to a ground point on the preamp would presumably not work either.

While Lalit has very graciously offered to let you try the speaker-to-line level converters he will be receiving, I don’t think it would be safe to use them with your particular amp. I would envision that most such converters would attenuate the level that is provided to their signal input, but would route the ground that is provided to their input directly to their output. Since your balanced amp has full-amplitude signals on both its + and - output terminals (rather than the amp’s - output terminals being connected to its circuit ground), the result of routing both output channels of your amp through such converters to the left and right channel RCA input connectors of a single sub would almost certainly be that the full amplitude signals on the negative output terminals of the two channels are shorted together by the sub’s internal ground. Definitely a no no.

Given that the amp does not provide RCA input connectors, or any other circuit ground connector, the one **possible** alternative I can envision to attaching the sub’s black wire to a chassis screw, as Jeff suggested, would be to solder the black wire to the ground shell of a 1/8 inch mini-plug, while leaving the signal pin(s) of that plug unconnected, and inserting that plug into the amp’s remote on/off jack.

This assumes three things, though:

1) It assumes that the ground shell of the remote on/off jack is internally connected to the amp’s circuit ground. You would need to confirm that with Jeff.

2) I suspect that it wouldn’t matter whether the mini-plug is a stereo type or a mono type. Again, though, that should be confirmed with Jeff.

3) It assumes that you presently have nothing connected to the remote on/off jack. Although if you are presently using it you could probably solder the sub’s black wire to the ground shell of the plug that is being used, if assumption (1) is confirmed by Jeff.

Good luck. Best regards,
-- Al

Al,

As always thanks so much for your response. Your post highlights my concern. If I don't ground it properly I will damage my amplifier and/or sub. Like I've already stated, is does work via the low level input, but I'm wondering if it will sound better via the high-level input. For sake of comparison, if the high-level connection is a 100 for sound, what is the low-level connection, 80, 90, 95? I'm not concerned if there's only a slight difference in sound between the two inputs; however if there's a significant difference than I would like to find a way to safely connect through the high-level input.

Richard,

I am quite surprised that REL unable to help or provide amicable solution. They were extremely helpful when I contacted them about high level connectivity with my ARC amp.

Let me PM you my contact at REL. 

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.