Ayre amplifier to Subwoofer connections

This is an interesting and timely topic as I just today picked up an AX-7 to play around with. I connected my REL to it the way I normally would, with the one black lead connected to one channel's "-" terminal. Drewh1, did Ayre suggest what to use for chassis ground on the unit? There are no obvious screws on the back to use.

(In case anyone at Ayre is reading this, the Cardas binding posts are not ideal when you are connecting a subwoofer this way because you end up tightening down for the terminal with the subwoofer lead and then it's not tight enough on the other pole.)

For subwoofers that only offer line level connection, such as the JL Audio subs, how would you connect them to the Ax-7, which has no pre out -- through the tape out?

I connected my REL to it the way I normally would, with the one black lead connected to one channel's "-" terminal.

Drubin -- What model REL is it? And does it have a 3-prong power cord? If so, you definitely don't want to do that. For the reasons I explained above, and also note the cautions on page 5 of the AX7 manual:

http://www.ayre.com/pdf/Ayre_AX7e_Manual.pdf

Regards,
-- Al

It's an R-205 and, yes, it uses a 3-prong power cord.

I've lifted the ground. Sound seems to be the same either way.

Drubin,

The R-205 manual indicates in multiple places that for a fully balanced amplifier the black wire of the high level input should go to amp chassis.

Not sure why you didn't hear a difference when you lifted the ground. Perhaps its signal ground and ac safety ground are not common, the way they normally are with amps and preamps. If you have a multimeter, it would be interesting to see if there is continuity between the black wire and the safety ground pin of the power plug.

In any event, even if things are somehow isolated so that you avoid the risk of damage to the amp, I don't think you will get the right sound with the black wire going to the negative terminal of one of the amp output channels.

If we denote the instantaneous voltage between the amp's left positive terminal and the amp's ground as Lvolts, and the instantaneous voltage between the amp's right positive terminal and the amp's ground as Rvolts, the corresponding voltage that the sub provides to its driver should be proportional to (Lvolts + Rvolts), which is a mono signal obtained by summing together the left and right channels.

That is what will happen with the black wire from the sub connected to amp chassis. However, if it is connected to, say, the left channel negative terminal of the amp instead, what will result is ((2Lvolts) + (Rvolts-(-Lvolts))) = (3Lvolts + Rvolts). So instead of the summation to mono giving equal weight to the two channels, the left channel would receive very disproportionate emphasis (the factor of 3 corresponding to about 9.5db).

Drew -- Upon re-reading my earlier post, I want to make sure it's clear that no disrespect at all was intended when I used the word "ouch." We've all made comparable mistakes at one time or another, including me.

Regards,
-- Al

Drubin,

I have Ayre MXR's and a Rel Studio. I was instructed by Ayre to connect the red wire (positive) from the Rel to one amp's positive and the yellow wire(positive) from the Rel to the other amp's positive terinal. The black wire from the rel (negative) is to be connected to the center post that is used to tighten the Cardas terminals on one of the amps. This gives the black wire a connection to ground. Hope this helps.
Bob