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Ayre amplifier to Subwoofer connections

I am trying this question again with a more specific title to try to get responses . . .

I am intending to hook an Ayre, fully balanced amplifier to a subwoofer via the high level (speaker) inputs. Ayre has told me NOT to connect negative to black but to chassis ground. A balanced amplifier cannot be connected to anything with a common ground.

The subwoofer amplifier manufacterer (O-Audio) says the plate amplifier has no common ground by virtue of the fact that it only connects 2 prongs to the outlet.

I have also heard that other audiogoner's have connected Ayres to subs via the red and black speaker connections without a problem. How have you accomplished this?

Can anyone explain to me in more detail what is up with this technically and what connections I should be using.

Additionally, can you tell me the pros and cons of connecting the speaker leads to the sub from the speakers vs the amp. Does it have to do with length, noise, etc?

thanks to everyone in advance!
drewh1
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drubin
3,275 posts
 
Interesting. The REL has a three-prong plug. I will say that I think the system sounds better connected the standard way (i.e., not to chassis ground), but that may be the 6db volume difference at work. I don't want to blow up the Ayre of course, but...
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drubin
3,275 posts
 
I have a new question on this subject. How do you connect a stereo pair of subwoofers to a fully balanced stereo amp, such as the Ayre.? The REL cable for each sub has two channels of "hot" (red and yellow) plus a ground. I assume that, for each sub, you would connect both hots (or just one?) to the plus side of the appropriate channel on the amp. But what about the grounds? Would you connect both subs' grounds to the chassis?
drewh1 OP
115 posts
 
Drubin - you might want to start by calling Steve at Ayre about this one. I am sure they have encountered this issue before.
almarg's avatar
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almarg
9,670 posts
 
Drubin -- Yes, you would want to connect both hots (yellow and red) to the plus output of the corresponding channel of the amp, and both subs' grounds to amp chassis.

The subs' electronics sums the difference between its red and black together with the difference between its yellow and black inputs. If you connect both red and yellow to the + output of a fully balanced amp, and black to ground of the amp, then since two identical signals are being summed together, the mono signal the sub provides to its driver will be proportional to the output of that channel of the amp.

If you were to connect sub black to amp negative for the corresponding channel, then as we discussed earlier in this thread you create, under some scenarios, the risk of damaging the amp. However, fwiw, the other downside of doing that which I had mentioned (creating an imbalance favoring one channel in the summation to mono) would not occur in this situation.

Regards,
-- Al
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drubin
3,275 posts
 
Thank you, Al. After i posted my question, I looked around on AA and found a response from a REL representative to a customer in India concerning his hum problem.
Since your Ayre amp is balanced and since you are using two subs, you must have a balanced hi level inupt which your model does not have. It is not a product defect. The unbalanced hi-level input can be used on balanced amps so long as there is only one sub. Also, since the black speaker terminal on a a balanced amp is not ground but rather positive-inverse, you must ground to the chassis, any screw that stops the hum.

Therefore you can use one sub on the Ayre with the sub grounded to the chassis, or perhaps just take the ground from the LFE and leave the black wire out of the equation if that works for you.

If you wish to have two subs on this amp, you must have one of the larger models that are equipped with balanced hi-level inputs. This is, in fact the only circumstance (two subs in stereo on a balanced amp) where the balanced hi-level input is used. This also gets wired up quite differently. Each channel is red-positive, yellow-negative, and black to chassis ground.
This would suggest that I'm SOL regarding using two subs with the Ayre and will need either different models of RELs or a different approach to amplification, such as separates with two sets of preamp outs, or monoblocks, or an unbalanced stereo amp. However, I'm not sure I believe the guy's answer. I have sent a note to REL and will also call Ayre at some point to try to get more clarity.
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