Parralleled Alephs

audionut · 21st November 2002, 09:14 PM

I have parralleled two Aleph 3 channels in order to drive a low impendance load of two scan speak 7 inch woofers. (this is a bi-amped system)

One aleph channel powering that load sounded pretty good...I think that the two parralleled channels sound better...or is this my imagination?

Nelson Pass · 21st November 2002, 09:59 PM

No, they measure better also, as each thinks it's
driving twice the actual impedance.

Bill Fitzpatrick · 21st November 2002, 10:30 PM

This begs the question - can any two identical amps be paralled?

Nelson Pass · 21st November 2002, 11:34 PM

If they are perfectly matched, generally yes.

The problems arise from the channels not being identical,
as they then will argue with each other. The lower the
output impedance, and the more feedback, the worse it
gets. Alephs are pretty laid back with regards to these
parameters, and so they get along pretty well.

For amps with lots of feedback and/or high damping factors,
it helps a lot to (a) match the gain carefully and (b) adjust
the DC offset to match.

After that, it often is helpful to place some resistance in
series with each amp's output, say a fraction of an ohm,
which limits the amount of current which will flow from one
amp to another.

So why do this? Because the distortion of most amps is
highly dependent on current, reducing the output current
requirements of each amp will drop the distortion fairly
dramatically. This is also a reasonable way to tackle very
low impedance loads.

Zens and Alephs seem to love being paralleled; just connect
the inputs and outputs together.

Bill Fitzpatrick · 22nd November 2002, 12:30 AM

Nelson:

In audionut's scenario he could just as well drive each of the woofers separately using one channel of the Aleph for each. Yet it's in his mind to parallel both amps and woofers. Based only on the information you provided, there is no difference . . . or is there?

audionut · 22nd November 2002, 12:37 AM

I've got long wire runs to the speakers...so I use one pair of heavy guage wire...

Nelson Pass · 22nd November 2002, 04:26 AM

Quote:

Originally posted by audionut
I've got long wire runs to the speakers...so I use one pair of heavy guage wire...

A separate long cable for each parallel amplifier might fill the
bill.

"In audionut's scenario he could just as well drive each of the woofers separately using one channel of the Aleph for each. Yet it's in his mind to parallel both amps and woofers. Based only on the information you provided, there is no difference . . . or is there?"

Not much, except of course, that issues about amplifiers
arguing go away.

21st November 2002, 09:14 PM	#1
audionut diyAudio Member Join Date: Jan 2002 Location: Cleveland ohio	Parralleled Alephs I have parralleled two Aleph 3 channels in order to drive a low impendance load of two scan speak 7 inch woofers. (this is a bi-amped system) One aleph channel powering that load sounded pretty good...I think that the two parralleled channels sound better...or is this my imagination?

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21st November 2002, 09:59 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	No, they measure better also, as each thinks it's driving twice the actual impedance.

21st November 2002, 10:30 PM	#3
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	This begs the question - can any two identical amps be paralled?

21st November 2002, 11:34 PM	#4
Nelson Pass The one and only Join Date: Mar 2001	If they are perfectly matched, generally yes. The problems arise from the channels not being identical, as they then will argue with each other. The lower the output impedance, and the more feedback, the worse it gets. Alephs are pretty laid back with regards to these parameters, and so they get along pretty well. For amps with lots of feedback and/or high damping factors, it helps a lot to (a) match the gain carefully and (b) adjust the DC offset to match. After that, it often is helpful to place some resistance in series with each amp's output, say a fraction of an ohm, which limits the amount of current which will flow from one amp to another. So why do this? Because the distortion of most amps is highly dependent on current, reducing the output current requirements of each amp will drop the distortion fairly dramatically. This is also a reasonable way to tackle very low impedance loads. Zens and Alephs seem to love being paralleled; just connect the inputs and outputs together.

22nd November 2002, 12:30 AM	#5
Bill Fitzpatrick diyAudio Member Join Date: Jun 2001 Location: Eugene, OR	Nelson: In audionut's scenario he could just as well drive each of the woofers separately using one channel of the Aleph for each. Yet it's in his mind to parallel both amps and woofers. Based only on the information you provided, there is no difference . . . or is there?

22nd November 2002, 12:37 AM	#6
audionut diyAudio Member Join Date: Jan 2002 Location: Cleveland ohio	I've got long wire runs to the speakers...so I use one pair of heavy guage wire...

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