Outlaw Model 7140 7 Channel Amplifier Review

[dc655321]

All channels driven in multi-channel amps are not a good indicator of its capabilities in real use since surround systems do not have equal levels of content in all channels.

For that particular application, sure.
I'm interested in these devices for an N-way, DSP-based system (per-driver amplification).
Yes, I realize the power required depends on input signal spectra and per-driver passbands.

An amplifier's performance is independent of any application it may be used for.

Given the mediocre results of multi-channel AVRs measured here, it would not surprise me to find significant performance degradation for M>2 channels driven hard (additional noise, sagging outputs, etc).

 

[amirm]

Amir will need some extra dummy loads to properly test this aspect.

I have more dummy loads. What I don't have time for is many combination and permutation of such tests. And usefulness of them.

 

[Burning Sounds]

Good question Amir.... it looks like Audioholics did it in a couple of different ways - against all channels and against adjacent channels...whichever way you think will give the most useful results is fine.

With all channels acting as the noise source or disturber, I measured each idle channel one at a time to determine the worst case channel to channel crosstalk. At 1kHz the UPA-7 yielded -70dB @ 1kHz and -50dB at 10kHz for its noisiest channel. I consider anything less than -40dB @ 10kHz acceptable so the UPA-7 met that minimum requirement with 10dB to spare. With only 1 channel acting as the disturber, the adjacent channel produced -85dB @ 1kHz and - 60dB @ 10kHz. Again these are very good numbers but not the best of what we've seen from Emotiva, most notably with their XPA-2 delivering a staggeringly low -140dB at 1kHz of channel to channel crosstalk isolation.

 

[audimus]

An amplifier's performance is independent of any application it may be used for.

An amplifier’s design performance is usually tuned to the primary application that the unit is designed/marketed for (The labeling on the back of the various channels on this unit might be a hint), not some fringe off-label use.

Given the limits on time and resources, this site would be better off evaluating a unit for its primary use than go chasing after off-label uses for the benefit of a few, IMO. YMMV.

 

[SEKLEM]

One problem with testing large amps is shipping cost to and from Amir.

Agreed. A 50lb amp shipped from the midwest to Amir costs about $100 one way.

 

[pozz]

Agreed. A 50lb amp shipped from the midwest to Amir costs about $100 one way.

I hope that doesn't deter people. I've paid at least $100 for rare books many times: the knowledge has always been worth it.

 

[amirm]

Agreed. A 50lb amp shipped from the midwest to Amir costs about $100 one way.

I now have access to discounted shipping on UPS so it is not as bad as it used to be. I am certainly willing to pay the return shipping that way.

 

[pozz]

Have done a DBT to prove this as required of all listening reports on this site?

How many dBs of droop necessary before it becomes audible?

You know, it's often simpler to just read the literature instead of asking for new listening tests.

IIRC Floyd Toole has stated in his book that there is evidence that slopes of 0.1dB—0.2dB per octave are audible (a 1dB tilt across 20Hz—20kHz), although the effects are generally benign and listeners will quickly adapt.

 

[Labjr]

I now have access to discounted shipping on UPS so it is not as bad as it used to be. I am certainly willing to pay the return shipping that way.

Just last week, I had a fight with UPS because they gave me a discount for shipping and insurance for an expensive guitar. Approx $5,000 value. They then charged my card the non-discounted rate which was $40 more then the shipping cost, clearly on the invoice. You got to watch them. UPS is the worst when dealing with claims. They deny every claim. You have to threaten them legally.

FedEx will not insure musical instruments and other valuables for full value. You have to ask.

 

[amadeuswus]

I wonder how the Sunfire and Carver A-series multi-channel amps would do on Amir's test bench. Distortion figures for these have always seemed on the high side.

https://www.sunfire.com/product/7-x-400w-power-amplifier-TGA7401

https://hometheaterhifi.com/volume_4_2/av705.html

(The A-series Carvers were supposed to be load-invariant and thus flatter than most amps into real-world loads. Not sure if this would show up with standard tests.)

 

[dc655321]

An amplifier’s design performance is usually tuned to the primary application that the unit is designed/marketed for (The labeling on the back of the various channels on this unit might be a hint), not some fringe off-label use.

Given the limits on time and resources, this site would be better off evaluating a unit for its primary use than go chasing after off-label uses for the benefit of a few, IMO. YMMV.

Using each and all amplifier channels for amplification is fringe and off-label?
If the use of a multi-channel amplifier is not to provide > 2 channels of simultaneous amplification, please enumerate the legitimate uses.
My simple request (not demand, as you're intimating) seems like a "primary use" to me...

I would simply like to know that this and similar devices do what they're advertised to do when all channels are involved.

 

[audimus]

Using each and all amplifier channels for amplification is fringe and off-label?
If the use of a multi-channel amplifier is not to provide > 2 channels of simultaneous amplification, please enumerate the legitimate uses.
My simple request (not demand, as you're intimating) seems like a "primary use" to me...

I would simply like to know that this and similar devices do what they're advertised to do when all channels are involved.

Is this a trick question?

Using a multi-channel amp sold with labeling of its channels as L, R, C, SL, SR, RL, RR for a multi-way speaker crossover amping is an off-label use ... literally. Both uses require simultaneous amplification but with different characteristics. Does this really need to be explained?

 

[amirm]

Let's not get personal please. We have higher standards here.

 

[Deleted member 2944]

I have more dummy loads. What I don't have time for is many combination and permutation of such tests. And usefulness of them.

I wouldn't view those tests as particularly useful. I think your two-channel testing scheme on multi-channel amps should sufficiently characterize them. How much amplifier X would "de-rate" based on full-range multi-channel usage, is probably not that relevant to most users setups.

Dave.

 

[dc655321]

Let's not get personal please. We have higher standards here.

Fair enough...
When you measured this amp, did you use the "Left" and "Right" channels as indicated on the back panel? I am assuming you did...
Do you think (or even better, could you measure?) the results of the measurements would be otherwise using any other pair of channels on this unit?

 

[Labjr]

Barring some major design flaw, testing all channels probably won't vary much from two channel testing. And who uses a 7 channel amp with all channels driven to clipping? If he tested all channels with every combination of tests everyone thought it needed, it would never end! The factorial of 7 = 5040!

 

[amirm]

When you measured this amp, did you use the "Left" and "Right" channels as indicated on the back panel? I am assuming you did...
Do you think (or even better, could you measure?) the results of the measurements would be otherwise using any other pair of channels on this unit?

I did use the designated channels. As to doing more tests, it all depends on how fond I am of going to a back doctor after lifting it one more time....

 

[dc655321]

I did use the designated channels. As to doing more tests, it all depends on how fond I am of going to a back doctor after lifting it one more time....

That's reasonable.
Do you think there would be significant measurable difference between using "Center" and "Left Rear" channels, rather than "Right" and "Left" though? I would not think so: it is a device with 7 (presumably) independent channels of amplification...

 

[audimus]

That's reasonable.
Do you think there would be significant measurable difference between using "Center" and "Left Rear" channels, rather than "Right" and "Left" though? I would not think so: it is a device with 7 (presumably) independent channels of amplification...

Depends on the measurement. There should not be much difference in power output or FR for each channel driven separately in modular units like these. But there is anecdotal evidence that noise/distortion measurements can vary between channels from topology induced effects. So much so that some units have tacit “undocumented features” within their user groups on which channels to use in preference over others if not using all channels.

 

[Deleted member 2944]

Depends on the measurement. There should not be much difference in power output or FR for each channel driven separately in modular units like these. But there is anecdotal evidence that noise/distortion measurements can vary between channels from topology induced effects. So much so that some units have tacit “undocumented features” within their user groups on which channels to use in preference over others if not using all channels.

The topology on this amp is identical in all seven channels.
A couple of the modules are located physically a bit closer to the transformer, but other than (possible) effects related to that, the performance should be identical in all seven channels. Note the transformer has seven secondary windings to support the configuration.

Dave.