Outlaw Model 7125 Power Amplifier Preview

[RichB]

Think of it as a high current high-pass filter.

So do you think it will do more good or harm?

- Rich

 

[Irvrobinson]

So do you think it will do more good or harm?

- Rich

Since we don't know if DC offset is causing your transformer hum issues, the only easy way to see if it helps is to buy one and try it. I can't believe the Emo will do any harm, it just may not do any good.

 

[Pyrrho]

...
Of course, all channels driven into an 8 ohm load isn’t what truly separates an amplifier like the Model 7125 from a run of the mill receiver. The raison d'etre to make the move to a separate amplifier is performance into more difficult loads, and into a 4 ohm load, the Model 7125 can deliver a whopping 190W, again all channels driven (20Hz-20kHz, <0.05% THD). Quite frankly, there aren’t many AVRs with the cajones to deliver that kind of juice, regardless of price, let alone anywhere near the $1,000 mark. In fact, bench testing of the $1,100 Yamaha RX-A1010 suggests few midrange receivers can deliver that kind of 4 ohm performance with 2 channels driven (the Yamaha delivered 155W, full bandwidth, 0.1% THD).
...

The difference in volume between 155 watts and 190 watts is only 0.9dB. That is very little for spending an extra $1000 (extra, because one still needs to buy a receiver for the processing and other things the receiver does that a power ąmp can't do). That is a trivial gain for the price. In most cases, it would just be a waste of money.

Here is a handy calculator for comparing two different power outputs for how many decibels of difference there is:

dB Power Ratio Calculator

Or one can simply remember that to get a mere 3dB difference, one needs to double the power. So getting just 3dB more than that 155 watt Yamaha would require 310 watts. And while one is calculating how much power one needs to get enough extra volume to be worthwhile, one also needs to remember the limits of power handling of the speakers. If the speakers will be destroyed with 310 watts, then one will not be getting even 3dB more than what the Yamaha can deliver, no matter what amplification one has. And one also should consider how loud it really needs to be, particularly if one wishes not to damage one's hearing with loud sounds.

 

[Steve81]

The difference in volume between 155 watts and 190 watts is only 0.9dB. That is very little for spending an extra $1000 (extra, because one still needs to buy a receiver for the processing and other things the receiver does that a power ąmp can't do). That is a trivial gain for the price. In most cases, it would just be a waste of money.

155W vs 190W isn't a huge difference to be sure, but you're still comparing what an AVR can do 2CH driven to a power amp all channels driven. That same Yamaha managed to put out 70W ACD, 1kHz with 1% THD into 8 ohms versus the Outlaw's rated 125W, full bandwidth, with 0.05% THD. That's a 2.5dB difference with much tougher qualifications on the Outlaw's figures. Now what do you think that Yamaha is going to do with 7 channels driving 4 ohm loads versus the Outlaw?

 

[PENG]

Can that be measured?

For the record, there is no hum coming from my Outlaw 7500 nor Parasound A51.



- Rich

A scope would be great but you could get an idea with a good digital multi meter using the proper DC range. If your other amps don't hum then quite likely dc offset isn't the culprit though not 100% sure.

 

[RichB]

A scope would be great but you could get an idea with a good digital multi meter using the proper DC range. If your other amps don't hum then quite likely dc offset isn't the culprit though not 100% sure.

Thanks, I have one of those.
I'll see if my EE friends knows how to measure it.

- Rich

 

[Pyrrho]

155W vs 190W isn't a huge difference to be sure, but you're still comparing what an AVR can do 2CH driven to a power amp all channels driven. That same Yamaha managed to put out 70W ACD, 1kHz with 1% THD into 8 ohms versus the Outlaw's rated 125W, full bandwidth, with 0.05% THD. That's a 2.5dB difference with much tougher qualifications on the Outlaw's figures. Now what do you think that Yamaha is going to do with 7 channels driving 4 ohm loads versus the Outlaw?

When they start making soundtracks with all channels simultaneously at maximum volume, then it will matter what it can do all channels driven. Otherwise, it is irrelevant to useful real world performance. You might want to read this thread:

http://forums.audioholics.com/forums/amps-pre-pros-receivers/14222-all-channels-driven-fallacy.html

No one is saying that the Outlaw isn't better. It just isn't enough better to be a good thing for most people to buy.

 

[Steve81]

When they start making soundtracks with all channels simultaneously at maximum volume, then it will matter what it can do all channels driven. Otherwise, it is irrelevant to useful real world performance.

What can I say, when I compare a power amplifier's ACD rating to what a receiver can put out into 2 CH and the power amplifier still wins, I find that pretty relevant to real world performance. When that same receiver struggles to deliver 70W ACD into 8 ohms, and the odds are that it isn't going to put out much more than 40W into 4 ohms ACD, and and you're looking at a power amplifier that can deliver better than 6dB extra output on top of that, I find that also to be quite relevant to real world performance.

 

[PENG]

Thanks, I have one of those.
I'll see if my EE friends knows how to measure it.

- Rich

[/COLOR]http://assets.fluke.com/manuals/87vex___umeng0000.pdf
Rich, above link to a Fluke manual, please read page 16 (p24in the pdf file) of the manual and take similar precaution regardless of thedigital brand/mode you have. I doubtyou would get much accurate result ifthe offset level is very low but it should give you an idea.

 

[RichB]

Since we don't know if DC offset is causing your transformer hum issues, the only easy way to see if it helps is to buy one and try it. I can't believe the Emo will do any harm, it just may not do any good.

I believe some of these can limit current and therefore harm performance.
I am not going to try any more of these devices until someone I trust measurements show they do something good and do not do something bad.

- Rich

 

[Steve81]

No one is saying that the Outlaw isn't better. It just isn't enough better to be a good thing for most people to buy.

Whether it's a "good thing for most people to buy" isn't relevant to the discussion. From my POV, an amplifier is simply a tool that needs to cleanly feed my speakers enough power such that they can reproduce the levels I desire. From that standpoint, the Outlaw is considerably more capable than the amplifiers featured in most receivers, particularly into low impedance loads. If you're running a system composed of highly sensitive true 8 ohm loudspeakers in a small room and you don't care to push the volume too hard, yes it's overkill. For other folks though, it might be just the ticket.

 

[PENG]

The Emotiva is rated to deliver 300W per channel, all five channels driven, yet it only has a 1200KVA rated transformer. PENG's observation is that 1200KVA looks a bit underrated for that power level, yet in Emotiva's published test results it does indeed seem to produce 300W/ch at four ohms, though they are a bit fuzzy about whether or not all five channels are driven simultaneously.

I do believe their test results because power transformers are known for excellent short term overload capability. If they say those results are not for "short" duration but for "continuous" duty, then we need to ask them for their definition. For example, HTM's lab also uses the term "continuous" but if you ask them what it means you would be very surprised. If that Emo does 5X300W that would require at least 1500W/0.8=1875W of input power that is >>1200W (even by assuming power factor=1 and efficiency as high as 80% for class A/B at rated output that is unlikely) continuously all day long, the thing will either trip on thermal overload before too long, or melt down. For short duration I see no problem. On the other hand, that Outlaw should be able to work at their rated ACD output or close to that all day long, at least theoretically. This power rating thing is really a big confusing mess. ATI, Outlaw, Parasound seem to be among the very few at the lower price range that do not take advantage of the existing mess in specifying their rated outputs.

 

[PENG]

Whether it's a "good thing for most people to buy" isn't relevant to the discussion. From my POV, an amplifier is simply a tool that needs to cleanly feed my speakers enough power such that they can reproduce the levels I desire. From that standpoint, the Outlaw is considerably more capable than the amplifiers featured in most receivers, particularly into low impedance loads. If you're running a system composed of highly sensitive true 8 ohm loudspeakers in a small room and you don't care to push the volume too hard, yes it's overkill. For other folks though, it might be just the ticket.

I agree, the discussion is more about output power comparison, not so much about whether one is going to sound better than the other.

 

[Steve81]

Regarding DC offset issues, I did note this tidbit from the gentleman I was corresponding with over at Outlaw:

Hum from the unit itself is indicative of one of three possibilities.
One of which (a defective transformer) is permanent and would not go away without corrective action. This type of hum is due to mechanical vibration of the transformer windings. It may be possible to affect this symptom, to see if this is the case, by directly pressing down on the transformer in an attempt to stifle the vibration. This has not proven to be 100% effective though.
The other two can occur intermittently. The first, and more common of the two, is voltage sag. Sometimes a voltage stabilizer or relieving the load (such as supplying a dedicated circuit, usually 15 amps for a multi-channel amplifier) on the corresponding circuit will resolve the transformer hum.
The second is DC on the AC power line. This type of hum can be distinguished by the nature of the hum itself. Voltage sag typically results in a hum that stays consistent in frequency and intensity. When DC is the cause of the hum, the noise will change in both frequency and intensity when it is present. If you have encountered DC on your AC power line, you'll need to remove it with a dedicated DC filter.

 

[Pyrrho]

I agree, the discussion is more about output power comparison, not so much about whether one is going to sound better than the other.

No one has said that it isn't more power. It is, however, trivial going from 155 watts to 190 watts. It isn't going to make any more difference than 0.9dB no matter how much people go on about it or protest such facts being pointed out. If people want to spend a thousand dollars to gain 0.9dB, instead of the generally significant improvements that spending that much more money would have been for better main speakers or subwoofers in most cases, then they are free to make that choice. But they should know what they are getting for their money, and not have silly unrealistic ideas about it.

 

[fuzz092888]

No one has said that it isn't more power. It is, however, trivial going from 155 watts to 190 watts. It isn't going to make any more difference than 0.9dB no matter how much people go on about it or protest such facts being pointed out. If people want to spend a thousand dollars to gain 0.9dB, instead of the generally significant improvements that spending that much more money would have been for better main speakers or subwoofers in most cases, then they are free to make that choice. But they should know what they are getting for their money, and not have silly unrealistic ideas about it.

When you say going from 155 to 190 watts, are you talking about moving from a receiver to an external amp or between external amps?

 

[surveyor]

What is DC off set- you ask?
What is DC offset? - diyAudio

 

[Irvrobinson]

I believe some of these can limit current and therefore harm performance.
I am not going to try any more of these devices until someone I trust measurements show they do something good and do not do something bad.

- Rich

That's up to you, but I think your fears are unfounded.

 

[Steve81]

It is, however, trivial going from 155 watts to 190 watts. It isn't going to make any more difference than 0.9dB no matter how much people go on about it or protest such facts being pointed out.

Nobody is suggesting that the jump from 155W to 190W is anything of great importance. I am saying that comparing the two channel output capabilities of a receiver to the all channel output numbers of an external amplifier isn't a valid apples to apples comparison to show that the Yamaha is extremely close to the Outlaw in performance. For starters, the Outlaw is capable of delivering more than 190W into 4 ohms when driving only two channels. More importantly for HT, the Outlaw has the capability to push seven channels worth of four ohm speakers to moderately high levels (say 20-30W per speaker) and still easily have the reserves to peak two or three at 200W+. I wouldn't count on the Yamaha pulling off that feat without dropping the level 3+ dB.

 

[RichB]

That's up to you, but I think your fears are unfounded.

This is not a fear but an observation.
I have plugged amps into the Panamax AMP socket and did not think much of it. Over time, I felt something was not right so I began to consider an AMP upgrade.

A friend brought over his Outlaw m2200 mono blocks over for an audition.
I plugged the mono blocks directly into the wall.
They sounded great, better than my Sunfire 7400 driving my Salons.
The m2200 had cleaner than the Sunfire which was a bit harsh in the upper end. It wasn't that the Sunfire was bad, it just wasn't as good.
No one expected that.

Another friend brought over his Focal bookshelf speakers.
I asked which amp my friend would preferring use the, he picked the M2200. Days later, I plugged the Sunfire directly into the wall and the performance improved.

When I read professional amp reviews they are plugged directly into the wall.

- Rich