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Review and Measurements of Onkyo M-282 Amp

RayDunzl

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#42
Tubes and class A solid state amplifiers are terribly power hungry.
They're greener than driving around looking for some little something to do.

I don't think our little devices are as much of a concern as simply the number of people that are using them. That's the problem, from my perspective.

Where will it peak?
 

Sal1950

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#43
I want a 3HP amp, maybe shoot some N2O in one of these amps so we can reach those levels of power with good distortion figures.
SAE makes the 2HP amp, but that's a cheat since it's only 1HP per channel.
http://hear-sae.com/products/sae-2hp/
N2O is fine for the 1/4 guys but for sustained power top to bottom of the range I'll take supercharging any day. Maybe run a 110v amp on 220v? :eek:
 
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Sal1950

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#44
I bought the amp in August 2008 to set up a second zone in the house, but it never got used. The price new was $195.
A nice little amp for the money and probably transparent under most conditions.
That's going to be very dependent on the speaker, the load it presents and it's sensitivity. Both low impedance and low sensitivity with add to the stress presented and may effect the sound at some point. Add to that my main concern of reliability due to the reported heat issues and again you need to be thoughtful of the speaker used.
Thanks for providing the amp to amir for testing and also thanks to amir testing. A interesting time in amplifier development to be looking at things closely again.
 

amirm

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#45
I can test a lot more of these products but the logistics are a major issue. Shipping these back and forth is expensive as both the size and weight are high. And there seems to be little consensus unlike DACs and such as to what is popular outside of a few class D modules.

Probably the only practical solution is that I start buying these things but requires a lot more donation than is coming in so far.

I do have a few more amps coming so this is not the end of the run.....
 

RayDunzl

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#46
I need donations too...

New roof next week.

Crashed car.
 
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#47
This is a review and detailed measurements of Onkyo M-282 Power (speaker) amplifier. It is on kind loan from a member who bought it a few years ago but had not used it. Seems like it was just discontinued as I checked the price yesterday and it was being sold for $300 or so from Amazon. The suggested replacement by Amazon is lower power (75 versus 100 watts for M-282) but is also cheaper at $210.

The box is quite large but other than the left side that is weighted down by a transformer, it feels rather light:


The front looks slick and high quality.

The back has two pairs of RCA connectors: one for input and one for output. There is a switch to select auto-on with audio, 12 volt trigger, or always on which is the mode i used.

There is trim potentiometer in the back to set the input sensitivity. At first I left this in the default middle setting but that showed fair amount of channel mistmatch. So I set it to max and the two equalled out.

There is a delayed on which I assume also includes a protection circuit.

The unit is rated down to 6 ohm I think but she had no problem handling my 4 ohm load for testing.

Let's get into measurements and see how it performs.

Measurements
Unlike previous amplifiers I have tested, this is a traditional class AB amplifier meaning it is much less efficient. This point was amply made during my warm-up exercise with copious amount of heat oozing out of its relatively small internal heat sink. I was only using 20 watts/channel but with less than 50% efficiency, the thing was likely generating 50+ watts of heat. Here is how the distortion rated during that time:

View attachment 20202

Pretty odd in that the more distorted channel (blue) got fair bit better as it warmed up but the other did not change much.

The infrared thermal image shows that the thing was cooking and cooking good:

View attachment 20203

The cursor indicating 71 degrees C is on the heatsink that holds the power devices for the amplifier. They are using a heatsink with very large fins which is good but there is just no mass to it. It is not connected in any substantial way to the chassis so relies on ample convection from the bottom through the top vents. Better give this amp plenty of room to breath.

Given the much elevated temps, I did not dare to run it for 5 minutes at full power. I did however sweep the input level to see how she could do in shorter period:

View attachment 20204

We are getting 110 watts which is just a hair over the rated 100 watts but that is at 8 ohm and my test is with 4 ohm. So not much headroom here with lower impedances due to shortfall of the power supply current.

Compared to the other two switching amplifiers, the Crown XLS 1502 (brown) is more noisy than it but has much lower distortion and has far more output power. The Hypex ncore (blue) beats it on all fronts but is also four times more expensive.

SIgnal to noise ratio is good and matches the spec from what I recall at 110 dB:

View attachment 20205

Frequency response is essentially perfect since class AB amplifiers don't need the output filters that switching amps have:
View attachment 20206

Likewise ultrasonic spectrum above 20 Khz is clean (sans the harmonic distortion of the amplifier):

View attachment 20207

Distortion+noise was very revealing of the amplification issues with respect to topology:
View attachment 20208

Notice how the distortion climbs on the switching Crown XLS 1502 above 1 kHz or so. The more power they produce (dashed lines), the more distortion climbs.

The class AB Onkyo M-282 had the opposite response. At lower levels of 1 and 5 watts, its distortion and noise was clearly better than Crown especially as frequencies rose.

Once pushed to tune of 150 watts, the Onkyo distortion rises up across the board which is not surprising. But look at the huge rise in distortion as source frequencies got lower than 50 Hz. The inadequate power supply has more of a problem with long cycles of low frequencies.

Both of these show evidence of what I subjectively hear when testing amplifiers with speakers: class AB amplifiers run out of steam in low frequencies first. Play something with heavy drums and gradually increase the level and pay attention to bass to see if the "thumps" get anemic.

In contrast, with class D/switching amplifiers, I find that they are exceptionally good at bass so the above test doesn't work. Instead, focus on clarity of high frequencies as you increase levels. Use content that has isolated high notes to make this easier.

Conclusions
I am torn when evaluating such equipment. On one hand I am astonished that a brand name power amplifier using class AB can be made, shipped and sold for so little money. The economics of this are mind boggling. I suspect these companies lose money on these low-end products and try to make it up with higher tier products.

On the other hand, this is not the type of performance I like to see in my system. We are so far, far away from level of distortion of our digital sources to the tune of 30+ dB. Designers often work hard to improve a system by 3 dB and here we have such a massive shotfal. As such, I can't recommend this amplifier unless funds are very low.

As we test more of these amplifiers we should get a better idea of what is out there that is a great find.

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In the end, do you think powered monitors to be a safer bet?
 

Ron Texas

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#48
I can test a lot more of these products but the logistics are a major issue. Shipping these back and forth is expensive as both the size and weight are high. And there seems to be little consensus unlike DACs and such as to what is popular outside of a few class D modules.

Probably the only practical solution is that I start buying these things but requires a lot more donation than is coming in so far.

I do have a few more amps coming so this is not the end of the run.....
There is a lot of interest in this area. So far the data suggests it's hard to find good performance at low prices, unlike DAC's.
 
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#50
Once pushed to tune of 150 watts, the Onkyo distortion rises up across the board which is not surprising. But look at the huge rise in distortion as source frequencies got lower than 50 Hz. The inadequate power supply has more of a problem with long cycles of low frequencies.

Both of these show evidence of what I subjectively hear when testing amplifiers with speakers: class AB amplifiers run out of steam in low frequencies first. Play something with heavy drums and gradually increase the level and pay attention to bass to see if the "thumps" get anemic.

In contrast, with class D/switching amplifiers, I find that they are exceptionally good at bass so the above test doesn't work. Instead, focus on clarity of high frequencies as you increase levels. Use content that has isolated high notes to make this easier.
This is something I have noticed as well, along with a few others I have spoken too. Class d subjectively has more bass authority. I have noticed this with nearly every class d amp I have owned aside from little TPA and Tripath amps. The IRS, Hypex, and Icepower ones I've had seemed to have more bass slam than AB amps I've had. I like the sound of class d specifically because of this. For systems where one is using as powered sub and the mains crossed over 80hz or above I can see where an amp like this would do just fine though. Thanks for the post.
 

RayDunzl

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#51
I hope nobody got hurt.
Just the wallet.

We'll see how the roofers do. Watched one fall off a two story, fall in a bush, brush himself off, climb right up the ladder again.
 
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#52
A nice little amp for the money and probably transparent under most conditions.
That's going to be very dependent on the speaker, the load it presents and it's sensitivity. Both low impedance and low sensitivity with add to the stress presented and may effect the sound at some point. Add to that my main concern of reliability due to the reported heat issues and again you need to be thoughtful of the speaker used.
Thanks for providing the amp to amir for testing and also thanks to amir testing. A interesting time in amplifier development to be looking at things closely again.
I don't think that most people will run these anywhere near 20W average power, unless we are talking about a cavernous room.
 
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#54
Distortion+noise was very revealing of the amplification issues with respect to topology...
I found this chart difficult to read. Clearly indicating which component is solid & which dashed would help, especially when colors repeat. (And the dashed-line explanation under the graph is misleading.) I'd suggest putting that info directly into the PNG, too, so that it's obvious in quotes, etc. Even better if the key can have a consistent order for both devices.

Both of these show evidence of what I subjectively hear when testing amplifiers with speakers...
Fair enough, but it sure looks like you've demonstrated the Onkyo's response to abuse. It's not rated for 4 ohms, and the 150W curve is past its clipping knee. Meanwhile, the Crown's running several dB below its limit.

While I believe this is good information which helps to highlight where audible differences might appear, I fear that less experienced readers might misinterpret it. Am I missing the mark here?

Amir, I totally get why you don't recommend this amp. (It's not something I can imagine buying, either.) OTOH, I'd say you're rating this on a more absolute scale, which is always difficult to correlate with subjective comments. Maybe I'm overthinking this, but consider a technically challenged newbie's reaction to the end of your review.

Rather than clutter this review with tangential rambling, I'll try to clarify my thoughts in another thread. If I can clarify my thoughts! The technical content's already here; it's simply making this info accessible that concerns me.
 

bigx5murf

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#55
I can test a lot more of these products but the logistics are a major issue. Shipping these back and forth is expensive as both the size and weight are high. And there seems to be little consensus unlike DACs and such as to what is popular outside of a few class D modules.

Probably the only practical solution is that I start buying these things but requires a lot more donation than is coming in so far.

I do have a few more amps coming so this is not the end of the run.....
Because of the SAWC it's probably more efficient to test AVR and integrated amps. Because that way you a DAC and AMP review out of it.
 
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#56
A nice little amp for the money and probably transparent under most conditions.
That's going to be very dependent on the speaker, the load it presents and it's sensitivity. Both low impedance and low sensitivity with add to the stress presented and may effect the sound at some point. Add to that my main concern of reliability due to the reported heat issues and again you need to be thoughtful of the speaker used.
Thanks for providing the amp to amir for testing and also thanks to amir testing. A interesting time in amplifier development to be looking at things closely again.
It ain't top of the list, to be sure, but it's likely all many people will need, especially for 2.1.

I bought a beat-up Onkyo Integra ADM 2.1 in a pawn shop for $20 as a spare, and I have been quite pleased. My regular amp is an old Thule PA100 running in balanced operation. When I put the Integra in, it sounded great, too. Audibly (to me) indistinguishable from the Thule, even running unbalanced. And I do appreciate the still-too-rare practice of an analog pass-through for subwoofer use, something the Thule doesn't have. (I have no desire to buy some honkin' massive HTR. I like movies, but I don't watch them for the awesome sound, which I usually find distracting. I get that those are dinosaurs up there, I don't need to feel them on my shoulders.)

The Integra has never run hot for me, though I never approach maxing it out power-wise. And my speakers (Monitor Audio) are 6 ohms, so the amp never gets stressed. (Frankly, I've never owned a pair of 4 ohm speakers, and likely never will. Nor will most people, I'd wager.) So while some find the measurements here disappointing, this amplifier is actually pretty good for most uses in the consumer arena.
 

bigx5murf

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#57
The Integra has never run hot for me, though I never approach maxing it out power-wise. And my speakers (Monitor Audio) are 6 ohms, so the amp never gets stressed. (Frankly, I've never owned a pair of 4 ohm speakers, and likely never will. Nor will most people, I'd wager.) So while some find the measurements here disappointing, this amplifier is actually pretty good for most uses in the consumer arena.
Some 8ohm speakers will dip real close to 4ohms at times. The ones I've owned off the top of my head that do are Polk Audio SDA-2b, and ADS L710, and Thiels as well.
 
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#58
Some 8ohm speakers will dip real close to 4ohms at times. The ones I've owned off the top of my head that do are Polk Audio SDA-2b, and ADS L710, and Thiels as well.
Sure, they bounce around, to phrase it inartfully. My point is feeding nominal 4 ohm speakers is a different task than feeding nominal 8 ohm speakers. And I doubt 4 ohm speakers constitute anywhere near even a plurality of home audio speakers.
 
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