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Review and Measurements of Onkyo M-282 Amp

maty

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#22
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#23
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.
The manual recommends leaving it at max under normal use actually.

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.
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.

I wonder if using a 4 ohm load increased the power requirements on the amp and led to more heat?
 
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#24
That looks a lot as if bias on one channel (at least) is wrong, or busted.
One can see that the 2nd and 3rd harmonics of the power supply frequency are at different levels on the two channels. That might just be a layout issue, but is curious. It would be interesting to see the distortion spectra for both channels separately, as overlain it is hard to see the differences that are contributing to the different results.
 

Willem

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#26
There are two expensive components in power amplifiers: the case and the power supply. As this test shows, the power supply is indeed an important comnent, en here it seems to be the limiting factor, and responsible for a quite mediocre performance. For consumers, the only tentative way to be sure the power supply is adequate is to look at the weight of the unit: in this case 8.5 kg, and that is comparatively light.
For really good results for a 100 watt integrated amplifier, see this test of the Yamaha AS 700: https://www.avhub.com.au/product-reviews/hi-fi/yamaha-a-s700-integrated-amplifier-393552 Its almost identical successor, the AS 701, sports digital inputs as well (optical and coaxial, the AS 801 has an additional usb input) and sells for 549 euro in the Netherlands. It weighs 11.2 kg.
100 watt per chanel is fine for medium siz erooms, but if more power is required, there was until recently the Yamaha PS series of beefy pro audio amplifiers. I recently bought the 2x250 watt P2500s for my son for just 299 euro. Thus far the fan has never come on in domestic use. See here for a bench test of the 2x350 watt P3500s: https://www.homecinema-fr.com/forum...mpli-yamaha-p3500s-mise-a-jour-t30056383.html
For my own main system I went the secon hand route. My main speakers are Quad 2805 electrostats, ands since stats are a hard load I decidedto play safe and get a second hand 2x140 watt Quad 606-2. I paid 350 euro for a completely and professionally refurbished one (all resistors and capacitors replaced). It weighs 12 kg. I later paid 175 euro for a similarly refurbished 2x100 watt Quad 405-2 for my desk top system (driving Harbeth P3ESRs that need quite a bit of power).
 

maty

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#27
For really good results for a 100 watt integrated amplifier, see this test of the Yamaha AS 700: https://www.avhub.com.au/product-reviews/hi-fi/yamaha-a-s700-integrated-amplifier-393552 Its almost identical successor, the AS 701, sports digital inputs as well (optical and coaxial, the AS 801 has an additional usb input) and sells for 549 euro in the
Hummm....

[Polish] https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2786-yamaha-a-s801

to English: https://translate.google.com/translate?sl=pl&tl=en&u=https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2786-yamaha-a-s801



YAMAHA A-S801
  • Rated power (1% THD + N, 1 kHz) [W] 8 Ω, 2x 130
  • Rated power (1% THD + N, 1 kHz) [W] 4 Ω, 2x 132
  • Sensitivity (for maximum power) [V] 1x 0.22
  • Signal / noise ratio (A-weighted filter, with reference to 1W) [dB] 83
  • Dynamics [dB] 104
  • Damping factor (relative to 4 Ω) 94
 

Vovgan

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#28
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.
Hi, thanks a lot for another in-depth review! Really looking forward to seeing more reviews of such AV amps/receivers (particularly in the higher price ranges) of this and similar (Denon, Marantz) brands.
A small question, if I may: why would you take an amplifier which is rated for 100W max and first test it at 5W (which it apparently handles decently) and then push it all the way up to 150W (beyond it’s rated capacity to where it “not surprisingly” fails) and then make the conclusion based on its performance on this “overclocked” test? Isn’t it akin to judging a family sedan to be not good enough when its mileage is terrible at 150 mph? Could it be that at levels most likely to be asked from this amp (70 - 90W) it handles the bass and all the rest of it just fine? Thanks!
 
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#29

anmpr1

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#30
Back in the day, the FTC (for better or worse) regulated amplifier output claims, stating that amplifier advertised measurements had to be taken after a preconditioning of 30 minutes at 1/3 power, and then at power before clipping, along with distortion components. I don't think this is required in advertising, anymore. At the time of the ruling, legacy amp manufacturers argued that this protocol was rather arbitrary (it was) and penalized tube amp manufuacturers as far as "real world" power output goes (it did). David Hafler was on the forefront of this line of thinking. In a way he was correct. I have a set of Hafler/Laurent designed monophonic amps rated at about 40 watts @ 8 ohms/1KHz with less than 1% distortion, and it sounds as "strong" using fairly efficient mid 70s era JBL monitors as does my SS Yamaha amp, rated at 100 FTC watts per channel. Using the FTC rule, its power rating would easily drop by half, and the tubes would be overly stressed.

On the other hand, the FTC regulation was a standard, and back then a standard was certainly needed, given typical advertising claims. Most solid state amps were subsequently designed around this schedule, and it was not uncommon to find massive Japanese stereo recievers measuring at over 200 watts per channel in to 8 ohms, with low distortion. However, as current demand increased into lower impedances, it was usually goodby Charlie.
 

Willem

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#31
Yes it is one of the few sites with proper measurements, just like that Australian site that I linked to for the Yamaha AS 700 results. It really is a shame that this is not done more often, but I guess it is not commercially attractive as it erodes advertising income.
 

SIY

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#32
That looks a lot as if bias on one channel (at least) is wrong, or busted.
Beat me to it. A small touchup of idle current would likely help things a lot. The distortion versus time through warmup was the giveaway. It's also possible that whatever thermal sensor they use (often a diode or one of the bias transistors clipped to the heatsink near the output devices) needs tightening down.

Amir, it really would be useful, in the absence of a Power Cube, to whip up a couple of reactive test loads. I'd be happy to help, if you wish.[/QUOTE]
 

btom

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#33

sergeauckland

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#34
I would also suggest putting four large 4 ohm resistors on a heatsink, with croc-clips so they can be configured as 2x8 ohms, 2 or 4 x 4 ohms or 2 x 2 ohms or even 1x16 ohms for testing old valve amplifiers or 1x 1 ohm for testing Krells.

Testing amplifiers at 4 ohms only, is much like testing DACs at 44.1 only, it doesn't give the full picture.

Using an old THD analyser which can display the residual is also very useful as well as the FFT.
Testing analogue amplifiers is a speciality in itself and does need a certain amount of equipment.

S.
 

anmpr1

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#35
Testing amplifiers at 4 ohms only, is much like testing DACs at 44.1 only, it doesn't give the full picture.
S.
The best "picture" of amp output performance that I've seen is the 'powercube' measurement box from Swedish company, Audiograph, that integrates into the Audio Precision instrument. It measures variable loads, both capacitive and inductive. But is quite expensive (I've heard the device costs 20 large or so, but am not sure). You get a graphic display of amplifier power into various loads. I've attached a pic. If I had a ton of spare dollars, I'd buy one for amirm. But I don't. If it's the thought that counts, then he's got that going for him! LOL

1547225503022.png
 

RayDunzl

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#36
I want a 3HP amp, maybe shoot some N2O in
Based on my experience, an N2O injection would cause distortion. I found it interesting, but my accuracy suffered.
 
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#37
I just stumbled across this forum. Very interesting stuff. It's rare to find someone performing meaningful tests on power amplifiers, particularly lower cost amplifiers. Even with higher end products, most people just measure the 1kHz distortion vs power and call it a day. That really doesn't tell you much, unless something is very, very wrong. It's not that hard to get low THD numbers at 1kHz. Mostly that will tell you if the output stage or power supply start working hard as the power rises.

For higher frequencies, it doesn't tell you much to test, as Stereophile used to do, THD vs frequency at 1W. You just end up measuring noise. I assume that's why they quit doing that. The best place to test that is just below the "knee", if the amplifier has a clearly defined knee like the XLS1502. If it does not, you pick a level. For, say the NC400, I might test it at 50W and 200W. For the Onkyo you might test at perhaps 5W and at 100W. At 150W, the amp has already started clipping. Yamaha, I think, used to do a THD vs Output overlay plot at 20Hz, 1kHz, and 20kHz. That's very informative. That gives a fairly decent visual of the power supply, the distortion of the input and output stage, and the overall linearity of the amp.

Another great test is the 19+20kHZ IMD test. That will also tell you a lot about how linear the amplifiers is and whether it is neutral. It is also particularly useful for digital amplifiers. See https://www.diyaudio.com/forums/sol...rdell-distortion-analyser-24.html#post2810564.

All in all, really nice job on this. It's interesting to see someone testing a $300 stereo amp with meaningful tests!
 

sergeauckland

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#38
The best "picture" of amp output performance that I've seen is the 'powercube' measurement box from Swedish company, Audiograph, that integrates into the Audio Precision instrument. It measures variable loads, both capacitive and inductive. But is quite expensive (I've heard the device costs 20 large or so, but am not sure). You get a graphic display of amplifier power into various loads. I've attached a pic. If I had a ton of spare dollars, I'd buy one for amirm. But I don't. If it's the thought that counts, then he's got that going for him! LOL

View attachment 20219
I find the Powercube to be a useful 'quick and dirty' visual representation of an amplifier's performance envelope, but only as an addition to the various graphs of power vs frequency, distortion vs power, distortion vs frequency, as well as distortion FFTs and residuals, frequency response into different loads and levels, IMD figures, noise etc etc. In other words, there is no one measure that characterises an amplifier, there are lots of separate measurements needed for that. That's why purely analogue instruments like the Lindos LA100 system have automated sequences as doing this sort of thing manually is pretty tedious.

I'm personally much more interested in analogue measurements, as digital products are now almost universally quite 'good enough' so would be interested in seeing more extensive measurements of analogue equipment on ASR.

S
 

anmpr1

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#39
I find the Powercube to be a useful 'quick and dirty' visual representation of an amplifier's performance envelope, but only as an addition to the various graphs of power vs frequency, distortion vs power, distortion vs frequency, as well as distortion FFTs and residuals, frequency response into different loads and levels, IMD figures, noise etc etc. In other words, there is no one measure that characterises an amplifier, there are lots of separate measurements needed for that.
S
During the 'amp wars' of the '70s, there were many different views on what made a 'good amplifier.' The 'sounds different' crowd went through a lot of different ideas, the most well known 'single cause' likely being Matti Otala's TIM, transient intermodulation distortion idea. Marshall Leach, Professor of EE at GIT and first rate audio designer, once stated (unironically, I presume) that "there exists no standards for the measurement of TIM" (Audio 2/76), but then designed a 'low TIM' amplifier that could be built as a kit. TIM was supposed to be 'aggravated' by the use of large amounts of overall negative feedback, however Julius Futterman's OTL (output transformerless tube amplifier) used a lot of negative feedback, and was supposed to sound wonderful. Then there was the class wars exemplified by the Mark Levinson class A stuff (John Curl/Tom Colangelo ). And so on, and so on. How much of this was simply hallucinogenic wishful thinking, I won't say. But I have my own views. Get something you enjoy, and enoy it. :)
 
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Willem

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#40
I am surprised the ecological argument is not used more often. Tubes and class A solid state amplifiers are terribly power hungry. In the EU we already have mandatory efficiency standards for things like vacuum cleaners (our new one only consumes half of what the old one did, and works better), refrigerators (new ones only consume about a third to a quarter of models from a decade ago), or televisions. It is only time until such standards will also be applied to audio gear.
 
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