Cherry Audio Class D Amplifier Review with Measurements!

[Movie2099]

Made in America or not, 6K is a sh?t ton of money to put on an amp that requires an upgrade on its power supply to drop the noise floor. Thats just not right anyway you want to look at it.

5 channel amp is $3090. For the "King" version its $3590. I don't find that expensive at all for a 5 channel amp. For the Mono amp is $4900. Not a bad price at all. For a high end American made product. Sign me up! Yes, the offer an "upgrade" but you don't have to. Especially something you will never ever hear or notice.

 

[Movie2099]

This is a very good point regarding cost.

I bet McIntosh, Mark Levinson, Krell and Bryston amps also use Asian-made parts.

But I doubt many consumers really care at the end of the day if they can get them for $7,500 or $6,000.

Shoot, the blue meters alone are worth the $10k-$15k asking price!

 

[buckchester]

This right here is what bothers me the most about all measurements from all sites.

Many of us here have done REW measurements of our speakers and subs and know how EXTREMELY finicky it is.

We have seen a few times already how the same components measured “poorly” on ASR can overnight become SOTA with a few tweaks. It seems if people worked hard enough on tweaking, many components could easily become SOTA overnight.

Many of us have pointed out many times that these measurements don’t show the actual sound quality of these components. It only shows how “SOTA” these components measure.

But if measurements are so finicky and can be easily changed from POOR to SOTA anytime, what’s the real “value” in these measurements especially since we cannot hear any difference?

In addition to being inaudible, there is absolutely no correlation between (tweaked) SOTA numbers and RELIABILITY either, is there?

If there is a correlation, man, it seems AVRs might be more reliable than separates, which is the opposite of what audiophiles have been preaching since forever.

You make some great points. While it is interesting to read and learn about all of the technical differences between these amps, at the end of the day these differences should only matter if people can reliably tell the difference between them in a blind listening test.

I think this review is significantly better than the vast majority of amplifier reviews out there, however, one way to take it to an even higher level would be to better answer these sorts of questions - what are the actual sonic differences? Some sort of blind testing against a reference, maybe? I get the sense that most of these technical achievements do not lead to differences that we can reliably distinguish from poorer measuring devices.

 

[AcuDefTechGuy]

if you spend a bit extra (I know it’s a big bit) the distortion actually reduces quite a bit, down to .002% I believe.

But since nobody can hear the difference between about 0.006% vs 0.002% THD+N, why spend the extra $1,500?

And even at $7,500, the 0.002% THD+N is still higher than the ATI, some other amps, and some AVRs. Not that anyone can hear the difference among any of these THD+N and SINAD.

Well, I hope you get to measure a lot more amps, AVP and AVR. Inaudible measurement numbers, but still fun to talk about.

 

[AcuDefTechGuy]

Shoot, the blue meters alone are worth the $10k-$15k asking price!

Even if those blue meters are made in Asia somewhere out there beneath the pale moonlight.

 

[PENG]

Even if those blue meters are made in Asia somewhere out there beneath the pale moonlight.

To me, for audio electronics we are already seeing very high quality China made gear for less money and that's why my opinion is that as American, buy American made is a good thing to do. Just don't delude oneself that it is always for quality related reasons. I still remember those jokes/sarcasm about the made in Japan Toyotas when I was a kid.

 

[Matthew J Poes]

But since nobody can hear the difference between about 0.006% vs 0.002% THD+N, why spend the extra $1,500?

And even at $7,500, the 0.002% THD+N is still higher than the ATI, some other amps, and some AVRs. Not that anyone can hear the difference among any of these THD+N and SINAD.

Well, I hope you get to measure a lot more amps, AVP and AVR. Inaudible measurement numbers, but still fun to talk about.

What AVR has less than .002% THD+N? I don't think any are anywhere near that low in noise. Remember I measured at 1 watt, Amir does 5 watts. Big difference.

 

[AcuDefTechGuy]

What AVR has less than .002% THD+N? I don't think any are anywhere near that low in noise. Remember I measured at 1 watt, Amir does 5 watts. Big difference.

True. I forgot about his 5W measurement, instead of 1W. Why oh why?

And also true about the Amplifier section measurements of the AVR. I was thinking of the Pre-amp/pre-out section.

I seem to remember 1W and full-power specs @ 1kHz and 20-20kHz are the usual “standard” throughout the years.

It seems adding more variations like 5W-spec (and SINAD instead of SNR) only adds to the confusion.

1. None of these specs are audible and prove better SQ
2. Measurements are so finicky (depends on how, who and tweaks)
3. Measurement specs vary significantly (1W vs 5W, SINAD vs SNR, etc.)
4. None of these numbers prove better reliability

 

[lovinthehd]

I seem to remember 1W and full-power specs @ 1kHz and 20-20kHz are the usual “standard” throughout the years.

It seems adding more variations like 5W-spec (and SINAD instead of SNR) only adds to the confusion.

1. None of these specs are audible and prove better SQ
2. Measurements are so finicky (depends on how, who and tweaks)
3. Measurement specs vary significantly (1W vs 5W, SINAD vs SNR, etc.)
4. None of these numbers prove better reliability

Nor if they are aesthetically pleasing as eye candy or furniture or how they "sound" You can use measurements as a guideline certainly for some level of engineering excellence and performance to help wade thru the choices, altho that doesn't necessarily indicate build quality/longevity as you say. Beats "listening" to every damn possibility, too. Comparing like spec is always the challenge, tho if you're going to compare the smallest differences.

 

[PENG]

What AVR has less than .002% THD+N? I don't think any are anywhere near that low in noise. Remember I measured at 1 watt, Amir does 5 watts. Big difference.

Hello Matthew, in your review you said it was at 10 watts, not 1 watt, was it typo? Anyway, it is easy enough to use one to estimate the other (from 100 W, or 5 W, to 1 W) since SNR is a ration and the noise part is relatively constant, close enough to assume it is anyway so we just have to account for the higher output signal level.

When Amir measured the SNR of the AVR he usually use the analog inputs and unless stated otherwise it would be at 5 W as you said. If it was measured at 1 W, the resulting difference would be about 7 dB. Keep in mind in those tests, he would be capturing the overall SNR, from preamp analog input to the power amp output.

So his SNR for the AVR-X6700H and SR8015 or 93-94 dB @5W, or 86-87 dB @ 1W seemed better than the Cherry that you measured at, as you wrote "SNR at 10 watts was a good but not great 92.6 dB, again strongly impacted by power supply noise, with the 120hz power supply spur at -100dB. " And that's just the power amp, without the noise of the preamp, any preamp no matter how quiet would introduce some noise too.

Edit: Just did a re-read and noted that you also mentioned "Moving onto the S/N at 1 watt into 8 ohms, we see it comes in at 85.9 dB."

Unless I missed something, It seems to me ADTG's point is quite valid.

I know these are mainly academic, as ADTG just said.., but we are discussing measurement results regardless.

 

[PENG]

I seem to remember 1W and full-power specs @ 1kHz and 20-20kHz are the usual “standard” throughout the years.

It seems adding more variations like 5W-spec (and SINAD instead of SNR) only adds to the confusion.

I don't know about Matthew as he hasn't measured too many devices for AH yet. If it was Gene or Amir, I would bet they follow Audio Precision's (or something like that..), unless otherwise stated, such as the 5 W thing.

From Audio Precision:

The “Big Six” Audio Measurements – Part II - Audio Precision (ap.com)

"Signal-to-Noise Ratio

How much noise is too much? That all depends on how loud your signal is.

Signal-to-noise ratio (or SNR) is a measure of this difference, providing (like THD+N) a one-number mark of device performance. The signal is usually set to the nominal operating level or to the maximum operating level (or MOL) of the DUT. When SNR is made using the MOL, the result can also be called the dynamic range, since it describes the two extremes of level possible in the DUT. (Dynamic range in digital devices has a somewhat different meaning). SNR is usually stated in decibels, often shown as negative.

Using traditional methods, SNR requires two measurements and a bit of arithmetic. First you measure the signal level, then turn off the generator (and often, terminate the DUT inputs in a low impedance as well, to fully reduce the noise in the device). Then the noise level (often called the noise floor) is measured, using filters to restrict the measurement bandwidth. The ratio between the two is the SNR."

In Gene's most recent review/measurement, he measured only the preamp section's SNR and it was measured at 2 V. The results were within 1 dB compared to Amir's, about 110 dB. Again that's the pre section, ASR did measure the power amp section, @ 5W and the results was a little better than the Cherry's that was measured at 10 W.

 

[ski2xblack]

So everyone can choose what fits their purposes...

I believe in the maxim "too much is just enough" when it comes to power, to avoid any clipping, balanced against the reality that unused power is simply unused, thus wasteful.

I have a hard time figuring the practical need for the power this amp is capable of, at least in a domestic setting. For subs, maybe, but then the exacting specs and performance is overkill. I personally don't own any speakers capable of taking the full brunt of that amp without going up in smoke.

 

[Matthew J Poes]

For Americans, there are obviously good reasons to buy such an amp that is made in America but "sound quality" is unlikely to be one of the reasons. So everyone can choose what fits their purposes, as long they are informed, and now they are, after Matthew's reviewed and his follow up posts. For me, I'll buy Bruno's, given the information currently available.

Which I think is fine. I had both. I too really like Bruno's amps and I consider Bruno a friend. His amps blow me away and the fact that so many companies are selling amps based on his modules is allowing for SOTA amps at a pretty low price.

Just keep in mind, this amp puts out twice the power of the Hypex amps in question (and more than twice that of the Purifi). Which is more important, .002% vs .001% THD or 250 watts vs 400 watts? I know there has been some comparisons of .006% vs .001% but that isn't the right comparison since Amir measures at 5 watts. This is actually why. Gene prefers to do a 1 watt test since we listen at or below 1 watt quite a bit. However, most amps are pretty noise limited at 1 watt, so he does 5 watts. That does a better job highlighting the area where the amp is no longer noise limited and is operating in it's most linear range. In this case, the 5 watt test puts it at something like .002% or less. I think I got .0025% into 4 ohms for 10 watts. I can't recall what I posted, it was something like that. Point is, this amp has ever so slightly higher noise and distortion, but produces quite a bit more maximum power.

I've talked to Bruno about this before, its not totally clear what is going on, but for whatever reason, the Hypex and Purifi amps put out different amounts of power under different conditions. So the module may technically be capable of putting out a clean 400 watts. But when I ran continuous tones through it and measured what came out the other side, it wasn't 400 watts, it was like 250 watts. When Amir tested the ATI amplifier based on the NC500 module, he too only got around 250 watts at .1% THD. It's supposed to do quite a bit more than that. The NC1200 module hasn't been tested by others yet. One of these days I hope to test one myself, I am curious how it does. But as I understand it, the higher rating is thermally limited by the amplifier output inductors. So it can do it for a short period of time, but not sustain it. The Cherry amp does this all day long and doesn't seem to care. I'm sure it too has a thermal limit, but I tested it by running continuous tones, so it had to maintain that level indefinitely. I ran the rest for at least 30 seconds to ensure stability, typically longer. With the Purifi amplifier that I have, if I do the continuous tone I get a different result than if I do the THD+N vs output sweep or the test that just blips the tone for a moment. Bruno said that is because the amplifier can put out a lot more output in that short time window. Technically these are both RMS tests, not Burst tone tests. There is no way to make the sweep extend the tone length other than to make the FFT longer, which I've been told not to do. Amir and Gene told me that if I make the FFT longer it artificially can lower the distortion. I'm trying to keep what I do consistent with what they do, and both of them are far more competent than I am when it comes to measuring amplifiers.

 

[Matthew J Poes]

I don't know about Matthew as he hasn't measured too many devices for AH yet. If it was Gene or Amir, I would bet they follow Audio Precision's (or something like that..), unless otherwise stated, such as the 5 W thing.

From Audio Precision:

The “Big Six” Audio Measurements – Part II - Audio Precision (ap.com)

"Signal-to-Noise Ratio

How much noise is too much? That all depends on how loud your signal is.

Signal-to-noise ratio (or SNR) is a measure of this difference, providing (like THD+N) a one-number mark of device performance. The signal is usually set to the nominal operating level or to the maximum operating level (or MOL) of the DUT. When SNR is made using the MOL, the result can also be called the dynamic range, since it describes the two extremes of level possible in the DUT. (Dynamic range in digital devices has a somewhat different meaning). SNR is usually stated in decibels, often shown as negative.

Using traditional methods, SNR requires two measurements and a bit of arithmetic. First you measure the signal level, then turn off the generator (and often, terminate the DUT inputs in a low impedance as well, to fully reduce the noise in the device). Then the noise level (often called the noise floor) is measured, using filters to restrict the measurement bandwidth. The ratio between the two is the SNR."

In Gene's most recent review/measurement, he measured only the preamp section's SNR and it was measured at 2 V. The results were within 1 dB compared to Amir's, about 110 dB. Again that's the pre section, ASR did measure the power amp section, @ 5W and the results was a little better than the Cherry's that was measured at 10 W.

Are you talking about the recent Marantz 8 series receiver measurement? I may have missed that. But if so, the Cherry came in at .00282% into 4 ohms. As you can see in the factory report, the THD+N is the same at 5 and 10 watts, so that would be comparable. Distortion is under .002% into 8 ohms at that wattage, I just can't measure that, its below the noise floor of my measurement device without the notch filter. I wasn't able to measure this amp with the notch filter.

The Marantz, into 8 ohms, is .006% into 8 ohms. So they aren't comparable. The Cherry is in another league from the Marantz. As for Signal to Noise ratio, its 26 dB between its 8ohm 1 watt measurement and max output. So we are talking about 112dB unweighted. It's about 3dB better A weighted. However, I am not totally confident my noise specs are right. The best way to have figured that out is if I had actually tested the amp with my notch filter. So worst case scenario, with the power supply noise, It has a Dynamic range number of around 112dB. To compare to Amir's (mine were not bandwidth limited at all) it is closer to 115, so roughly 5dB better than the Marantz. The upgraded power supply puts it at 120. When Tommy and I went back and forth, it was obvious the cleaner model does achieve that 120dB of dynamic range.

 

[Eppie]

Outside of this frugal bunch there is obviously a market for these amps. Living in Canada I'm more familiar with Bryston and Moon (Simaudio). Bryston has been around for ages, including the venerable 4B. The 4B3 is a true dual monoblock at 2x300W with dual power supplies and like the Cherry is locally handcrafted. Around the same price point which gives an indication of the market segment they're after, but there is that 20 yr warranty that Bryston offers. You'll want good airflow around it though. The Simaudio Moon amps appear to be favorites of the Europeans. Watch any video on a european trade show and you'll see Moon amps from Quebec. Maybe not worth mentioning here as they are really a boutique brand with pricing to match. Gorgeous designs but a similarly powered amp costs 3 or 4 times as much. $4k for 125W/ch and to get 225W/ch it's $18k. Have to commend Cherry for venturing into that segment with something home brewed.

 

[Movie2099]

Outside of this frugal bunch there is obviously a market for these amps. Living in Canada I'm more familiar with Bryston and Moon (Simaudio). Bryston has been around for ages, including the venerable 4B. The 4B3 is a true dual monoblock at 2x300W with dual power supplies and like the Cherry is locally handcrafted. Around the same price point which gives an indication of the market segment they're after, but there is that 20 yr warranty that Bryston offers. You'll want good airflow around it though. The Simaudio Moon amps appear to be favorites of the Europeans. Watch any video on a european trade show and you'll see Moon amps from Quebec. Maybe not worth mentioning here as they are really a boutique brand with pricing to match. Gorgeous designs but a similarly powered amp costs 3 or 4 times as much. $4k for 125W/ch and to get 225W/ch it's $18k. Have to commend Cherry for venturing into that segment with something home brewed.

20 year warranty??? Damn!! Wish we saw more of that.

 

[PENG]

Are you talking about the recent Marantz 8 series receiver measurement? I may have missed that. But if so, the Cherry came in at .00282% into 4 ohms. As you can see in the factory report, the THD+N is the same at 5 and 10 watts, so that would be comparable. Distortion is under .002% into 8 ohms at that wattage, I just can't measure that, its below the noise floor of my measurement device without the notch filter. I wasn't able to measure this amp with the notch filter.

The Marantz, into 8 ohms, is .006% into 8 ohms. So they aren't comparable. The Cherry is in another league from the Marantz. As for Signal to Noise ratio, its 26 dB between its 8ohm 1 watt measurement and max output. So we are talking about 112dB unweighted. It's about 3dB better A weighted. However, I am not totally confident my noise specs are right. The best way to have figured that out is if I had actually tested the amp with my notch filter. So worst case scenario, with the power supply noise, It has a Dynamic range number of around 112dB. To compare to Amir's (mine were not bandwidth limited at all) it is closer to 115, so roughly 5dB better than the Marantz. The upgraded power supply puts it at 120. When Tommy and I went back and forth, it was obvious the cleaner model does achieve that 120dB of dynamic range.

Yes I was referencing the SR8015 measured by both Gene and Amir.

I am sure the Cherry, as a power amp is in another league in terms of output power, especially into 4 Ohms. My point was just about SNR, that they seem comparable. Yes the Cherry will have a higher number at rated output but that's because its rated output is much higher. At 1 W, they are about the same based your and Amir's measurements.

By the way, why didn't you use the Audio precision APx585? I thought you are located close to Gene's?

 

[PENG]

Outside of this frugal bunch there is obviously a market for these amps. Living in Canada I'm more familiar with Bryston and Moon (Simaudio). Bryston has been around for ages, including the venerable 4B. The 4B3 is a true dual monoblock at 2x300W with dual power supplies and like the Cherry is locally handcrafted. Around the same price point which gives an indication of the market segment they're after, but there is that 20 yr warranty that Bryston offers. You'll want good airflow around it though. The Simaudio Moon amps appear to be favorites of the Europeans. Watch any video on a european trade show and you'll see Moon amps from Quebec. Maybe not worth mentioning here as they are really a boutique brand with pricing to match. Gorgeous designs but a similarly powered amp costs 3 or 4 times as much. $4k for 125W/ch and to get 225W/ch it's $18k. Have to commend Cherry for venturing into that segment with something home brewed.

The funny thing is, not that I want to, but so far I could not take advantage of my 4BSST's 20 years warranty yet. I bought it about 15 years ago so it has about 5 years left.

 

[Matthew J Poes]

True. I forgot about his 5W measurement, instead of 1W. Why oh why?

And also true about the Amplifier section measurements of the AVR. I was thinking of the Pre-amp/pre-out section.

I seem to remember 1W and full-power specs @ 1kHz and 20-20kHz are the usual “standard” throughout the years.

It seems adding more variations like 5W-spec (and SINAD instead of SNR) only adds to the confusion.

1. None of these specs are audible and prove better SQ
2. Measurements are so finicky (depends on how, who and tweaks)
3. Measurement specs vary significantly (1W vs 5W, SINAD vs SNR, etc.)
4. None of these numbers prove better reliability

It is very confusing to be honest. When I talk to Gene, he says its a standard and we should follow it. When I talk to Amir, he claims its not a real established standard and he thinks its silly. Disagrees with Gene. I understand both perspectives. From a technical standpoint, 1 watt is at the point where you spend a lot of your time. I also understand Amir's point, 5 watts is the point where the amp tends to be out of its noise limited state. Both make sense for different reasons.

You will hate it if I explain all the differences in S/N and Dynamic Range. AP's docs don't make clear the extent of differences. Their system doesn't measure S/N the way that link shows. That is a way to measure it, but nobody does. If so, add a few dB's to all our specs. So you have the following methods, as I understand it:

1. Measure the output at a set level or maximum clean output (what is that level, .1%, .5%, 1%, 10% THD, something else). Then measure the noise floor by unplugging the source and shorting the input. That is the lowest noise state. The ratio of the two is either S/N or Dynamic range (the latter simply being the S/N at the maximum output).
2. Measure the noise floor with the input connected to your signal generator and generating a very low signal, -60dB or something like that. Then Measure the output at maximum output (or again, at a set signal level). The ratio is the signal to noise ratio. Slightly worse than above in dB's but more accurate to real world.
3. Measurement the signal, then notch out the fundamental and harmonics of the fundamental and take the average noise of that. This works very similar to the above and helps in the event that the noise floor of the measurement system is close to that of the DUT, especially if the noise floor of the device changes with level.

The AP script does 2, my system does a version of 3 (which is outlined in a TI paper on how to measure dynamic range). In theory they should be identical. I've compared and its very similar. Maybe a dB or so difference. None of these systems can natively do 1 in a script. You have to do it manually. I did that and Gene wanted to me to be able to show my work, like he does, so I didn't bother reporting. It is better, gives a cleaner number, but its probably unrealistically good. It's also problematic for receivers, you can't short an HDMI input and the receiver might have a muting circuit (in fact it probably does). So for receivers, you have to do the 2 or 3, only option that works if you want to test the full signal path.

As for your comment about going from junk to SOTA, I actually think that is more about people sensationalizing results that aren't that bad. While I see differences depending on what I do or how I do it, I've never had small changes in my approach make that big a difference. I just mean, it might go from .003% to .0025%. But if the true value is .0025%, manufacturers want me to be accurate. I also assume that Amir, Gene, and others who test amps and report data are competent enough to ensure they are getting the best results. When they don't, I assume its because of something like a firmware glitch in the product. That is not uncommon. Some products work fine under most conditions but have issues in the very contrived nature of this testing.

The one exception to this (but I know Amir and Gene are fine in this regard) is that I discovered the load resistors makes a big difference. Junky load resistors (like those sold by Parts express) give really bad distortion figures. They are only right down to around .05% or so, if not worse. With an output filterless amp, it was off by even more, it was .5% THD+N best case, when the true performance with a good load was actually .05% or better. Eek! I ordered dozens of samples and eventually found a really good ARCOS resistor that is so clean I am able (with a notch filter) to measure crazy low distortion on the Purifi amp accurately. I am measuring down to .00025% , at this point, and S/N of better than 124.5 dB. The Purifi is cleaner still than that, but to get that close is pretty good. I have new equipment and software coming from QA that will help me get to the next level. In fact I am measuring .00015% THD, and the noise problem is noise in my measurement it appears.

 

[Matthew J Poes]

Yes I was referencing the SR8015 measured by both Gene and Amir.

I am sure the Cherry, as a power amp is in another league in terms of output power, especially into 4 Ohms. My point was just about SNR, that they seem comparable. Yes the Cherry will have a higher number at rated output but that's because its rated output is much higher. At 1 W, they are about the same based your and Amir's measurements.

By the way, why didn't you use the Audio precision APx585? I thought you are located close to Gene's?

This review wasn't recent. I actually reviewed and measured this close to a year ago. But with COVID, me moving, etc. It never got posted.

I do live near Gene now, I didn't back then. Having said that, if you can believe, Gene's AP isn't quite clean enough to measure this amp and isn't clean enough to measure a Purifi. With the notch filter (and only with the notch filter) I can actually measure much cleaner with the QA stuff. We will probably use both going forward. The AP is still a lot better in a lot of ways, including a far lower noise floor, far wider input voltage handling, and a better generator.