Review and Measurements of NAD M27 PWR Amp

[HammerSandwich]

If they rate at 0.003% @150W/8ohms and you find the amplifier puts out 200W @1% what have you actually discovered? Nothing really. If the amplifier fails to hit its rated power at the rated THD, then you have something to bleat about.

In that case, you don't learn anything about the datasheet's accuracy, but you do learn a bit about the device's abilities. (If you need a powerful amp, this one's clearly better than another that makes 80W at 3%, right?)

My subjective(!) impression is that @amirm doesn't beat up companies for missing the specs by a fraction. He'll mention it, at least most of the time, but he doesn't harp on it. OTOH, when a product is truly low-res, the reviews state it clearly. And regardless of the product's price, though the expensive ones are beaten more severely. That gives me a pretty objective view of the landscape, even if it's not 100% consistent scientific.

The issue really boils down to this: "Single-point figures of merit don't paint a full picture." Looking only at 5W SNR or a DAC's 0dBFS SINAD might be simple for the measurement newbie to start ranking devices, but Amir posts the AP graphs, too. Perhaps a "this ain't everything, kids!" disclaimer for the product-ranking charts?

 

[digicidal]

The issue really boils down to this: "Single-point figures of merit don't paint a full picture." Looking only at 5W SNR or a DAC's 0dBFS SINAD might be simple for the measurement newbie to start ranking devices, but Amir posts the AP graphs, too. Perhaps a "this ain't everything, kids!" disclaimer for the product-ranking charts?

I thought that disclaimer was implied in everything found on the Internet? (Especially charts/graphs) While true in a general sense, I think the key in using a comparison metric is simplicity. Sure using SINAD as the primary metric can be debated (and has on here), but it's a very good baseline for determining both the quality of components, and competence in implementation. Even with just this one measurement it's often possible to not just compare, but identify the problem (i.e. is the mains leakage, 2nd harmonic, or switching noise the one "setting the bar").

 

[restorer-john]

My subjective(!) impression is that @amirm doesn't beat up companies for missing the specs by a fraction.

No he doesn't. Personally, I think he's way nicer than I would be when gear fails, shuts down or misses the mark. And ripping into a small manufacturer for misleading specs is probably also a shortsighted attitude, especially if it gets someone known as a "ball buster"- nobody is going to want to send in gear to test are they?

You can't please all of the people all of the time I guess.

 

[digicidal]

I've found it fairly difficult to please anyone all of the time - let alone all of the people. Plus I'm sure my back couldn't handle the strain. Maybe we should get @Thomas savage to weigh in on the topic.

 

[starfly]

It would be nice to see reviews of multi channel power amps from Monolith / Emotiva / Outlaw Audio, as those tend to be more affordable and otherwise have a good reputation.

 

[amirm]

Also, was the SNR measured "A" weighted or "unweighted" and was any AES17 filter used? It says 22.5 kHz BW, so it seems unweighted but if some sort of low pass filter right?

Here are the settings for analog SNR measurements:

The capture bandwidth is 22.4 kHz but as you see, the noise measurement is limited to 20 to 20 kHz.

No weighting is used (signal path means flat 22.4 kHz).

The filters are not brickwalled so I am assuming response extends some beyond 20 kHz and hence the notation I have on the graph. I am open to changing the title to 20 kHz.

 

[peng]

Here are the settings for analog SNR measurements:

View attachment 33923

The capture bandwidth is 22.4 kHz but as you see, the noise measurement is limited to 20 to 20 kHz.

No weighting is used (signal path means flat 22.4 kHz).

The filters are not brickwalled so I am assuming response extends some beyond 20 kHz and hence the notation I have on the graph. I am open to changing the title to 20 kHz.

All good, I thought it was no weighting anyway based on the BW, but before I tell the guys at Audioholics.com (who asked..) I thought it's better if I hear that from you first. Thank you.

 

[TomJ]

The direct competitor would be ATI 527/528nc which is using multi NC500 modules in similar price range.

FWIW I bought a new ATI 522NC earlier this year expecting good build and sound quality consistent with their reputation. I was disappointed with both. It had a rising tilt in frequency response, intermittent transformer buzz, intermittent 60Hz hum, and unexpected protection circuit shutdowns with clean XLR input (Mytek) in a system that was 100% stable and reliable before the ATI arrived. Perhaps the SQ was compromised by the IC op amp on their buffer board. Bummer...

 

[laidick]

FWIW I bought a new ATI 522NC earlier this year expecting good build and sound quality consistent with their reputation. I was disappointed with both - rising tilt in frequency response, intermittent transformer buzz, intermittent 60Hz hum, unexpected protection circuit shutdowns with clean XLR input (Mytek) in a system that was 100% stable and reliable before the ATI arrived. Perhaps the SQ was compromised by the IC op amp on their buffer board. Bummer...

Very well said, that's why I sold my ATI 528NC and keep Apollon 8350.

 

[RichB]

FWIW I bought a new ATI 522NC earlier this year expecting good build and sound quality consistent with their reputation. I was disappointed with both - rising tilt in frequency response, intermittent transformer buzz, intermittent 60Hz hum, unexpected protection circuit shutdowns with clean XLR input (Mytek) in a system that was 100% stable and reliable before the ATI arrived. Perhaps the SQ was compromised by the IC op amps on their buffer board. Bummer...

Very interesting.

My AT522NC is a bright sounding amplifier when directly compared and level matched with an AT4002 and AHB2.
I have had issues with transformer hum so will be buying amplifiers with SMPS power supplies going forward. Although, with AHB2's that may be never

- Rich

 

[TomJ]

Very interesting.

My AT522NC is a bright sounding amplifier when directly compared and level matched with an AT4002 and AHB2.
I have had issues with transformer hum so will be buying amplifiers with SMPS power supplies going forward. Although, with AHB2's that may be never

- Rich

cool, good luck Rich with your new AHB2

 

[RichB]

cool, good luck Rich with your new AHB2

Thanks, I have had them for months now and love them. The only potential issue would be lack of power. They have excellent per-channel clip indicators and I have found that I don't clip them at any level I care to listen driving the Salon2s (without bridging).

Both the AHB2 and AT522NC sounded more dynamic than the AT4002 in my game room driving the Revel M20s, though I don't know why.

- Rich

 

[geronimo1958]

Is this amp in production still? I cannot find one anywhere.

 

[geronimo1958]

I spoke with a rep at the locate stereo store and they said the M27 is being replaced with the M28. Nothing on NAD's website.

 

[Kal Rubinson]

I spoke with a rep at the locate stereo store and they said the M27 is being replaced with the M28. Nothing on NAD's website.

Yup and it will be a "Purifi-based" design.

 

[geronimo1958]

Yup and it will be a "Purifi-based" design.

The rep said it would have a MSRP of $5000.

 

[Kal Rubinson]

The rep said it would have a MSRP of $5000.

I have an M33 just in which might be indicative of what to expect from the M28.

 

[geronimo1958]

Do manufactures pull products when a new model is imminent? I cannot find a M27 anywhere. Does NAD only make them when ordered?

 

[Deleted member 11516]

I have an M33 just in which might be indicative of what to expect from the M28.

And what is your impression in the M33?

 

[Kal Rubinson]

And what is your impression in the M33?

Looks nice. All other details will be in the published review.