NAD M28 Seven Channel Power Amplifier Review

[PeteL]

Fully agree.

There are a few things NAD has done very well here, all in marketing. I just wish they had done as good a job in engineering. I just hate to reward companies that don't and rely more on hype and marketing. The more your reward them, the more they do that.

I wonder if they hired a marketing executive from Apple or a sneaker company or a toothbrush company because that is the model they are following in product marketing.

First, jumping on the latest Class D model is a good move for pricing power. Separates the initial adopters that get excited about the latest from their wallets easily. Second, most of the competition in Class D right now are small boutique players and a multi-channel amp just does not have a big enough market for their meager marketing budget to make developing one economically feasible. NAD on the other hand, has the brand power and marketing reach to position it for that multi-channel separates market even if it is not high volume. This is positioned to sell along with their pre/pros and so it is a leveraged ecosystem play rather than just a market for a separate amp. They are getting more and more into life-style market segment and so wise to bring in an external design team for the exterior. It works. They don't have to compromise on the engineering but they do because marketing and hype works. This is what kills me.

Yes, I disagree with poor engineering, but we'll not reach agreement on this. There is one big enough to compete, It's ATI, Why not judge NAD on how they compare to those? The M27 is 4400 msrp, the AT527NC is 4200 msrp. I don't know the street price and unfortunatly the ATI is not reviewed here. But considering that it's hard to dismiss the fact that the industrial design of the NAD is more polished, easily justifying a 5% premium, in my opinion. Can we honestly say that, engineering for engineering, the ATI is much better? Remember that the M27 got a golfing panter,one of the best measuring amp. Can we honestly say that NAD engineering is subpar and you pay only for the branding? come on. Now yes this one has a 3 dB lower SINAD, but by itself it doesn't mean much, it's still an extremely low noise and distortion amp. NAD didn't just unlearn how to engineer a power amp, they just, like any manufacturer, judge that those little compromises were justified for the design they wanted to accomplish, and yes, it's not impossible that ATI comes up with a slightly better measuring one maybe, maybe not, But any way we look at it, the M28 is a very very good multichannel amplifier.

 

[Chromatischism]

But any way we look at it, the M28 is a very very good multichannel amplifier.

Even 30 dB better SINAD would not sound any different than this, so by most standards it would be considered excellent.

 

[HTNut1975]

Yes, I disagree with poor engineering, but we'll not reach agreement on this. There is one big enough to compete, It's ATI, Why not judge NAD on how they compare to those? The M27 is 4400 msrp, the AT527NC is 4200 msrp. I don't know the street price and unfortunatly the ATI is not reviewed here. But considering that it's hard to dismiss the fact that the industrial design of the NAD is more polished, easily justifying a 5% premium, in my opinion. Can we honestly say that, engineering for engineering, the ATI is much better? Remember that the M27 got a golfing panter,one of the best measuring amp. Can we honestly say that NAD engineering is subpar and you pay only for the branding? come on. Now yes this one has a 3 dB lower SINAD, but by itself it doesn't mean much, it's still an extremely low noise and distortion amp. NAD didn't just unlearn how to engineer a power amp, they just, like any manufacturer, judge that those little compromises were justified for the design they wanted to accomplish, and yes, it's not impossible that ATI comes up with a slightly better measuring one maybe, maybe not, But any way we look at it, the M28 is a very very good multichannel amplifier.

This is along the same line I was thinking. Even though we don't have another multichannel with Purifi (i.e., above at least 3 channels), we could use the ATI multichannel and NAD M27 as analogs to give us some sort of idea the kind of discount that might be had when you add nc400 or nc500 modules together in the same unit. From there, you can get a general idea of what pricing might look like with Purifi multichannel amps. It is a little hard for me to believe that, for example, an ATI 7 channel Purifi would be the same price as its nc400 counterpart. This is where I was objecting to the idea that the M28 was priced "at a premium" because it was the first kid on the block.

 

[Vasr]

Yes, I disagree with poor engineering, but we'll not reach agreement on this. There is one big enough to compete, It's ATI, Why not judge NAD on how they compare to those? The M27 is 4400 msrp, the AT527NC is 4200 msrp. I don't know the street price and unfortunatly the ATI is not reviewed here. But considering that it's hard to dismiss the fact that the industrial design of the NAD is more polished, easily justifying a 5% premium, in my opinion. Can we honestly say that, engineering for engineering, the ATI is much better? Remember that the M27 got a golfing panter,one of the best measuring amp. Can we honestly say that NAD engineering is subpar and you pay only for the branding? come on. Now yes this one has a 3 dB lower SINAD, but by itself it doesn't mean much, it's still an extremely low noise and distortion amp. NAD didn't just unlearn how to engineer a power amp, they just, like any manufacturer, judge that those little compromises were justified for the design they wanted to accomplish, and yes, it's not impossible that ATI comes up with a slightly better measuring one maybe, maybe not, But any way we look at it, the M28 is a very very good multichannel amplifier.

I see what you did there. Use the M27 comparison and then slip in the M28.

I am tired of repeating myself on this since all of the above has already been discussed before. So I am going to stop here.

1. M28 is a worse engineered product than the M27. They have taken a much better amp module and made it perform worse than the lesser module. This is like a DAC manufacturer using a ESS 9018 chip and making it distort/noisy more than their model with a ESS 9016 chip. No amount of kool-aid is going to make it look like good engineering. If people still want to pay more for it for the "newest thing", that is their prerogative.

2. Switching back and forth between engineering goals (the best that can be built) and audibility goals (sufficient spec) is sophistry. Either you measure something by engineering goals and measurements as to how much they have achieved in an objective scale of engineering or you consider that far less goals (for far less money) are also equally inaudible and compare prices in a larger pool. But "this is higher SINAD ranking than that" but it is only "3 db less than that other one" is just internet debate nonsense. Right now, the argument seems to be I want Purifi because it is a far superior amp module but I am going to buy it even if an implementation of it is less performing than the one without Purifi.

There are other options - not to buy any Purifi multi-channel until one that performs to the full potential comes to the market (for an engineering goal) or say I am not going to buy a Purifi since it won't make any audible difference to this mass-market traditional multi-channel amp at half the cost or less (consumer goal).

Otherwise, it is just a post-rationalization for a "I like the newest good-looking toy" on the market. Apparently, NAD is betting there is a taregt market of such people and may be they are right.

 

[carlob]

In any case if you really really want a 7-channels Purifi amp and can DIY it is absolutely possible to make one.

 

[PeteL]

I see what you did there. Use the M27 comparison and then slip in the M28.

I am tired of repeating myself on this since all of the above has already been discussed before. So I am going to stop here.

1. M28 is a worse engineered product than the M27. They have taken a much better amp module and made it perform worse than the lesser module. This is like a DAC manufacturer using a ESS 9018 chip and making it distort/noisy more than their model with a ESS 9016 chip. No amount of kool-aid is going to make it look like good engineering. If people still want to pay more for it for the "newest thing", that is their prerogative.

2. Switching back and forth between engineering goals (the best that can be built) and audibility goals (sufficient spec) is sophistry. Either you measure something by engineering goals and measurements as to how much they have achieved in an objective scale of engineering or you consider that far less goals (for far less money) are also equally inaudible and compare prices in a larger pool. But "this is higher SINAD ranking than that" but it is only "3 db less than that other one" is just internet debate nonsense. Right now, the argument seems to be I want Purifi because it is a far superior amp module but I am going to buy it even if an implementation of it is less performing than the one without Purifi.

There are other options - not to buy any Purifi multi-channel until one that performs to the full potential comes to the market (for an engineering goal) or say I am not going to buy a Purifi since it won't make any audible difference to this mass-market traditional multi-channel amp at half the cost or less (consumer goal).

Otherwise, it is just a post-rationalization for a "I like the newest good-looking toy" on the market. Apparently, NAD is betting there is a taregt market of such people and may be they are right.

You certainly have a very strong opinion on what are the engineering goals, yes we will not agree, and it is just your opinion. There are other engineering goals than achieving the Highest SINAD. And I am in this industry, and I design audio products. I don't know how you can on one side the argument "I want Purifi because it is a far superior amp module". It is contradictory. According to the metrics of THIS website. ALL Hypex modules measures THE SAME. From Ucd to Ncore to Purifi Their implementation differs on manufacturers choices on what to do with them. I also believe thar Purifi is superior, but according to your metrics, they aren't. The developpers enumarated them, look it up, none of that would show on Amir's measurments. NO DACS reach the theoretical limit of the chip. Last thing on the M27 there are no measurments on here of all channels driven simultaneously to full power, so we don't even know, and if just for this, this is a huge achievment on the performance of the power supply regardless of who designed it. Just looking at graph, and come up with an extremely strong Statement like: M28 is a worse engineered product than the M27. I don't want to be condescending, but you don't know that.

 

[Casey Leedom]

If you are willing to live with three boxes you can purchase two 3-channels Purifi amps and one monoblock. Now a better question would be: who needs 7 channels of Purifi?
...

I am hugely space constrained and really only have room in my home for a single 7-channel amplifier which satisfies my Stereo Music and Home Theater needs. I'd like the highest possible quality for Stereo Music, the other 5 channel come along for the ride ...

And yeah, I had been thinking of a DIY approach, but I really don't have the skills for that.

Casey

 

[carlob]

I am hugely space constrained and really only have room in my home for a single 7-channel amplifier which satisfies my Stereo Music and Home Theater needs. I'd like the highest possible quality for Stereo Music, the other 5 channel come along for the ride ...

And yeah, I had been thinking of a DIY approach, but I really don't have the skills for that.

Casey

Get a 7-channels Hypex based amp. Difference between nc500 and 1et400a modules is going to be minimal. You save some money and gain more wattage.

 

[HTNut1975]

You certainly have a very strong opinion on what are the engineering goals, yes we will not agree, and it is just your opinion. There are other engineering goals than achieving the Highest SINAD. And I am in this industry, and I design audio products. I don't know how you can on one side the argument "I want Purifi because it is a far superior amp module". It is contradictory. According to the metrics of THIS website. ALL Hypex modules measures THE SAME. From Ucd to Ncore to Purifi Their implementation differs on manufacturers choices on what to do with them. I also believe thar Purifi is superior, but according to your metrics, they aren't. The developpers enumarated them, look it up, none of that would show on Amir's measurments. NO DACS reach the theoretical limit of the chip. Last thing on the M27 there are no measurments on here of all channels driven simultaneously to full power, so we don't even know, and if just for this, this is a huge achievment on the performance of the power supply regardless of who designed it. Just looking at graph, and come up with an extremely strong Statement like: M28 is a worse engineered product than the M27. I don't want to be condescending, but you don't know that.

What other attributes would look for in measurements besides what is discussed in this review? I'm not technically proficient, but I'm curious. I recall reading Allen March and Bruno say something to the effect that the Purifi module just sounds better. Perhaps I'm assuming incorrectly, but I'm assuming there is more to the story than SINAD and perhaps even some of the other measurements here. I don't know--just asking.

 

[carlob]

I think there is 0.5dB difference in FR around 19KHz, if you can hear it. Also Purifi has better sinad and distortion, even if probably inaudible.

https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/
https://www.audiosciencereview.com/...-and-measurements-of-nord-one-nc500-amp.7704/

 

[PeteL]

What other attributes would look for in measurements besides what is discussed in this review? I'm not technically proficient, but I'm curious. I recall reading Allen March and Bruno say something to the effect that the Purifi module just sounds better. Perhaps I'm assuming incorrectly, but I'm assuming there is more to the story than SINAD and perhaps even some of the other measurements here. I don't know--just asking.

I'll let you do the reading on how the creators believe that the Purifi is the better technology,
They discuss, among other things:
-The filter having a more linear phase in the audible band (class D amps need a filter
-A behavior post clipping point more similar to class AB for strong peaks
-a lower output impedance
-A better, more mathematically exact feedback circuit, making the amp more stable.
Much other stuff, but they word it better than me.
https://purifi-audio.com/wp-content/uploads/2020/06/Purifi-news-by-Jez-Ford-SoundImage-magazine-.pdf

 

[HTNut1975]

I'll let you do the reading on how the creators believe that the Purifi is the better technology,
They discuss, among other things:
-The filter having a more linear phase in the audible band (class D amps need a filter
-A behavior post clipping point more similar to class AB for strong peaks
-a lower output impedance
-A better, more mathematically exact feedback circuit, making the amp more stable.
Much other stuff, but they word it better than me.
https://purifi-audio.com/wp-content/uploads/2020/06/Purifi-news-by-Jez-Ford-SoundImage-magazine-.pdf

Appreciate the quick reference!

 

[Chromatischism]

Not to debate you as you're just listing their claims, but:

I'll let you do the reading on how the creators believe that the Purifi is the better technology,
They discuss, among other things:
-A behavior post clipping point more similar to class AB for strong peaks
-A better, more mathematically exact feedback circuit, making the amp more stable.

You aren't listening to your amps in clipping so that behavior doesn't matter, and

A lot of their marketing of NCore was about this:

Chief distinguishing features are flat frequency response irrespective of load impedance

Therefore, it's hard for us to determine what exactly is better about Purifi other than high SINAD which was already beyond human perception with NCore.

 

[PeteL]

Not to debate you as you're just listing their claims, but:

You aren't listening to your amps in clipping so that behavior doesn't matter, and

A lot of their marketing of NCore was about this:


Therefore, it's hard for us to determine what exactly is better about Purify other than high SINAD which was already beyond human perception with NCore.

But I'm looking at the chart, and I see a SINAD of 105 for a nc400 build, and 104 for the Purifi reference design, Yes, at this level it doesn't matter, To be honest, never heard Purifi, but we are seeing on these pages that strictly from audio science review measurments, There is no evidence that Purifi is better than NCore. Raises questions don't it? Why they would put work on tweeking a already almost perfect design, for in the end coming up with a lower SINAD? I know the cynics could say that it's then just marketing and they are just slapping a Purifi sticker on a lower performing nCore design. I find it difficult to believe. I'd like to trust that a brilliant engineer like Putzeys don't just say things for their marketing values, but I may be wrong.

 

[PeteL]

I think there is 0.5dB difference in FR around 19KHz, if you can hear it. Also Purifi has better sinad and distortion, even if probably inaudible.

https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/
https://www.audiosciencereview.com/...-and-measurements-of-nord-one-nc500-amp.7704/

The NC400 build scores better, It's a reference design, where the other one is Nord's shot at nc500. What it says, is that it varies, they are small numbers all around.

 

[Vasr]

You certainly have a very strong opinion on what are the engineering goals, yes we will not agree, and it is just your opinion. There are other engineering goals than achieving the Highest SINAD. And I am in this industry, and I design audio products. I don't know how you can on one side the argument "I want Purifi because it is a far superior amp module". It is contradictory. According to the metrics of THIS website. ALL Hypex modules measures THE SAME. From Ucd to Ncore to Purifi Their implementation differs on manufacturers choices on what to do with them. I also believe thar Purifi is superior, but according to your metrics, they aren't. The developpers enumarated them, look it up, none of that would show on Amir's measurments. NO DACS reach the theoretical limit of the chip. Last thing on the M27 there are no measurments on here of all channels driven simultaneously to full power, so we don't even know, and if just for this, this is a huge achievment on the performance of the power supply regardless of who designed it. Just looking at graph, and come up with an extremely strong Statement like: M28 is a worse engineered product than the M27. I don't want to be condescending, but you don't know that.

 

[carlob]

The NC400 build scores better, It's a reference design, where the other one is Nord's shot at nc500. What it says, is that it varies, they are small numbers all around.

I know, but the NC400 module is for DIY. The one tested here was a diy amplifier not a reference build. You won't find it in commercial amps.
https://www.audiosciencereview.com/...and-measurements-of-hypex-nc400-diy-amp.5907/

 

[PeteL]

I know, but the NC400 module is for DIY. The one tested here was a diy amplifier not a reference build. You won't find it in commercial amps.
https://www.audiosciencereview.com/...and-measurements-of-hypex-nc400-diy-amp.5907/

OK, they are all in the same ballpark, that's the point, there is an other NCore further down, and this NAD here is in between, my point is simply that the examples on this site is not enough to prove the superiority of a module over the others. We have variables that are about the implementations, small differences.

 

[carlob]

OK, they are all in the same ballpark, that's the point, there is an other NCore further down, and this NAD here is in between, my point is simply that the examples on this site is not enough to prove the superiority of a module over the others. We have variables that are about the implementations, small differences.

The NC400 seems to perform better than the NC500 which is the OEM module. As I said before in the thread, all else being equal (hypex modules, hypex SPMS and correct assembly) the only variance is in the buffer which is specific of the implementation and is the only element that makes a difference between the small "manufacturers".

 

[PeteL]

The NC400 seems to perform better than the NC500 which is the OEM module. As I said before in the thread, all else being equal (hypex modules, hypex SPMS and correct assembly, the only variance is in the buffer which is specific of the implementation and is the only element that makes a difference between the small "manufacturers".

I agree with this, so from what we have here, which one perform better between the all Hypex NC400 DIY kit, and the all Purifi et400a dev Platform?