NAD M28 Seven Channel Power Amplifier Review

[ririt]

That makes a lot of sense. Surely you dont need purifi for surround channels?

Definitely not

 

[voodooless]

It’s spooky how similar the xlr and rca measurements are.. is it even a real balanced input?

 

[RichB]

Not bad really. It is not easy to find a powerful, cool running, 7-channel amplifier that does not break your back.

Are there any internal pictures? I'd love to see the layout.

- Rich

 

[Vasr]

That makes a lot of sense. Surely you dont need purifi for surround channels?

Definitely not

I would think the power ratings would be more important than the already minuscule noise and distortion.

First of all, I am not entirely sure using Purifi itself is needed for any channel in HT use but if there indeed is a reason (higher efficiency for more continuous use?), the conventional wisdom that surrounds only have peripheral/transitory audio or not as important audio is not really justified any more. An increasing number of video productions are moving a lot of the background music often at loud volumes as well as a lot of the off-screen voices ("god effect") into surrounds combined with fronts for a more immersive 3D experience. Even more so with height effects thrown in.

The FR and room correction are more than sufficient to make the main dialogues clear in the fronts using any competent amp.

If you are using the same system for both music and HT then focusing on LR for the whole chain that works well for both music and HT would make sense. C isn't any more or less important than surrounds in my opinion. This is my approach in the next iteration of upgrades. It is also easier to find optimal stereo chains (from processing to DACs to amps) than an optimized 3 channel chain.

 

[PeteL]

Definitely. I am on the way to buy such combo from March Audio and it will cost me much less than the NAD M28

From their website, only the P451mono block is Purifi based and it's 1165$, everything else is ncore based. Not that it should matter but it's not a direct comparison, 7 channel of that would be 8500$ I get that yes you could buy 7 channel of amplification from them for less than 5000$. But not sure I would say "much less" and the pricing of nc252 is a different by a good margin, may be very good tough I just don't think it's a fair comparison. If As you say you'd like to have 3 channel of "Purifi" tough, you still end up a bit over

 

[amirm]

Are there any internal pictures? I'd love to see the layout.

I will take the top off and take some pictures later.

 

[stunta]

I will take the top off and take some pictures later.

Of who?

 

[asruser2020]

As noted, we have dropped 5 dB in noise performance which more or less explains the similar drop in SINAD. This is a shame as noise can be audible unlike low levels of distortion. Fortunately we still clear my hurdle of 96 dB for 16 bit content even at 5 watts so practical consequence will be small.

This is a good point of reference to argue against those who are unnaturally obsessive about SINAD (95% of the members here).

 

[ririt]

From their website, only the P451mono block is Purifi based and it's 1165$, everything else is ncore based. Not that it should matter but it's not a direct comparison, 7 channel of that would be 8500$ I get that yes you could buy 7 channel of amplification from them for less than 5000$. But not sure I would say "much less" and the pricing of nc252 is a different by a good margin, may be very good tough I just don't think it's a fair comparison. If As you say you'd like to have 3 channel of "Purifi" tough, you still end up a bit over

Pete L, with the coming P452, their new stereo Purifi amp, combined with the P451 (to get a 100% front stage) + 2 P252 power amps, I can ensure you that it can be much more cost effective than the M28! you can contact Alan from March Audio to double check.

 

[boXem]

great news for providers like March Audio or Apollon who are able to provide excellent implementation of the original purifi design !

Maybe, maybe not. While not measured, you can't be sure.

 

[Casey Leedom]

Have any of them built a 7-channel amp?

Actually @March Audio volunteered to take a whack at doing a 7-channel Purifi amplifier for me, but it would have been a one-off and I didn't feel that it would have been fair to Alan to put him through that effort since I'm probably one of the few people interested in a high-end 7-channel amplifier ... If I had the space I would have bought 7 of Alan's Purifi mono blocks ...

Thanks for testing it @amirm! I don't suppose anyone from NAD is on Audio Science Review? It would be interesting to get their input on the tradeoffs they made ...

Casey

 

[Casey Leedom]

Oh, and the reason I went for the NAD M28 was because of space constraints. I need a single system for both Stereo Music and Home Theater ...

Casey

 

[AudioJester]

Pete L, with the coming P452, their new stereo Purifi amp, combined with the P451 (to get a 100% front stage) + 2 P252 power amps, I can ensure you that it can be much more cost effective than the M28! you can contact Alan from March Audio to double check.

But 4 boxes versus 1!
Nord may be a better option for multi-channel combined amp.

 

[stunta]

More boxes also mean more power outlets, more power cords.

 

[HTNut1975]

Definitely. I am on the way to buy such combo from March Audio and it will cost me much less than the NAD M28

Wow. Is this a custom discount of some kind? You can get NAD stuff for discounts from dealers. I secretly wanted March stuff (March amps are slick looking, and it would've been nice to be able to talk to the actual maker of the units), but the discount with the NAD per channel was hard to overcome. I'm a little disappointed with these results, but it is more of a shoulder shrug for me, as I'm not sure I'd be able to ever tell the difference (my M28 just arrived a couple of days ago).

 

[phoenixdogfan]

Even with its "Tis Hamartia" this still has to be regarded as the bleeding edge of multichannel amps.

 

[TomJ]

Point taken that NAD engineering didn't go the distance like they did with the M27 for whatever reason (who knows), but that said, the M28 does stand as one of the very best AV amps ever tested. Suggestion - would it make sense to create a separate rankings category for AV amps? Not sure that a 7 channel amp with 29dB gain should be ranked against stereo amps where the leading product has much lower gain (AHB2).

 

[Vasr]

Not sure that a 7 channel amp with 29dB gain should be ranked against stereo amps where the leading product has much lower gain (AHB2). Even among the stereo amps, sometimes I wonder whether the rank should be normalized in some manner as to gain.

Not sure I understand your point. People don't buy an amp for its gain number (any more than a damping factor). It is how much power (including dynamic/peak/burst) they can realize (starts to lose relevance beyond some 200W/ch) and at what cost (monetary and noise/distortion). What is the point of normalizing to gain?

 

[Kal Rubinson]

The one thing I am not a fan of is the touch on/off button on top. It is not responsive. I wish the NAD logo was a hard switch.

I've been complaining about switch for the last 5 years:
"In fact, the M17's is the best info display yet, but is compromised by a niggling issue: Remember, the touch-sensitive Standby/On switch is at the center of the top edge, just where I'm likely to rest my hand when using the touchscreen. You can imagine how infuriating it was to be continually turning off the M17 just when I wanted to interact with it. It took me weeks to learn not to do that, and I still sometimes forget."

I actually broke it.

 

[Vasr]

Even with its "Tis Hamartia" this still has to be regarded as the bleeding edge of multichannel amps.

Bleeding edge of Class D based multichannel amps? Multichannel amps have been around for decades. They are pretty much commoditized products with a not so compelling business case. Class D has beneficial thermal and power benefits from its inherent switching design, of course. But for the people slapping third party amp modules into a chassis what bleeding edge work are they doing that is even close to the complexity and wizardry of their own Class A/AB amps.

Multichannel amp with bleeding edge Class D modules might be more accurate and perhaps what you meant?