NAD M28 Seven Channel Power Amplifier Review

[Kal Rubinson]

Not sure if anyone noticed this or not, but the NAD M33 has a bridge mode.

This makes me think that they plan to simply update the M22v2 with the new purifi amps (aka M23 or M22v3), meaning similarly powered and bridgeable to whatever crazy amount of power matches the bridge mode of the new M33.

I noted that in my review and speculated as you do.

 

[ReciprocalSpace]

Actually our 4,5,6,7 and 8 channel Purifi miltichannel based amps are coming out next month. Enclosures are our new premium in house made enclosures just like our PNC1200 and 1ET400A mini.

Our upcoming multichannel Purifi based amps have all power available from each 1ET400A module per channel even when all channels are driven and the harmonic distortion stays low @ 0.0006% THD+N for all channels.

The price will be around 2.990 Euro excl. VAT for the 8-channel version and less for other versions.

Would love a 5 channel Purifi amp, when are you planning on releasing?

 

[Apollon Audio]

Would love a 5 channel Purifi amp, when are you planning on releasing?

You can already order it. We will start shipping next month.

 

[ReciprocalSpace]

You can already order it. We will start shipping next month.

Price? Still not seeing listed under multichannel > Purifi (only see 3 channel).

Does it come with 20A rated cable and fuse? Like the higher gain at 28dB you guys offer over the 26/27dB of others given I'll be using XLR to RCA with a AVR for a few more years.

 

[eduardw]

Did anyone compare the nad m28 with the nad c298? Would love to see a 3 channel high powered version.

 

[zachery2006]

Did anyone compare the nad m28 with the nad c298? Would love to see a 3 channel high powered version.

I just got my M28, it works as it supposed to be. My current amp is Emotiva A-300, Pre-amp is Topping E30, speakers are KEF Ls50s. I feel M28 has more tight bass, a little cold treble. M28 is a very nice amp, but just not a big surprise(excitement) to me to be honest.

I saw the pic of inside of C298. it seems that it has the same switch power as M33. I think C298 would sound almost identical as M28.

 

[JimB]

...
Sweeping at different frequencies shows some small oddities but nothing of major concern:

View attachment 82538

Note that our normal testing for power per industry standard uses 1 kHz but the most need is at lower frequencies. For that reason, I have started to annotate power at 20 Hz as seen above. All amplifiers I have tested reduce their power at low frequencies.

...

Sorry if I missed it in other posts, but what accounts for the ability of this amp to pass this test at low frequencies, when the reference Purifi demo amp did not?

 

[amirm]

Sorry if I missed it in other posts, but what accounts for the ability of this amp to pass this test at low frequencies, when the reference Purifi demo amp did not?

Multichannel amps have far more powerful power supplies when used in stereo mode. So that limitation is not there whereas it would be in purifi reference design.

 

[JimB]

Multichannel amps have far more powerful power supplies when used in stereo mode. So that limitation is not there whereas it would be in purifi reference design.

Thanks, @amirm. So, the limitation with the Purifi demo unit was PSU, not thermal? I know that at the time of that review, you speculated that additional cooling might be required. There was quite a lot of discussion about how such amps should not be rated as high as they claim due to limitations like that (how much power, for how long, etc.). Did you happen to run that test on the reference demo with only a single channel driven? I realize that would make it easier for both for the PSU and the thermal dissipation.

 

[bobof]

Not sure if anyone noticed this or not, but the NAD M33 has a bridge mode.

This makes me think that they plan to simply update the M22v2 with the new purifi amps (aka M23 or M22v3), meaning similarly powered and bridgeable to whatever crazy amount of power matches the bridge mode of the new M33.

The manual for the Purifi modules recommends against bridging.
https://purifi-audio.com/wp-content/uploads/2020/01/1ET400A-Data-Sheet-1.00.pdf

Similarly, bridging two 1ET400A Designs will result in performance degradation as the circuit is not configured
to sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A
Designs. Bridging is therefore not recommended. All operation and performance specs are void in this
configuration.

 

[Vincentponcet]

You can already order it. We will start shipping next month.

I don't see it on your website, only the 3 channels one.

 

[mistaleung]

Any news from Apollon Audio? I sent them an email but no luck.

 

[ReciprocalSpace]

Any news from Apollon Audio? I sent them an email but no luck.

You can actually order 4-8 channel amplifiers now from them through email to get a Paypal inovice:
"We need to take professional photos so that I we can add this model to our website. I can make a Paypal invoice for you. The amplifier is available in piano black or lacquere white. The enclosure is our premium in house made just like our Purifi mini or PNC1200.
Best regards
Tibor"

For 5 Channel
"The 5 channel Purifi based amplifier is 2.490 Euro. Because of the higher manufacturing costs the 8 channel version will be a bit more than 2.990 Euro. The input buffers have ic based opa1612 op amps just like the input buffers from Purifi. There are no class A discrete op amps installed

The price is 2.490 Euro without VAT. Since you are from USA you don’t have to pay additional VAT like European citizens do. 12V trigger and XLR+RCA options comes as standard included. The amplifier has one power mains inlet. The amplifier is already available for order. We have a lead time of 21 working daS for our multichannel amplifiers. Shipping to USA is around 120 Euro.
Best regards
Tibor"

 

[Vincentponcet]

You can actually order 4-8 channel amplifiers now from them through email to get a Paypal inovice:
"We need to take professional photos so that I we can add this model to our website. I can make a Paypal invoice for you. The amplifier is available in piano black or lacquere white. The enclosure is our premium in house made just like our Purifi mini or PNC1200.
Best regards
Tibor"

For 5 Channel
"The 5 channel Purifi based amplifier is 2.490 Euro. Because of the higher manufacturing costs the 8 channel version will be a bit more than 2.990 Euro. The input buffers have ic based opa1612 op amps just like the input buffers from Purifi. There are no class A discrete op amps installed

The price is 2.490 Euro without VAT. Since you are from USA you don’t have to pay additional VAT like European citizens do. 12V trigger and XLR+RCA options comes as standard included. The amplifier has one power mains inlet. The amplifier is already available for order. We have a lead time of 21 working daS for our multichannel amplifiers. Shipping to USA is around 120 Euro.
Best regards
Tibor"

Any idea about the power supply configuration ?

 

[ReciprocalSpace]

Any idea about the power supply configuration ?

That I don't know

 

[Apollon Audio]

Any idea about the power supply configuration ?

Hello,

we use one 3.000 watt power supply for the 4-6 channel version and two 3.000 watt power supplies for the 7-12 channel version.

 

[Apollon Audio]

Any news from Apollon Audio? I sent them an email but no luck.

Can you please PM me your email address? Unfortunatelly I'm sorry but I can't find your email in our inbox.

Thank you.

 

[bobof]

We use one 3.000 watt power supply for the 4-6 channel version and two 3.000 watt power supplies for the 7-12 channel version.

Does that mean you're also having to drive half the channels out of phase to combat pumping? How does that hold up if the channels aren't loaded symmetrically?

 

[Vincentponcet]

Hello,

we use one 3.000 watt power supply for the 4-6 channel version and two 3.000 watt power supplies for the 7-12 channel version.

That's really great configuration.
When would you publish the photos ?
Any plan to have Amir doing a review ?

 

[Apollon Audio]

That's really great configuration.
When would you publish the photos ?
Any plan to have Amir doing a review ?

We will publish the photos very soon. We are already manufacturing the first batch of units.

A multichannel Purifi based amp will be sent to Amir for a review.