OP
- Thread Starter
- #61
I only measured the rightmost two channels.
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NAD M28 Seven Channel Power Amplifier Review
- Thread starter amirm
- Start date
OP
- Thread Starter
- #62
You mean post the point where the reference clips? Because prior to that the M28 has both more noise and distortion:
NAD has more power likely because it has a larger power supply to feed 7 amps.
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This is actually very good performance, even though a small step down from NAD’s previous model and a bigger step down from the Purifi reference implementation. Still, it is refreshing to see after the last few NAD product reviews. It seems that NAD can still make great amps but fumbles the ball on AV and streaming products.
It's a great feature that this AMP provides equal power to all channels when driven, where others cannot. If they traded SINAD for more power, my question is why? Is there an application for this much power per channel? Should they have taken a lower power target and tried to reduce SINAD? I'm not sure if there is a large segment of high end speakers that need 250watts of continuous power (outside of a subwoofer of course). Anyone have an opinion on whether there is a need for this amount of continuous power per channel?
restorer-john
Grand Contributor
Fair enough, the combinations are too many to test.
restorer-john
Grand Contributor
Because you can never have too much quality continuous rated power. 200wpc@8R/350wpc@4R is pretty much where serious power to run just about anything starts.
400-500wpc@8R means you'll never need to upgrade- ever.
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No thank you re: Pascal modules.
The rised distortion is obviously due to loading. The issue is very likely to be ground connections.
MakeMineVinyl
Major Contributor
How many SMPS does it have? It seems it would need more than one.
OP
- Thread Starter
- #70
I don't know until I open it.
TomJ
Active Member
Wondering the same about the new C 298. Spec sheet states the same input impedance on XLR and RCA, hmm....
Purifi module are balanced by design. It wouldn have an effect in input impedance to send the ground signal to cold. Plus, since the AP x555 has floating unbalanced outputs, the lack of cmnr on this configuration wouldn’t impact performance. if you don’t have interference, and no grounding induced noise or loop CMNR doesn’t really serve anything. The advantage of Balanced is case related, it’s not absolute
That’s correct. And the reason is definitely not the input buffer redesign.
restorer-john
Grand Contributor
Note this NAD is another product which is safety earthed.
It also needs a buffer, so all bets are off.
In general yes, however you still have the advantage of the 3dB higher input signal, so at least noise should be 3dB down, unless the noise of the input stage is higher already or the 3dB gain is lost by gain difference.
The last seems to be the case.. the input voltage of both is exactly the same. Which at least means they do handle the two signals differently. Since output is equal with equal input, the balanced input must be 3dB down in gain, explaining no gains in SNR.
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Something like a Y filter at the PS input or do you have something else in mind?
No. Loops and internal signal ground return. Possibly also bypass electrolytes ground return.
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I don't have much faith in Pascal in terms of performance. The last Pascal amplifier tested was this: https://www.audiosciencereview.com/...ff-rowland-535-stereo-amplifier-review.12531/The other class D alternative is the D-Sonic (Pascal modules) that can be configured in many different ways
Then again, they are used in the Dutch&Dutch 8C so they aren't that bad.
Nord already sells configurable multichannel amps (up to 8 channels) but based on Hypex modules, not Purifi.
https://www.nordacoustics.co.uk/pro...custom-configuration-channel-amplifier-silver
https://www.nordacoustics.co.uk/pro...custom-configuration-channel-amplifier-silver
Maybe I am missing something with what you say, but there shouldn't be a "gain difference" a balanced OUTPUT would have 3 dB gain over a unbalanced one if a designer do it the simplest way. But the amp would have the same 29 dB gain. I do have to admit that my own comment also contained some pre-assumptions that could be erroneous, and yes, I don't know the design of the buffer. Diggin in now I see that the M28 has different input impedance for balance and unbalanced, where the upcoming c298 have the same. I'm surprised by that but it does mean they would use a different input buffer. Still, i see no reason to design an input buffer that would not be symmetrical, knowing the module has ressources for symmetrical inputs. Maybe it's worth investigating, not sure. My guess would be that the M28 would go the extra step of converting to balanced the unbalanced input, not the other way around. For what it's worth, the m28 product page has a paragraph titled "fully balanced audio" and the c298 only mention balanced inputs. NAD are not known to lie about their specs, but yes the c298 specs could be ambiguous, but it's not out yet it's just a spec sheet.
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