NAD C 298 Power Amplifier With Purifi Eigentakt Amplification

[ebslo]

What assumptions did you use for the speaker, among other things?

8 Ohms, just like amp manufacturers use. Point is you don't need a special amp feature to see what a lower DF amp would sound like.

 

[pogo]

The short paragraph on '7.4.3 Damping factor' is sufficient to understand how complex the theory can be and I think this one is closer to reality:
Link

-> In reality with transient signals, each turn of the voice coil couples individually and proportionately, so the resistance is distributed!

 

[peng]

But... My speakers now are bi-amped by CXR200, maybe C298 would be even a downgrade...

You are joking right?

The short paragraph on '7.4.3 Damping factor' is sufficient to understand how complex the theory can be and I think this one is closer to reality:
Link

-> In reality with transient signals, each turn of the voice coil couples individually and proportionately, so the resistance is distributed!

I read what's in the link, saw nothing new but would have to read the whole article to know if there is anything to support the need for DF higher than 150 based on steady state calculations. I doubt there is, otherwise the author would have said something about it already.

 

[pogo]

Heco Celan Revolution 3. Would it be a good upgrade from Cambridge Audio CXR-200 to NAD C 298?

They will most likely sound thinner.
According to STEREO (a German audio magazine, who have tested the T+A A200) and my experience with different amp DFs:
All loudspeakers, from large-volume bass monsters to compact shelf speakers or speakers with low chassis mass, should now be able to exploit their full potential. DF switching is done by means of a push button.

 

[ebslo]

They will most likely sound thinner.
According to STEREO (a German audio magazine, who have tested the T+A A200) and my experience with different amp DFs:
All loudspeakers, from large-volume bass monsters to compact shelf speakers or speakers with low chassis mass, should now be able to exploit their full potential. DF switching is done by means of a push button.

Your "experience with different amp DFs" appears to be an advertisement for a random amplifier. Again.

 

[peng]

Your "experience with different amp DFs" appears to be an advertisement for a random amplifier. Again.

Exactly.. DF is hardly an issue any more, and if one wants to play it safe, get one that has it higher than 150 as per Benchmark's article, that imo is super conservative. With that kind of conservatively high numbers there is absolutely no need to do any transient analysis in the article he linked alluded to.

 

[ihvar]

They will most likely sound thinner.
According to STEREO (a German audio magazine, who have tested the T+A A200) and my experience with different amp DFs:
All loudspeakers, from large-volume bass monsters to compact shelf speakers or speakers with low chassis mass, should now be able to exploit their full potential. DF switching is done by means of a push button.

Well, it a sin for T+A allowing users to play with holy audiophile parameters ) Like an EQ or color scheme presets of monitors
I've already played with NOS filter and EQ -> +3.5db for 14.5 kHz on my RME. And I like it )
So now there's no way back, and NAD C 298 is on it's way to me. T+A 200 is pretty expensive

 

[MaxBuck]

Many knowledgeable reviewers have not only praised the C298, but purchased it. It's a really good amplifier.

With that said, it won't magically turn mediocre speakers into Revel PerformaBe F328Bes. Or even into TuneTots.

 

[pogo]

Of course, the C298 is a very good amp. I have the M33 Purifi myself. But many people don't seem to realize that such a high DF should also match the own taste and LSP design used. It can work amazing on potent LSP without any DSP correction.

 

[minus3dB]

Very welcomed addition with good features at a fairly affordable price, considering this is from a well established brand. Look, however, is... nothing to talk about, really.

Trying to understand why it is rated lower than the M33 (200W/8Ω, 400W/4Ω) using the same modules (assuming there's only one Purifi ET out there). Could be downpowered by the SMPS, or the ajsutable gain too low at maximum? I don't know.

Stereophile measured 1% THD+N power at 255 and 275 into 8 ohms for the M33 and M298 respectively and 460 and 510 into 4 ohms, respectively. The knees of the curves are also at higher output powers for the C298. Regardless of how NAD rated them the C298 measures more power out at 1%. Perhaps the ambient temp inside the M33 case is a good bit higher due to all of the digital processing that is not present in the C298. Otherwise their internal arrangement is similar as are the heat sinks attached to the bottom plates of the Purify modules.

 

[Norway]

am pulling the plug on ether two C298 or the M23 for my Altec VOTT A2 system active crossover via the MiniDSP SHD. I need the variable gain in order to lower the gain to match the ultra high efficiency drivers( 110 db+). The M23 has fixed 3 position where the C298 is continually from 8-30 db gain. Will the rather high price premium for the M23 be worth it? I’m not interested in the looks as the amps will be stoved away in the back of the enormous Altec cabinets.

 

[nothingman]

I very much doubt there are audible differences, but check these measurements:

SoundStageNetwork.com | SoundStage.com - NAD C 298 Stereo Amplifier Measurements

www.soundstagenetwork.com

Variable gain added a bit of THD and channel imabalance on the C298. I’m going to guess the switch to a three position switch on the M23 cleans up all of that. With your speakers I can’t imagine you wouldn’t be on the lowest setting in either case.

 

[Norway]

I very much doubt there are audible differences, but check these measurements:

SoundStageNetwork.com | SoundStage.com - NAD C 298 Stereo Amplifier Measurements

www.soundstagenetwork.com

Variable gain added a bit of THD and channel imabalance on the C298. I’m going to guess the switch to a three position switch on the M23 cleans up all of that. With your speakers I can’t imagine you wouldn’t be on the lowest setting in either case.

Yes! That’s bothering me… in my mind lowering gain should lower THD, not add!?

 

[nothingman]

Might just be the fact it adds a potentiometer to the chain.

I don’t see much use in the M23 over the C298 for most people, but considering your extremely (extremely!) sensitive speakers, in your case I’d want the absolute quietest, cleanest, best channel-matched amp possible from a given manufacturer. If it’s comfortably in your budget you will probably rest much easier knowing things are as good as they can be with the M23.

 

[ebslo]

Yes! That’s bothering me… in my mind lowering gain should lower THD, not add!?

Are you referring to this part?

In fixed mode, THD+N (A-weighted) at 10W into 8 ohms measured approximately 0.0004%, while variable mode yielded 0.0006%

If so, the difference is completely insignificant. Also, that's THD+N so could just be thermal noise from the pot resistance; that .0004% is -108dB at only 10W, which is very close to the noise floor of the device.

Also, you can use your SHD per-channel output level to correct any slight channel imbalance introduced by the gain pot if you have a volt meter to measure the speaker terminals while playing a test tone.

FWIW, I don't think the M23 is worth any premium over C298, especially since we haven't seen measurements of it yet (not that I'd expect any surprises).

 

[pogo]

I don’t see much use in the M23 over the C298 for most people

NAD announced the M33 last year as a suitable upgrade for the M33:
The NAD M23 is essentially the power section of the M33 in its own cabinet, and both amplifiers can be bridged to mono power amplifiers via a switch on the rear panel.

 

[peng]

Yes! That’s bothering me… in my mind lowering gain should lower THD, not add!?

True, except when you do it with a "variable" feature you have to add something and that "something" will add distortions and/or noise. The difference is only 0.0002% that is negligible in this case.

 

[pogo]

True, except when you do it with a "variable" feature you have to add something and that "something" will add distortions and/or noise. The difference is only 0.0002% that is negligible in this case.

But how does the whole thing look after a few years later, when e.g. a mechanical poti has aged?

 

[peng]

But how does the whole thing look after a few years later, when e.g. a mechanical poti has aged?

I highly doubt such a modern amp use a "mechanical pot" for gain control. The mechanical part, i.e. the knob, likely is just the man machine interface (MMI). I can't be wrong, but you can email NAD tech support if you are concern.

 

[ihvar]

Yesterday I bought C 298, so now I'm very happy with it's clear stage, all frequencies' transparency and mighty power. Stereo now sounds much wider. It's really good upgrade from CXR200.