NAD C 298 Power Amplifier With Purifi Eigentakt Amplification

[Aventador_SVJ]

I can compare the Arcam SA30 (which I sent back because if intermittent distortion issues) and the MiniDSP SHD/Nad C298 combination.

I've only used both of these with Dirac enabled on both systems, so all things being equal, they should be very similar. I would give the MiniDSP SHD/Nad C298 the slight edge but I think we're really on the path of diminishing returns here.

They are both that good (SA30 when there is no distortion obviously) that it is all down to the speakers.

I would be surprised if anybody had an issue with either of them from a pure sound quality perspective, as I suspect that both of them are going beyond your ear's capability when played with suitable quality music files.

I did notice that the MiniDSP SHD/Nad C298 produce virtually no hiss from the speakers with nothing playing, whereas the Arcam did produce some.

 

[lalit09]

I can compare the Arcam SA30 (which I sent back because if intermittent distortion issues) and the MiniDSP SHD/Nad C298 combination.

I've only used both of these with Dirac enabled on both systems, so all things being equal, they should be very similar. I would give the MiniDSP SHD/Nad C298 the slight edge but I think we're really on the path of diminishing returns here.

They are both that good (SA30 when there is no distortion obviously) that it is all down to the speakers.

I would be surprised if anybody had an issue with either of them from a pure sound quality perspective, as I suspect that both of them are going beyond your ear's capability when played with suitable quality music files.

I did notice that the MiniDSP SHD/Nad C298 produce virtually no hiss from the speakers with nothing playing, whereas the Arcam did produce some.

And tonally which 1 sound sweeter to you?

 

[Aventador_SVJ]

And tonally which 1 sound sweeter to you?

The same, both are set up with the Harman curve as the Dirac target, so this will determine whether one is sweeter (i.e. more treble emphasis if that is what you mean?).

If you viewed both outputs on REW, both frequency responses would look the same.

I would say that the MiniDSP SHD/Nad C298 gives slightly better clarity/transparency of sound reproduction (vs Arcam SA30) but you really are splitting hairs.

I am very happy with the MiniDSP SHD/Nad C298 combination from a sound quality perspective and will not replace them with anything else, until they break as there is no point. Increases in objective measurement beyond these products will not be realistically heard by human ears!

What we have here is a combination that measures well objectively and combines the key ingredient of Dirac to produce a neutral system.

 

[NYfan2]

If your looking for measurements this is the only I'm aware of at this time.

I'm very interested in the C298 and had been searching for a review with measurements so thanks for posting this. But when I check the measurements I have the feeling that these are not as good as the Purifi 1ET400A measured by Amir.
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/

These are the measurements of the NAD C298

1ET400A:
Power 257W in 4 ohm, 131W in 8ohm (the 260W and 516W in the C298 must be wrong)
Frequency response is ruler flat with -1dB at 50kHz
THD at 4 0hm 50mW 0,007%, 5W 0,001% Pmax 0,0002%
Crosstalk -121dB at 1Khz (-88db at 20Khz)

My knowledge of the measurements is not sufficient to compare the intermodulation and Signal to noise ratios.
So maybe somebody else can help out.

Whats is your opinion? Are the differences between the 1ET400A and the C298 negligible or are the differences to big?

Best regards, Marc

 

[Aventador_SVJ]

I'm very interested in the C298 and had been searching for a review with measurements so thanks for posting this. But when I check the measurements I have the feeling that these are not as good as the Purifi 1ET400A measured by Amir.
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/

These are the measurements of the NAD C298

View attachment 110176
1ET400A:
Power 257W in 4 ohm, 131W in 8ohm (the 260W and 516W in the C298 must be wrong)
Frequency response is ruler flat with -1dB at 50kHz
THD at 4 0hm 50mW 0,007%, 5W 0,001% Pmax 0,0002%
Crosstalk -121dB at 1Khz (-88db at 20Khz)

My knowledge of the measurements is not sufficient to compare the intermodulation and Signal to noise ratios.
So maybe somebody else can help out.

Whats is your opinion? Are the differences between the 1ET400A and the C298 negligible or are the differences to big?

Best regards, Marc

I believe the continuous output is for both channels, so for the 1ET400a, this would be 257 * 2 = 514w (@4ohms) and 131 * 2 = 262w (@8ohm), i.e. near on identical.

For SINAD calculation (@5w) of the Nad C298 = a factor of SNR and THD = 97dB (@5w), which is an effective 15.8 bits. The 1ET400a measured 104dB (@5w), which is an effective 17 bits, so it is higher.

Interesting, this is a very good result for the Nad vs most amplifiers but not against the 1ET400a Purifi reference design.

 

[lappy]

First person I have seen or heard of that run the C298 bridged

 

[MJR]

First person I have seen or heard of that run the C298 bridged

Quite the setup! Not sure which speakers were in use though....

 

[mSpot]

Quite the setup! Not sure which speakers were in use though....

It's in the YouTube title: Reference 3a Royal Master

 

[Kal Rubinson]

First person I have seen or heard of that run the C298 bridged

Could be. I'm doing that now.

 

[nothingman]

I'm very interested in the C298 and had been searching for a review with measurements so thanks for posting this. But when I check the measurements I have the feeling that these are not as good as the Purifi 1ET400A measured by Amir.
https://www.audiosciencereview.com/...easurements-of-purifi-1et400a-amplifier.7984/

I think the general gist is that nobody’s Purifi build is going to test as well as the evaluation unit. I’m pushing the boundaries of my understanding of amp design, but from what I read that wasn’t really a consumer grade product and was missing some components (certain filters?) that all builders are using.

You should be looking at the M33 measurements for a general indication of what NAD is doing with Purifi. In terms of manufacturer specs, NAD is rating the output of the C298 below the M33 by a hair (e.g. 200W @ .003%THD vs. 185W @ .005%THD), but that might just them playing it conservatively to give the M33 space as the halo product. We’ll have to see how much they hamstrung the C298, or maybe they’re fibbing and without all the other crap jammed into the chassis the C298 performs better? A man can dream.

 

[Aventador_SVJ]

I think the general gist is that nobody’s Purifi build is going to test as well as the evaluation unit. I’m pushing the boundaries of my understanding of amp design, but from what I read that wasn’t really a consumer grade product and was missing some components (certain filters?) that all builders are using.

You should be looking at the M33 measurements for a general indication of what NAD is doing with Purifi. In terms of manufacturer specs, NAD is rating the output of the C298 below the M33 by a hair (e.g. 200W @ .003%THD vs. 185W @ .005%THD), but that might just them playing it conservatively to give the M33 space as the halo product. We’ll have to see how much they hamstrung the C298, or maybe they’re fibbing and without all the other crap jammed into the chassis the C298 performs better? A man can dream.

I am not a betting man but I would see it as highly likely that the C298 would perform quite a bit better than that of the M33.

In fact, we have already shown above that the C298 has the following measurements:

• SINAD of 97dB (@5w)

The M33 has been measured with:

• SINAD of 93dB (@5w)

I would expect this as the C298 is a dedicated analogue Purifi power amplifier and the M33 is a digitised streamer with a Purifi amplifier. The digitalisation and power supply complexities could easily cause this loss in SINAD.

 

[lappy]

Could be. I'm doing that now.

Very interested to hear your impressions, e.g compared to running one in stereo.

 

[boXem]

... from what I read that wasn’t really a consumer grade product and was missing some components (certain filters?) that all builders are using.
...

The Purifi demonstrator has proper filtering

 

[muslhead]

Very interested to hear your impressions, e.g compared to running one in stereo.

As would I. Hopefully this isnt one of those teasers where we have to wait to read it in the magazine

 

[nothingman]

The Purifi demonstrator has proper filtering

You're right, I was a little mixed up (big surprise!). @Aventador_SVJ quoted 104db SINAD which was Amir's measurement with the 14db gain stage and input buffer engaged. What I incorrectly assumed was that he was quoting the SINAD measurement with the gain/buffer off -- that's the "not a consumer grade product" note I made in my head. That config measured at 108db SINAD but I don't think anyone is offering Purifi without the gain/buffer since that means it needs up to 11V from the source, so it's sort of irrelevant.

104db to whatever the C298 can produce is a fair comparison. Same goes for the other builders. Would be interesting to see if Nord, Apollon, VTV, the French outfit whose name escapes me, etc., are turning out products closer to the apparent 104db SINAD limit.

If @amirm ever does get his hands on a C298, him messing around with the variable gain to see if there is any benefit to certain settings would be great. Currently I'm using it at full strength "fixed" gain, but have half a mind to spend some time dialing it in just right.

 

[nothingman]

You're right, I was a little mixed up (big surprise!). @Aventador_SVJ quoted 104db SINAD which was Amir's measurement with the 14db gain stage and input buffer engaged. What I incorrectly assumed was that he was quoting the SINAD measurement with the gain/buffer off -- that's the "not a consumer grade product" note I made in my head. That config measured at 108db SINAD but I don't think anyone is offering Purifi without the gain/buffer since that means it needs up to 11V from the source, so it's sort of irrelevant.

104db to whatever the C298 can produce is a fair comparison. Same goes for the other builders. Would be interesting to see if Nord, Apollon, VTV, the French outfit whose name escapes me, etc., are turning out products closer to the apparent 104db SINAD limit.

If @amirm ever does get his hands on a C298, him messing around with the variable gain to see if there is any benefit to certain settings would be great. Currently I'm using it at full strength "fixed" gain, but have half a mind to spend some time dialing it in just right.

Edit to add: I would be happy to see these measurements (or simple mention that it makes no difference, etc.) from JA as well, @Kal Rubinson ! I'm not picky!

(It appears I made a whole second post to reply to myself. Apologies. I hang my head in shame.)

 

[Kal Rubinson]

Very interested to hear your impressions, e.g compared to running one in stereo.

Will do. Also have the Benchmark AHB2s and the PSAudio M1200s on hand!

 

[Aventador_SVJ]

If @amirm ever does get his hands on a C298, him messing around with the variable gain to see if there is any benefit to certain settings would be great. Currently I'm using it at full strength "fixed" gain, but have half a mind to spend some time dialing it in just right.

The 97dB SINAD measurement would have almost certainly been tested with the fixed gain setting. Using the variable gain has potential to improve the SINAD at it's optimal gain setting and bring it closer to the Purifi reference design.

Are you going to send your C298 to Amir for test?

 

[nothingman]

Are you going to send your C298 to Amir for test?

No. I just received my v1.08 firmware version yesterday after two months of having an amp that sporadically shuts off. I’m extremely thankful for anyone who does submit their equipment but I’m not in a position to be without my only amp in my only system for that long.

When it comes to the C298 I think we’re well covered, fwiw. It seems we can expect JA measurements and SoundStage also has a C298 in their pipeline.

 

[Aventador_SVJ]

No. I just received my v1.08 firmware version yesterday after two months of having an amp that sporadically shuts off.

Again, I am extremely thankful to this forum to alert me to the previous firmware issue, as I checked with the supplier before they dispatched and they updated the firmware to v1.08.