NAD C 399 HybridDigital DAC Amplifier

[pogo]

All the controls are the same but in a slightly different arrangement.

This is not quite correct. You can also change the volume and player settings with the apps.

 

[Jone5]

@Jone5 very interesting that you think have heard the same thing. Although the thumps in the clip above seem fairly regular it definitely seems to be random. I have certainly had it happen every second or two for a few seconds then silence for a while, then again.

I have heard it on Line In inputs too, both from my desktop DAC and also from my Allo Boss2 player.

Yeah, so I also investigated a bit further, analog inputs seem to have it always present since they are always "active" but digital inputs need to have some signal in them to cause the thumbs. I only tried it with optical 1 , but I assume that's the case with the rest as well. The thumb sound is volume dependent, so its most easily detectable when you turn the volume to -30...-20 dB and past that. And its also present in my unit regardless of DL being active or not, enabling sub seems to trigger it.

I indeed noticed this when measuring freq response with my computer connected to the amp, but since then I have only used streaming input so I forgot to go back and investigate more. I'll probably inform the dealer about the issue and also open a ticket at NAD user support as well. I guess there is no hurry returning the amp yet, since this HAS to be fixed by NAD at some point and its easily demonstrated to the dealer that there is something seriously wrong. Its hard to believe that this could be hardware related since the streaming input is flawless, how on earth have they managed to get this into production.

I have to recommend anyone not buying the amp at the moment, at least with intention to use subs with it.

Anyone without the bluos/dirac module, is it behaving similarly when sub out is enabled? I'm too lazy to take mine out for testing

 

[pogo]

I guess there is no hurry returning the amp yet, since this HAS to be fixed by NAD at some point

In the meantime, you can connect a SW via the pre-outs. Hereby no SW should be enabled on the C399 menue and the crossover frequency and level is set directly on the SW as required. If no DL is used, the phase must also be set on the SW.

 

[unexperienced]

It's very interesting to me now. Does it make sense to buy a NAD M33 when there is now a NAD C399. Is the imaginary increase in sound quality, which will cost $2,500 on top, justified?

 

[pogo]

Here are some points that come to mind:
1)
ADC Chipset M33
AKM AK5578 (8 channel ADC with 4 channels used per stereo channel to improve SNR and distortion)
DAC Chipset M33
Dual ESS ES9028QM (each run in mono mode)
Which ADC the C399 uses, I couldn't read anywhere. According to the description it uses only one DAC, while the M33 uses two in a different mode.

2)
Different damping factors, which should make the C399 more interesting even for less potent LSP. As an example, consider a T+A A200 with switchable DF. According to STEREO:
Thus, from large-volume bass monsters to compact shelf speakers or speakers with low chassis mass, all speakers should now be able to exploit their full potential can be exhausted. Switching is done by push button.

3)
The M33 has the additional option of processing MC phono.

4)
The M33 has XLR inputs (analog/digital).

5)
The M33 has a large touch display.

6)
The M33 can bridge its Purifis and be expanded by an M23 that is also bridged.

I think the C399 is a very good offer. The units are designed for different audiences and the Master/Classic gap is definitely there.
I previously had the C388 with similar C399 DF and the M33 just has more grip at any volume, even at lower volumes, that my speakers need.

 

[pogo]

7) I have still forgotten:
The digital VU meter on the M33 is optimal to properly level the analog and digital input signals to get the maximum performance.

 

[unexperienced]

It's all good, but is it worth 2500 bucks? These are two C399...

 

[pogo]

Correct, and that's why it's best to always listen with your LSP for comparison. I would say that the C399 is the better choice for the majority of users. As already written before, it depends very much what LSP should be powered with it.

 

[unexperienced]

Does someone really need an ADC now ?

 

[pogo]

If you want DSP correction (Dirac Live, ...) of analog input signals like phono,... you need one. Furthermore, you can also distribute these signals digitally (BT HP, multi-room, ...).

 

[Jone5]

@Jone5 very interesting that you think have heard the same thing. Although the thumps in the clip above seem fairly regular it definitely seems to be random. I have certainly had it happen every second or two for a few seconds then silence for a while, then again.

I have heard it on Line In inputs too, both from my desktop DAC and also from my Allo Boss2 player.

I also contacted the user support and they verified that we are the only ones who has so far complained about it and they are investigating but havent yet managed to replicate the issue. I mentioned this discussion in my message to them.

You mentioned replacing the unit once already, but did you get a new bluos module as well? If no, could it actually be something related to the module itself?

I assume that in the vanilla C 399 the subout is generated from common dac and just analog LPF applied . If the extra dac needed for the subout is located in the bluos module and analog signal is passed back to the unit, then there is also possibility of the thumb being analog circuit related (crosstalk). But maybe there is spare unused dac channels/chip in the main unit already and the bluos module only adds dsp capabilities This is also supportes by the fact that I havent at least heard it in streaming and you mentioned that it was only present in your setup when dirac is enabled. For me its present regardless of dirac.

 

[Deleted member 22141]

I also contacted the user support and they verified that we are the only ones who has so far complained about it and they are investigating but havent yet managed to replicate the issue. I mentioned this discussion in my message to them.

You mentioned replacing the unit once already, but did you get a new bluos module as well? If no, could it actually be something related to the module itself?

I assume that in the vanilla C 399 the subout is generated from common dac and just analog LPF applied . If the extra dac needed for the subout is located in the bluos module and analog signal is passed back to the unit, then there is also possibility of the thumb being analog circuit related (crosstalk). But maybe there is spare unused dac channels/chip in the main unit already and the bluos module only adds dsp capabilities This is also supportes by the fact that I havent at least heard it in streaming and you mentioned that it was only present in your setup when dirac is enabled. For me its present regardless of dirac.

Yes it was a new BluOS module too.

As far as I know the unit I returned is being tested by the dealer and they have not been able to replicate the issue. I suspect that I do have a periodically noisy mains. I live in an apartment block and it certainly seems worse in the evening - perhaps a neighbour has a particularly nasty appliance. I have done everything I can think of to isolate it on my side.

My view really is that it may well be an unusual issue which requires other things to be in place to make the problem emerge. However it does seem to occur only when the DL module is engaged in 2.2 mode, and turning it off immediately makes the problem go away, so I don't think it can simply be written off as a problem with my power.

I do have a DDRC24, I have been testing with subs running via pre-out and at this point have not been able to replicate the issue, though I assume the DL doesn't get applied to the pre-out signal. Can anyone confirm that?

I will next try to run the sub out through the DDRC24 and see if a notch filter at 50Hz sounds okay. It may well be that they will simply write this off as a problem they cannot solve at this time.

I suppose then it will be up to me to decide whether to keep the unit or not. Is using EQ on the subs to take out 50Hz acceptable or not? Different subs would allow me to do the EQ in the sub itself (thinking of some Arendals) or just keep on using the DDRC24.

Or alternatively get myself a set of full range speakers (which I was thinking of doing anyway) and run DL in 2.0 mode, which seems fine. Heck, it's even possible that simply changing the subs might resolve the issue by itself.

There are a lot of variables involved.

In some ways this is all very interesting, but I do wish that it was happening to someone else.

 

[Alexx]

Il rivenditore mi ha risposto (ha trovato il problema).

Mi ha detto che Nad sta creando un aggiornamento del firmware.

Può essere scaricato e inserito su una chiavetta USB

Questo aggiornamento risolve il problema del subwoofer

Aggiornato anche il menu dove ci saranno altre opzioni utilizzabili al momento solo con il modulo Bluos...

Sinceramente mi sembra troppa elettronica per un amplificatore a 2 canali e ho fatto il reso.

Compro un Rotel 1572 lo pago 400 euro in meno, spero sia di buona qualità audio.
Presto.

 

[Jone5]

Yes it was a new BluOS module too.

As far as I know the unit I returned is being tested by the dealer and they have not been able to replicate the issue. I suspect that I do have a periodically noisy mains. I live in an apartment block and it certainly seems worse in the evening - perhaps a neighbour has a particularly nasty appliance. I have done everything I can think of to isolate it on my side.

My view really is that it may well be an unusual issue which requires other things to be in place to make the problem emerge. However it does seem to occur only when the DL module is engaged in 2.2 mode, and turning it off immediately makes the problem go away, so I don't think it can simply be written off as a problem with my power.

I do have a DDRC24, I have been testing with subs running via pre-out and at this point have not been able to replicate the issue, though I assume the DL doesn't get applied to the pre-out signal. Can anyone confirm that?

I will next try to run the sub out through the DDRC24 and see if a notch filter at 50Hz sounds okay. It may well be that they will simply write this off as a problem they cannot solve at this time.

I suppose then it will be up to me to decide whether to keep the unit or not. Is using EQ on the subs to take out 50Hz acceptable or not? Different subs would allow me to do the EQ in the sub itself (thinking of some Arendals) or just keep on using the DDRC24.

Or alternatively get myself a set of full range speakers (which I was thinking of doing anyway) and run DL in 2.0 mode, which seems fine. Heck, it's even possible that simply changing the subs might resolve the issue by itself.

There are a lot of variables involved.

In some ways this is all very interesting, but I do wish that it was happening to someone else.

In my case I dont believe in noisy mains, this is a separate house in a city with underground cable all the way to the house and all in house electrics are only 10 years old.

One thing that also came to my mind is some ground loop issue, what sub do you have (I dont at least recall the model from earlier posts)? Mine is Elac Sub 2090, but its not grounded to the grid since it only has a 2 pin IEC connector, which is bit suprising for this level of product. Anyway I did not have any issues when using NAD M10 with same setup.

Also, I mentioned this to the user support as well: I unplugged the USB mic dongle while powered off and then switched the amp on, for 10-20 seconds the thumbs were very frequent, multiple ones within a seconds. Almost like it was modulated by some cpu/chip activity. At this point the sub was already on (auto detect) and source was line input so I could hear it right from the start. It seems to be unrelated to the dongle but happens sometimes when you turn on the amp after some time power being off. Not every time, not even after completely switching off. I managed to replicate this once but usually after powering off the amp is left to streaming input and thus this is not observed.

 

[pogo]

Mi ha detto che Nad sta creando un aggiornamento del firmware.

It sounds good that NAD will provide a firmware update for this subwoofer issue.

 

[Eric2]

Il rivenditore mi ha risposto (ha trovato il problema).

Mi ha detto che Nad sta creando un aggiornamento del firmware.

Può essere scaricato e inserito su una chiavetta USB

Questo aggiornamento risolve il problema del subwoofer

Aggiornato anche il menu dove ci saranno altre opzioni utilizzabili al momento solo con il modulo Bluos...

Sinceramente mi sembra troppa elettronica per un amplificatore a 2 canali e ho fatto il reso.

Compro un Rotel 1572 lo pago 400 euro in meno, spero sia di buona qualità audio.
Presto.

Hi Alex. I am in the exact situation with you. Please compare the audio quality, and post here, if you get the 1572 MK2. I have a recent NAD C399 purchase, but I didn't find the audio to be much of my taste. Maybe it is the class D Hybrid amp, I don't know. EARC doesn't work, and the Toslink is not very reliable. I am thinking of returning, and getting the Rotel. Thank you.

 

[pogo]

I didn't find the audio to be much of my taste.

What don't you like about the sound and what speakers do you use on it?

 

[Alexx]

@Eric2:
Certamente.

Spero di arrivare la prossima settimana poi vi dirò le mie impressioni.

Mi è stato detto che Rotel è un po' più "rivelatore" senza aggiungere o sottrarre nulla.

Ho deciso per questo dispositivo perché ha tutte le cose di cui ho bisogno (mi piaceva anche il Musical Fidelity5 ma dovevo mettere un Dac esterno e non ha il controllo del tono).

Ti farò sapere al più presto.
Grazie.

 

[Deleted member 22141]

In my case I dont believe in noisy mains, this is a separate house in a city with underground cable all the way to the house and all in house electrics are only 10 years old.

One thing that also came to my mind is some ground loop issue, what sub do you have (I dont at least recall the model from earlier posts)? Mine is Elac Sub 2090, but its not grounded to the grid since it only has a 2 pin IEC connector, which is bit suprising for this level of product. Anyway I did not have any issues when using NAD M10 with same setup.

Also, I mentioned this to the user support as well: I unplugged the USB mic dongle while powered off and then switched the amp on, for 10-20 seconds the thumbs were very frequent, multiple ones within a seconds. Almost like it was modulated by some cpu/chip activity. At this point the sub was already on (auto detect) and source was line input so I could hear it right from the start. It seems to be unrelated to the dongle but happens sometimes when you turn on the amp after some time power being off. Not every time, not even after completely switching off. I managed to replicate this once but usually after powering off the amp is left to streaming input and thus this is not observed.

I have 2x REL T5i subs. I don't think it's a ground loop, I have grounded the subs as REL recommend. There is certainly no hum, and if it was a ground loop I don't see why it would happen only with DL turned on, and it's not been evident with any other amplifier I've used.

There is a single pop when the unit is turned on, but I think that's not terribly uncommon with Hypex amps? I'm sure someone will tell me if I'm wrong.

When streaming - just for interest's sake - do you hear a pop before each song on a playlist? I do.

When streaming a whole album it only pops before the start and not between tracks, but with a playlist it pops between each song.

 

[Eric2]

What don't you like about the sound and what speakers do you use on it?

I am waiting for calibration items (Sonarworks Sound ID), and acoufoams to arrive. I will listen after those, and maybe even be able to compare with the Rotel.