NAD C 298 Power Amplifier With Purifi Eigentakt Amplification

[jshelbyj]

I just ordered a “scratch and dent” unit from Crutchfield. Besides the hum is there anything I should look out for on these units?

 

[mbsaph21]

I just ordered a “scratch and dent” unit from Crutchfield. Besides the hum is there anything I should look out for on these units?

I got a "scratch and dent" unit from Crutchfield a few weeks ago. Unfortunately, it made the hum from the unit that others have mentioned, AND the speaker outputs when I used variable gain were significantly imbalanced left vs right. I just returned it.

 

[nothingman]

I asked NAD support and they answered: "Since the C 298 is a completely different type of power amplifier technology than the C 268, a certain amount of noise cannot be avoided."

This is absolutely nonsense!

That quote from NAD support is shocking. I'm sure they're just trying to avoid another return, but saying this is expected behavior for the device (even if it's BS) should be devastating.

Yes, completely indefensible from NAD. I have to wonder if they truly understood you mean the sound is coming from the chassis itself. If they did, whoever answered like that doesn’t appreciate how wrong that is. See if you can talk to someone higher up at NAD. They know that noise isn’t supposed to happen.

 

[Aventador_SVJ]

It is completely unacceptable to have a high quality power amp such as the C298 buzz, hum or make any other unexpected sound.

Clearly, there are some faulty units and thankfully mine doesn't have any foibles and if it did, it would go straight back to the dealer.

An owner of the C298 should expect close to state of the art performance with zero foibles.

 

[Deleted member 24907]

After I had sent the first device back, because it always went off after an hour (that was fixed with a firmware update, some others here in the forum have also reported that), a humming noise could be heard from the device itself on the second one. It is the device itself that hums, even if all cables except the power cable are disconnected. So it's not from the speakers. I've tried it on multiple outlets in multiple rooms with multiple power cords. That's why I sent the second device back. The third device also had a humming noise, but a little less than the second. In a noiseless environment, it can be heard about 1 m away if you listen carefully. I had the C 268 before, which was completely silent. I asked NAD support and they answered: "Since the C 298 is a completely different type of power amplifier technology than the C 268, a certain amount of noise cannot be avoided." To be honest, I can't hear any difference to the C 268 in terms of sound quality. In retrospect, I would prefer the C 268, which doesn't cost much more than a third.

Here is a 30-second recording of the humming so you can hear it.

https://www.dropbox.com/s/uaz96g7athw5op1/recording2.caf?dl=0

The c268 uses hypex ucd102 units. Also used in the NAD C368 and their T778. I am thinking of adding the c298 to my c368 but am in doubt now. Anyone else heard-tested the c298 vs NAD's classic line integrated amps?

 

[mocenigo]

The c268 uses hypex ucd102 units. Also used in the NAD C368 and their T778. I am thinking of adding the c298 to my c368 but am in doubt now. Anyone else heard-tested the c298 vs NAD's classic line integrated amps?

I would say that when there is buzzing it is more likely that it comes from the PSU. Some SMPS buzz, whistle, squeak… I had some that did that. Those I am using now in my DIY stuff are totally silent, but they are not the cheapest ones on the market.

 

[JoetheLion]

I would say that when there is buzzing it is more likely that it comes from the PSU. Some SMPS buzz, whistle, squeak… I had some that did that. Those I am using now in my DIY stuff are totally silent, but they are not the cheapest ones on the market.

I'm pretty sure it's the PSU.

 

[mocenigo]

I'm pretty sure it's the PSU.

Some SMPS are very sensitive to mains quality. What’s the actual voltage from the power outlet ? and is there DC in the mains?

 

[JoetheLion]

Some SMPS are very sensitive to mains quality. What’s the actual voltage from the power outlet ? and is there DC in the mains?

In Germany we have a mains voltage of 230 V. But I didn't measure it. No DC. The PSUs of my other devices (Denon AVC-X3700H, Topping DX7pro, Topping A90, NAD C 268) are dead silent.

 

[jshelbyj]

I got a "scratch and dent" unit from Crutchfield a few weeks ago. Unfortunately, it made the hum from the unit that others have mentioned, AND the speaker outputs when I used variable gain were significantly imbalanced left vs right. I just returned it.

Wow that's ridiculous. I thought NAD had a great reputation, but this thread is looking rough.

 

[mocenigo]

In Germany we have a mains voltage of 230 V. But I didn't measure it. No DC. The PSUs of my other devices (Denon AVC-X3700H, Topping DX7pro, Topping A90, NAD C 268) are dead silent.

I am in Germany as well, and I have 236-237 at my home, I measured it ;-) and I have no DC on the mains (just a few mV), but the west of Munich is not necessarily representative of the whole federal

 

[Moto]

Sorry to bring this back to an old question on input levels, but would really appreciate some guidance.
I have an SMSL SU-9 balanced output (bypassing preamp mode) into the C298. From the line out on the C298 I go into an SVS SB-3000.
I assume(does anyone know differently?) that the signal level (5.3v rms according to Amir’s test) from the SU-9 into the C298 comes out it’s Line Out at the same level( no response yet from NAD yet on that). After inquiring re the SB-3000 SVS said keep the input below 3v rms (they said the volume control on the SB-3000 does not attenuate input levels but is just a variable gain control).
So that means I have to reduce the level going into the C298 from the SU-9. If I want to leave the SU-9 in bypass mode, then I will need to use the 64bit digital volume in roon before the signal gets to the dac.
If I use roon to reduce the signal -10db then the 5.3v should become 1.68v correct?
I haven’t gotten any response from NAD yet on whether 5.3v rms on the balanced inputs to the C298 is acceptable either( specs just say if I recall, 1.6v gives 185w into 8 ohms at rated distortion).
Any thoughts on the best way to configure these 3 components level wise?

 

[elgeeko]

I picked up my NAD c298 a few weeks ago. Having read this forum I was concerned about the issue where the amplifier powers off after 2 hours even if it is actively playing. Many here indicated this was associated with the v1.7 firmware, so I spoke with the dealer and he did some research as well. He concluded, contrary to what some here have said, that the issue was not specific to firmware, but appeared to be a hardware issue. I checked and the model he had was firmware v1.7, but I went ahead and gave it a shot. The issue hasn't come up in three weeks use.

And also... this thing freaking rocks. I'm driving Focal Electra 1028s with it and it sounds amazing. I think this is an incredible value for an amplifier.

Thanks everyone here for contributing information to help me make my decision, very happy with the outcome.

 

[sumpao]

Sorry to bring this back to an old question on input levels, but would really appreciate some guidance.
I have an SMSL SU-9 balanced output (bypassing preamp mode) into the C298. From the line out on the C298 I go into an SVS SB-3000.
I assume(does anyone know differently?) that the signal level (5.3v rms according to Amir’s test) from the SU-9 into the C298 comes out it’s Line Out at the same level( no response yet from NAD yet on that). After inquiring re the SB-3000 SVS said keep the input below 3v rms (they said the volume control on the SB-3000 does not attenuate input levels but is just a variable gain control).
So that means I have to reduce the level going into the C298 from the SU-9. If I want to leave the SU-9 in bypass mode, then I will need to use the 64bit digital volume in roon before the signal gets to the dac.
If I use roon to reduce the signal -10db then the 5.3v should become 1.68v correct?
I haven’t gotten any response from NAD yet on whether 5.3v rms on the balanced inputs to the C298 is acceptable either( specs just say if I recall, 1.6v gives 185w into 8 ohms at rated distortion).
Any thoughts on the best way to configure these 3 components level wise?

Why not use SU 9 as preamp and set roon as fix volume?
I heard that change sound level in program is the last thing you want to do

 

[sumpao]

I picked up my NAD c298 a few weeks ago. Having read this forum I was concerned about the issue where the amplifier powers off after 2 hours even if it is actively playing. Many here indicated this was associated with the v1.7 firmware, so I spoke with the dealer and he did some research as well. He concluded, contrary to what some here have said, that the issue was not specific to firmware, but appeared to be a hardware issue. I checked and the model he had was firmware v1.7, but I went ahead and gave it a shot. The issue hasn't come up in three weeks use.

And also... this thing freaking rocks. I'm driving Focal Electra 1028s with it and it sounds amazing. I think this is an incredible value for an amplifier.

Thanks everyone here for contributing information to help me make my decision, very happy with the outcome.

I plan to buy C298 in 2 weeks.
What checklist I need to check it? is below enough

1.Firmware V1.08 or above
2.Unit switch off after 15 minute with no signal
3 No hiss or hum when not play music even sensitive speaker

 

[elgeeko]

I plan to buy C298 in 2 weeks.
What checklist I need to check it? is below enough

1.Firmware V1.08 or above
2.Unit switch off after 15 minute with no signal
3 No hiss or hum when not play music even sensitive speaker

I'm not sure (1) is conclusive. I can confirm with my v1.7 amp I have not had premature shutoff, and my dealer said his research found folks with v1.8 firmware experiencing the issue (sorry I don't have a more detailed source). The safer check would be that you can play music straight for over 2 hours without the device shutting off, if you can do so practically.

 

[mocenigo]

I plan to buy C298 in 2 weeks.
What checklist I need to check it? is below enough

1.Firmware V1.08 or above
2.Unit switch off after 15 minute with no signal
3 No hiss or hum when not play music even sensitive speaker

The hiss/hum should not even come from the casse, IMNSHO.

 

[sumpao]

The hiss/hum should not even come from the casse, IMNSHO.

Yes it should come from speaker normally I check by not play anything but increase the volume to some high level to see is there any noise in Speaker.

Some cheap class d amp (SMSL DA8S) have this problem but it a bargain so i don't mind.

 

[jshelbyj]

I just got the amp. The faintest hiss comes from the power supply inside. Have to put the ear to it to hear it. Frustrating.

 

[mbsaph21]

I just got the amp. The faintest hiss comes from the power supply inside. Have to put the ear to it to hear it. Frustrating.

Ugh, so you had the same experience I did with the S&D unit from Crutchfield; sorry to hear. Wonder if yours has the same issue as mine did with the channel mismatch using the variable gain.