NAD C 298 Power Amplifier With Purifi Eigentakt Amplification

[MaxBuck]

It's back from being repaired. It is dead silent from listening position, if you get within a few inches/or press your ear to the unit there is still an oscillating/hum.

But it is much better than before. I can for sure live with it!.

Can anyone else who has one put their ear to it and see if there has this now small issue.

I hear absolutely no hum when mine is operational.

 

[eduardw]

It's back from being repaired. It is dead silent from listening position, if you get within a few inches/or press your ear to the unit there is still an oscillating/hum.

But it is much better than before. I can for sure live with it!.

Can anyone else who has one put their ear to it and see if there has this now small issue.

From very close my two nad also make a very slight hum. Speakers are dead silent.

 

[MichaelEA]

Reading here all the quality problems with the C298, I'm dissapointed that NAD haven't improved! Many years ago I bought one of their large T753 receivers. It ended up back for repairs a few times until they gave up and offered to replace it with a newer model T765 (plus a small upgrade charge). The T765 then slowly developed cooling fan problems - the bearings failed and the fans would rattle horrible. I've slowly been disconnecting the fans and it's down to (I think) 2 out 4, but I don't drive the amp hard so I'm crossing fingers it's ok.

 

[aslan7]

I love my Nord! Zero problems, great performance, great design. NAD fumbled here.

 

[steadilyfred]

Reading here all the quality problems with the C298...

Quality problems, MichaelEA? Don't be fooled by vocal minority effect.

 

[ba1473]

The C298 is a very good power amplifier and has high sound quality, backed up by very good objective measurements.

It is unlikely that anybody on audio science review will recommend a tube preamplifier as all this will do is

 

[Jedi77]

Which of these Amplifiers would be best matched with a pair of dali rubicon 2s, nad c298 or roksan blank? Want to hear clarity (all the instruments etc)and bass control(bass texture etc), have a nad c700 at the moment which is nice can't help but suspect the speakers will benefit from better amplification.
Cheers

 

[peng]

Which of these Amplifiers would be best matched with a pair of dali rubicon 2s, nad c298 or roksan blank? Want to hear clarity (all the instruments etc)and bass control(bass texture etc), have a nad c700 at the moment which is nice can't help but suspect the speakers will benefit from better amplification.
Cheers

I read the specs of all 3, assuming the Roksan Blank is actually the Roksan Blad, then I am sure either amp will sound the same. I do believe amps can sound different but in this case, as in many cases, when used well within their limits, such obviously well designed (based on specs, and available published information such as bench test results, technical papers/reviews etc.), will sound transparent.

Between the two, I would take the C298 because it has far better audio specs, including output voltage/current capabilities than the Roksan Blak that is just an integrated amp. So, unless you need an integrated amp, it is an easy choice. The NAD C700 should be fine for the Rubicon 2 as well but if you listen loud enough and/or sit far enough, it may not have enough juice for those 4 ohm nominal speakers that the manufacturer recommends 40-150 Watts. You can see that in the following from their website, it clearly would not be the best if you want to get the best of the 4 ohm nominal Rubicon 2 if you listen close to it's 107 dB (presumable at 1 meter) maximum SPL that it supposedly can deliver, but for near field, say 2 to 3 meters max and at 10-15 dB below reference level, the C700 would be fine and you won't hear a difference (may be a little, subtle difference due to peaks in some contents) even if you get a much more powerful amp.

C700 specs:

 

[Jedi77]

Would damping factor make a difference?, the c700 is only around 90 where as the c298 is at least 800, not sure about the roksan but having a large transformer it must be pretty good.

 

[SIY]

Would damping factor make a difference?, the c700 is only around 90 where as the c298 is at least 800, not sure about the roksan but having a large transformer it must be pretty good.

No significant difference. When you add in the terminal and wire resistances, that difference becomes negligible. If you model a closed or vented box alignment with a series resistance of 8/90 = 0.09R versus 8/800 = 0.01R, you'll see that, even if you manage to have zero resistance terminals and wire, the response is almost entirely unaffected.

 

[Jedi77]

It's an open design, so even the c700 should sound similar to the other 2 at reasonable volume, why such a big price difference? What does that pay for ultimately?
Cheers

 

[ahofer]

I’ve had my used c298 for a few years, and I use the auto-on feature exclusively. No issues. I don’t hear any hum even when I open up the cabinet it is hiding in (the amp, as well as the Raspberry-Pi I use as a roon endpoint and a variety of cabling are all hidden in those cabinets, with only the RME DAC in the open).

 

[peng]

It's an open design, so even the c700 should sound similar to the other 2 at reasonable volume, why such a big price difference? What does that pay for ultimately?
Cheers

Damping factor could make a difference if low enough. If it just say 90, without specifying the conditions when it was measured, 90 may not be high enough. For example, is 90 at 1 kHz, or 90 within 20-10,00 Hz? With just a single number, I would say the C298's 800 is a much surer bet that it is high enough for transparency whereas I may be skeptical about 90.

It depends on what your reasonable volume it, try an online calculator to get some idea, such as Crown audio's (they are many, so are more useful, I used my own).

Crown Audio - Professional Power Amplifiers | English (US)

www.crownaudio.com

For example, if your need calls for no more than 80 W into 4 ohms even during the highest peaks in the contents (movie sound tracks or music) you listen to, then yes the C700 should sound similar, likely same enough you can only tell a difference in sighted listening tests but not in blinded one.

The C298 costs a lot more because it high voltage and current capabilities, especially for sustained durations (i.e. not for 20 ms kind of short duration)
Below may be a quick and good read for you:

usafaq

faq.yamaha.com

For class AB amplifiers, the linear power supply typically include a high voltage/current capable power transformer and capacitors do costs a lot of money, versus the smaller ones. Class D amplifiers such the ones made by Purifi Eigentakt that has comparable voltage/current capabilities also cost a lot, take a look of the pricing info below, and that's just for modules, nothing else and is before tax, shipping, import duties etc.:

EVAL1 Stereo 1ET400A Evaluation Kit

purifi-audio.com

Using those modules, NAD can ensure their amps such as the C498 will be transparent, as evidenced in Amir's review (have you read it yet?):

NAD C298 Stereo Amplifier Review

This is a review and detailed measurements of NAD C298 stereo class D power amplifier based on Purifi Eigentakt modules. It is on kind loan from a member and costs US $2,399. The unit is quite heavy for a class D amplifier. The front is plain as most power amps are. I was not a fan of the...

www.audiosciencereview.com

 

[pogo]

Would damping factor make a difference?, the c700 is only around 90 where as the c298 is at least 800

It has made a difference for me.
The C298 purifi is similar to my M33 and the C700 UcD to my former C388.
My speakers have benefited from the extra control at any volume.

 

[Jedi77]

Yes i have read the review, thanks for taking the time to answer, probably go with the c298 then, probably use less power than an equivalent a/b amplifier too I assume?

 

[Jedi77]

Some also say the a/b amplifiers are more warm sweet sounding, is this just added distortion that becomes more apparent as volume increases?

 

[312elements]

Some also say the a/b amplifiers are more warm sweet sounding, is this just added distortion that becomes more apparent as volume increases?

That’s probably just a bad generalization. Very few class AB amps that produce this much power have such a low distortion profile. The other place it “can” make a difference is that a lot of AB amps can handle bursts much greater than their rated output while class D amps seem for the most part to clip past their rated output. This is only a problem when you’re using a class D amp that’s underpowered for your needs.

 

[SIY]

Damping factor could make a difference if low enough. If it just say 90, without specifying the conditions when it was measured, 90 may not be high enough.

Even with increase in source impedance in the top octave due to falling open loop gain, it's ridiculously better than what's needed, especially with conventional dynamic tweeters. We have one guy here who is obsessed with these numbers, has claimed major audibility, and has resisted any attempt to provide evidence (beyond links to the usual magazine uncontrolled "wow, it was amazing!" stuff).

 

[peng]

Even with increase in source impedance in the top octave due to falling open loop gain, it's ridiculously better than what's needed, especially with conventional dynamic tweeters. We have one guy here who is obsessed with these numbers, has claimed major audibility, and has resisted any attempt to provide evidence (beyond links to the usual magazine uncontrolled "wow, it was amazing!" stuff).

Haha I am aware of at least such "one guy" who like to link something as evidence.., but I don't think he really understands enough on the topic (by the way, we both know just because someone link technical paper/articles, does not mean that someone understand fully or at least enough about what's described in such articles). though there could be more than one lol.. In this one example, I remember others have even provided him with the formula to calculate what is needed, to no avail. That said, I do feel 90, while most likely is high enough, the concern is, could it be much lower, say less than 20 at some point within the 20-200 Hz range? So it would have been better if we know it is >=90 at any range between at least 20-200 Hz (100 Hz is just my arbitrary selected range).

 

[SIY]

could it be much lower, say less than 20 at some point within the 20-200 Hz range?

In a cosmic sense, yes. In a "do I ever see that in a real amplifier?" sense, no.

And even 20 is fine for 99+% of speakers.