NAD C 298 Power Amplifier With Purifi Eigentakt Amplification

[nothingman]

A small item, but thought I’d share the official trigger input specs that I just got from NAD. I had bugged them about this months ago and didn’t get an answer, then remembered to follow up last week and ask again.

Trigger input spec is 2-18V, 0.2mA-2mA. A nice wide range if you’re using something unconventional that doesn’t run on 12V. I told them they should share this spec, like other companies like Parasound and Benchmark do. Anywho, that’s all.

 

[RGibran]

I have my NAD C298 for sale if anyone interested check out the For Sale forum. Thanks,

 

[nn_in]

Is pairing NAD 268 or NAD298 with Denon DNP 800NE ok
OR is it best to pair with NAD 658 or 368 ?

Thank You.

 

[Shoaibexpert]

Got a C298 yesterday and have observed the very low transformer type buzz from the amp box/ chasis as well as very very low hissing/buzzing from the speakers - both noises when I put my ears besides the tweeter/amp and nothing is playing. Is this something I should be concerned with and does this affect the clean performance/SNR of the amp?

How to I check the SW version of my unit?

People who had these issues...did you guys get replacements easily?

Thanks

 

[JoetheLion]

Got a C298 yesterday and have observed the very low transformer type buzz from the amp box/ chasis

Several owners (myself included) have had this experience. NAD support says this is normal for this model, because of "the type of power amplifier technology". In my case, replacement did not bring any improvement.

 

[jmillar]

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.

The M33 has all the SOTA bells and whistles to provide halo effect and plenty of ohs! and ahs from prospective buyers.

The C298 is a good, basic, purposeful amp. No sense in hobbling it. It targets a totally different customer. If NAD were to needlessly restrain the C298 there are Nords and Marches and VTVs and Apollons at slightly lower price points that basically attain close to full current Eigentakt performance

 

[mocenigo]

Actually I didn't realize this particular model was out. This may indeed be the way to go--thanks. rt

But then, why do not buy the Eval 1 kit, a Hypex SMPS, and a Ghent case with the proper cable harnesses? I think it can be a no-soldering affaire, to be completed in 10 minutes or so...

 

[Shoaibexpert]

The M33 has all the SOTA bells and whistles to provide halo effect and plenty of ohs! and ahs from prospective buyers.

The C298 is a good, basic, purposeful amp. No sense in hobbling it. It targets a totally different customer. If NAD were to needlessly restrain the C298 there are Nords and Marches and VTVs and Apollons at slightly lower price points that basically attain close to full current Eigentakt performance

I can say that in my setup, the C298 makes my rather low sensitive R7s with ease. It's super clean and from what I have heard on the grapevine, has the low end closer to the AB performance. Have a pending replacement of the C298 though due to the buzz from within the C298 itself when I put my ears to the unit....I am sure, that would affect the SNR somehow!

 

[Matias]

But then, why do not buy the Eval 1 kit, a Hypex SMPS, and a Ghent case with the proper cable harnesses? I think it can be a no-soldering affaire, to be completed in 10 minutes or so...

No need even to assemble it: VTV sells the EVAL-1 board and Purifi modules finished for 1,040 usd.
https://vtvamplifier.com/product/vtv-amplifier-purifi-eigentakt-stereo-amplifier-based-on-eval-1/

 

[mocenigo]

No need even to assemble it: VTV sells the EVAL-1 board and Purifi modules finished for 1,040 usd.
https://vtvamplifier.com/product/vtv-amplifier-purifi-eigentakt-stereo-amplifier-based-on-eval-1/

Yep, but in the US. However, 1040 USD + VAT + customs is stil about 1060 EUR (to Germany, which I picked since I live there ), to which one should add shipping costs (and VAT and customs on them as well). Purchasing the EVAL 1, Hypex SMPS, and Ghent Case with harnesses will cost around 1360 EUR including all separate shipping costs (and VAT+ customs). It is difficult to imagine how the DIY option in this case could cost less than the VTV - clearly bulk purchases and delivery directly from Malaysia or Thailand to the US without going to Denmark first gives VTV an advantage. Also, one in the EU can always purchase the VTV amp and then service it themselves, treating it like a DIY product.

 

[MaxBuck]

I can say that in my setup, the C298 makes my rather low sensitive R7s with ease. It's super clean and from what I have heard on the grapevine, has the low end closer to the AB performance. Have a pending replacement of the C298 though due to the buzz from within the C298 itself when I put my ears to the unit....I am sure, that would affect the SNR somehow!

I'm thinking the buzz isn't directly related to the C298. Mine is dead quiet feeding my R11s. Check your ground situation.

 

[matteroll]

Hey guys, long time lurker and reader of ASR here. I just created an account to report that my new C298 that just arrived my doorstep a few hours earlier has hissing coming from my tweeters of my speakers that is only noticeable when I'm really near the speaker and nothing is playing. Such a shame, this is my first power amp and it does sound really really good though. I'm using them to drive a pair of Revel M106's. DAC that I use was the DX7 Pro. Using my Marantz SR6014 as the preamp didn't yield any changes with the hiss. Changing the DAC/RCA cable/power extension doesn't remove the hiss. I didn't notice it when I first set it up but after grabbing some dinner and coming back excited to listen to it, I noticed it was there. I also broke my Topping because in a stroke of stupidity, I accidentally plugged the white RCA cable into the line out of the NAD and now I'm wondering if I also managed to damage the NAD somehow but it seems like it's playing fine with my Dragonfly Red. RIP DX7 Pro. I don't have any hum from the unit though so at least there's that. Now I'm wondering if I should spin the wheel and hope an RMA might fix the hissing issue though judging from the messages here, it might not be worth it. FWIW, I've never had this hissing issue with my NAD C316BEE V2 and Marantz SR6014.

EDIT: I just put my ear right next to the case of the NAD and there is some humming coming from the case. It's not loud enough to effect the listening experience. I'm more concerned about the hissing coming from my tweeters.

 

[Shoaibexpert]

Hey guys, long time lurker and reader of ASR here. I just created an account to report that my new C298 that just arrived my doorstep a few hours earlier has hissing coming from my tweeters of my speakers that is only noticeable when I'm really near the speaker. Such a shame, it does sound really really good though. I'm using them to drive a pair of Revel M106's. DAC that I use was the DX7 Pro. Using my Marantz SR6014 as the preamp didn't yield any changes with the hiss. Changing the DAC/RCA cable/power extension doesn't remove the hiss. I didn't notice it when I first set it up but after grabbing some dinner and coming back excited to listen to it, I noticed it was there. I also broke my Topping because in a stroke of stupidity, I accidentally plugged the white RCA cable into the line out of the NAD and now I'm wondering if I also managed to damage the NAD somehow but it seems like it's playing fine with my Dragonfly Red. RIP DX7 Pro. I don't have any hum from the unit though so at least there's that. Now I'm wondering if I should spin the wheel and hope an RMA might fix the hissing issue though judging from the messages here, it might not be worth it. FWIW, I've never had this hissing issue with my NAD C316BEE V2 and Marantz SR6014.

I have hissing and a very very faint buzzing sound from my C298. As you said, it sounds great though...

 

[matteroll]

I have hissing and a very very faint buzzing sound from my C298. As you said, it sounds great though...

Yeah it sounds great, can't deny that. Using variable gain and lowering the gain did help eliminate the hissing that was coming out of my tweeters but I kind of felt like it didn't sound as good as fixed gain even at higher volumes but maybe it was just placebo. Was going to replace the Marantz with a Denon X3700H but now that my DX7 Pro is dead (it's not producing any sound but still turns on), I'll have to sadly delay that purchase. Kind of sad, I really liked the sound coming from the Topping DX7 Pro + NAD C298. Not too keen of the sound coming from the Marantz (pure direct) + NAD combo, it's like I can hear the DAC filter roll-off hindering the treble performance, it's not as airy......I'm just not engaged in the music as much with this combo. Idk how to really describe it. Maybe I'll change my mind after re-running audyssey.

Anyone know if it's safe to use the NAD with a passive speaker switch selector? I'm kind of afraid it might short it somehow and just destroy my whole system. It did say in the manual to not use a speaker switch. Been using this speaker switch I have with my Marantz SR6014 with no issues.

EDIT: I just plugged my speakers into the Marantz and I just realized it is also making my tweeters hiss, although not as loud as the NAD. I think I may just have grounding issues even though I'm using a grounded outlet. How should I go about fixing the grounding issue?

 

[Head_Unit]

They appear to be running the two channels in opposite polarity (an NAD favourite since the 2200) to reduce strain on the PSU. As we have seen with Amir's testing for channel separation, things can go awry due to that.

How does it reduce the strain? My brain is not quite grabbing that idea. And what happens with the separation? Separation or also S/N? As I recall when you bridge something the noise level increases.

 

[Doodski]

How does it reduce the strain? My brain is not quite grabbing that idea. And what happens with the separation? Separation or also S/N? As I recall when you bridge something the noise level increases.

In a normal amplifier the speaker output positives are both a positive output and both channels draw from the same power rail of the power supply at the same time.

In a opposite polarity configuration they each draw from the negative and positive rails at the same time where one is outputting the positive power and the other outputting the negative power at the speaker terminals. In a opposite polarity configuration by having the two speaker outputs out of phase they put everything back in phase. So that means one of the speaker positives is actually the ground and if you connect the 2 grounds together it will blow the amp because the positive speaker output is being connected to the ground of the other speaker channel. If one looks at the back speaker terminals they will see some indicate the grounds are not to be connected together and some even use blue colored plastic for the ground terminals to show they are different rather than using black plastic for the terminal. Using the out of phase configuration is very common in car audio and people fry their amps all the time because they twist the grounds together and short out the amplifier. The purpose of using a out of phase speaker output is to allow the power supply to provide more power output. By not having both channels drawing from the same power supply rail the power supply regulation is tighter and more power is available via more voltage available from the power supply.

 

[Matias]

C 399 announced.

NAD C 399 HybridDigital DAC Amplifier

Streaming integrated amplifier with ESS ES9028Q2M and Hypex nCore NC252MP. https://nadelectronics.com/nad-launches-new-c-399-hybriddigital-dac-amplifier/ Flagship Classic Series integrated amplifier featuring Masters Series grade HybridDigital nCore amplification, ESS Sabre DAC and MDC2...

www.audiosciencereview.com

 

[jmillar]

I just noted that the power supplies in the M33 and the C298 are very similar, if not identical:
View attachment 87278
C298 top, M33 bottom.

Makes sense. Same amp modules.

 

[jmillar]

Wait what? Your C298 has some sort of auto off without trigger cable? That's not even supposed to be a feature according to NAD.
Mine manages to do auto on with the unbalanced input. I have had it since the release and I still do not understand why they didn't implement the most important part of auto on/off, namely auto off. It is mandated by EU law I think. Auto on is just for convenience.

Looks like the logic controller hasn't been debugged throughly. This will surely be set right in the next iteration of firmware.

(In any case IMHO nothing beats a good old fashioned mechanical switch, toggle type if possible)

 

[JRS]

Good to see more Purify based options. How did they do bridgeable version? As far as I know, Purifi shouldn’t be run in bridge mode?

This manufacturer (VTV amps) intrigues me as there are many options for the input board, some of which reduce the price of Eigentakt module based amp to a point hard to beat (1000 USD), even when rolling your own with chassis. Am wondering if anyone has experience--online chatter has been very positive about the customer service and upgrade options. He also has various flavors of Class D available (Hypex, PASCAL, in addition to Purifi) in the same chassis family. AS if this wasn't enough flexibility, there are also 3,4,5,6 and more single unit offerings. I'm very tempted to go with the 500 x 3 for bass, the Purifi 200 x 2 for midbass and 125 x 2 (Hypex) for tweeters.

In summary, this is quite an interesting ensemble of amps at very fair prices. Add to this a 30day free trial period and only a week before shipping.

It's obviously riskier than buying from a well established company like NAD, but highly tempting at these prices. Anyone here have experience with this firm? It looks very legit, but longevity is always a ??

EDIT: Hadn't read the entire thread, see that this has been mentioned. Anyhow still curious if anyone has experience with VTV.