NAD T778 Audio/Video Receiver (AVR) Review

[MarkyM]

<snip> I first noticed distortion when listening to James Blake - Limit to Your Love, which isn't exactly a badly mastered track. The issue manifested as a subtle "pop" sound on one of the piano chords in the intro, which I could reliably A/B test by switching back and forth between applying the crossovers.<snip>

That intro section has a peak level of about -0.7dB:

I can hear some distortion in the vocal at times there (in the recording) but I do not hear any popping from the piano notes on my Denon with the Roon headroom management off. Maybe the Denon has a smidge more headroom than the NAD.

The heavy synth-bass sections in that track though are mastered LOUD. -0.1dB sustained and 0dB peak:

 

[MarkyM]

<snip>Out of interest, how much headroom adjustment is necessary to completely avoid the clipping issues? Your screenshot says -3dB, but is it possible to get away with less?

I could still hear the distortion at -1.5, at -2 it was mostly gone but I thought I could still hear it and it was completely gone at -3.

So Roon's advice of starting with -3 seems sound.

 

[GigaChunk]

I could still hear the distortion at -1.5, at -2 it was mostly gone but I thought I could still hear it and it was completely gone at -3.

So Roon's advice of starting with -3 seems sound.

Thanks for the feedback - I'm going to start a Roon trial and see how it behaves with the NAD.

If it takes a digital level reduction of 3dB to avoid clipping, surely tracks which are mastered with slightly less insane levels (- 1 to -2dB sustained) would still run into clipping issues with the crossovers applied? Logically I would've expected a 1dB reduction in level to have completely remove the distortion. The high pass crossover must be pushing the signal well into clipping range, rather than only a fraction of a dB over the maximum.

 

[carlob]

Thanks for the feedback - I'm going to start a Roon trial and see how it behaves with the NAD.

If it takes a digital level reduction of 3dB to avoid clipping, surely tracks which are mastered with slightly less insane levels (- 1 to -2dB sustained) would still run into clipping issues with the crossovers applied? Logically I would've expected a 1dB reduction in level to have completely remove the distortion. The high pass crossover must be pushing the signal well into clipping range, rather than only a fraction of a dB over the maximum.

If you have an oscilloscope feed the AVR (Dirac enabled) with a 0dB sine wave, you can use REW signal generator sweeping specifically the frequencies boosted by dirac, and check if it clips. If it clips reduce the signal level (in rew) until it doesn't clip anymore. The difference is your headroom ie how much you need to attenuate the signal to be sure it never clips. I'm starting to think that the gain structure in various Dirac implementations has not been really nailed.

Paging @QMuse since we were discussing a similar issue with the Minidsp SHD

.

 

[MarkyM]

Thanks for the feedback - I'm going to start a Roon trial and see how it behaves with the NAD.

If it takes a digital level reduction of 3dB to avoid clipping, surely tracks which are mastered with slightly less insane levels (- 1 to -2dB sustained) would still run into clipping issues with the crossovers applied? Logically I would've expected a 1dB reduction in level to have completely remove the distortion. The high pass crossover must be pushing the signal well into clipping range, rather than only a fraction of a dB over the maximum.

No problem.

Good point. I suspect this has to with overshoots being generated in the DSP crossovers etc. by the pushed mastering so not being linear, more headroom is needed to keep these overshoots from clipping.

I am not an expert on DSP filters but perhaps there is a member here that is.

I just know that for now I am keeping the Roon headroom management on at -3.

 

[carlob]

This is something that could be easily measured by Amir in his reviews of dirac enabled devices, the only downside is that you need to run dirac at least once before measuring it.

 

[peng]

That last bit rolls off your keyboard quite easily. But I have not been able to find a reasonably elegant way to do it. Unless one is happy to put an analog miniDSP Dirac unit in line with the AVRs analog out. A/D=>Dirac=>D/A then off to the amps. Hmm.

Right, I actually thought of that too after... so that's not a good alternative.

 

[Brian6751]

Right, I actually thought of that too after... so that's not a good alternative.

Yep, I have been down that road already as well and another plus of the T778 IMO

 

[Matyam]

Just stumbled upon this very interesting site and as a new 778 owner going through reviews it would be rude not to comment especially as it seems most of you haven't got a scooby how it actually sounds,cmon green eyed boys first rule of hifi go listen .

 

[JBH129]

Just stumbled upon this very interesting site and as a new 778 owner going through reviews it would be rude not to comment especially as it seems most of you haven't got a scooby how it actually sounds,cmon green eyed boys first rule of hifi go listen .

Are you implying that it sounds good, great or something else?

 

[iLoveCats]

Just stumbled upon this very interesting site and as a new 778 owner going through reviews it would be rude not to comment especially as it seems most of you haven't got a scooby how it actually sounds,cmon green eyed boys first rule of hifi go listen .

Prepare to be crushed by measurements but you will emerge as a better consumer and probably an advocate for independent testing such as this.

You are now in AV gear hell: Stage 1- Denial

 

[amirm]

Well if they've reversed the flow ,by mistake positioning the fan backwards then the filter does nothing.
Logic would be to suck air from the back after the filter and put it out from the top , hence help the natural air circulation.

That wouldn't work in a rack though. Seeing how it has rack ears, maybe they did reverse the fan.

 

[Dj7675]

Just stumbled upon this very interesting site and as a new 778 owner going through reviews it would be rude not to comment especially as it seems most of you haven't got a scooby how it actually sounds,cmon green eyed boys first rule of hifi go listen .

Welcome. This is a great site full great nfo. Generally Amir’s reviews will focus on measurements, specs on electronics. This will give you a very good idea on how well the product is engineered/implemented. If the product is well engineered which will show up on these variety of tests, you an infer the quality of sound. If it measures well, it will sound good. He pretty much reviews a piece of electronics or speaker per day. He can speak for himself but I don’t think there is a lot to learn about how solid state electronics “sound“ unlike something like speakers. Also, there are a bunch of reviewers that offer subjective opinions (without any measurements), so those are usually readily available elsewhere. I would be very skeptical of the value they provide. For example, read subjective reviews on the NAD T758V3... after reading those you would think it was the best engineered product out there... then look at the review/bench test here and you will see that it had quite a few issues and tested poorly. You alone can establish how much importance you attribute to bench tests, audibility of what is good enough, and the value of subjective reviews. But after being here a bit, I can tell you I don’t attribute any value to a subjective review of sound quality. I do seek out other reviews for things like how to use the product, features, etc but will rely quite heavily the bench tests to determine if a product is well build and will sound good.

 

[Matyam]

Are you implying that it sounds good, great or something else?

Well I don't feel qualified to say as everyone seems to know better than the owners who have already posted.

 

[Matyam]

Prepare to be crushed by measurements but you will emerge as a better consumer and probably an advocate for independent testing such as this.

You are now in AV gear hell: Stage 1- Denial

I'm all for a bit of science but we are human after all and I'm guessing a lot of you haven't got 21 year old ears anymore and dirac will help fill in the blanks.

 

[iLoveCats]

I think people believe Dirac improves SINAD. To me, Dirac gets you the most out of what you have but it doesn't increase what you started with.

 

[Vasr]

I think people believe Dirac improves SINAD. To me, Dirac gets you the most out of what you have but it doesn't increase what you started with.

Most people don't know what SINAD is or what it relates to in hearing.

But you are correct that people do confuse "Dirac makes it sound better" with "it makes your equipment/content better". Nevertheless, that is more audibly persuasive than when a measurement like SINAD doesn't translate easily into what they are hearing (or not hearing) even without Dirac and even when SINAD is meh. NAD is obviously counting on it.

 

[Urgo]

It is clear, if it sounds so good it is that Dirac must do his job very well, because the performance of the avr is bad, and the latter is what has been put into evidence.

 

[Dmitri]

It is clear, if it sounds so good it is that Dirac must do his job very well, because the performance of the avr is bad, and the latter is what has been put into evidence.

It’s disingenuous to design a receiver with poor measurements and rely on the room equalization system to correct those deficiencies. Not everyone will use Dirac either. In a well treated room they may prefer less manipulation of the signal in a stereo source. At the very least a receiver should be expected to provide a flat signal response, which the NAD does not.

 

[Vasr]

Not everyone will use Dirac either. In a well treated room they may prefer less manipulation of the signal in a stereo source.

You are absolutely right but those people are not the primary target market for NAD or for this unit (at least not any more). Those are very small niche markets.