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NAD T778 Audio/Video Receiver (AVR) Review

amirm

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#1
This is a review and detailed measurements of the new NAD T778 Home Theater AVR. It was kindly purchased by a member new and send to me and costs US $3,000. It is only sold through dealers and looks like if you contact them, you may get some discount from that price.

The NAD looks gorgeous and highly differentiated from your typical AVR:

T 778 AV Surround Amplifier AVR Dolby Atmos 4K  Review.jpg


The large high resolution display is a joy to look at. There are even "ear racks" included so you can mount it in an equipment rack!

A very fancy remote with motion detection and back light is included which even has a USB port. So I imagine it may be programmable. More on this a bit later.

The back connections are ultra modern, dispensing with yesterday's video inputs and such:

T 778 AV Surround Amplifier AVR Dolby Atmos 4K  Back Panel Inputs HDMI Pre-out Review.jpg


Despite using (modified?) Hypex class D amplifier modules, the T778 is fairly heavy, weight similarly to other AVRs. The class D amplifiers do bring a major benefit in how cool the unit runs. Only the front warmed up during my testing and even then, barely so. This is a major advantage for those of us who use our AVRs as our main TV Sound and in closed cabinets no less.

After I powered the unit with Ethernet cable plugged in, it prompted me for a firmware update which I allowed to do. This took some 15 minutes. Upon restart: the fan on the back started to go on full power blowing like nobody's business! It was so powerful that I could feel the air being sucked in from the top vents. Alas, there were two problems with this:

1. On full blast the fan is super noisy. I am talking computer server class of noise.

2. There was no reason for fan to be on! The on-screen temperature monitoring did not inspire confidence either:

T 778 AV Surround Amplifier AVR Dolby Atmos 4K  Fan stuck firmware bug.jpg


A power cycle fixed the issue and the fan remained off for the rest of the testing.

The remote control has serious issues. For one, it doesn't have proper "key debounce" and sometimes repeats the button you have pressed. This is stuff that they teach first month new hire embedded programmer, not something from an established audio company who has been supplying remotes for decades.

The second issue is odd use of the four-way arrow and "enter" center button. You would think you would push the "enter" button to select the item but no, it seems to just do what the down arrow does! This is like making a stick-shift car but having the H shape being side-ways or something. Quite maddening until you get used to it.

There is a button called "RTN" next to the four-way arrows. You think that would just be the same as back but it is not. Hitting it while in menus started to select the sleep timer! There is a faint "sleep" label below it but how you select that I don't know.

Researching online there are horrendous reliability issues reported on multiple units suffering from same failures and such. If you buy this, you better use it heavily so that if anything is going to fail, it fails during warranty period.

AVR DAC Audio Measurements
Feeding HDMI input to an AVR and checking the performance of pre-out has become one of the key tests in my reviews as many AVRs pick very low voltages for this, and distort a lot post that. Let's see how the T778 did with volume set to 0 dB:

T 778 AV Surround Amplifier AVR Audio Measurements.png


This is not half-bad! SINAD which is a sum of distortion and noise is "reasonable" by AVR standards:

Best 4K AVR DAC Review 2020.png


And a huge step above T758 which brings in the rear. Alas, the indicator was complaining about clipping so I turned the volume down until the indicator went away which was at -8 dB on the volume display:

T 778 AV Surround Amplifier AVR -8 dB Audio Measurements.png


Usually this improves AVR performance but not here. We actually lose performance due to noise increasing and dragging SINAD down with it. Indeed, you do better to ignore the clipping indicator and drive as much as 4 volts output if you need it:

T 778 AV Surround Amplifier AVR THD+N vs Output Level Audio Measurements.png


I think the hypex amps don't suck down the power supply for the DAC like classical class D amps do or else there is independent power supply for the DAC section. Their efficiency means that even if they are driven while you use an external amp, they don't generate much heat so in that case it is "fine" that they are being driven. Of course being able to disconnect their inputs as we see in Denon/Marantz AVRs would be a superior solution.

DAC dynamic range is barely above CD's 16-bit requirement of 96 dB:

T 778 AV Surround Amplifier AVR Dynamic Range Audio Measurements.png


Note that in general you want this metric to be 10 dB higher than what you need or else it will degrade the content's signal to noise ratio. For CD then this translates into 106 dB which we miss by fair bit here.

Intermodulation versus signal shows the same high noise floor issue:

T 778 AV Surround Amplifier AVR IMD Audio Measurements.png


Notice that if you run at - 8dB (in green), you are almost as bad as a phone dongle (dashed orange) when it comes to noise! We could argue that distortion is hard to hear but noise is not if you have sensitive speakers.

Multitone test shows what we already know:

T 778 AV Surround Amplifier AVR Multitone Audio Measurements.png


Jitter shows lack of good hygiene when it comes to design but is typical of many AVRs and processors:

T 778 AV Surround Amplifier AVR Jitter Audio Measurements.png


I discovered a major issue here in that I could not get the Coax input to work. I tried it twice but it would not produce an output. I then switched to Toslink and it worked. This may be operator error but in the span of time I had, it would not work.

DAC filter could use more attenuation but is typical of such implementations:
T 778 AV Surround Amplifier AVR DAC Filter Audio Measurements.png


THD+N versus distortion showed quite high levels due to wide bandwidth of this test unlike the dashboard:

T 778 AV Surround Amplifier AVR THD+N vs Frequency Audio Measurements.png


So I made a spectrum analysis with the same bandwidth to see what is above audible band:
T 778 AV Surround Amplifier AVR 1 kHz FFT Audio Measurements.png


We see some DAC filtering issues around 48 kHz but also good bit of other noise spikes which are visible even with the input shut off (in red). A bit of attention in design and measurement could have identified the sources.

Linearity is good:

T 778 AV Surround Amplifier Linearity AVR Audio Measurements.png


AVR Amplifier Measurements
When testing AVRs amplifiers, I have a choice of using analog or digital input. The former is preferred since it eliminates the effect of the DAC. But then again if that input is digitized, then it can be worse. To test for that, I run a frequency response test:

T 778 AV Surround Amplifier AVR Analog In Frequency Response Audio Measurements.png


Sad to see such poor response truncated just a hair above 20 kHz which tells me the ADC is run at 44.1 kHz. I could not find any "pure" mode in my quick look so if there is one, it may remedy this but as is, performance using analog input is not acceptable:
T 778 AV Surround Amplifier AVR Analog In Audio Measurements.png


I switched to HDMI as the input and got improved response:
T 778 AV Surround Amplifier AVR HDMI In Audio Measurements.png


Still not much to write home about though:

Best AVR Amplifier Review 2020.png


And among all amplifiers tested so far:
best stereo amplifier review meaurements 2020.png


A high-end product producing average measurements is a bad combination.

Noise performance is an issue again:

T 778 AV Surround Amplifier AVR Analog In SNR Audio Measurements.png


Crosstalk is typical of AV products:

T 778 AV Surround Amplifier AVR Analog In Crosstlak Audio Measurements.png


Let's see how much power and distortion we have into 4 ohm load:

T 778 AV Surround Amplifier AVR HDMI In Power into 4 ohm Audio Measurements.png


I have run that at two different volume levels (0 and -8 dB). Both show very early rise in distortion starting at just 5 watts! The rise is so steep that it is hard to determine where that ends and real clipping occurs. I looked up the hypex UCD102 which I believe is what NAD uses here and it too shows the same issue:

1598642843969.png


So this is not the Ncore series we love from Hypex.

Good amount of power is available if we allow 1% THD+N though:

T 778 AV Surround Amplifier AVR HDMI In Max and Peak  Power into 4 ohm Audio Measurements.png


Testing for frequency dependency, we don't see much except for 20 kHz where it oddly performed better:
T 778 AV Surround Amplifier AVR HDMI In Power into 4 ohm vs frequency Audio Measurements.png


This again agrees with Hypex measurements above.

Switching to 8 ohm gives us the same issue with early distortion:

T 778 AV Surround Amplifier AVR HDMI In Power into 8 ohm Audio Measurements.png


Finally, let's see how power scales as we turn on amplifier channels one by one:

T 778 AV Surround Amplifier AVR Power per channel Audio Measurements.png


This is quite good and a testament to efficiency of class D amplification.

Conclusions
NAD gets a lot of things right with T778 with high efficiency and cool running amplifiers, large beautiful display, excellent cooling if needed and good DAC performance (for an AVR). Alas, there just isn't enough attention to detail with respect to noise, bugs, input digitization, etc. Given all of this, I give up and let you all decide if it fits for your purpose. I hope NAD takes this platform and this data and makes a clean up pass for next year to build a truly superior product. As it is, it doesn't get there.

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As always, questions, comments, recommendations, etc. are welcome.

I figured out a great way to save money with panthers. Instead of paying them to pose for every review, I can take their pictures once and photoshop them in for future reviews!!! No more having to buy expensive steaks and clothing for them. Alas, I have a signed contract with them and I need to hire a top-tier lawyer to help me get out of it. And as usual, I lack the funds for that so please donate using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

Dj7675

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#3
Had higher hopes for this unit with a newer model the the T758/T777 models. Good to see it is better for sure than the T758 but for $3k I would expect more. I had high hopes when they referenced hypex in their press release. Amps are better but still not much to write home about. NAD is making some beautiful looking gear.. m27, m22, m10, m33 Many of which also measures very well. Still haven’t nailed the performance yet on the AVR front yet. And yes, if you read the T758 thread or even much of the T778 threads it does appear reliability is an issue (on avsforum).
 

zimberto

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#4
Go NAD!

NAD appears to be having difficulty dealing with the demands of the 21st century AV customer. You have to wonder what the premium you're paying for their products is for if it isn't for attention to detail.

Meanwhile, elsewhere on the blogosphere the T778 gets superlative reviews. Thank heavens for ASR!
 
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Tks

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#5
Not understanding why this isn't a headless panther but alrighty.

I know we might ought to temper expectations from AVR's. I just wonder though.. why? Is it that hard to clear CD quality in the year 2020 from a $3,000 device? Surly it can't be that challenging from a company that boasts a pedigree in the same fashion NAD does.
 
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peng

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#6
One point I would like to make about the last chart:

The $3,000 NAD is rated 140 W and measured 141 W at 1% THD; and its 5 channel driven number looks impressive, at 80% of the two channel driven output.

Compared to the AVR-X3700H that is rated only 105 W, but measured 163 W. So by %, the NAD dropped to 80% 5 channel driven based on the lower starting point of 141 W whereas the $1,200 AVR-X3700H dropped to only 61% but from a higher starting point of 163 W. So even at 61%, its still a respectable 100 W.

80% vs 60% seems significant, but 116 W vs 100 W is not.

It looks to me this NAD still cannot beat a lower mid range Denon for use as either a standalone AVR or with an external power amp. Even if I must have Dirac (and I don't), I could get the AVR-X3700H and use the left over money to try and get some sort of separate add-on option to implement Dirac, assuming it is possible, I think minidsp might has something.



1598645027276.png
 

carlob

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#7
I could not find any "pure" mode in my quick look so if there is one, it may remedy this but as is, performance using analog input is not acceptable
I think there is an "analog bypass" setting in the listening modes menu
 
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#9
Hi Amir, thanks for the review. Also thanks to whichever kind member sent it in :)

If you still have the T778, would you mind testing for an issue which is plaguing NAD receiver owners? As known in the NAD receiver threads over on AVS, this is known as the "Rhye distortion" issue. The same problem has been documented on the T778, T777, and T758. Additionally I personally have experienced this same issue on both an Arcam AVR550 and a Denon X3600 in addition to my T778.

In short, when the T778 is being fed a stereo PCM stream and the high pass crossover is engaged (i.e front speakers set to "small"), it results in severe digital clipping when playing signals close to -0 dBFS. The song commonly used to test for this is"Feel your weight" (album version) by Rhye. At 2:50, there is extremely bad crackling, but the issue goes away when either the front speakers are set to "large", or if the same content is played through a multichannel stream. This is independent of sample rate. There are obviously differences in the signal processing pathway depending on whether the content is recognised as stereo or multichannel. With stereo streams, activation of the high pass crossover seems to push the signal hard into clipping territory.

If you'd like to hear what this sounds like to the end user, here are a couple of recordings of my speakers I took a while ago:

Soundcloud Link

On the version without distortion, this is being played via a Windows PC via HDMI with output set to 7.1. The version with distortion is playing the same content but with output set to stereo.

Would you be able to run a few quick tests with the signal generator output set to two channel so that the receiver recognises the incoming signal as 2.0 PCM, and with the speakers set to "small"?
 
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amirm

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Thread Starter #10
This is supposed to have Dirac at 96khz instead of 48khz. It would be interesting to test if you have time.
Unfortunately this is already packed and going to its owner in an hour.
 

Vasr

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#11
NAD appears to be having difficulty dealing with the demands of the 21st century AV customer.
Companies with attention to detail that got into the AVR business (e.g., Cambridge Audio) soon found out that the AVR business was messy and they could not maintain the standards they had set for themselves at low margins and discontinued those products than market sub-par equipment. NAD decided to put the Dirac/Hypex lipstick on and rely on brand marketing to push out sub-par stuff.

I think it is time to acknowledge contemporary Denon has surpassed NAD in quality and performance/value while NAD gets more and more into the "lifestyle" product business where engineering isn't the sole criterion.
 

3dbinCanada

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#13
Based on NAD's previous build quality, I wont be dropping any of my Yamahas anytime soon.
 

voodooless

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#14
This is supposed to have Dirac at 96khz instead of 48khz. It would be interesting to test if you have time.
Test what? What would you expect? The thing is already bad.. doubling sampling rate won’t make it any better.

In any case.. they even managed to botch the Hypex amps. By comparing pictures to the original Hypex OEM counterpart one can clearly see that they saved quite a bit money. Only look at the output coils... and that for such an expensive device. Real shame.
 

Tks

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#15
I would expect a 3000$ product to get the frequency response right. Seriously, that's bad.
Oh my goodness.. what the heck is that??? I didn't even notice. I would LOVE to hear the excuse for why this is so bad, or how it's justified. That's just terrible. Even the worst measuring devices almost always have FR that's basically flat.
 

Vasr

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#16
I could get the AVR-X3700H and use the left over money to try and get some sort of separate add-on option to implement Dirac, assuming it is possible, I think minidsp might has something.
Problem is you can't get digital outs (licensing issues with HDMI sources) and so the external Dirac will have to do a ADC first and then you can't get it back into the AVR that was doing the decoding of source as they don't have a multi-channel loop concept to have the original source selected but play the processed input.

If someone can pull off a $3000 retail ($2500 street) up to 16 channel pre/pro with latest codecs, digital inputs only including HDMI and with Dirac Live, it would be the hottest thing going.
 
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GXAlan

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#17
Unfortunately this is already packed and going to its owner in an hour.
No worries, it wouldn't change the overall impression since the performance is already pretty lousy given the price point.

Test what? What would you expect? The thing is already bad.. doubling sampling rate won’t make it any better.
I don't think anyone has confirmed that the T778 can do Dirac at 96kHz. It would be interesting to see if there is a test case where the T778 actually shines in the name of science. You are correct that the thing is already bad, and it would not have changed a purchase decision for anyone.

I have gear w/Amir that probably won't get tested until November or December, so if anything I'm biased to having him put out short reviews, but I cannot help but be curious to see if there are instances where products redeem themselves under specific conditions.
 

GD Fan

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#19
I was considering buying a T 778 but I think I’ll stick with my trusty Pioneer Elite SC-LX801.
Same here with respect to my Yamaha A1080, which was purchased mere months before Amir's review of the same. It underperforms most of the recent AVR's tested here, but cost me <$1000 and frankly the performance shortfall seems fairly minimal for the cost savings and reliable functionality.
 

starfly

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#20
I think we can just permanently write off NAD as a brand worth considering for AVRs, unless you absolutely need Dirac. For the performance, these things are extremely overpriced.

Better to just get a Denon or Yamaha. I currently own a Yamaha, but my next one will likely be a Denon.
 

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