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Review and Measurements of NAD 7050 Streaming Amp

amirm

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#1
This is a review and detailed measurements of the NAD 7050 integrated DAC, amplifier and streaming playback. It is on kind loan from a member. It appears the product was announced in 2014 and since discontinued as I can't find it on sale anywhere. The cost was USD $999 from what I can gather.

The unit can be used both horizontally and vertically. A rotational sensor changes the display orientation conveniently. Here is its upright position which I consider better for sound since the electrons can naturally free fall into the speaker terminals:

NAD 7050 Networked Amplifier USB DAC Review.jpg

The outside has what appears to be some sort of rubber glued to it. It is soft to touch but picks up dirt very easily and is impossible to clean due to sticky nature of it.

The large knobs imply great feel which they don't have. They wobble as you rotate them. The larger knob is the volume control which had an odd delay in updating the display as you rotated it. Overall, a good effort has been made to create an unusual design but didn't quite get there in feel and functionality.

The back panel shows off the inputs and speaker output:

NAD 7050 Networked Amplifier USB DAC Back Panel Review.jpg

For my testing, I focused on USB input as I suspect that is the most common interface for consumers. Alas, the USB interface is class one so only goes up to 96 kHz. To get the advertised 192 kHz you need to use the other inputs. I downloaded the NAD drivers which nicely gave me ASIO interface for testing.

There is an app to control it and I downloaded it from Android play store. It is a simple remote control but allowed me to change the audio-out to be full range so I could use it for DAC testing. Otherwise it is filtered for subwoofer out. Despite its simplicity the app crashed on me once.

There is no analog input so I had do all of my testing with USB digital interface.

As expected from a brand name company, the NAD 7050 comes with full set of safety and emissions regulatory certifications.

The amplification in NAD 7050 apparently is a scaled down version of what is in NAD M2. Here is what NAD says about it:

1551900288629.png


My read is that it is a power DAC similar to Lyngdorf TDAI-3400 I reviewed recently. Measurements will confirm if so.

DAC Measurements
As usual, where possible I try to isolate the performance of the subsystems, in this case the DAC. Here is our dashboard view using USB input/Line Out. I hope you are sitting down if you owan the 7050 and use it as a DAC:

NAD 7050 Networked Amplifier USB DAC Measurements.png


What the heck is going on here? Even at 0 dB the unit doesn't get to 2 volts yet it severely clips resulting all of those harmonic distortions. Dialing down to -2 dBFS improved performance but just to 83 dB. By then the output voltage was even lower, making it not so useful as a DAC anyway. My thinking is that this is a split off output from the power amplifier as opposed to a traditional DAC output. I guess for the assumed subwoofer duty it may be OK.

Naturally, with the SINAD as measured falls at the bottom of the graph of DACs tested:
NAD 7050 Networked Amplifier USB DAC SINAD Measurements.png


After the first bad impression, the 7050 almost nails the rest of the measurements such as linearity:

NAD 7050 Networked Amplifier USB DAC Linearity Measurements.png


And jitter:
NAD 7050 Networked Amplifier USB DAC jitter Measurements.png


Since USB doesn't support 192 kHz, I had to run a different multi-tone test at 44.1 kHz:

NAD 7050 Networked Amplifier USB DAC Multitone Measurements.png


Amplifier Measurements
As usual, the dashboard view is at 5 watts of power into 4 ohm:

NAD 7050 Networked Amplifier USB Power Amplifier Measurements.png


As power amplifier measurements go, this is not too bad actually and almost matches the vaguely stated 90 dB spec by NAD.

Power versus distortion+noise is also pretty decent:
NAD 7050 Networked Amplifier USB Power Amplifier Into 4 Ohm Measurements.png


The downward part of the curve is always dominate by noise as the output level is low. Here, that part of the curve is flatter than I am used to seeing which is good as far as level of noise. Likewise, distortion is kept under complete control until onset of sudden and massive clipping at 54 watts. This too is good (sans the clipping). Stated rating is 50 watts at 4 ohm and we beating that a bit which is nice. Then again, 50 watts is not that much power in grand scheme of things.

THD+N versus frequency using my default 45 kHz bandwidth shows pretty awful results (in red):

NAD 7050 Networked Amplifier USB Power Amplifier Distortion vs Frequency Measurements.png


Suspecting ultrasonic noise at play, I re-ran the test with 22.4 kHz (as with the dashboard) in blue which shows that effect quite conclusively. One channel is worse than the other though which is strange. Note that the drop above a few Khz is due to bandwidth of the test being too low to capture all the harmonics (and hence the reason I like to use 45 kHz bandwidth normally).

Broadband FFT shows of 1 kHz tone shows us what is going on:
NAD 7050 Networked Amplifier USB DAC FFT Noise Spectrum Measurements.png


This is without my Audio Precision high-frequency filter (AUX-0040). All the other tests used that filter.

On the extreme left we see our 1 kHz tone as a spike rising to 0 dB or so. We have a single and large spike at 850 kHz. That seems to indicate to me that 850 kHz may be the switching frequency. Given its high frequency, the power DAC is running likely with as a single bit converter which would create a lot of quantization noise. Noise shaping is used to push that above 30 kHz or so with the peak at about 80 kHz. This is the drawback of power DACs as we have seen in the Lyngdorf and SONOS Amp versus class D amplification which doesn't need noise shaping. You can see the effect of high frequency noise in the thickened sine wave of the same signal in the inset.

Conclusions
Usually, by the time I get to the end of testing, I have a good idea of if I like or don't like a device. Here, I am not quite sure. Let's agree that no one should be using the NAD 7050 as a DAC with external amplification as NAD suggests in the manual. You will be listening to a heap of distortion products with anemic output to boot.

The amplifier seems to have some good tricks under its sleeves with lower than normal noise and very controlled distortion until a very hard limit. My issue there is the 50 watt rating for a $1000 device. That is just not enough power for a product in this category.

Seeing how the NAD 7050 is discontinued, maybe it doesn't need my recommendation or lack thereof anyway. So I will leave it at that. :)

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

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miero

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#3
For some reason the USB input has a lower distortion when a sample rate is 96kHz:
NAD D 7050 analog out, vol -0dB, USB in -0dB, 96000fs, 1kHz.png
 

miero

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#4
"NAD DirectDigital, using CSR’s patented DDFA technology."

EDIT: A picture of internals on audio.com.pl[5] reveals there is CSRA6601 used.
- https://www.qualcomm.com/products/csra6601
CSRA6601: 8 channel digital modulator.
I2S digital audio inputs, mixing and multiplexing, parametric EQ, limiting and compression volume control, integrated protection, SPI digital control.
I guess there is only one (EDIT: this is false) DDFA chipset with a public specification - CSRA6600/6601[1][2]:
Outstanding sound quality Typical power levels from 25W to 100W into 8Ω
THD+N 0.004% ... -88dB
Dynamic range 120dB
Residual output noise <60μV rms
High efficiency Class D architecture
Compatible with digital sources
On chip DSP resources
Platform solutions with CSR wireless and DSP products
[1] https://www.qualcomm.com/products/csra6600
[2] http://static6.arrow.com/aropdfconv...7b4534d428894506bf4/389778066767082243370.pdf

Another DDFA chipset is CSRA6620[3], notice "-1dBFS" in the specification[4]:
THD+N:
< 0.002% (8 Ohms, AD 400Khz modulation, 1kHz, -1dBFS)
< 0.01% (AD modulation, 20Hz-20kHz/ -1dBFS)
Noise Floor Modulation:
< 2dB (-60dBFS to -1dBFS)
[3] https://www.qualcomm.com/products/csra6620
[4] https://www.qualcomm.com/media/documents/files/csra6620-ddfa-evaluation-kit-product-brief.pdf

[5] https://audio.com.pl/testy/stereo/wzmacniacze-stereo/2608-nad-d7050
 
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amirm

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#5
No, the distortion is lower because the input is set to -3.5 dBFS. Here is my measurements which at that level which is pretty close:

1551904271029.png


Note that I have set my signal to 0 dBr which the other graph has not.

Here it is at 96 kHz sampling (but still 22.4 kHz bandwidth):

1551904336879.png
 

miero

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#6
No, the distortion is lower because the input is set to -3.5 dBFS...
That is the volume on the sound card input. And I guess I used some voltage divider (but I'm not sure, it was 2 years ago). Are you measuring the Analog Out?
 

March Audio

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#8
How do products with faults like this get released???
 

PuX

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#9
nice, I wonder how a traditional, not Class D amp would perform in comparaison to this. C 326BEE maybe? or 356 might be closer in price (is it discontinued? not sure). here's why: I have a NAD amp and a CD player. in terms of power and sound they are nice, but NAD products can have weird electronic glitches - CD tray can't close, can't open, buttons not doing what they are supposed to and so on. so I'm not surprised they can't make a DAC or an app that has no issues.

seems like this whole lineup where 7050 was top of the line was replaced with D 3045 and D 3020 V2.

btw NAD has a whole new modern-looking lineup.
 

daftcombo

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#10
Hi,

It would be interesting to have a measurement and review of the NAD D1050, which has almost the same design but is DAC-only. Maybe the DAC part is the same?
From what I have read, the S/PDIF, especially toslink, is better than the USB in, perhaps it is the same for the D7050 ?

I have one, which I use as an external DAC for a CD player, with a miniDSP in-between.
I would lend it but I'm in France so it won't be very interesting I think...
 

miero

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#11
Yes. What are you measuring, speaker out or line out?
It was the line out. But I used Linux operating system for USB playback. Maybe there is a problem in driver for Windows.

And also I might be wrong and I really measured the USB input at lower volume than 0dBFS.
 
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daftcombo

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#12
nice, I wonder how a traditional, not Class D amp would perform in comparaison to this. C 326BEE maybe? or 356 might be closer in price (is it discontinued? not sure). here's why: I have a NAD amp and a CD player. in terms of power and sound they are nice, but NAD products can have weird electronic glitches - CD tray can't close, can't open, buttons not doing what they are supposed to and so on. so I'm not surprised they can't make a DAC or an app that has no issues.

seems like this whole lineup where 7050 was top of the line was replaced with D 3045 and D 3020 V2.

btw NAD has a whole new modern-looking lineup.
On their website, it is for sale for 1099$, so not discontinued.
https://nadelectronics.com/product/d-7050-direct-digital-network-amplifier/
 

miero

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#13
It would be interesting to have a measurement and review of the NAD D1050, which has almost the same design but is DAC-only. Maybe the DAC part is the same?
The D1050 seems to be a completely different product:
Inside the NAD D1050 is a USB Audio Class 2 XMOS USB receiver, a Cirrus Logic CS4398 DAC chip, and a Texas Instruments LME49860 op-amp. The Cirrus Logic CS4398 is their flagship processor, capable of 120 dB dynamic range and even has support for DSD, although NAD did not include this feature.
Source: https://hometheaterhifi.com/reviews/dac/nad-d-1050-usb-dac-review/

Notice: the CS4398 is the chip used in the Topping D30.

The D7050 probably does not use any external DAC besides of DDFA chipset which is capable of I2S input.
 
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amirm

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#17
It was the line out. But I used Linux operating system for USB playback. Maybe there is a problem in driver for Windows.
I am using NAD's ASIO driver so I suspect all is well here. Even with what you measured performance is not that great.
 

amirm

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#18

Xulonn

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#19
I'm currently writing another post on my quest for a new DAC/AMP, and this review adds to my prejudice against the new NAD 3045, which seems to be more of a replacement for the D7050 rather than addition to their DAC/AMP product line.
 

confucius_zero

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#20
What about dynamic range of speaker output? the SNR is missing

and 89 sinad makes it one of the best speaker integrated amp currently measured for that price.

Just look at the track record so far:

105 : Hypex nc400 DIY amp
101: Neurochrome modulus
95 : Accuphase e270
89 : Nad 7050
86 : Onkyo M282
83 : Sony Hap S1
80 : Denon AVR 4306
78 : FX502S
78 : Dayton APA150
76 : Crown XLS 1502
70 : Topping TP60
68 : Nuforce STA200
67 : Behringer A500
 
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