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Review and Measurements of NAD T758 V3 AVR

doodlebro

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Anyone notice any improvements on the BluOS update released 4 days ago? I'm hoping that weird loudness bug I keep experiencing finally goes away but didn't see anything specific in the version notes.
 

SpoOokY

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Anyone notice any improvements on the BluOS update released 4 days ago? I'm hoping that weird loudness bug I keep experiencing finally goes away but didn't see anything specific in the version notes.

Do you mean the LPCM surround loudness bug resulting in huge volume jumps and deactivated Dirac corrections (even though Dirac is activated according to OSD)? If yes, I have just sent a new mail to support. The problem has been confirmed by one of their support crew members which is almost a year ago. Nothing changed since then!

Edit: Found you post with the problem description. It does only occur with PCM surround signals. Switching the PS4 to Dolby encryption solves the problem. Would it be okay for you to draw NAD's attention to you post?

Edit2: And no, the latest firmware did not solve it. I have done a factory reset twice with a long period off the power cord. Then I flashed latest firmware via USB and did a complete new calibration using latest Dirac. Volume bug still persists...
 
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SpoOokY

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I have just tried to simulate the PCM volume bug and was able to replicate it "on purpose". I have hooked up my MacBook vial HDMI and started RoomEQ Wizard to send a PCM sine wave signal to the front right speaker. Volume was at -25 dB. Then I sent the same signal to the front left. It was as loud (- 25 dB). Things started to get messy after I sent the same signal to either the LFE or surround left/right speaker. Signal was much louder and stayed on that level even though the volume on the display did not change. Front left/right were boosted from -25 dB to -10 dB until I either switched to another Dirac slot or entered the OSD.
I have recorded a video and sent it to Jade (NAD). Maybe that helps.

Are you guys able to replicate the same behaviour? It only occurs with Dirac enabled!
 

doodlebro

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I have just tried to simulate the PCM volume bug and was able to replicate it "on purpose". I have hooked up my MacBook vial HDMI and started RoomEQ Wizard to send a PCM sine wave signal to the front right speaker. Volume was at -25 dB. Then I sent the same signal to the front left. It was as loud (- 25 dB). Things started to get messy after I sent the same signal to either the LFE or surround left/right speaker. Signal was much louder and stayed on that level even though the volume on the display did not change. Front left/right were boosted from -25 dB to -10 dB until I either switched to another Dirac slot or entered the OSD.
I have recorded a video and sent it to Jade (NAD). Maybe that helps.

Are you guys able to replicate the same behaviour? It only occurs with Dirac enabled!

Yes, that sounds exactly how I get the bug to come up. As soon as you send LFE to the receiver over HDMI from a laptop, it happens. I haven't noticed Dirac disabling, but believe you. I usually just power cycle the receiver and then it goes away, and it happens probably once every few months without connecting the laptop. Similarly, I only use the laptop for REW and configuring my MiniDSP so I rarely notice it anyways. Feel free to quote my posts as needed, I'm sure NAD will figure it out eventually.
 

snackiac

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Yes, that sounds exactly how I get the bug to come up. As soon as you send LFE to the receiver over HDMI from a laptop, it happens. I haven't noticed Dirac disabling, but believe you. I usually just power cycle the receiver and then it goes away, and it happens probably once every few months without connecting the laptop. Similarly, I only use the laptop for REW and configuring my MiniDSP so I rarely notice it anyways. Feel free to quote my posts as needed, I'm sure NAD will figure it out eventually.
@SimpleTheater: Are you also affected by this bug? The more we are, the better we can push NAD to find a solution!

I feel like I hit this like once or twice a week, and it finally forced me to get rid of it. No esoteric setup or anything, just Apple TV into the NAD which is connected to my LG.

I have my Apple TV set to output PCM, so I guess the AVR would get frequent switches between 2.0 and 7.1 depending on content, which seems to be what this thing can't handle.
 

doodlebro

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I feel like I hit this like once or twice a week, and it finally forced me to get rid of it. No esoteric setup or anything, just Apple TV into the NAD which is connected to my LG.

I have my Apple TV set to output PCM, so I guess the AVR would get frequent switches between 2.0 and 7.1 depending on content, which seems to be what this thing can't handle.

My T758 just stopped outputting sound. After some troubleshooting discovered the "DSP unknown" bug for the first time and I'm starting to understand the annoyances. At least up till this point I had minimal issues. Currently updating to see if that helps.
 

SpoOokY

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Keep my thumbs pressed for you. So far I heave not heard anything back from NAD. Almost 1,5 weeks after submitting the ticket.
 

Nicklas1988

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Hi,

In the
EB9FACDB-4295-4941-8BB8-2431053909D5.png
specification for NAD T758 v3 they are specifying that pre out THD+N at 2V is less than 0.006%.
How come you’r numbers show something entirely different?
Either you have something wrong in your measurements or NAD have, I suppose?
Can you tell us a little bit more of your measurment setup? Have you confronted NAD about these numbers?

Best regards,
 

Nicklas1988

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Hi,

In theView attachment 88339 specification for NAD T758 v3 they are specifying that pre out THD+N at 2V is less than 0.006%.
How come you’r numbers show something entirely different?
Either you have something wrong in your measurements or NAD have, I suppose?
Can you tell us a little bit more of your measurment setup? Have you confronted NAD about these numbers?

Best regards,

Ok, I answer my own question. I suppose they have measured pre out using the analog inputs. And just ignored adding data for the DAC.
 

peng

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Ok, I answer my own question. I suppose they have measured pre out using the analog inputs. And just ignored adding data for the DAC.

I think you've got that right. By the way, ASR's measurements on THD+N at rated output on the power amp actually beat the 0.08% spec. It isn't that the NAD is really bad (amp section), just Denon, Marantz and Yamaha's were much better, especially in the 4 Ohm tests. D+M measured even better at lower output such as the important range from 50 mW to 5 W.
 

RichB

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The damping factor at >60 Ohms is a bit low given that it is half that into 4 ohms.
Does Denon post damping factors for it AVRs?

- Rich
 
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The Nad T758 V3 deactivates its internal amp of the channel when using pre out, this was told to me by a Nad employee, dunno how much truth is in this. Is this right?

Thanks.
 

peng

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The Nad T758 V3 deactivates its internal amp of the channel when using pre out, this was told to me by a Nad employee, dunno how much truth is in this. Is this right?

Thanks.

I bet there is zero truth to that.. However, you can find out easily yourself just by trying it.
 

Theriverlethe

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The Nad T758 V3 deactivates its internal amp of the channel when using pre out, this was told to me by a Nad employee, dunno how much truth is in this. Is this right?

Thanks.

Amir’s measurements strongly suggest the opposite, unless this was changed in firmware somehow.
 
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I have the T758 v3 since a while & plan to use it as a processor with a Nad M27 powering my speakers. With all the bad measurements posted in the review, will that be in effect when using it as a processor?

Thanks.
 

peng

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With all the bad measurements posted in the review, will that be in effect when using it as a processor?

Thanks.

Base on the measurements, if you don't need more than 1 V output it should be reasonably good and if you need higher voltages it would likely degrade quite a bit, reaching 50 dB SINAD at close to 2 V. -52 dB THD+N is 0.2511%, likely audible.
 
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Base on the measurements, if you don't need more than 1 V output it should be reasonably good and if you need higher voltages it would likely degrade quite a bit, reaching 50 dB SINAD at close to 2 V. -52 dB THD+N is 0.2511%, likely audible.

Just saw the M27 Input Sensitivity, it is 1.3V for full rated power(180 X 7 @8 ohms)
So i guess with the T758 v3 as the processor i should get at least 70% of the power of the M27 without distortion?

Thanks.
 
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