NAD T 757 A/V Receiver HT Labs Measures

HT Labs Measures

Five channels driven continuously into 8-ohm loads:
0.1% distortion at 75.2 watts
1% distortion at 91.2 watts

Seven channels driven continuously into 8-ohm loads:
0.1% distortion at 71.2 watts
1% distortion at 81.6 watts

Analog frequency response in Analog Bypass mode:
–0.22 dB at 10 Hz
–0.07 dB at 20 Hz
–0.11 dB at 20 kHz
–3.08 dB at 50 kHz

Analog frequency response with stereo signal processing:
–1.91 dB at 10 Hz
–0.59 dB at 20 Hz
–1.06 dB at 20 kHz
–43.07 dB at 50 kHz

This graph shows that the T 757’s left channel, from Audio1 input to speaker output with two channels driving 8-ohm loads, reaches 0.1 percent distortion at 94.3 watts and 1 percent distortion at 121.9 watts. Into 4 ohms, the amplifier reaches 0.1 percent distortion at 146.9 watts and 1 percent distortion at 181.0 watts.

Response from the multichannel input to the speaker output measures –0.22 decibels at 10 hertz, –0.07 dB at 20 Hz, –0.08 dB at 20 kilohertz, and –3.07 dB at 50 kHz. THD+N from the Audio1 input to the speaker output was less than 0.027 percent at 1 kHz when driving 2.83 volts into an 8-ohm load. Crosstalk at 1 kHz driving 2.83 volts into an 8-ohm load was –57.84 dB left to right and –58.01 dB right to left. The signal-to-noise ratio with an 8-ohm load from 10 Hz to 24 kHz with “A” weighting was –105.48 dBrA.

From the Dolby Digital input to the loudspeaker output, the left channel measures –0.44 dB at 20 Hz and –0.94 dB at 20 kHz. The center channel measures –0.45 dB at 20 Hz and –0.90 dB at 20 kHz, and the left surround channel measures –0.44 dB at 20 Hz and –0.87 dB at 20 kHz. From the Dolby Digital input to the line-level output, the LFE channel is –0.20 dB at 20 Hz when referenced to the level at 40 Hz and reaches the upper 3-dB down point at 149 Hz and the upper 6-dB down point at 199 Hz.—MJP

Video Test Bench
The NAD performs no video processing. Its video circuitry is passthrough only (resolution in = resolution out). It does cross-convert from a component input to an HDMI output, also with no available upconversion and/or deinterlacing.

In our Digital tests, the NAD passed above white, but barely, responding only up to a level of 239. Video peak white is 235, and digital video levels extend from 0 to 255. There’s no need to go all the way to 255, as video sources don’t, but they can sneak above 235 (even though they shouldn’t). Because of this, we like to see more than the NAD’s 1.7 percent of headroom. (To be fair, the late, lamented Pioneer Kuro plasma HDTVs barely responded above white—one of their few shortcomings.) The T 757 definitely clipped below black, extending only to the level 17 (video black is 16). It also failed horizontal chroma resolution, but only at the highest burst—not an uncommon shortcoming and one that, in our experience, won’t be visible on most program material.

In the Analog tests (1080i component in to 1080i HDMI out), the T 757 clipped both above white and below black. When I switched to a 480i input with a 480i output (both analog and digital), the NAD cleanly passed both below black and above white by a wide margin. It’s a puzzle as to why it could do so and yet not pass them equally well at 1080i.The receiver also failed analog chroma resolution in the same manner as in digital.—TJN


fredmant's picture

Thanks Bucky! Of course, sound is subjective, isn't it, but you did happen to ask specifically about Marantz. I have an SR8002 AVR from them (a few years old) and like it a great deal. Sound-wise, I'd say the Marantz is perhaps smoother and more forgiving, but still very resolute. You should try and listen to them both, with speakers similar to yours if you possibly can.

Ladyfingers's picture

I am an owner of the T747, and I love the sound and simplicity, but the inability of the unit to maintain lock during silence, and the 1/2 second or so it takes to re-lock, means it often trims the opening notes of songs and video tracks.

Has this been fixed? I would like something simple and powerful, but the T747 has been a disaster for me.

fredmant's picture


I don't recall a consistent problem with the T757, but most processors or AVRs seem to consistently have at least an intermittent problem with re-locking, be it on a 2 channel PCM or Dolby True HD track. However, in your case, it sounds like this effect is the truly bothersome. I can say that I didn't experience anything that rose to that level with the T757, but by all means, bring some discs to your dealer and check it out for yourself. I would be your defacto tester if I could, but the T757 is already on its way back to the mfg. Good luck!

Watthead's picture

Hello Fred,

Enjoyed your article very much. Could you please help me with the following: I've owned a Nakamichi Stasis Pa-5 (first version) stereo amplifier (100 x 2) for a pretty long time now, and i'm looking for an upgrade, but id like something that I can use in stereo mode, as I mostly use, and also for a little hometheater. My speakers are Paradigm Studio 20 V5. Would I miss the power of a dedicated 2 channel amp if I go with the NAD? I'd connect the Nak to the NAD and use the NAD as a pre-pro, but i'm gonna have to sell the Nak to be able to afford the NAD.