- Manufacturer & Model
- NAD T 758 v3 A/V Surround Sound Receiver
Seven generously powered speaker outputs, DTS Master Audio and Dolby ATMOS, Dirac Live state-of-the-art room correction, BluOS streaming High Res Audio.
The NAD T 758 v3 A/V Surround Sound Receiver is built to satisfy the 2-channel enthusiast and the home cinema buff in an irresistibly high-valued package. NAD’s “Simple Is Better” design philosophy reaches beyond look and feel to deliver a fluid user-friendly experience from initial setup through cranking up your favorite album or movie.
The streamlined but attractive aesthetic that is characteristic of NAD products might fool some into confusing their economical approach with cheapness. Do not let the lack of glitz and exotic materials deceive you. The T 758 v3 A/V Surround Sound Receiver wins you over with features and performance. The T 758 v3 starts with a beefy power supply with plenty of reserve for cleanly handling dynamic program peaks, and the ability to drive current-hungry loads with full stability. Solid specs are the rule, with enviably low distortion numbers and more than enough power for ear-endangering volume from most speaker sets. Not that you need it, but because it is so much FUN! (Please listen responsibly!)
A rule the NAD design philosophy espouses is that “Simple Is Better” and flexibility need not be sacrificed for its attainment. Lip service to a marketing catch phrase? The rule holds true in the visual, in the combination of technology and capabilities to be wed in the product, and in the control and setup menus, in the front panel and remote designs, and in the supporting PC-side application interfaces that accompany the product. This sense of economy reaches beyond price and dollar signs, in evidence in the feature set and user interfaces, all housed with simple, no-nonsense attractiveness. This is all well summed up on their website: “Innovation, Performance, Value, Simplicity.”
The feature set combined in the T 758 v3 is just about ideal for a music fanatic who also enjoys a good flick once in awhile. NAD’s website says that their designs put “Music First,” and all indications are that they mean it. Get the music right and - with a modicum of care - the cinema sound will follow. The BluOS Player, from sister company Bluesound, and NAD’s PowerDrive™ amp design, with high output current and high Dynamic Power, help make it all happen.
Starting with seven generously amplified outputs - who uses an unpowered subwoofer these days? - with 110 W FTC stereo power and Full Disclosure Power rated at 60 W RMS per channel available with all 7 channels driven at once at full bandwidth and full rated power with only 0.05% distortion. Odd speaker loads are no great challenge for this beast. For those who like to use an AVR’s physical weight - mostly in the power supply - as a rough measure of power supply resilience, the T 758 v3 weighs in at a hair under 34 lbs (15.4 kg), a manageable weight for the shipping delivery person and for the end user. Anyone who has purchased a 60 lb plus AVR only to find it DOA because of a broken motherboard from a drop during shipping will appreciate that maximum power supply mass is not the only measure of goodness in an AVR.
The company’s proprietary Modular Design Construction (MDC) approach allows new features to be introduced with ease and even delivered as upgrades to customers in the field, “future- proofing” products that make use of the modular system. Of course the T 758 v3 contains all the essential A/V technology one would expect in an AVR: HDMI (supports 4K@60 4:4:4), HDCP 2.2, 3D and 4K Ultra HD video, DTS Master Audio, and Dolby Digital. Video processing is minimal, being left for the video display, “where it belongs.”
Then the list gets exciting: Dolby ATMOS transports the cinema buff into the world of 3-dimensional cinema audio. And Dirac Live room correction - I am a HUGE Dirac fan and would not consider running a system without it - is supported with Dirac Live LE supplied and full Dirac Live available for a $99 upgrade, and BluOS Streaming Hi Res Audio via USB/WiFi/Bluetooth.
The “Simple Is Better” philosophy along with a keen sense for “easy flexibility” results in a product that might not include every possible option that an end user might look for. For instance, volume is controlled in 1 dB increments, where many AVRs allow ½ dB increments. Hunting for that and other options had me thinking that the idea might have been carried too far, but by the end of the evaluation period I was won over. The economy of available options and the menus for accessing them have been very well imagined and that is not always an easy task for designers. Often it seems that unless the user can manage to get into the head of the designer for a given product, one is forever a bit lost in finding that certain option once happened upon a few months back. A set of user interfaces that is simple and flexible at the same time is far from easy to achieve, and in the end I have to agree that the NAD designers nailed the task. Any options I initially thought of as needed but missing were either forgotten about or found to be not really needed or missed. NAD’s “easy flexibility” approach is not just a cool marketing motto, it goes to the heart of their product concept and makes user accessibility as much of a reality as their power and distortion specs.
As with most surround AVRs, there is a fair amount of flexibility in the way the speakers can be set up. Beyond the seven power-amplified outputs, supporting either a 7.1 surround setup or a 5.1.2 ATMOS setup with 2 height speakers and all channels amplified, there are also two sets of preamp outputs that allow additional possibilities.
One pair of the speaker outputs can be assigned to Zone 2 duties. With this assignment made and the additional 4 ATMOS line-level height outputs put to use driving external amplifier channels, the max configuration becomes 7.1.4, or a 7.1 surround system plus 4 ATMOS Height speakers, with all four height speakers amplified external to the NAD T 758 v3. With no Zone 2 assignment, the max configuration is also 7.1.4 with only 2 of the ATMOS Height channels requiring external amplification. In both cases, Dirac Live is able to provide room correction for all 12 channels. For this review, the emphasis was on the T 758’s music performance, so explorations into the ATMOS realm were limited.
The first setup task was to connect and initialize the BluOS subsystem. This BluOS kit (supplied) includes an external USB hub, a USB extension cable, a WiFi dongle, a Bluetooth USB micro adapter, and a Quick Start guide. I was initially a bit thrown by the process wherein the NAD’s WiFi, initially a client on my home WiFi, is mysteriously transformed into a WiFi host of its own, but simply following the instructions step-by-step got the BluOS set up and handling BluOS and T 758 v3 system firmware upgrades with a mouse click. Even the Dirac Live calibration application, once installed, reached out and found the BluOS system when needed with no effort from me whatsoever.
The BluOS USB extension cable hangs off the back of the T 758 v3 unit and my first thought was that it looked like a design afterthought. But WiFi connectivity is not always what one might want it to be, and Bluetooth can be even touchier. A foot of distance from the T 758 v3 chassis can make a world of difference for connectivity where it is marginal. So my final verdict is that the BluOS kit is just fine as is.
Additional setup tasks were quickly accomplished. Speaker distances and level calibrations would be taken care of by Dirac LIve, so I entered fake values there and selected speaker sizes and crossover frequencies and was ready to play music.
BluOS is NAD’s lossless wireless streaming offering. The HiFi audio industry is rife with them at this time, the producer of each hoping with crossed fingers that his system will somehow become entrenched and a way of life for audiophiles. Some will succeed, one or two might eventually become industry standards. And alas, some worthy offerings will disappear with the companies that invented them, technology Darwinism working as it does.
BluOS uses WiFi and Bluetooth technologies to facilitate lossless streaming up to 24-bit/192 kbps using the existing protocols, plus a pinch of custom programming. The smartphone-hosted app allows one to sync multiple devices on the same network - anywhere in your home or business - or to play multiple music sources simultaneously. So the T 758 v3 has no FM/AM radio tuner, and is the first AVR I have worked with that does not, although I never use the feature, as we are finally arriving at the point where one can say, “The Internet is my radio.”
Master Quality Authenticated (MQA), integral to BluOS, helps ensure proper delivery of the finest Internet-streamed Hi-Res Music to the T 758 v3. The BluOS smartphone app gets you started with a wide array of Internet radio presets, and you can always add more.
The smartphone app can control numerous BluOS devices, and allows access to many of each device's controls. The T 758 v3's main volume control is an example. The onscreen touch-drag slider for this is very sensitive and could all too easily end up jiggled to full volume, at worst a speaker- or ear- damaging event, at least an annoyance. I was relieved to find that one has the option of limiting the volume range for that control via the app's settings.
The smartphone app also manages updates to BluOS and to the audio and control DSP code in the T 758 v3 itself, making the process ridiculously easy. The days of “download update, run updater, select file, apply update, reboot” are long past. It is now as simple as pressing “Yes, Confirm” wait a minute or two, then start the music again. I have never found a firmware update to be as easy as the process with the T 758 v3. The BluOS alone might just be enough reason to go NAD.
I was impressed. At one time, while switching back and forth between two sources, I experienced a technology moment, witnessing all the technologies at play. On one hand, via the NAD T 758 v3, I was playing a lossless CD-quality track from an Internet radio station that only plays lossless CD-quality tracks, from who-knows-where on planet earth, over the Web, from my Internet Provider at 200 Mbps, through my WiFi router and over the airwaves via one of its three bands to the BluOS WiFi dongle/USB hub/T 758 v3 USB port, through the T 758 v3, being converted from D to A therein, through its amplifiers and to my reference MartinLogan electrostatic speakers, all controlled by the BluOS app installed on my smartphone. Then I switched to a lossless CD-quality track from a Tidal server located who-knows-where on planet earth, over the Web, WiFi, and airwaves to my smartphone, then over Bluetooth via LDAC technology - capable of 24/192 High Res lossless equivalence - to the new cordless, rechargeable Bluetooth earphones I was auditioning, enjoying my favorite of its 4 possible built-in EQ settings. What a time to be alive!
Front Panel Design and Operation
Simple Is Better, and the T 758’s front panel is very simple and uncluttered. Yes, it LOOKS like an NAD! The two-line vacuum fluorescent display is sharp and easy to read but not too bright for a home theater. It is also dimmable and has a temp mode if you want it to shut off altogether after a few seconds. The information displayed can be changed via the setup menus. My display is now set to dim but on all the time, with line one showing the source, switching to display the listening mode or other pertinent info as called for, and line two displaying the volume setting. There is also a five-way multi-function navigation/select switch, and there are buttons for menu activate, listening mode, and source select.
The front panel design follows the Simple Is Better pattern and the T 758 v3 operating theme in general, centered on source selection, with optional changes in listening mode and EQ - the Dirac Live setting and Tone controls.
Two remotes come with the T 758 v3, an AVR4 remote with all functions covered and a minimalist ZR7 remote for Zone 2 control. The AVR4 remote, in addition to source and volume controls, allows real-time changes to tone settings, room EQ filter selection, preset selection, and lets one quickly scroll through the pertinent information about the T 758's audio and video processing via the unit's front panel display. A simple yet complete on-screen display (OSD) menu system provides access to all advanced functions and settings. Library codes for other NAD devices may be entered to allow an AVR4 remote to control other NAD devices in a system, helping eliminate "remote clutter."
Power, Distortion, Noise
The T 758 v3 was used first to drive a pair of SVS Prime Towers, and later a 5.1 surround setup with two MartinLogan Classic ESL 9 speakers as mains and two MartinLogan Electromotion ESL speakers as surrounds. This makes for a reasonably stressful set of speakers load-wise, the electrostatic panels for both models approaching a 2-Ohm load at high frequencies. The impedance curves for the two electrostatic models are included in the Measurements section below.
My target curves for the Dirac Live Full Version calibration were purposely flat out to 10 kHz, so the HF content was full-range with lots of treble, especially on the crunchier Porcupine Tree tracks, “Deadwing,” “Shallow,” “Halo,” and “Arriving Somewhere But Not Here,” all from the DVDA surround version of their Deadwing album. After 15 minutes of these hard-driving tracks, I put my hand on the top of the T 758 chassis, expecting it to be hot from elevated power draw. The chassis heat level was just above room temperature, not more than a few degrees warmer than normal idle (not standby) temperature. In essence, it appears that the amp could work like that all day without stress or significant temperature elevation. Credit NAD’s PowerDrive™ amplifier design for combining high current drive and high Dynamic Power capabilities to effortlessly tame the unruly electrostatic loads.
Soundstage and Imaging (SS&I)
One spec that is neglected by some HiFi audio manufacturers is Channel Separation, or Crosstalk. It is sometimes specified at 1 kHz, but only rarely at high frequencies. It is natural for there to be channel-to-channel interaction at high frequencies, where little inductances in common-current ground paths and odd capacitive coupling between conductors become significant and Channel Separation often drops off at 6 dB per octave relative to 1 kHz. SS&I at high frequencies can suffer, and image clarity becomes less sharp on vocal sibilants, high bells, any instrument or sound that occasionally reaches into the high frequency range. The dark space of silence between those sounds shrinks as a result.
Measurements were taken with a resistive load and with the MartinLogan Classic 9 electrostatics as load. Channel Separation with resistive loading was very low, 80 dB or beyond, well below the noise floor for my measurement setup. The capacitive load of the Classic 9 clearly put a greater stress on channel interaction than the non-inductive dummy load, and Channel Separation at 10 kHz decreased to about 40 dB. My tests show this to be around the point where SS&I might begin to suffer, but targeted listening tests never gave any indication of the T 758’s SS&I performance being impacted.
Tone Controls and Room EQ
The T 758 v3 comes with treble and bass Tone Controls for simple EQ tasks. How quaint! I have not seen basic treble and bass controls in a serious AVR for quite some time. Many AVRs come with a what amounts to a graphic equalizer, not terribly useful, or a handful of parametric EQ bands. Parametric EQ can be a help in applying some gentle pre-EQ before running a Dirac Live Room EQ calibration, and this approach is quite common among enthusiasts where the main Room EQ application is not quite able to tame a sizeable room mode peak, for instance.
But Is that technique necessary with Dirac Live on board? Will Parametric EQ be missed with the T 758 v3? I have not found it to be necessary in my own Dirac Live experience, although some might stubbornly insist upon using it out of habit if it were available, having become used to needing it along with lesser Room EQ products. As I see it, anything PEQ can do, Dirac can do better. Apparently, the user interface designers at NAD saw the matter the same way, and the limitations imposed by the feature set become freeing without any real sacrifice in capability.
A better way of thinking of the T 758’s Tone Controls is to add a shelf-style lift to the bass when playing a track or album mixed a little weak through the lows, or to cut the treble on a track that is brighter than one might care for. The earlier mixes by Todd Rundgren, one of my personal favorites, tend to be light on bass, so I set up a preset with a 4 dB bass boost.
Presets (5 max) can have custom names and can include or exclude by category Listening Mode Setup, DSP Options (Dirac Live, 3 slots max), Tone Controls, Speaker Setup, and Front Panel Display Setup. My “TR Mix” preset was just the ticket, the bass guitar lines on “The Want Of A Nail” were given new life, and with the preset programmed it became instantly available with two remote clicks. Dirac Live and Tone Control settings are also available directly with the T 758’s remote.
Phase shift introduced by shelf-style Tone Control changes might interfere with the accuracy of Dirac Live’s filters. The diagram below shows how the combination of tone controls and Dirac Live Full, with a Dirac Full calibration and the bass control at +6 dB shows the phase shifted off a bit, and the impulse diagram modified a little. There was no obvious change in the SS&I, but SS&I is vulnerable to sources of phase shift as well as frequency response, so boost and cut with care. Also, the band boosted by Dirac Live at 80 Hz is now 12 dB hotter out of its amp channel than before, which potentially amounts to 16x power demand at that frequency. This is precisely the kind of power demand that NAD’s PowerDrive™ amp is designed to deal with transparently.
The approach is valid and satisfactory for occasional tracks but for demanding use, a dedicated DL filter slot with appropriately altered target curve is the better move. Remember that once a set of measurements has been taken in the middle of the DL calibration process, then saved, the same measurements can be used over and over with different target curves to satisfy different Room EQ needs, like one DL setting for cinema, one for music, and one for music needing boosted bass.
The tone control curves are included in the Measurements section at the end of this review. As they indicate, each of the two controls works in 2 dB increments over a +/- 10 dB range. The contours and break points appear have been carefully chosen. The boosted Bass contours in particular avoided a tendency to induce a “boxy” tone to vocals when the boost creeps too high into the lower mids range. And 2 dB increments - I wondered if that would be enough granularity - turned out to be just right.
Note; The bass tone control does not affect any bass-managed signal. It will affect the L and R mains signals but not the subwoofer signal in a 2.1 setup, for instance, where the signal below the crossover frequency will not be boosted/cut and the signal above the crossover will be boosted/cut.
Dirac vs Dirac
The combination of Dolby ATMOS and Dirac Live makes the T 758 v3 a serious solution for the home cinema buff who insists on the best audio possible. Bass management and the various operations are performed in the order most effective for both subsystems and their sonic purposes. Few products have been available before now making that possible.
Dirac LIve has, from its earliest releases, been steadily and consistently establishing itself as the de facto standard for serious 2-channel room and home theater room correction. At a time where room correction applications have been released by many AVR manufacturers, presumably either to avoid expensive licensing fees or to attempt to make their own improvements on the state of the art, Dirac Live appears to have cornered the science and produces a product that, to my ears, is all upside and no downside.
That last point bears repeating. I have worked with Dirac Live on a half dozen devices over the last few years. As with any room correction application, it is possible to mess up a calibration and get a lousy result, the setup complexities being what they are, but the setup process is vastly simplified with Dirac running in the AVR. Dirac Live, applied with the proper TLC, has never exhibited a sonic quality that I disliked or doubted. Targeting a knowledgeable DIY audio crowd, it is exceptionally forgiving of user flubs, and the finished sound is always a couple of giant steps beyond hand-tuned EQ or no-EQ or what any competing room EQ product can produce. As a technology, I am convinced it is an automatic win.
The Dirac Live calibration program is a PC or MAC application that provides a full set of tools for measuring frequency response from each of the speakers in the system at up to 9 locations around the listening position, then generating the appropriate filter set to compensate for frequency response aberrations for each system speaker. This is accomplished with mixed-phase filter technology that also judiciously applies time and phase correction to sharpen the Imaging and unclutter the soundstage. Also referred to as impulse response correction, the result can be seen in the impulse response for each of the speakers in the system.
The tool set in the Dirac Live calibration program allows the user to define a speaker configuration, then to select the calibrated microphone to be used for measurements and install the appropriate calibration curve for that microphone. Other Dirac versions I have dealt with lock the user into a specific microphone model for the Dirac Live calibration process. A calibrated microphone and USB mic adapter are supplied with the T 758 v3.
Next, the mic sensitivity and the relative playback levels for each channel are set using a built-in pink noise test signal. Then the calibration application directs the user through a series of up to 9 sets of measurements around the listening position, with a frequency response measurement for each speaker at each mic position. Don’t worry, Dirac keeps track of it all for you. Just move the mic when told to. Although the chair and couch guidance diagrams suggest where those mic locations should be, only the first is critical. The others can be chosen at random, although the picky user who wants to verify calibration results using Room EQ Wizard will benefit from a method for achieving placement repeatability. Another little tip: save the project after optimizing to the target curve, then export the filter set to the NAD T 758 v3, and the filter set name will be the same as the saved project file name, thus easier to identify.
Dirac Live LE vs. Full Version
Starting out with a 5.1 Dirac Live LE calibration and export to the T 758 v3, I was pleasantly surprised by the improvement in SS&I over the raw speaker SS&I. With correction limited to the frequencies below 500 Hz, Dirac Live improves image clarity immensely, yet does not disrupt the speaker’s natural voicing. This gives a spirited delivery with very good SS&I due to the excellent matching between the left and right mains, in my case.
Then the Dirac Live Full Version, which corrects full range (20 Hz to 20 kHz) was downloaded, a $99 upgrade and an absolute must as far a I am concerned. The LE Version must be uninstalled before the Full Version installation is run, a fact that makes it difficult to compare the two calibrations directly. One can save a DL LE calibration in one of the three filter memory slots, uninstall DL LE, install DL Full, and save a DL Full calibration in another of the filter memory slots, and - with music or movie running - switch between the calibrations for a near-zero-delay A-B comparison, if desired. During my tests, the saved project with measurements under Dirac LE could be successfully loaded into the Dirac Full application and the correction re-optimized with full-range target curves. This made a true apples-to-apples comparison possible between the two Dirac Live versions, working from the same set of calibration measurements. Whether that level of project compatibility will be maintained through future Dirac LE and Dirac Full application upgrades remains to be seen. I predict that most will prefer the Full version of Dirac Live hands down, so the point is a minor one for all but the most curious users.
For the Full Version calibration, the custom target curves in Dirac Live could easily be tuned to protect a speaker’s voicing if so desired, but I put the emphasis on a flat high end with some rolloff starting at 10 kHz. The combination of electrostatic transparency and a peak-free flat high frequency response is deliciously detailed and balanced with most mixes from 90s vintage onward, and the SS&I takes on an almost eerie lifelike quality with very good depth acuity and in-the-room image clarity that has to be experienced to be appreciated.
Switching back and forth between the two calibrations - the T 758 can hold three Dirac filter sets if desired - each of the two calibrations has qualities to love. In the end, it was the Full Version calibration that won. A flat corrected frequency response is a good - make that GREAT! - quality to attain, but the lifelike and all-sorted-out soundstage with precise image sharpness, deep, dark separating spaces, and reach-out-and-touch depth acuity that are sure to win over even a jaded skeptic. Once heard, there is no going back.
As measurements show, a compensated amp output response curve indicates frequencies where there is a fair amount of boost. The PowerDrive™ amp design is a good match for Dirac Live room correction, handling the needs of those boosted frequencies with no apparent overdrive problems.
Opening the cover of the T 758 v3, we find the output drive duties for each channel are handled by a 2SB1647 + 2SD2560 complementary Darlington transistor pair. The fourteen TO3P packages, two per amplified channel, are mounted directly to a single, long, generous heat sink. There is no fan to enhance the cooling, but I am completely satisfied with the thermal design. Several times after a loud listening session I placed my hand on top of the T 758 v3 to check its heat level and found there to be no significant temperature rise. Each of these transistors has a free-air safe operating current rating of 15 A, so with heat sinking and design choices taken into account, their choice is adequate for the critical task they must perform.
The power transformer occupies roughly 20% of the T 758’s internal volume. It is mounted on the chassis, physically independent of the main output board but closely associated with it. While the mass of this transformer is a factor in the unit’s ability to drive multiple speaker loads to high volumes, it is far from being either the solitary or the most important factor in a time-refined design that touts PowerDrive™ amp design and high Dynamic Power capability. Extended listening has left me assured that the goal has been accomplished with honors.
Spacing of the dual-banana speaker connectors is a non-standard one inch, so you might need to abandon some of your regular ¾-inch dual-banana connectors and procure a set of individual banana plugs for your speaker cable terminations.
What is Missing?
Simple is Better - until a feature is left out that you really miss. There were only a couple of these for me:
- Preamp outs are not cut off when headphones are plugged in. This is not a huge deal for me. For most serious headphone listening I use a separate headphone amp. But once in awhile, especially with a movie late at night, it is handy to be able to quickly plug in a pair of phones so no one else is bothered by the sound. With the current design, the pre outs are not disabled by headphones, so one must turn off subwoofers and external mains amps before starting a headphone session.
- Absence of digital outputs, especially optical. Coaxial and optical digital inputs are present, but no outputs. Sticking with HDMI for all digital output is certainly simpler in design terms, with HDCP to consider, but fiber is unbeatable for isolating and eliminating a system ground loop, and I missed it more than once.
(King Crimson / Basing Street Studios)
With the 5.1 surround electrostatic setup, I listened to tracks from the 5.1 surround mixes of Wish You Were Here by Pink Floyd, and of Porcupine Tree’s Deadwing, all at high volume and with Dirac Live active (LE calibration and Full Version calibrations). The Pink Floyd tracks were run at a 3 dB higher volume setting than the Porcupine Tree tracks, since the Floyd mix - even being a recent remix and remaster, is one of those odd critters with actual dynamic range, and somewhat lower average levels.
The T 758 v3 drove the electrostatics with apparent ease. Delivery was clean, effortless, completely transparent, absolutely free of any indication of onset of clipping. A lesser amp, with the same loads, will tend to feel or sound strained at the early onset of clipping. Perhaps an indication of an occasional peak being clipped. This never occurred with the T 758 v3.
King Crimson, Discipline "Elephant Talk, Frame By Frame"
Fripp’s and Belew’s guitar tones, somewhat rich and a little twangy, really stand out in these tracks, and became useful clarity test examples. Those tones remained clear even at high volumes with the T 758 v3, whereas a pair of pro digital amps with much higher output capability displayed the slightest tendency toward a little rattiness on the peaks of those tones.
Those tones did cause a hint of widening of the images at high frequencies with the T 758 v3, evidence that SS&I suffered slightly. After exhaustive comparisons, the T 758 is the winner of this tiny spec competition. The SS&I smearing was so slight that it would be undetectable without direct comparison, but the pro amp’s higher distortion level was a slight annoyance.
King Crimson, Discipline "Matte Kudasai"
Clarith on Adrian Belew’s vocals is simply impeccable.
King Crimson, ConstruKction of LIght "ConstruKction of Light"
Here are more of those pristine guitar tones, back and forth, dizzying at times, and perfectly clean and clear. I expected, even feared a little, that the T 758 v3 might choke on those tones while driving the MartinLogan electrostatic panels, and approached higher volume levels cautiously at first. After awhile, I simply stopped worrying about it.
Radiohead, Kid A "The National Anthem"
If you ever run across a track that seems too dense for its own good, it is time to activate the Dirac Live. The densest track gets a thorough combing out, leaving all of the sounds and images separate and spaced apart. This track’s chaotic ensemble makes sense with Dirac Live’s imaging scrub. Details that were buried in those dark sonic crevices can now stand forth and be recognized.
Radiohead, Kid A "How to Disappear Completely"
The bigness of the reverberant space tended to reveal a slight crackling distortion I had never noticed before. Turns out it was in the recording. A Receiver like the T 758 can start to reveal details you might rather not know about with favorite recordings, unless you crave truth ih reproduction.
Radiohead, Amnesiac "Sail To The Moon"
This track invites you to move in close and get lost in its folds. This time I heard little bits of distortion that I had not heard before. Again, they were part of the recording, never before revealed.
The modern AVR is the hub in most home theaters and 2-channel listening rooms. It must manage a multitude of video and audio formats, source selections, presets, DSP options, room correction, EQ, preamp and speaker outputs and zones, and the list goes on… The complexities threaten to increase exponentially at every turn, until an enterprising engineering team devises the means to chunk it all down to a manageable system or standard with straightforward setup and control interfaces.
The NAD T 758 v3 demonstrates NAD’s dedication to deliver innovative products that excel in performance and provide irresistible value. This model represents an exciting set of features at a terrific value, and simplicity that will have you wondering why other AVR makers do not do the same. “Innovation, Performance, Value, Simplicity.” The NAD T 758 v3 is a great example of all four qualities, and comes with my highest recommendation.
Diagram 1: Measurements at the Listening Position (LP) before Dirac Live calibration show typical uneven frequency response in spite of reference speaker quality and careful setup (1/12th octave smoothing).
Diagram 2: Dirac Live LE calibration flattens frequency response below 500 Hz and clarifies the soundstage and imaging (SS&I), leaving the speaker’s natural voicing intact.
Diagram 3: Dirac Live Full Version, a $99 upgrade option, corrects the full frequency range for all system speakers, with a custom Target Curve for each. The result, with proper setup, is near-perfect soundstage and imaging (SS&I), along with very flat frequency response.
Diagram 4: T 758 v3 Tone Control curves. The shelf-type control covers the +/- 10 dB range in 2 dB increments for the Bass and Treble ranges. Tone control settings are available even with Dirac Live active, and can be easily turned on or off or changed without interrupting the program being played.
Diagram 5: Impedance curve for test speakers - SVS Prime Tower.
Diagram 6: Impedance curve for test speakers - MartinLogan EM ESL (blue) and MartinLogan Classic ESL 9 (green).
Diagram 7: High Frequency Channel Separation with an 8 ohm resistive load is 65 dB at 10 kHz (orange). With an electrostatic speaker load, it is significantly lower, only 52 dB at 10 kHz (green) and approaching 40 dB at 20kHz. Measurement noise floor is shown for reference (blue).
Diagram 8: T 758 v3 Frequency Response at speaker terminals with 8-ohm non-inductive load (green) and with electrostatic speaker load (blue)
Diagram 9: T 758 v3 Frequency Response at speaker terminals with electrostatic speaker load and Dirac Live LE calibration active (1/48th octave smoothing). The peak at 80 Hz receives a 6 dB (4x power) boost beyond the normal unequalized gain at that frequency. The T 758 v3 gave no indications of any trouble handling this boost comfortably.
Diagram 10: T 758 v3 Frequency Response at speaker terminals with electrostatic speaker load and Dirac Live Full calibration active (1/48th octave smoothing). The T 758 v3 gave no indications of any trouble handling this LF power boost comfortably.
Diagram 11: T 758 v3 Frequency Response at speaker terminals with electrostatic speaker load and Dirac Live Full calibration active and 6 dB bass tone control boost (green, 1/48th octave smoothing). Now the boost at 80 Hz is 12 dB, or 16x power. This setting was only used on tracks with weak bass, so there was never any concern about overloading the T 758 v3.
Diagram 12: T 758 v3 Phase Response at speaker terminals with electrostatic speaker load and Dirac Live Full calibration active and 6 dB bass tone control boost (red, 1/48th octave smoothing). Note the extra phase shift between 80 and 200 Hz can potentially disrupt Dirac Live’s filtering in that range.
Diagram 13: Uncorrected impulse response at the LP with electrostatic speakers at L and R mains (red & green) and surround (blue & orange) positions.
Diagram 14: Dirac Live Full corrected impulse response at the LP with electrostatic speakers at L and R mains (red & green) and surround (blue & orange) positions. The surround speakers were shifted forward slightly, accounting for the closer timing between mains and surrounds. Note the impulse shapes are much closer to ideal than in the uncorrected plot above.
Diagram 15: Comparing the USB measurement microphone (green) supplied with the T 758 v3 against an analog reference microphone, the BeyerDynamic MM1 measurement mic (red), which requires an audio interface and which comes with an individualized calibration file (each mic produced has its own calibration file to correct minor inaccuracies while in use). The calibration file can work with the Dirac Live calibration program and with Room EQ Wizard, used for most of these measurements. The MM1 is known to be accurate to +/- 1 dB, The NAD measurement mic stays within 3 dB except in the range above 12 kHz. This would be acceptable to many users These are raw frequency response measurements taken at the LP, the critical first calibration position where Dirac Live calibration measurements begin.
Diagram 16: Impulse response timing repeatability is important for all Dirac Live calibration measurements, but especially for the measurements done at the first calibration position. As shown, the NAD mic’s repeatability is within a range of 1.5 ms, which equates to a potential 20 inch inaccuracy in timing measurements, not adequate where sharp SS&I are desired. The eight measurements shown were taken successively and should overlay one another closely.
Diagram 17: The MM1 measurement mic’s impulse response timing repeatability is typically within 50 us, equating to a potential 0.7 inch inaccuracy in timing measurements, a 30x improvement over the supplied USB calibration mic, and consistent with very sharp SS&I results. This plot shows eight measurements which were taken successively and overlay one another perfectly. In this case repeatability error is close to 0 us, which is ideal.
NAD T 758 v3 Specifications
- Power output Stereo Mode: 110W (8Ω within rated distortion)
- Full Disclosure Power (all channels driven simultaneously): 7 x 60W (0.05% THD, 20-20kHz)
- IHF Dynamic Power: 137W (8 Ohms), 243W (4 Ohms)
- Total Harmonic Distortion at rated power: <0.08%
- IM distortion at rated power: <0.08%
- Damping Factor, 8 ohms: >60
- Input Sensitivity and Impedance: 750mV/50 kilohms
- Frequency Response: ±0.8dB (ref. 1kHz, 20Hz-20kHz)
- Signal/Noise Ratio: >100dB (ref. rated power at 8 Ohms, A-Weighted), >90dB (ref. 1W at 8 Ohms, A-Weighted
- Idle Power: 53W
- Standby power: <0.5W
- Unit Dimension (WxHxD): 17 1/8" x 6 13/16" x 15 11/16”*
- Net weight: 33.9lb
- Shipping weight: 39.6lb
From the bottom view, it appears that there are three cooling fans for the output section power transistors in the T758, situated close to the front panel on the bottom. They are triggered by output drive voltage level, and possibly by other factors, to help provide safe operating area protection for the output devices. During some more recent testing using line outputs with speakers disconnected, the fans turned on instantly in response to a high signal level, then turned off again instantly when the signal was removed. There were no on/off delays like one would expect if the fans were triggered by heat buildup.
I like this kind of cooling, mainly because it remains inaudible, always hidden by music, and with some design care and a little heat sink overkill (well covered, by all appearances), the chance of thermal buildup not being handled by the fans is negligible. Other than during this special testing, I have never heard the fans in the T758 running, and the top cover has never been more than warm to the touch even after extended listening workouts.
ATMOS Overhead Speaker Settings:
In response to a recent question, I had to do a little extra-deep digging into the Speaker Setup settings, specifically into the Speaker Configuration settings for ATMOS overheads. FOLLOW THIS LINK to that information in another post.