Panasonic TX-40AS640 LED TV Review

We miss Panasonic plasmas, especially after the results of our recent TV comparison event. But there’s no point crying over spilt milk: the Japanese manufacturer isn’t going to reverse its decision to exit the PDP (plasma display panel) market, and its television future is exclusively LED LCD, at least for the time being. When we reviewed the Panasonic Viera AX802 4K Ultra HD series some four weeks ago, we declared it one of the best LED TVs we’ve tested. Now it’s the turn of a more modest proposition to go through grilling.

Panasonic TX-40AS640

The Panasonic AS640 is a model that’s exclusive to Currys and PC World in the UK, coming in three screen sizes: the 40-inch TX-40AS640B (which we’re reviewing today), the 48-inch TX-48AS640B and the 55-inch TX-55AS640B. Features include direct LED backlighting, dual core processor, active-shutter glasses (ASG) 3D technology, inbuilt WiFi connectivity, and Freetime catch-up TV service.

Design

Differing from yet another run-of-the-mill, industrial-looking design characteristic of Panasonic flat-screen tellies of yesteryears, there’s an attractive two-tone theme going on with the Viera TX-40AS640. The top and bottom borders of the bezel carry a brushed metallic silver finish, whereas the sides are polished black. Being a direct-lit LED TV, the chassis is obviously chunkier than most edge LED TVs on the market, but we’re not one to complain if it contributes to better picture and sound quality.

Pedestal stand, remote controls and 3D glasses

The LCD panel sits on a low-profile stand with an open-frame, rectangular base. Build quality reflects the affordable price point.

Connections

Rear connections
Rear: 3x HDMI, 2x USB, component, RGB Scart, Freeview HD aerial, LAN & audio outs

Calibration

Note: We calibrated our Panasonic TX40AS640B review sample in [True Cinema] mode (the most accurate out-of-the-box preset) using CalMAN 5.3, the industry-leading video calibration software.

Greyscale

In [True Cinema] mode, the default [Colour Temperature] of “Warm2” yielded decent greyscale tracking, though red channel was deficient throughout:

Pre-calibration RGB Tracking
Pre-calibration Delta errors
Pre-calibration RGB tracking and delta errors (dEs)

The 40in Viera AS640 offers both 2-point [White Balance] controls and a more precise 10-point system. We used the former to bring RGB balance in the ballpark of D65, then utilised the latter to flatten out any kinks in the tracking:

Post-calibration RGB Tracking
Post-calibration Delta errors
Post-calibration RGB tracking and dEs in [True Cinema] mode

After calibration, delta errors (dEs) dropped below 2 (the commonly acceptable dE cutoff before inaccuracies become visible to the human eye is 3) across the entire luminance range, ensuring tint-free images be them dark or bright.

Gamma

In our review of the Panasonic AX802 4K Ultra HD TV, we praised the company for embracing 2.4 gamma which has been decreed by no less an authority than the International Telecommunications Union (ITU) as its recommended electro-optical transfer function (EOTF) for flat-panel HDTVs used in a dark room for studio mastering.

Pre-calibrated Gamma tracking in [True Cinema] mode Post-calibrated Gamma tracking in [True Cinema] mode
Pre-calibration gamma tracking (2.41) Post-calibration gamma tracking (2.4)

We’re pleased to report that this standard-conforming practice has also dripped down to this year’s midrange Vieras such as the TX40AS640 whose [Gamma] in [True Cinema] mode defaulted to “2.4“. And when measured, overall gamma tracked fairly close to 2.4 too, contributing to a contrast-rich picture with realistic tonal transition from black to white.

Colour

We’re not sure if any ingredient of Panasonic’s “Super Chroma Drive” technology so beautifully implemented on the high-end AX802/ AX800 is present on step-down models, but colours were outstandingly accurate on the AS640 even before calibration. While the TX-40AS640B’s colour management system (CMS) allows for adjustment of all six primary (red, green, blue) and secondary (cyan, magenta, yellow) colours, we only needed to tweak blue to achieve the following results:

Post-calibration Colour saturation tracking in [True Cinema] mode
Post-calibration colour saturation tracking

Delta errors (dEs) were below the humanly perceptible threshold of 3 across all the measured saturation tracking points, which means colours should look supremely authentic in real-world viewing.

Post-calibration colour errors in [True Cinema] mode
Post-calibration colour errors (<3 not appreciable to the eye)

Benchmark Test Results

Dead pixels None
Screen uniformity Fantastic for an LED LCD TV
Overscanning on HDMI 0% with [16:9 Overscan] set to “Off
Blacker than black Passed
Calibrated black level (black screen) LEDs shut off
Calibrated black level (4×4 ANSI) 0.048 cd/m2
Black level retention Auto-dimming with full black screen
Primary chromaticity Very good
Scaling Very good
Video mode deinterlacing Effective jaggies reduction
Film mode deinterlacing Passed 3:2/480i & 2:2/576i with [Film Cadence Mode] on
Viewing angle Decent for VA LCD
Motion resolution 800 with [Intelligent Frame Creation] engaged; 300 otherwise
Digital noise reduction Optional; effective when engaged
Sharpness Defeatable edge enhancement
Luma/Chroma bandwidth (2D Blu-ray) Full Luma; chroma vertically softened
1080p/24 capability No judder in 2D or 3D
Leo Bodnar input lag tester 59ms in [Game] mode
Full 4:4:4 reproduction (PC) [1080p Pure Direct] improved chroma resolution, but not fully

Power Consumption

Default [Normal] mode 36 watts*
Calibrated [True Cinema] mode 41 watts
Standby <1 watt

*Note: [Ambient Sensor] was enabled by default in the out-of-the-box [Normal] mode.

Picture Quality

The Panasonic TX-40AS640’s VA-type LCD panel produced a deep shade of blacks by LED LCD standards: native black level measured 0.048 cd/m2 on a 4×4 ANSI chequerboard pattern with peak white pegged at 120 cd/m2. Backlight and screen uniformity on our review unit was fantastic – we’re sure the direct LED backlighting system played a major role in this. We witnessed some VA black trailing and overdrive errors which fortunately were pretty much invisible in non-game photorealistic content.

VA subpixel structure
Subpixel structure indicating VA matrix

Whereas [Adaptive Backlight Control] on the Viera TX-50AX802B 4K TV comes in three strengths (“Min“, “Mid” and “Max“), the same option on the TX40AS640B is merely an on/off toggle, which is hardly surprising given that the Panasonic AS640B is only equipped with frame dimming and not pseudo-local dimming. As a consequence, engaging [Adaptive Backlight Control] would cause the whole panel including brighter elements on screen to dim down when the frame dimming kicked in, leading to excessively darkened midtones and skewed gamma tracking. Since the AS640’s black-level response was good enough natively, we saw no reason to use [Adaptive Backlight Control] at all.

Although we really liked last year’s Panasonic TX-L42E6B which we called the best LCD-based display we’ve seen from the company at that time (it’s since been surpassed by the Viera WT600 and more recently the AX800/ AX802), we did lament the E6’s low motion resolution and lack of 3D capabilities. Well, both complaints are no longer valid on the TX40AS640.

Motion-wise, the 40AS640 is blessed with Panasonic’s motion-compensated frame interpolation (MFCI) technology in the form of [Intelligent Frame Creation], boosting motion resolution (as determined via the horizontally scrolling lines pattern in Chapter 31 of the FPD Benchmark Software test disc) to 800 from the baseline LCD level of 300. We preferred the “Min” setting which introduced the least interpolation artefacts and soap opera effect to 24fps material.

We did spot a small anomaly during the numerous World Cup live football broadcasts we watched late into the evenings. With [Intelligent Frame Creation] disabled, we saw some microstutter (panning shots appeared mildly jerky/ unsmooth) with 50Hz video content through the internal Freeview HD tuner and also an external Sky+HD box. We think it might have something to do with the Freetime integration – summoning the user menu worsened the stutter as the menus slid in. In any case, the jerkiness was fairly subtle (hence “microstutter”), and was easily cleared up by engaging [Intelligent Frame Creation].

3D is of the active flavour on the Panasonic TX-40AS640B which ships with two pairs of active-shutter glasses (ASG) included. Using our own custom-authored 3D resolution test pattern, we established that the 40″ AS640 couldn’t resolve full HD 3D resolution, a not-so-desirable trend that’s increasingly common among active 3D displays in recent times. The TV was essentially throwing away half the vertical resolution in the third dimension, resulting in visible line twitter and jaggies – even the characters in the on-screen menu appeared jagged in 3-D mode.

3D resolution

Of course, given the apathy among the general public towards 3D, not to mention the popularity of passive 3D technology despite similar limitations in resolution, we don’t think half-res 3D would put many potential buyers off the TX-40AS640. There wasn’t much crosstalk, and where present the ghost images were quite faint, making them easier to ignore. As we’ve come to expect from Panasonic, the Viera AS640 handled all types of tri-dimensional content – 50p, 60p or 24p; film or video – flawlessly without exhibiting any judder.

Input lag

For playing video games, the TX40AS640B wasn’t as responsive as the Samsung UE40H6400, let alone the super-low-lag Sony Bravias. Our Leo Bodnar input lag tester returned a figure of 59ms with [Game Mode] activated, rising to 92ms outside [Game Mode]. Enabling [Intelligent Frame Creation] added 8ms (half a frame) to the lag time.

Verdict

The Panasonic TX-40AS640 is a lovely television that delivers lush and absorbing images, thanks to deep blacks, outstanding uniformity, natural colours, 2.4 gamma and high-quality video processing. Some minor 50Hz motion instability (which can be eradicated by enabling [Intelligent Frame Creation]), lower-res 3D and higher input lag don’t stop the TX-40AS640B from being a bit of a bargain, especially when it’s available to buy for £500 at this time of publication.

Ironically, being the highest-ranked model in Panasonic’s 2014 full HD 1080p Viera TV lineup to feature VA LCD panel, the AS640 may actually outperform step-up models like the AS740 and AS802 series (both IPS) in terms of picture quality. In the coming months we’ll try to review one of them to see if this is true.

Highly Recommended

34 comments

  1. Hi, thanks for the review. Do you have any clue whether the AS650 models (rest of europe) are similar to AS640? In addition, do you know if the the larger AS640/AS650 TVs feature similar panels (100Hz, VA, Direct LED)?

    Thanks.

  2. Nice review as usual, Vincent. I wish you’d still include the menu screens though as Panasonic have a new design this year with customisable background colours IIRC.

    Panel looks like PSA from a Chinese manufacturer, but the 48″ size is throwing me (thought it would be Samsung). Can only guess that it’s coming from CSOT….?

  3. …and also, would you think it’s fair to say that Panasonic TVs are more consistent in quality than Sony?

    Hurts me to say it as I’m a Sony man at heart (but undersaturated reds on the W829, the W955 flagship! and those 2012 models we don’t like to mention…)

  4. @Vincent
    Do you think the full led solution with local dimming on the AS800 can compensate for the IPS panel?
    If I’m not mistaken, Panasonic has chosen full led IPS for its top range AX900 model too.

  5. Vincent so the 3D on this active set is the same resolution as PASSIVE TV’s ?!!!!!

  6. Another LCD reveiw where the first words are about plasma, more negativity towards 3D in general again . I think I’m going to have to give up on audio visual forums for a while ;-

  7. @3D lover Well, it’s just the reviewer’s view, not everyones, and Panasonic do have a long heritage in Plasma, so it’s justified. As for 3D, it is on the sharp decline so I think it’s fair to say that. Look at how few 3D Blu-ray releases are planned for the year ahead. I think we all know where that’s going….

    @nenito2k The W829 by Sony has the same kind of half-res Active 3D and I think Samsung do too on the mid range models. Not sure of the technical reason why though.

  8. 3D lover , aka panman40

    @ loopthrough, well I don’t see it that way mate as you know… Say something’s dead enough times and it will be, I just don’t see the need to keep on about plasma when its an LCD reveiw . There’s quite a few upcoming 3D films, I’m looking forward to Avatar 2 though. Got several animations on pre order.

    There is one review site that’s pro 3D and I will be spending more time there I think.

  9. So putting [Intelligent Frame Creation] to [Min] increase the motion resolution to 800 WITHOUT the
    SOE effect ?

  10. @nautilus7: As far as I’m aware, AS650 is IPS panel, whereas the AS640 is VA.

    @loopthrough: Yeah, looks PSA, though not sure on the exact vendor. I’ll have to open up the TV to find out, but if I do so, Panasonic won’t be sending any more review samples to me in the future! :-)

    Re Panasonic vs Sony… it depends… we haven’t reviewed any Panasonic IPS this year. ;-)

    @njs: Only one way to find out… when we review it. :-)

    @nenito2k: I know!!!! Might as well go passive 3D, right?

    @3D lover aka panman40: As loopthrough correctly pointed out, I mentioned plasma in context of Panasonic. You don’t see me opening Sony and Samsung LED LCD reviews with references to plasma.

    Out of interest, which review site is pro 3D? Do they calibrate 3D?

    @ford99: There’s still very mild SOE, but we don’t advise using IFC/ [24p Smooth Film] for 24fps films anyway.

    Warmest regards
    Vincent

  11. I like to hang out at Home Theater Forum where they have a dedicated 3D thread which doesn’t talk constantly about how 3D is dead or dying ot unwanted by the general public, i absolutely agree with Panman40 that HDTV Test is talking down 3D too much instead of trying to talk it up and get more interest going.

    Now Hollywood is trying it’s best to kill off 3D with all these depth only 3D conversions, i call them 2 and a half D releases, i think if James Cameron keeps to his promise and is more aggressive with Avatar 2 it will bring a resurgence in the format and more filmmakers will use depth and popout to create interesting and entertaining films, we need review and cinema sites to keep people interested in 3D by talking it up and not tlaking it down, if you are truly a 3D fan then talk it up, don’t just put it down all the time.

    I used to be a member of HDTV Test, i left because frankly the forum was dead, just half a dozen or so regulars taking part, it was fun while it lasted but i also felt there was a bit of Pro Panasonic bias and no love for 3D, i also felt my comments were not really taken on board, for example why is there still no link to ALL the projector reviews, a simple link to all reviews would be easy enough to do.

    On the bright side this site got me more interested in proper calibration, i now have my own meter and software so i can properly calibrate my television and projector, so i thank it for that.

    Best wishes to all the folks who still hang out at HDTV Test.

  12. P.S. Excuse the typos, i never check em’ before posting.

  13. One more thing, you use Calman, read this and start using BT.1886, it makes much more sense than a gamma of 2.4 and it especially suitable for displays such as the one reviewed here.

    http://www.spectracal.com/Documents/bt.1886.pdf

  14. @panman40 Fair play mate but in the eyes of the average consumer, 3D is dead. Although I do admit it’s partly the fault of it not being pushed properly. There was no proper pact between film companies and manufacturers/stores so it confused the general pubic.

    @Vincent Teoh Ah, ok, I guess I’ll have to decide then. Probably on Sony’s favour though! Panasonic have things that annoy me (ugly menus and the like)…

  15. I own this tv and while this test may show that the 3d is only half resolution it is vastly superior in image quality in 3d mode to my previous hd ready samsung 3d plasma tv and as good as ive seen on a smaller screen tv.Ive also been on another forum where the motion panning problem was also mentioned.
    Im of the opinion that this isnt a fault of the tv as i cant see it at all on my tv with IFC control set at minimum i also read that world cup football broadcasts have been converted from 60hz to 50hz for that is the tv standard used by most countries viewing the world cup and i think that this has also played a part.
    Its a great tv there is also a review of the 48 model as welll on the net and it also gets a great review.

  16. Would it be fair to presume that much of this review could also apply to the 48″ and 55″ models of the AS640B range? Or should I consider these models on their own merits?

    Does the same apply generally, for other manufacturers?

  17. @gunflash: Yes, the 3D is very good despite the halfed vertical resolution.

    You can mention AVForums here safely without being reprimanded. We welcome discussion. :-)

    @TimRex: There shouldn’t be any significant difference between different screen sizes within the Panasonic AS640 range, although there’s a possibility that the larger models are full HD 3D.

    We will usually clarify if the findings are not applicable throughout the range.

    Warmest regards
    Vincent

  18. @Foxy Mulder
    They almost certainly are using BT.1886 black level compensated gamma calculation, otherwise the darkest few shades would get clipped. I don’t believe that hdtvtest is not checking a black level pattern to see that the bottom few shades are still there after calibration.

    In HCFR, I just tick “use black level compensation” for gamma, then it gives me the new brighter gamma targets that take your black level into account therefore adding the black level as an offset as per BT.1886.

    @gunflash

    I think you are correct in saying that the World Cup is being converted from 60hz to 50hz which is why there is the occasional motion anomaly even on a perfect display. I noticed the first day of coverage was crudely converted from 60hz to 50hz with lots of motion judder. After this they seemed to switch to a better motion compensation algorithm which is almost perfect, although tricky scenes such as the ball travelling across a highly detailed crowd tends to cause the ball to stutter a bit, which is understandable. Although I wonder whether this just an MPEG encoding artefact and whether they are actually shooting at some framerate which is divisible by both 50 and 60, such as 300.

  19. Thanks for the great review :D! I was wondering, how does this panel compares to the Sony KDL40W605? For receiving both excellent reviews one would wonder why to choose the far more expensive Panasonic over the Sony (aside from the 3D functionality)? The Sony even seems to win within for its low input lag. Love to hear your opinion.

  20. And I can only get the TX40AS640E in Holland, not the B version. On some websites I read it has an IPS panel, could this be correct?

  21. Hi
    I was hoping to read something on the sound quality of the TV. To me thats just as important. Havent bought a TV since hmmmm, 6 years? i usually stick with panasonic because the sound quality was always much better out the box than other sets (as well as great screens)
    I dont want to attach some external sound system.
    My existing panasonic has switch on issues for the last year, doesnt always come on so looking for a replacement, plus this is £450 in a large electrical store right now.

  22. Great review as allways! I am considering H6400 against the AS640. Which one has the better picture quality for films and football? Which one has the better SmartTV features?

  23. Hi Vincent,

    Along with Martijn, I would also like to know if the AS640 has better picture quality than the W605. They are both a very similar price in Currys at the moment. I went to check them out today and the salesman advised me that the W6 is a better buy. Which would you choose? Many thanks.

  24. Hallo Vince.

    Which one would you pick, this Panasonic or the Samsung UE40H6400?

  25. Hi, does anybody know what are the exact parameters which need to be applied during the video conversion / transcoding of the nonsupported file/mkv mostly so it can be played in media player? Some mkvs namely play and some don’t. I’ve tried on my own, mkv, x264, aac, custom and default presets, but with few success. It seems to be very picky. I used mediacoder, FF and Any Video Coverter Ultimate.

  26. Hello everyone,
    Is it Panasonic 48as640 better than Panasonic 50as600, basicly the main difference is 3D.

  27. Hi, can you post the detailed settings of the tv?

    Greez

  28. @Martijn. I would suspect, that the 640B is the British model, whereas the 640E is the Western European model :-) There may be slight differences, but in essence the models are identical.

  29. Which one to choose between Panasonic TX40AS640B & Samsung UE40H6400?

  30. Write to settings on the TV for movies.
    Thank you.

  31. Hi

    We still need an answer to Fabian’s question!

    I’m about to install the 48AS640 and it would be much easyer with your settings ?

    Happy Holidays

  32. Do not buy 48AS640! You will make a big mistake!

    Content via a 50Hz signal is near unwatchable owing to a very distracting judder. Whatever you do with the IFC, set to a minimum, medium or even at maximum, judder is always there. It’s not just the British versions, I am from Croatian. I’ve tried multiple TVs in different stores, and all have the same problem. I can not understand how someone can recommend this 48AS640. I think the problem is not in the software. New update Ver. 3096 it has not improved anything. Panasonic is aware of this, but is silent…The TV goes on sale. I will never buy a panasonic.

  33. I think this kind of reviews should be only informative. The buyers should only open their eyes and choose what they like. I have a Panasonic TX-40AS640, I’m only satisfied with it. Of course, it’s better than samsung 6400, i have a friend which has one. I hate the it. I also have a 47 inch philips 6007. I think it has incredible image quality(I bet the reviews are bad :):):) ) Philips has bad smart tv , can’t play dts.. etc but i love it. My advice is to choose what you like, with your eyes. I think Sony and Philips TV’s are way better than Samsung & Panasonic in terms of image quality. Be careful with internet reviews, they are just numbers.

  34. Hi. can you please share the calibrated values? It makes no sense to buy a calibration solution for one time usage…maybe two. thanks

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