LG PM670 (50PM670T) 3D Plasma TV Review

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Mark Hodgkison gets our first look at LG's 2012 plasma range.

by Mark Hodgkinson Jul 25, 2012 at 12:00 AM

  • TV review


    LG PM670 (50PM670T) 3D Plasma TV Review
    SRP: £750.00


    It’s been a while since we last encountered a LG Plasma TV and we don’t think it would be unfair to suggest that LG are more interested in focussing their attentions on both their Smart LED TVs as well as the upcoming 55 inch, EM9690V OLED TV due later in 2012. If OLED proves the success LG obviously hope it will, we wouldn’t mind betting LG will be the first of the remaining manufacturers to drop plasma altogether and sooner rather than later.

    Still, at least at CES 2012, LG did promise an improvement in what were disappointing black levels in in the 2011 plasma ranges. The LG 50PM670 is in the upper mid-tier of their plasma line-up and is equipped with active-shutter 3D technology, the full Smart TV suite, ISF calibration controls and a fancy new stand to make it more prominent on the shop-floor. Can LG pull a cat out of the bag or will their plasma range limp weakly on its way to oblivion?

    Design and Connections

    The LG PM670 is a bit of a ‘plain Jane’ by 2012 standards but equally it doesn’t do anything to offend. The brushed charcoal bezel is actually quite thin (1.5cm at the top and sides and 2.5cm at the bottom) but the inactive pixel area of the screen kind of spoils that effect by adding a further centimetre, or so, of black border. There are some basic control buttons located on the underside of the bezel and the LG logo is emblazoned, just along, front and centre. By far the most avant garde element of the PM670’s design lays in its swivel stand which features an unusual cut-out section at the front to compliment a rather attractive two-tone, silver and black colour scheme.

    The supplied standard remote control is exactly the same one we saw with the mid-range LED TVs and doesn’t feature the backlight or the glow-in-the-dark buttons of the higher-end TVs. The new SETTINGS button makes accessing the Picture controls far easier than in last year’s LGs. There’s a recess to the rear for your index finger making it nicely ergonomic and all the buttons sit where you’d want them with the possible exception on the INFO button which is awkwardly placed to the bottom left. We actually really like the re-design, even if it is only slight.

    The PM670 doesn’t ship with either 3D eye-wear or the new (and very good) magic motion remote control but LG were good enough to send us a pair of their AS-S350 active-shutter glasses for the purpose of testing. We’ll give our thoughts on those in the 3D Picture Quality section

    The LG 50PM670T features the regular 4 HDMI ports - two of which are side-facing, along with 2 USB ports and a CAM slot – whilst the other two point outwards from the rear. Also on the back are a LAN port; D-SUB PC in with audio jack; the aerial connection; a headphone jack; a RS-232 service port; proper Scart, Component and Composite connections and an S/PDIF digital audio out.


    Before we get started on the picture controls, we would like to draw your attention to the AV Sync setting in the Sound Menu. During the review process we noticed a lot of audio lag from both HDMI sources and the internal tuner, and whilst we were never able to get it quite right, we were able to make improvements using the delay sliders in the sync menu.

    The LG PM670T has a number of Picture Modes – Intelligent Sensor, Vivid, Standard, THX Cinema, Game, isf Expert1, isf Expert2 – with the isf and THX Cinema modes providing the most accurate pictures out of the box. All the standard, front panel, Contrast, Brightness and Colour controls are present plus both vertical and horizontal Sharpness controls that we left at default in the Expert modes.

    The new 6-Axis 3D Colour Management System (CMS) is located in the Expert Control area of the Picture Menu along with both 2 and 20 point White Balance controls, some pre-set gamma curves and a choice of Colour Gamut options. Also, less usefully, in the Expert Control menu are the Dynamic Contrast, Super Resolution and Edge Enhancement options which were all set to ‘Off’. The Picture Options area houses settings for the Tru-Motion and Film Mode options that will be discussed later in the review, as well as a noise reduction feature we never found the need to engage.


    Along with Samsung, LG are currently leading the pack with their Smart TV offering. LG’s layout for their Home page is bright and colourful but, at the same time, doesn’t fall in to the Nintendo trap of looking like it was designed for children. The content is clearly presented in a card style format, with a card each for the Premium, 3D World, LG Smart World and Smart Share categories. Running along the bottom of the screen is a list of your favourite apps that can be added to and modified, at will, and is not limited to internet content.

    LG have upgraded their previous 3D Zone Smart TV app to become the 3D World card and there are around 70 items to watch encompassing entertainment, sports, documentary, kids, and lifestyle. There’s most of the usual 2D video on demand suspects and we're pleased to report that BBC iPlayer is now fully functioning on the 2012 LGs and whilst Netflix has yet to be added, there’s the likes of YouTube, Demand 5 and Lovefilm. There’s Facebook, Twitter and Skype video calling too provided the optional AN-VC400 camera/mic attachment is purchased.

    Users can hook up a hard drive to record from the internal tuners or engage in a reasonably non-frustrating spot of web browsing. Unfortunately there is no built-in Wi-Fi with this model so owners wishing to engage in a spot of wireless media streaming will need to invest in the LG Wi-Fi USB Dongle (AN-WF100), sold separately. Of course, the LAN socket will provide a wired connection to your home network and is preferred for the streaming of HD content, in any case. Owners are not limited to files on a PC as the LM670 will happily communicate with smartphones and tablets provided they’re equipped with the free app for iOS and Android devices.

    Test Results

    With just a few simple adjustments (and a couple of test patterns) we were soon on the road to hitting the industry standards. The PM670 features both a THX Cinema mode as well as isf CCC for accurate images but the THX mode is locked down so the isf Expert mode was our choice. Simply by setting Contrast and Brightness, as well as the best picture mode, we are able to make these drastic improvements:

    Greyscale tracking is now very good and the colour reproduction is even better, with only the blue primary in a position where there’s a noticeable error. Gamma tracking will be our biggest challenge but hopefully the 20 point White Balance controls will prove effective enough to flatten it closer to our 2.2 target.

    We’ve experienced one or two hitches and anomalies with the LG calibration controls in 2012 but we weren’t expecting the two point white balance controls to have become one point sliders, despite billing itself as the former. It’s fortunate there were no very large greyscale errors, else we fear the 20 point controls may not have had enough scope to achieve this kind of performance.

    We now have an almost perfectly balanced mix of red, green and blue in the greyscale and our only regret is that we weren’t able to flat-line the gamma. We could obtain a slightly better Gamma Point Graph but only at the expense of introducing banding in to real world material. We shouldn’t really complain, given these results, but we would suggest that LG reinstate the 2 point controls and replace the 20 point adjustments with a 10 point version. Let’s be honest, 20 point RGB in a domestic TV is just a bit overly fussy and no improvement on properly implemented 10 point controls.

    LG’s – new for 2012 – full 3 point, 6 axis Colour Management System (CMS) was almost redundant, given the excellent pre-calibrated results but it’s always nice to be able to tune to perfection, which is pretty much what we managed to do. We couldn’t fix the under-saturation of blue but with red and greens’ errors at miniscule levels we were more than happy with the results; at least at 100% saturation.
    Using the new CalMAN5 beta software, we are now able to demonstrate colour performance through various saturation points (we’ve chosen 25, 50, 75 and 100%) and whilst results are still very good, it does show that both red and green don’t fully saturate at lower levels. In the case of red, this will be easiest to notice in skin-tone that are a touch pallid and, with green, pale grass will be just that bit paler than it should. We’re still building up a picture of the comparative abilities of the various TVs we have in for review, in terms of hitting multi-saturation targets but we’d still class the PM670 as very good here.

    Contrast & Black Level

    Another new area of testing here at AVForums is our check on intra-frame contrast performance by way of measuring the sixteen segments of a 4x4 ANSI Checkerboard Pattern. In this way we should be able to build up an idea of real world contrast performance as well as screen uniformity; typically, with plasma TVs, the centre of the image is brighter than the outsides. First, however, we measured the On/Off contrast using a full black and 100% white pattern. In actual fact the PM670 out-performed our expectations in the on/off Test, returning a black level of 0.042 cd/m2 against a peak white output of 110 cd/m2, giving an On/Off contrast ratio of 2619:1. Having already viewed the PM670 for a number of evenings, the black reading didn’t really ring true and alerted us to some form of dimming trick that LG are trying this year. We’ll discuss that further in the Picture Quality section. The ANSI checkerboard gave us results much more in line with what our eyes had suggested with real world content, although in actual fact it probably paints a more dismal story than general viewing would give.
    Unlike the plasma’s from Samsung and (again) in particular Panasonic, the LG PM670 was unable to hang on to either its brightness or black level with mixed content on the screen. With an averaged black level of 0.13 cd/m2 against a peak white output of 65.45 cd/m2, the PM670 provides a very modest ANSI contrast of 485:1 putting it behind even the likes of its own IPS LED/LCD panels that are hardly famed for their dynamic range. Like black level measurements, this doesn’t give a full account and the dimming trick would give a good impression of black in very dark scenes, in most cases.

    Video Processing

    Starting with the SMPTE 133 pattern, the PM670 was able to cleanly scale a 576i signal without any loss of detail or unwanted ringing. The 50PM670 also scored well when it came to video deinterlacing with jaggies only appearing when the line was at an acute angle in the first test on the HQV disc. In the second test the motion adaptive deinterlacing was also good with slight jaggies only appearing on the bottom bar of the three moving bars.

    The 670 also performed well in the film detail test and correctly locked on to the image resulting in no aliasing. In the cadence tests the 55LM960 correctly detected both the 2:3 (NTSC - USA/Japan) format and the 2:2 (PAL - European) format and also quite a few obscure ones. The LG also had no problems handling film material with both horizontal and vertical scrolling video text, correctly displaying the words without any blurring or shredding.

    With our Blu-ray player set to 1080i the display correctly deinterlaced and displayed both the video and film resolution tests (provided the aspect ratio is set to Just Scan) and showed good scaling and filtering performance as well as good resolution enhancement. The LG 50PM670 also had no problems in showing video text overlaid on film based material and also handled 24p content without any problems.

    Using the S&M disc we checked the headroom performance of the 670 from reference white (video level 235) up to peak white (video level 255) with it unable to quite reach peak white but easily attaining reference white. In addition, the 50PM670 also correctly showed detail down to a video level 17 and reference black below that to video level 0, as long as you had Black level set to High. If you used the Low setting the blacks will appear darker but you will be crushing them and you will lose shadow detail.

    Image Retention

    We inadvertently used a new method of testing here as we had intended to use a multi-burst pattern to test image retention but having run the ANSI test just prior, we found that the checkerboard pattern had left a lasting impression on the LG PM670. In fact, we found that it took just over 8 hours of normal TV watching to totally get rid of it, which is far worse than our (unmeasured) recollections of either the Panasonic or Samsung 2012 plasma TVs.

    Gaming Performance

    LG have a bad reputation with gamers for input lag and the PM670 will do little to change that. Using our specialist device, we measured at lag at around 65 milliseconds, which is definitely on the high side. The lowest number we could get was by using Game mode with the HDMI 1 input relabelled to GAME, renaming to PC made no difference.

    Energy Consumption
    • Standby: 0.0W
    The following measurements were taken with a full screen 50% white pattern:
    • Out-of-the-Box - APS Mode: 163W
    • Calibrated - isf Expert Mode: 259W
    • Out-of-the-Box – 3D Vivid Mode: 306W
    • Out-of-the-Box – 3D THX Mode: 290W

    Picture Quality - 2D

    The LG 50PM670T possesses most of the usual strengths of plasma technology and,also, pretty much all of its weaknesses in equal measure. The slightly over-fussy 20 point white balance controls had enabled us to gain a reference greyscale performance and the resultant neutrality, on top of which the colours are built, certainly provided a very pleasingly accurate set of images. Motion handling was, as expected, very clean and save for the odd instance of dynamic false contouring – most easily visible on skin tones – our biggest regret about our review period with the PM670 is that there was not enough football on, at the time, to fully appreciate the benefits of the fluidity.

    The slight improvement in black levels and contrast performance was a welcome one although the PM670 still trails both Samsung – and in particular Panasonic – plasma TVs by some margin in that department. Shadow detailing was very good, with the 670 able to resolve most of the dark portions of the picture whilst displaying the brighter elements but it does have some issues when on-screen content goes very dark. We quite often noticed an unusual green pixellation to the screen during very low light scenes and particularly on black menu screens around white text. Had it not been a plasma TV we were reviewing, the way portions of the screen became illuminated in green would have been attributable to a problem in local-dimming backlight algorithms but as plasma is a self-illuminating technology, that isn’t the case. However, they do seem to be trying some kind of dimming trickery for portions of the screen when the material is very dark. It didn’t happen so often that it could be classed as a fault with the panel but it was eminently repeatable, as seen in the screenshot of a Netflix information display interface, below. The size and shape of the noise was entirely dependent on which elements of the picture it intruded upon so it’s certainly an unusual issue and one we’d like to see LG look in to further. At least the blacks barely fluctuated under pressure and if we did notice any ‘floating’, it was in very dark viewing conditions. We did, however, spot a fair number of brightness shifts with higher APL (average picture level) content that was akin to both the ‘brightness pops’ and ‘floating brightness' anomalies seen on recent plasmas from the other manufacturers.

    Although not strictly a picture quality issue, and something we alluded to earlier, but the LG PM670 does suffer a lot of audio lag via HDMI in the more accurate THX and isf modes. We clocked it at an eye-watering 181 milliseconds and voices were very noticeably out of sync with lip movements. There is the facility to correct this, somewhat, in the Sound menu under the AV Sync option but it’s quite a crude control and we could never get it quite where we wanted. By bypassing the internal sound and using an optical connection to our AV Receiver we were able to nullify the problem but that’s not going to be an option for everyone.

    The LG PM670T probably isn’t going to be the favoured choice for late night viewers

    The LG PM670T probably isn’t going to be the favoured choice for late night viewers that really like to turn the lights down low but it does offer a very appealing choice for those who watch in more conventional conditions. It’s not a great performer placed opposite a window, although to be fair, not many are but it is very reflective and some consideration of placement should be made if daytime viewing is a concern. Overall, we do see an improvement over last year’s LG plasma range - albeit a slight one – and we’ll take progress over the alternative, every time.

    Picture Quality - 3D

    In stark contrast to our high regard for LG’s passive Cinema 3D LED TVs, we had a fair amount of criticism for the active-shutter system built in to their plasma range in 2011. We’re pleased to report some improvements in 2012 but performance remains less than stellar. Our biggest complaint, by far, was reserved for the atrocious, crosstalk ridden presentation of side by side content at 50Hz. That's basically all 3D broadcast in the UK but, thankfully, LG have managed to cut down on the ghosting this year. Like we saw with the Toshibas recently, this seems to have come at the expense of a bit of a resolution loss, by applying a blurring technique but it is most definitely an improvement. 3D Blu-ray fared better, with no noticeable loss of detail but there was, again, a fair amount of crosstalk and some floating blacks in dark and high contrast scenes. The 3D eyewear was very comfortable to wear and had just enough shielding from ambient light in a dimly lit room.


    OUT OF

    The Good

    • Lovely, fluid motion
    • Very accurate colours in best picture modes
    • Tons of Smart content
    • Great value for money
    • Excellent menu system

    The Bad

    • Lacks dynamic range
    • Green noise in blacks
    • Audio and input lag
    • Luminance shifting
    • 3D could be better
    You own this Total 0
    You want this Total 0
    You had this Total 0

    LG PM670 (50PM670T) 3D Plasma TV Review

    The LG 50PM670 isn’t really setting the world on fire with its design but the cut-out, two-tone design of the swivel stand at least shows they paid some consideration to how it will look on the shop floor. The newly slimmed down remote remains a pleasure to use, even if the 670’s version is shorn of the backlight of the upper tier ranges. There are no such austerity measures when it comes to the connections, however, and we have what we’d consider to be the full complement of 4 HDMI inputs around the back.

    Both the menu system and Home page are bright and bold without ever slipping in to the trap of appearing too dumbed down and LG’s smart portal is cleverly designed in a card style layout, making content easy to find and access. There’s certainly plenty of on-demand content to view from the Home page and even though the new Magic Motion controller isn’t included in the box, we never really found it a problem to navigate the features with ease and owners could always utilise the free app for Android and iOS if the supplied controller doesn’t meet their needs.

    Once we’d performed a basic set up and got ourselves out of the awful, default APS mode, pictures took on a whole new light. The PM670 was actually very impressive in its unaltered THX and isf modes, which is just as well because LG have (possibly inadvertently) removed the 2 point White Balance control, replacing it with a one point adjustment. As it was, that was enough, in combination with the OTT 20 point sliders to bring a ruler flat greyscale response. Colour reproduction was already excellent but we managed to improve it slightly using the in-built colour management system. Video processing was typically excellent from LG and it flew through our testing regime with ease.

    Our ANSI contrast test returned extremely disappointing results with a ratio of just 485:1, from an averaged black level of 0.13 cd/m2 but it did perform much better in the On/Off test where the black level of 0.042 cd/m2 is far more respectable. Real world viewing would suggest the actual black level is somewhere between the two – albeit closer to the higher number – but thanks to the unusual dimming tricks (discussed below) the PM670 performed moderately well with darker content.

    The PM670T certainly provide some very high quality viewing, particularly with fast moving action where the panel's ability to handle motion with silky-smooth clarity really comes to the fore. Once calibrated, colours were very accurate but unfortunately the mediocre contrast performance is a carryover from last year although it does appear LG are trying some form of pseudo dimming tricks – very unusually for plasma – but that quite often results in a lot of green noise around picture elements in darker scenes. We did also notice quite a number of brightness pops and fluctuations when there were higher luminance images to deal with. Neither problem was overly obtrusive, in fairness, and most of our time was spent in admiration of the pictures on offer, once we had corrected the lip-sync issues with the aid of our AV receiver.

    In stark contrast to our high regard for LG’s passive Cinema 3D LED TVs, we had a fair amount of criticism for the active-shutter system built in to their plasma range in 2011. We’re pleased to report some improvements in 2012 but performance remains less than stellar. LG has managed to cut down on the ghosting on Side by Side material this year but, as we saw recently with Toshiba, this seems to have come at the expense of a bit of a resolution loss - by way of applying a blurring technique - but it is most definitely an improvement. 3D Blu-ray fared better, with no noticeable loss of detail but there was, again, a fair amount of crosstalk and some floating blacks in dark and high contrast scenes. The 3D eyewear was very comfortable to wear and had just enough shielding from ambient light in a dimly lit room. Unfortunately the noticeable audio lag through HDMI translated in to the gaming side of things also, albeit not to quite the same extent, but an input lag figure of around 65 milliseconds is hardly a gamers’ delight.

    The LG PM670 is certainly lagging behind the plasma ranges we’ve seen so far from the competing manufacturers in terms of most aspects of picture quality. It simply doesn’t have the dynamic range to compete but it does offer a very decent choice for sports lovers with its beautifully fluid representation of motion and accurate colours. The PM670 also has price on its side; with current online costs as low as £630, it’s a value proposition yet still packed with features. If your demands aren’t for late-night movie watching or gaming and you can get around the lip-sync issues, you might want to consider checking out the LG 50PM670T.

    Suggested retail price when reviewed: £750.00

    The Rundown

    Contrast/Dynamic Range/Black Level


    Screen Uniformity


    Colour Accuracy


    Greyscale Accuracy


    Video Processing


    Picture Quality


    3D Picture Quality


    Sound Quality


    Smart Features


    Build Quality


    Ease Of Use


    Value for Money




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