TBC means "Time Base Corrector" and DNR means "Digital Noise Reduction". Those two (relatively rare) features are what prompted people to engage in bidding wars up to $600 for old JVC svhs vcrs and the Panasonic AG1980 a few years back when dubbing your VHS collection to DVD or AVI became a hot hobby. Today, a large percentage of VHS conversion projects have been completed, so many of those higher-end VCRS have been put back into circulation. Also, the DVHS vcrs (which were ignored/unavailable initially) have gone into circulation, adding more choices and dropping prices. (The Panasonic AG2560 I mentioned is a sturdy, well-built option for a normal everyday vcr: it does
not include any TBC or DNR, and it is
not a true SVHS model.)
Like nearly everything we discuss on forums, the "need" for a TBC/DNR equipped VCR is highly subjective, and a lot of people get talked into buying one just because a few forum gurus recommend them. I am guilty myself here, and recently received a lot of pushback from people buying these machines at my suggestion and being disappointed when they don't work so great. So before I go any further describing the benefits of TBC/DNR, let me make a very clear disclaimer:
do not go hunting down one of these used VCRs unless you truly feel you need one and are prepared to pay for/deal with the possible repair requirements of used electronic items. Aside from the usual aging issues of older VCRs, keep in mind there was an absolutely ridiculous run on these units from 2003-2006, when practically everyone who read the forum musings of a handful of gurus (not me, I'm late to this party
) just "had to have one". This drove prices thru the roof, and relative scarcity means the same group of several hundred vcrs have been passed from user to user and beat on to transfer huge tape collections. Today, more than ever before, when considering a used high-end VCR you
must be aware we are talking about
seriously used gear. It will likely be worn, and very likely need repair. The sole exceptions being the DVHS vcrs, which are at least ten years newer and for some reason did not catch on with VHS>DVD enthusiasts until the initial craze died off (so they're typically in close to mint condition).
With that warning out of the way, here is why you might want to gamble with one of those specialty VCRs: they are the only consumer models with built-inTBC/DNR. If your tape collection is old enough and large enough, you probably have more than a few tapes that could benefit from being processed thru those features. For one thing, they "clean up" a VHS signal to make it more compatible with the somewhat picky digitizing circuits in many PC boards and most early DVD recorders (including the Pioneer 310/510/220/225/520). VHS tapes often include signal irregularities that are invisible to our eyes and irrelevant to older CRT televisions like a Sony Trinitron. But these irregularities can totally confuse a picky digitizer and often look dreadful on a modern LCD screen like a Samsung. A vcr with TBC/DNR can often minimize or completely eliminate those signal issues.
The TBC feature helps primarily with flagging or bending distortion of vertical objects like doors and buildings. It can also reduce jittering or juddering, and some forms of static that look like tracking distortion along edges of high-contrast objects. Depending on the specific VCR model, some TBC circuits will also help minimize audio lip-sync issues. The DNR feature completely smooths out color issues, often making a night-and-day difference in color noise and color blur (common to reds especially). But this "improvement" is highly subjective: it depends on your particular tapes, and how your own eyes perceive various types of video defects. The dancing splotchy color noise that drives some people crazy is totally acceptable to others, who would rather watch a "noisy but natural looking" tape transfer than one that looks "spotlessly clean but strangely fake". There is a price to be paid for "cleaner-looking" video: it looks kinda weird, because it goes thru two digitizing passes: one in the VCR, then again in the DVD recorder or PC.
The TBC/DNR circuits in the VCR aren't exactly professional-class $10,000 quality: they work amazingly well but they have performance limits, usually visible as plastic-looking faces on people and a hard-to-describe unnatural quality in movement. More often than I'd like, I end up making two VHS conversions: one with a TBC/DNR vcr, and one using a normal everyday vcr. Depending on the television display and size, I might prefer one or the other, so for future-proofing insurance I make both if the tape is really rare or important to me. The only way for
you to know which result you would prefer is to try both and judge with your own eyes. As a very rough guide, based on my own experience, the tapes that benefit most from TBC/DNR are recordings from analog cable TV made prior to 2004, analog camcorder tapes like VHS-C, and various bootleg or second-third generation tapes. Note the TBC built into high-end VCRs is not quite the same as an external TBC box like the DataVideo TBC-1000 or AVT-8710. External TBCs will allow you to make DVD transfers of your commercial copy-protected tapes, the TBC built into a VCR
will not. Most cases of lip-sync audio drift are best cured with an external TBC, although some VCRs do a remarkable job with this (lip-sync drift is more common when using a PC than a DVD recorder).
In some cases, such as
really poor multi-generatiion copies, you have to change the digitizing side of the equation. Really rotten signals cannot be improved much at the source, but you can get significant improvement by changing the DVD recorder or switching from a PC to a DVD recorder. Most PC boards and most DVD recorders made prior to 2006 just can't handle lousy tape sources, even if you use a TBC/DNR vcr and activate those features (which can make things worse instead of better). JVCs made before 2006, Pioneers made before 2005, and some Sony DVD recorders are especially sensitive and should be avoided when making DVDs from poor tapes. Pioneers and Panasonics made after 2005 are much more solid with crummy tapes, they will encode an exact DVD copy of bad source material with no added digital distortion even if the source VCR is a normal one (sometimes preferable to a TBC/DNR vcr when playing some tapes). The worst-case scenario I've seen is a Pioneer 220/520 trying to digitize a copy-protected commercial tape: really ugly results even with an external studio TBC hooked in. If you have a lot of commercial tapes to digitize, consider using something other than a Pioneer 220 (or just buy the commercial DVD versions).
The current Magnavox H2160 and 513 fall just slightly short of the late-model Pioneer and Panasonic recorders in this regard. The Magnavox encoder design occasionally suffers unpredictable reactions to TBC/DNR vcr sources: you can get a split-second picture roll a couple of times an hour. This is usually not a big deal but it does annoy some users who don't expect it (you don't see the glitches during the transfer, only when viewing the result).
