|How to Make Better VHS Dubs from DV Movies|
A CreativeCOW.net "Basics of Video Series" Tutorial
Doug Graham sees the question 'how can I make better VHS dubs from my DV movies?' so often that he's put together a comprehensive response.
TEN TIPS FOR BETTER DUBS:
We're all thrilled by the clarity of our DV equipment, and happy as clams that all that quality stays with us from the camera tape all the way through editing and on to the edited master tape. We're happy, that is, until it comes time to dub the master to VHS for delivery to the client. The video quality takes a big hit. What can we do to make the VHS dub look as good as the DV master?
The short answer is, "Not much." VHS has much lower horizontal resolution than DV. In addition, it has a lower bandwidth for color information. No matter what you do, your VHS dubs are NOT going to look as good as your DV master. If you really want to compare the end quality that using DV cameras and editing give you, compare a VHS dub made from a DV tape to one made from one of your old S-VHS or Hi8 master tapes. You should see a noticeable improvement. But even though your VHS tape can never look as good as your DV master, there ARE things you can do to improve the results. Here are some things that I've tried, and some that I've heard about from others.
- Direct head-to-head dub. Of the things we've tried here at Panda Productions, this gives the best results. Using a Sony WV-DR7 to produce one-off VHS dubs of a DV master gives tapes that are NEARLY as good as the original. I'm very impressed with this Japanese deck. However, if you have to run off more than two or three copies, this solution isn't very practical.
- Use S-VHS decks in the dub rack. Consumer S-VHS decks are down to a couple hundred dollars apiece, so this is a possible solution. The recording circuits in most S-VHS decks are better than those in consumer decks, and this additional quality can also improve the results when recording to plain old VHS.
- Use better quality consumer decks in the dub rack. This is what we do at Panda Productions. It's a good compromise between quality and cost. I've had good results using Sony decks, but others have also reported favorably on Panasonic and JVC machines. I'd stay away from off-brands like Emerson, etc. Definitely DO spend the few dollars extra for HiFi decks. Customers with home theater systems will appreciate the better quality audio.
- Use a signal enhancer between the player and the dub rack. Here at Panda Productions, we use both the Studio One proc amp and the companion Detail Enhancer box. We turn down the chroma level slightly to cut back on the amount of color bleeding in reds and saturated blues, and up the edge detail level slightly. This produces results that are only a little behind the quality we get with direct head-to-head copying using the WV-DR7. Elite Video sells a box (BVP4+) that combines the proc amp and detail enhancement functions. We haven't tried it here, but have seen several favorable user reports. Both Studio One and Elite offer a 30 day money back guarantee, so if a particular product doesn't work well for you, you can return it. Web sites are at http://www.studio1productions.com and http://www.elitevideo.com
- Use a distribution amplifier. This shouldn't have to be said, but some people are still chaining VCRs together, letting the output of one dub machine feed the input of the next. This is a sure way to degrade your results. Get a good DA so each machine in your dub rack gets a clean signal.
- Use good quality cables. Those expensive Monster cables are overpriced, but you can get good quality professional y/c and RCA cables from box houses like Markertek. Keep cable runs as short as possible. Route power lines away from video and audio cables, and if they must cross, try to have them cross at right angles. Don't lay cables on the floor where they'll be stepped on. Repeated foot traffic can kill a cable. If you DO get audio hum or picture distortion from AC interference, try hooking all the decks, including the playback unit, to the same AC circuit (Don't overload it though. Most consumer VCRs only draw about 20-40 watts, so you can plug quite a few of them into a standard 15 amp household circuit). If necessary, add ferrite chokes to your signal cables (you can get these at Radio Shack. They are round or square ferrite "donuts". You coil your signal wires around them a few times to make an RF-blocking coil.) For extreme cases of ground-loop caused hum, separate the shield of the signal cables from the connector at one end to break the ground path.
- Keep it clean. Periodically (every 3 months or 50 hours of operation) clean the heads and tape paths of your decks. Use compressed air to blow out dust. If your rack isn't used too often, consider making dust covers to put over the machines when not in use.
- Keep it legal. The best way to monitor your video signal is with a stand-alone waveform monitor and vectorscope. Signals that are outside NTSC limits for chroma or luminance may not play back correctly. Many of us (including myself) can't justify the $1,000+ cost of these test instruments, so we cheat. I use the software WFM/VS in my nonlinear editing system, as well as the LED luminance indicators on my Studio One proc amp, to verify my signal is within tolerance. If your playback deck does not have a built-in time base corrector, consider adding an external TBC to ensure a clean, solid sync signal.
- Use professional duplication decks. I haven't tried this one, but at least one company (in Colorado) is in the business of refurbishing and selling used duplicators. You can often find their ads on EBay. I sent them one of my S-VHS masters once and asked them to use one of their machines to make a dub. I wasn't impressed by the results, but that might have been due to problems with the master I sent them. Theoretically, these professional duplicators SHOULD turn out a better dub than the consumer machines, for the following reasons:
- Better quality electronics (same argument as for the consumer S-VHS decks).
- Sturdier transport mechanisms, to insure proper tape alignment.
- Much wider recording head width. The typical consumer deck has 19-micron heads. The pro duplicators have 52-micron heads. This means thateven if the customer's deck isn't aligned just like yours, there's enough extra width in the signal track that it will still be read OK. If your customers report that they get a rolling picture, or noise at the bottom of the screen, or other sorts of picture distortion, this may be a solution for you.
The drawbacks to pro duplicators are:
- They're used. Although a good reseller will replace worn heads and other parts, these decks were retired for a reason.
- Repair costs are high ($50/hr and up for technician time, plus parts). If your dub rack is consumer decks, and one breaks, you just unplug it, throw it away, and buy another. You can't do that with a $2,000 (retail, new) duplicator.
- They are big and heavy, and draw more power than consumer decks. If your space or power budget is very limited, squeezing eight or ten of these battleships in might be a problem.
- They can NOT record in extended play (6 hour) mode, only in SP. Of course, you shouldn't be dubbing in EP anyway. Bad dubber! Bad!
- The Ultimate Solution: Throw out the VHS decks and deliver the project to your clients on DVD!
Hope this answers some of your questions.
Copyright 2001 by Doug Graham and Panda Productions. Permission is granted to copy this material for personal use only, not for resale or profit.
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