Hmmmm... Would a DBX 3 BX Dynamic Range Expander improve the sound of my VCR?

Discussion in 'Archived Threads 2001-2004' started by NathanP, Jan 10, 2002.

  1. NathanP

    NathanP Supporting Actor

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    Hmm..

    I swore I was done with processors..

    Anyways, maybe Wayne Pflughaupt can help me out here.

    Well,

    I sold my older model Dynamic Range Expander because I thought I was done using it..

    Well, I sorta got into tweaking my VCR (flame suit on) and was wondering what a newer Dynamic Range Expander would do to improve it's sound?

    Thanks,

    Nathan
     
  2. Wayne A. Pflughaupt

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    Nathan,

    The dbx 3BX processors are great at what they do – increase the dynamic range of sources with poor signal-to-noise ratios, like cassette tapes and (especially) vinyl records. It does this by lowering the noise floor, and it is especially evident during quiet passages. It is not an encode/decode noise reduction scheme; it will work as much or as little as is needed, with any source separate from (and indeed, in conjuction with) Dolby B, C, etc. (I think you already know this; I’m just explaining it for the benefit of those who don’t.)

    That said, Nathan, who much the 3BX will do for you depends on your VCR and/or your tapes. It will work the best on the worst tapes – older, non-hi-fi fare with the (noisy) audio recorded on the edge of the tape.

    Thus, if you have a lot of old pre-hi-fi tapes, or a non-hi-fi VCR, the 3BX is a must-have, in my opinion.

    But if you have mostly tapes with hi-fi audio and a hi-fi VCR, then don’t bother. These tapes and these machines already have excellent dynamic range.

    By the way, I’m not sure what you mean by a “newer model.” dbx dropped these units many years ago; I don’t think anyone currently makes anything comparable. If so, I’d like to know who.

    Regards,

    Wayne A. Pflughaupt
     
  3. NathanP

    NathanP Supporting Actor

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    Oh, wait I meant by "older model" was that it was an older one(DBX 1BX).

    So Wayne,

    I do have a non Hi-fi VCR (Why not upgrade to something better? Well, a little while ago Dad gave me one of their older industrial, Prosumer quality VCR's. So I've been bonkers for it for awhile)

    It throws out a nice picture, but it sounds a bit "Cloudy" when someone is speaking and I know I can't get the volume up very high on this thing.

    So, a DBX 3BX would fix all of these?

    Thanks,

    Nathan
     
  4. Wayne A. Pflughaupt

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    Nathan,

    If it sounds “cloudy” that is a frequency response issue. If the highs roll out, sibilants are attenuated, rendering dialog “muddy” and unclear.

    While pro-sumer decks often have some cool and unusual features, it sounds like this one uses the old (and inferior) method of recording audio as a linear track along one edge of the tape. The dbx will be able to reduce any noise inherent in this recording process, it will not be able to address the frequency response issues.

    The reduced volume you are experiencing is also a characteristic of linear audio tracks. You can check this yourself if you have a cassette deck. Put the deck in pause/record mode and note the readings on the meter with a CD. When you switch to the VCR, you will see the meter level drop dramatically. While you could set up the 3BX to address this (i.e., using it as a de-facto gain control) you can accomplish the same thing with the volume control on your receiver.

    Bottom line, Nathan, old linear-audio VCRs deliver abysmal sound reproduction, be they consumer models, professional models, or something in between. By comparison, so-called hi-fi VCRs are able to utilize the full width of the tape for the audio, resulting in near-CD sound quality and dynamic range. For the going price of the second-generation 3BX Series II, you could almost buy a hi-fi VCR.

    Regards,

    Wayne A. Pflughaupt
     
  5. NathanP

    NathanP Supporting Actor

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    I know where I can purchase one for around $25-$30.

    Worth the money?

    Or should I just get a better VCR?
     
  6. Wayne A. Pflughaupt

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    Certainly can’t hurt at that price! Which version is it, first generation, Series Two or III (the black one with the colored knobs)?

    Regards,

    Wayne A. Pflughaupt
     
  7. NathanP

    NathanP Supporting Actor

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    Well,
    I can do both..
    But I prefer 2nd Generation as it's prettier [​IMG]
    Wayne,
    Also with DPL on, I here NO rear effects on all of my (200+)Dolby Surround encoded tapes..
    Another VCR problem that won't be fixed with one of these?
    Nathan
     
  8. Samuel Des

    Samuel Des Supporting Actor

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    Would this product work with a mono VCR?
     
  9. Wayne A. Pflughaupt

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    Nathan,

    Your VCR is mono, so it will not work with Dolby Surround tapes. You need a stereo VCR for that.

    By second generation you mean the Series Two version? The third generation (3BX III) model was the one with the colored knobs I mentioned.
     
  10. Jerome Grate

    Jerome Grate Cinematographer

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    Actually I just picked an older model up (hi Nathan[​IMG] ) anyway I have the t.v. going to the dbx and out to the receiver. Is there a particular setting to look for to gain optimal sound. I've been running it on bypass lately because I just don't know. Hope someone could help here.
     
  11. Wayne A. Pflughaupt

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    Samuel,

    I haven’t used a mono VCR in years, but back then the audio was pretty dreadful, including a lot of background noise. If nothing has changed since that time, then yes, a dbx dynamic range expander will do wonders to reduce the background noise, especially during silent passages.

    As far as I can tell from researching ebay auctions, etc., dbx made three models in each of four generations: The 1BX, 2BX and 3BX. The model numbers refer to how many bands of expansion the unit featured. Models designated as “Series Two” are second generation models, while third-generation models added Roman numerals to their name (i.e., 2BXIII). Fourth generation models carry a “DS” designation (i.e., 3BX-DS). There was a 4BX and possibly a 5BX model somewhere, I think during the third generation era only. I believe the 4BX may have had four bands of expansion, but I think the 5BX simply had more features. I could be wrong on both points, however. Typically on the used market, prices are progressively higher for the later generation models, as a result of improved performance and/or styling.

    In my opinion the best model (aside from the 4 and 5BX, both of which are rare and expensive) is the 3BX, which featured three fully independent bands of expansion. With separate processing for bass, mid, and treble only the frequency range that demands attention at any given moment is processed.

    Jerome,

    I’ve had mostly good results using a dbx for TV. It will help reduce background noise on old movies, as well as talk shows. In addition, with many TV shows it will push the level of soft music further into the background, making it more like what you would hear on a movie. Of course, making dynamics-challenged TV programming sound more like movies is never a bad thing.

    However, a lot of modern TV shows have very high levels of background noise during silent passages, caused by over-compression raising the ambient noise floor. In this situation, unfortunately, the noise is so high the dbx sees it as legitimate signal and ignores it.

    The dbx will attenuate any low-level signal, and this can be a problem on movie channels that limit the amount of compression used. For instance, last night I came across a ’70s western on AMC where the sheriff had just shot the bad guy and he was laying there dying. There was no music or anything else going on in the soundtrack – pretty much silence, except you could just barely hear birds faintly chirping in the background. Well, when I switched in the dbx it sucked those birds right out!

    In my opinion, the dbx can be left on for most normal television viewing, including the movies on most of the regular cable and broadcast networks. When you see a program that has a lot of gain reduction happening (as evident by the yellow LED’s lighting – more on that to come) – typically something with sparse dialogue and a moderate amount of background noise – switch the dbx in and out and you will be able to hear the difference. When you come across one of those programs, you’ll be glad you have the dbx, I assure you.

    However, dynamic range expansion will not work well with premium movie channels that feature the original uncompressed soundtracks, because it can reduce quiet passages to inaudible. Likewise, it is also probably a good idea to bypass the dbx when watching classic movie channels like AMC and TCM, unless they are playing a particularly noisy movie (typically the older B&W films).

    As far as how to set it, the manual states for the “Expansion” control that settings of 1.2 result in a 20% increase in expansion, 1.4 gives a 40% increase, and so forth. So in the second case, if the incoming signal had 40dB of dynamic range it would be expanded to 56dB, and a signal with 50dB would be expanded to 70dB.

    I typically set mine between 1.3 and 1.4 at most. As with all processors, it’s never a good idea to overdo it.

    For the “Transition Level” control, the manual says incoming signals above the setting will be expanded upwards, and signal below will be expanded downward. The manual recommends setting this control so that the red LEDs light up during loud passages and the yellow LEDs light during quiet passages.

    In my opinion, the dbx will work best when given a more-or-less constant-level signal, like you would get connecting it to a tape-monitor loop. Giving it a variable signal like that from a TV volume control will have you adjusting the “Transition Level” control all the time.

    Hope this helps,

    Wayne A. Pflughaupt
     
  12. Chris Zell

    Chris Zell Stunt Coordinator

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    I had a 4BX until recently (I was the original owner - bought it around 1980). It was acting flakey, so I could not sell it in good conscience, so I gave it away to Goodwill - had too much gear cluttering my rack, and I hadn't used it in years. My wife was so happy, and so proud of me - I also gave away a Dynaco Stereo 400 amp, PAT4 preamp, and FM5 Tuner (all of which I had built as kits in the early 70s).

    The 4BX had 3 frequency bands (with variable expansion - zero points), plus a feature called impact restoration, which enhanced transients. This was also continuously variable. It was a nice unit, but after a few years, I stopped using it for some reason - didn't need it, or want the artifacts it could cause as my system improved I guess.

    Cheers,

    Chris
     
  13. NathanP

    NathanP Supporting Actor

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    Hey Jerome, I've been meaning to ask you, how did life fair with the Dynamic Range Expander?
    I hope I gave you the right info on it, I was kinda nervous that you would start e-mail me threats and telling everyone "Man, that kid is a liar" [​IMG]
    Nathan
     
  14. Jerome Grate

    Jerome Grate Cinematographer

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    Well, I'm not sure yet only because I haven't copied Wayne's comment that I think will help me experiment with the thing. For now it's on bypass until I can play with it, I'll let you know.
     

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