Noise reduction tips from New Spectrum Sound

by Jason Olson.

In a nutshell, if your tapedeck does TRUE ENCODING and the playback deck has TRUE DECODING, then use it. More then likely it will sound better, but for all the detail, etc. read forth...

We have received a forwarded internet feed from our associate TechRat at He expressed a desire for us to send you information concerning your dilemma with to "Dolby or Not to Dolby". Direct from the article, it sounds like you have some hissing noise caused by your Mic's and/or distortion unit. If this is true, then Dolby and/or dbx tape noise reduction will _not_ remove it. This can be caused by improper shielding or a number of other problems. Another source might be your mic pre- amp inside of your multi-track recorder. Usually in semipro multi-track recorders for Electronic Musicians, they use high impedance mic pre-amps. This probably might not cause a large problem, but may induce some noise, especially if the input connector is not a balanced one (many are not). Make sure the gain on your mic pre-amp is not set to high or low, in which case, it can also induce hiss. We are assuming that you are using a pro quality microphone dynamic which uses a three-pin XLR connector which most microphones use. If this is true and you are using a 1/4" input, please use an impedance matcher which can be purchase inexpensively from Radio Shack for about $15.00/ea. and are of good quality. You can purchase, if the hiss is extremely apparent or must be removed, a denoiser/esser /hisser from several manufactures which specifically are meant to remove these. If your effects processor is giving you problems, check to make sure your I/O levels are working at the same levels, -20dB/-10dB/+4dB (or whatever).

If your mastering deck offers true Dolby Encoding and Decod- ing, it should offer some TAPE noise reduction. Many consumer decks offer a Dolby switch which really is _active_ during PLAY- BACK ONLY. This means, that if you have no apparent difference between recordings which use Dolby, and those which do not, then more then likely, the deck doesn't offer Encoding. Some decks offer a fake Dolby Noise Reduction by using their own home-brew equalization which knocks the highs down. They do not license the technology or chip from Dolby Labs. This may also cause unusual effects because it does not necessarily decode at the exact same frequency. Using Noise reduction during playback ONLY is not recommended. This will only reduce the high frequencies (Dolby B), or High's & Lows (Dolby C), or All frequencies (Dolby S). This tends to flatten the music out. Its brightness goes away. Although, sometimes this has no apparent effect because the frequencies at which reduction occurs, may be above all acoustical input.(Dolby B only) DO NOT use any form of Dolby or dbx NR during recording if the playback cassette machine does not support it. This will give the music a much brighter sounds, but the hiss will be right in there with everything else. We do not recommend using dbx on your mastering deck unless you are sure that your audience has dbx decoding (which many do not have). We recommend using Dolby 'B' if at all (it is more common). Unfortunately, your setup may have some unusual conditions which may cause unpredictable results.

Sometimes tape quality can cause problems to. Some tape can- not hold high frequencies and inhibit a hiss on their own. Use fresh tapes, our favorite are Maxell's XL II-S, but XL II is sufficient for most home-studios'. Your heads should be cleaned and demagnetized often (a kit can be purchase from most music stores). Although the most important fact is to listen carefully for what sounds the closest to what you want. What _sounds_ the brighest may not be what you are shooting for. Although another major drawback of listening at home is that everyone does not have your pair of speakers which may not be possible of reproducing the high frequency which the NR effects, so basically you may not be able to hear a difference even if it was doing something.

If you are sending this off as a demo tape to some profess- ional company, we recommend renting a pro-deck to record on, or better yet, rent a DAT (if budget permits).

Disclaimer: All information above is property of New Spectrum Sound, although New Spectrum Sound holds no responsibility for the text stated above. Any damages incurred by following the above instructions, direct or indirect is not the responsibility of New Spectrum Sound. It is recommended that you do not use experiment using your master tapes at any time. ALWAYS BACKUP!!!

Trademark Notice: Dolby, Dolby B/C/S are trademarks of Dolby Labs. dbx is a trademark of dbx which is a sub. of AGK Acoustics NewSpectrum Sound is a trademark of itself Maxell is a trademark of itself All other trademarks are to the enities who hold the rights =)

TechTip: Never use foil shield cable for cable which will be flexed often!

Music ramblings || Ram Samudrala ||