How was dbx noise reduction supposed to work? I could never use it properly...

I owned a Luxman deck some time ago. It has Dolby B, C, HX Pro and dbx. It made great copies of LPs.

One thing I could never use was the dbx noise reduction, though. Even after following the instructions to the letter (about setting the output levels), the tape would sound as if someone was selectively boosting the output level. I also remember the loudness indicators on the deck were around 3dB lower when I used it.

Did I really miss something great by not using dbx?

 

I have used dbx quite a lot. (By now you knew I was a contrarian, right?) I couldn't afford Dolby-A and it was the next best thing. (Frankly I think dbx-II, the consumer version, produces less audible artifacts than dbx-I, the original "pro" version.)

In order for it to work properly, despite rumours to the contrary, it is necessary to have a deck with flat response. If you have a bass boost it'll make it weird out. Contrary to popular belief, dbx does not just double frequency response errors, except on test tones. It does weird dynamic stuff when the recorder is not flat. Maybe that's the trouble you were having.

One thing it *is* quite immune to, that plagues Dolby, is level matching. As long as the response is flat the level calibration is more or less irrelevant as it acts in a linear 2:1 fashion over the entire dynamic range.

 

Interesting... I always thought I was doing something wrong. The end result always was what Steve (Hoffman ) describes: it was as if someone was playing with the volume control, raising up and lowering down the volume with the music.

 

Years ago when I worked at a recording studio, DBX was regarded as the bees' knees. There were real priests of this mumbo-jumbo in those days, but it never worked properly, IMO, and took up lots of our time. I'd all but forgotten it till this thread!

 

Ok, call me naive (it might be the best of the things you might want to call me!), but (a) isn't that what the setup tones are for, so you can get back to flat response even if the tape deteriorates a bit, and (b) I thought the studio was supposed to be a controlled environment. Isn't that part of what being a professional is, making sure things are set up correctly? (NOT a dig at your esteemed self! I'm sure you do that.)

To me dbx is like Dolby: an evil, but sometimes the lesser of the evils.

 

Interesting. My dad used to have a DBX standalone box for his hifi setup, back in the 70s. He was getting into hifi, and DBX was all the rage. I remember auditioning stuff with the DBX, and we were just nonplused at how bizarre it made everything sound. It was really just a novelty, and didn't last long in his hifi system.

 

OTOH, the Bob James SACD sounds terrific... so I guess dbx at a consumer level is WAY worse than what dbx was at a professional level.

Funny thing is, why did Nakamichi, Luxman and such included it on their products? I guess it was more of a marketing scheme than anything else.

 

Steve,

That would have to be one of the most apt and funniest descriptions of DBX and NR I've ever read.



In the past I've used various top of the line Nak, Teac, Yamaha domestic cassette decks with everything from Dolby B/C, DBX, even Nak's proprietory Hi-Com NR and they all did varying degrees of damage to the music.

NR is an evil alright, one best avoided.


cheers

 

But the record companies use Dolby on cassettes all the time.

 

Yes, but they also duplicate on low quality tape stock and expect their tapes to be played on low-fi equipment like car or portable cassette players.

Dolby is used as a bandaid.

IME noise is not a problem on a good stereo system.


cheerio

 

I'm learning far too much everyday to go away now. This is a great forum, full of great people.

 

I wouldn't know dbx from D. Boon but this thread is a perfect example of why this forum is so educational and fun at the same time. Give-and-take, differing opinions rendered politely, Steve's witty analogies, lotsa geeky techno-terms our wives roll their eyes at. Who could ask for more?

 

Guys,

I have on-board DBX I on the Reel machine pictured below. I purchased this unit in 1983 and it did not take me very long to realize that recordings sounded much better without NR. The sound was colored, changed and not in a 'good way'.

Bob

 

Steve, can you tell us which engineers tended to use DBX? Was there a pattern?

 

It's very hard to equalize something that was recorded with dbx (even when its played on the machine it was recorded on). It never sounds right. It just kills the sound. Especially acoustic stuff.