Did anyone else think that Dolby NR made sound quality worse back in the day?

Is decoding not a type of filtering codec ?

 

You may not be seeing my posts, but in case you are, I have stated in two posts already that Dolby is a compander system, meaning that it compresses on one action, and then expands on the other. It selectively boosts a certain frequency range by a certain number of db upon recording, then does the inverse of that boost on playback, taking some of the hiss with it. That's how it works. That is why you do not use Dolby on tapes that are not recorded with it. I keep thinking that some of the people who are complaining that it sounds dull don't know how it works, or how it is used.

Like Hoffman said, Dolby is NOT a filter.

 

As an aside you guys with tapes may want to hold onto them - apparently there is a growing movement in mainland China where audiophiles there (or collectors because it's tough to be an audiophile regarding tape) are collecting them up in droves.

 

Agreed, Dolby compresses then expands dynamic range ( preemphasis and deemphasis ) effectively reducing noise. Since magnetic tape is nonlinear constant biasing helped to overcome the problem.
Improper biasing or calibration could cause muffling. Dolby A used four filters to cut off frequencies, two high pass a low pass and a bandpass.
As I recall Ray Dolby was somewhat disenchanted by the final results and immediately went to work on a better system, called Dolby B for better, but the second version was intended for home use.

 

Up until around ten years ago, I always used Dolby B when recording. Even on my modest Technics DD deck, the sound without using Dolby is light years better. I barely hear any hiss, let alone think about it.

 

How much was Dolby or other noise reduction used in the studio? Was it used on multi tracks as well as 2 track master? Was DBX a noise reduction system?

 

I used to buy those high quality metal tapes - recorded without dolby and got quite excellent sound (hard pressed to tell the difference between it and CD) and even on my fairly modestly priced Pioneer CT-S 709. I usually recorded without dolby with the good cassettes. Man those were the times making all those mix tapes - the hours spent in front of that tape machine - Kind of miss that.

Loved the old meters

 

CT-S 709 was a great deck in it's day.

 

Yes, it was a lot of effort. We put in the hours - I do kind of miss it too.

 

Yes, IME a fair amount of NR was used in the studio. It was mainly used on multitracks thought there were plenty of 2 track mixes that were encoded.

IMO the amount of noise that a professional 2 track machine added to a mix was fairly insignificant. However, with the multitrack it was a slightly different matter. There the end user didn't get to hear what was on the multitrack tapes as those were considered work parts. Those signals were almost always run through a console for mixing in which case their final sounds were not yet determined. So if they were dull sounding it was because the production team wanted them that way, since they had the opportunity to correct any perceived dullness.

Besides, all kinds of things could be done on the multitrack that wouldn't be done on a 2 track. Optimizing bias or other setup paramaters for a specific type of instrument is an example. It was even possible to use NR on some but not all tracks of the multitrack. It was all about getting the best possible results as determined by the production team.

The bottom line is that one can often hear the sound of the multitrack NR on the process if you know what to listen for. DBX and Dolby A had different sounds. I wouldn't call those sounds dull but in a way Dolby A contributed to a somewhat softening of the sound to me. I guess some might construe that as dullness, but if you measured the frequency response you shouldn't see a change with NR, assuming it's properly calibrated.

Btw, somebody upthread eluded to tricks to use to get DBX to work well. I did a lot of recordings with DBX and there was one main trick that I can convey. It was to keep the levels conservative. Many figured DBX could increase the s/n ratio by up to 30db so tried to keep the levels high to maximize that gain.

The problem is that the DBX process requires a linear tape function to operate properly. If the tape is saturated the DBX just won't be able to track properly. So I found it best to sacrifice some of the potential gains and keep the process running in a linear fashion. Instead of the 30db gain in the dynamic range I'd back the record gain 3db and settle for a 24db gain.

That was still a significant advantage and IMO it sounded a lot better. Many of the tell tale artifacts just become harder to detect.

 

Great post.

 

Uh...no. Dolby acts on the frequencies. You may be thinking of DBX, which reduces dynamic range on recording, then expands them on decoding. They are both compander systems, though.

There were single-ended noise reducers like DNR, which some companies used instead of Dolby.


But, you know, in the 18 years that I used serious tape decks, I rarely thought to just not use the Dolby. When I first started out in the 70s, I thought it was so cool to play a Dolbyized tape without the Dolby. When I got my own deck, I realized the folly of it and stopped doing it. From then on, it just never struck me to record without it. I really hated tape hiss!

I really think that is the case with a lot of people who complain about dulled highs. If the bias and EQ is off, the Dolby circuitry will be too.

I recall Mr. Hoffman long ago saying something about how he disliked mastering tapes encoded with Dolby A, only because it was a pain to get the units calibrated correctly.

 

I never noticed a problem with Dolby B. I used it from the time that I started making cassettes. I always used it on tapes that I recorded myself - during recording and during playback. I recorded so that the peaks hit 0 DB. I was always fortunate to have nice cassette decks and used nice cassette tapes. I did not buy more than a handful of pre-recorded cassettes. (I did have a problem using Dolby B with the two mainstream label Dolby B encoded cassettes I owned. They sounded dull when played with Dolby B. I played them unencoded. The Advent label pre-recorded cassette I owned sounded fine with Dolby B decoding.)

I noticed that whenever Dolby B came up in the UK audio magazines that I read, it was uniformly stated that they did not use Dolby B. It was for sound quality reasons. I found that curious. When I tried it, I did not notice a difference in the sound other than an increase in tape hiss. I'm sure others have had different results.

I tried Dolby C and Dolby S and quite liked the sound. Since my primary use for cassettes was for listening in the car, I did not go beyond experimentaton with those. They would not have been compatible with the car player.

I tried out a DBX 122 (original version) and was not happy the sound of that. It caused a further reduction in tape hiss, but the hiss would change "tone" along with the tonal changes in the music. So while the hiss was lessened, the changing tone of the hiss caused me to pay attention to the hiss.

 

I notice that a LOT of people here used metal tapes. I never really liked the sound of metal tapes, preferring high-bias Type II tapes, or standard ferrics. I always got better results. The tonality seemed to change with the metal tapes.

 

Uh...no
If you do a bit of research , as I did you'll see Dolby A is just as I said and with it's four filters.
Dolby Labs do use the word " filters "

 

A great metal tape on a great deck that is designed to play metal tape sounds amazing. Properly set up for the tape one can get near ruler flat response to both typical frequency extremes, at least from my experience.

I still swear by Maxell Metal Vertex blanks, nothing short of amazing in my experience.

 

Great poat. I like hearing from people who worked in studios. If you were recording an album at various studios, is it correct to assume not every studio may have the same NR system and thus would be another sonic issue that could cause problems?

 

Never used cassettes !!!

 

True. Although I used (in late seventies - early eighties) mostly Ferro-Chrome tapes. (The differences between the tapes were almost unbelievable.) The results were, however, pretty much like you described. And the narrower frequency range wasn't a problem - especially if the cassettes were listened outdoors with Walkman (mainly rock).

 

That's right, man. I would get those meters peaking! And the recording industry thinks they invented brickwalling!

 

In my teenage and college days, I used to record the cassettes with Dolby switched on, but do playback with no Dolby. It seemed to increase the "presence" of the music. When turned on the playback sounded dull.

Back then TDK SA-90 were my tapes of choice.

 

Way back, I use to transfer some of my albums to tape for portability. I used a Nakamichi machine with Dolby B. I quite early on abandoned use of Dolby B and lived with the higher hiss level because that was more tolerable than the loss of liveliness that came with Dobly processing.

 

I was pretty young when Dolby B was introduced. My dad got a cassette deck with Dolby B. I knew that it was supposed to help, but I definitely heard problems with it, mostly 'muffled' treble on playback. I too usually recorded with it ON, and played back with it OFF using tone controls to do a little of the (re)equalization.