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Using Dolby when playing Dolby tapes.

Lavane

Lavane

Lunatic Member
So, I hooked up a second cassette deck in one of my secondary systems yesterday and listened to tapes while working on a phono preamp. They were Dolby tapes sounded much better without using Dolby. Personally I prefer playing a lot of tapes recorded using Dolby noise reduction without using Dolby on play back. They just seem to loose soundstage, dynamics, and responce. Its like listening to my speakers with a heavy wool blanket over them.
There are those few tapes recorded using Dolby though that sound really good played back in Dolby.
A Bowie and his Tin Machine band tape comes to mind.
So, how many others listen to tapes recorded with Dolby, but don't use Dolby when doing so?
 
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I always listen with Dolby off, no matter how it was recorded. I never liked Dolby from it's inception in the 70's. And being in the bootleg tape trading community from the latter 70's to the mid 90's when cd burners came around. It was a basic common rule to never use Dolby when making copies for others.
 
Playing a Dolby NR encoded tape without decoding simply means that low level high frequencies in the original sound are boosted as much as 10 decibels (at the quietest original levels) so that the effect is compressed treble response. This might sound "good," but it is not accurate reproduction. Accurate reproduction would require that the noise reduction circuitry gets the same output level from the tape that it was set to put on the tape during the recording process. A tape that has more or less sensitivity so that it provides less or more output than expected will alter the frequency response. That's why there were official reference tapes for standardization. They were ignored. So that's why the more expensive recorders used built-in 400 Hz tone generators to match the level coming off the tape matches the level being put on the tape. Listeners can choose however they prefer to hear music. If accuracy is their preference, they would have to decode Dolby-encoded tapes accurately.
 
To prevent unwanted treble loss Dolby record and playback levels have to be matched. Good decks had Dolby level calibration pots and three heads so that you could monitor the level while adjusting. At factory decks would have been adjusted using a reference tape and recording optimised for a particular brand of tape. Using a different tape usually results in an altered level recording when played back with Dolby on it, if that level is lower as is likely with a cheaper brand of tape then playback will sound muffled.

Back in the day everyone tended to use the Dolby button as a treble boost. Cheap decks seldom included Dolby but Dolby (B) encoded tapes always sounded good without decoding the added boost helped make up for the formats lackluster high end response.
 
Dolby tends to sound disappointing or flat out horrible. It can sound good, but then everything needs to be calibrated properly between the tape, and the deck, and the recording. Between two completely different decks it is nearly impossible to get it right. If you have a high-end deck, preferably with Dolby C or higher and you only use the recording on that deck, then Dolby is a viable option. In any other case more like cassettes where actually used, don't bother with it:)
 
I never liked Dolby until I tried a deck with Dolby-S..world's better than B or C..highly tape dependant but it makes my old tapes recorded in HX-Pro sound better than I ever thought they could..
 
They azimuth on the play head has to be adjusted properly for Dolby to sound good. If you notice that homemade tapes with Dolby played on the same equipment sounds good, but prerecorded tapes don't, that could be the issue. High-end Nakamichi decks self-adjust as the tape is playing. That's why they sound so good.

I've had very few decks where the azimuth was set correctly originally.
 
Bruno Primas said:
They azimuth on the play head has to be adjusted properly for Dolby to sound good. If you notice that homemade tapes with Dolby played on the same equipment sounds good, but prerecorded tapes don't, that could be the issue. High-end Nakamichi decks self-adjust as the tape is playing. That's why they sound so good.

I've had very few decks where the azimuth was set correctly originally.
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Thats a good point.
 
When I did my own recordings from borrowed records I always used normal bias tape. I still have some of those tapes and they still sound good.
I have a few tapes from friends that made tapes for me recorded from CD to tape using normal bias tape.
I didn't have a CD player at all until 2003 when I put one in a new JEEP Wrangler I bought. I still have that Jeep. Its on its 5'th stereo though. They don't last bouncing around on the trail.
The few Dolby tapes I do like played in Dolby have sohnded good no matter the tape deck I played them in. Thats the odd thing. The others never sounded good in any of the other decks I played them in.
I get that it depends on how the head is adjusted and how Dolby was implemented in a given deck though.
 
Govany said:
I never liked Dolby until I tried a deck with Dolby-S..world's better than B or C..highly tape dependant but it makes my old tapes recorded in HX-Pro sound better than I ever thought they could..
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I've never used or even heard tapes recorded with Dolby S.
 
Bruno Primas said:
They azimuth on the play head has to be adjusted properly for Dolby to sound good. If you notice that homemade tapes with Dolby played on the same equipment sounds good, but prerecorded tapes don't, that could be the issue. High-end Nakamichi decks self-adjust as the tape is playing. That's why they sound so good.

I've had very few decks where the azimuth was set correctly originally.
Click to expand...
Pre-recorded tapes vary widely Vis-à-vis azimuth. I always lusted for a Nakamichi Dragon!
 
Pre-recorded tapes vary widely Vis-à-vis azimuth.
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Duplicated tapes were almost always perfectly aligned as far as azimuth goes. Misalignment came from the cassette housings into which they were loaded. Those C-zeros varied widely up until the mid-1980s when BASF began supplying the Calibration Mechanism to housing manufacturers, record labels, and duplicators as a standard for correct azimuth. (In order to get a license for Dolby S, hardware manufacturers had to align their decks to that same BASF Calibration Mechanism.) From that point on, the accuracy and consisency of azimuth alignment improved dramatically.

A misaligned head gap will cause small wavelength/high frequency output to decrease because that little magnetic print does not cross the gap all at once; only a portion of the print does because the head gap is at an angle to the print. The signal goes out of phase and the output decreases. Turning Dolby NR decoding off will allow the player to read the boosted, encoded wavelengths so that the treble sounds louder but is still out of phase. It still comes down to the listener's preference: compressed treble that sounds "nicer" (a real advantage in car stereo playback) or accurate sound (as long as the azimuth is correct.)
 
Sure there are decks where head alignment plays a role but there are also a lot of mediocre prerecorded tapes that need help.
Sometimes tuning off Dolby is the easiest way to improve them.
Back when we always recorded our own tapes from the lp. It was nearly always better than the prerecorded tapes, at least up until they nearly faded out of popularity.
For a while prerecorded tapes got better, around the time HX pro started being used.
Before that they used cheap tape and mediocre shells that were glued together.
It’s not surprising that a treble boost helps them.
 
Lavane said:
So, I hooked up a second cassette deck in one of my secondary systems yesterday and listened to tapes while working on a phono preamp. They were Dolby tapes sounded much better without using Dolby. Personally I prefer playing a lot of tapes recorded using Dolby noise reduction without using Dolby on play back. They just seem to loose soundstage, dynamics, and responce. Its like listening to my speakers with a heavy wool blanket over them.
There are those few tapes recorded using Dolby though that sound really good played back in Dolby.
A Bowie and his Tin Machine band tape comes to mind.
So, how many others listen to tapes recorded with Dolby, but don't use Dolby when doing so?
Click to expand...
Generally only Dolby C with a good tape; I always found Dolby very heavy-handed with the top end frequency response as well. I was a tape snob back in the day so only chrome or better.
 
titanstats said:
Generally only Dolby C with a good tape; I always found Dolby very heavy-handed with the top end frequency response as well. I was a tape snob back in the day so only chrome or better.
Click to expand...
Too many Dolby NR equipped decks were never set up/aligned correctly either. Technics, Sony, and Nakamichi the usual exceptions. The Boston Audio Society had an article about this in the BAS Speaker.
 
Dolby Labs insisted that getting a license for Dolby S NR required aligning recorders with the BASF Calibration Mechanism to assure correct azimuth alignment. Every music label in the U.S. as well as most music duplicators and C-zero manufacturers also complied with that standard in order to improve compatibility for cassettes in the U.S.
 
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