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Pre Dolby, non Dolby

 

New member
Username: Teslaudion

Post Number: 1
Registered: Oct-16
First, I don't do internet searches. I'll read links and of course appreciate interaction, with humans..where free thought sometimes leads us in directions that cause answers to be obtained a few weeks later than if the optimum path is taken but people I'm here to say- (reread with the opening salvo of prince's "lets go crazy" playing in the background) that's way better than finding the answer immediately. If you don't understand this, come back and read it in 5 years and kick yourself for missing one key to the meaning of life.. Revised 1992 (for most of you).

To my topic.

I've recently switched hobbies again. The old ones I've got a 6th degree black belt in and bored with (that or I'm a pathological liar and have most of the defects Trump will eventually be diagnosed with). I've made a total of three goodwill purchases spending a sum of thirty dollars and I'm at the point where if I "cut into" one I feel that I must squeeze every bit of usefulness from the event in order to honor not only the 1970's designers, but the factory workers who assembled the thing as well. I'll be asking for your help to not let them down.

Let's start with the noise reduction switch/circuit! Would any of you chaps have knowledge of, and interest in what happens when that button is in? I'm here learning, not teaching.. I know nothing of them so be nice.. I already submit/admit every one of you is smarter/better/taller/etc. My dendrites may just have a little more reach.. And there's nothing either if us did to stack us that way so there's really no need for you to show everyone else in here that besides your 86,753.09 forum posts, your shoes are size 13 and you're way better than the new guy. Start that crap and I'm gone..and you'll never know what you never knew.

So let's talk circuits! Anyone want to pop in the most basic early patented or not nr ckt diagram? Or try a 9 sentence explanation of its operation? Ineffable?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18289
Registered: May-04
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"First, I don't do internet searches."


You also don't read forum headers. This is the "amps" section of the forum. Dolby has nothing to do with your somewhat vague topic.


You sound rather full of yourself and I don't care much for threats. Obviously, I don't know what I don't know. But neither do you (know what I know) and you don't really come across as someone I wish to share knowledge with.



Talk circuits? Just how much of a break down to a circuit are you requesting?

Think of Dolby A as the Genesis of consistent, useful noise reduction circuits.

The baseline is, Dolby became a multi-millionaire from his idea and no one with any other NR idea had before him.



Dolby NR is a closed loop system.

Noise from any source is most obvious in the upper frequencies. Basic psycho-acoustic theory which also leads you to the theories behind MP3 formats.

"Noise" is considered to be constant, always the same frequency, always the same level.

Music or speech is dynamic which distinguishes it from noise when you think about Dolby A.

Basically, during the recording process Dolby A artificially boosts the incoming music signal beginning at a fixed frequency and by a consistently rising level out to 20kHz. This pushes it up and above the level of the consistent noise floor.

During playback an inverse eq is applied to the music and the noise. The level of noise goes down as the music is returned to its proper level relative to the lower frequencies.

If you playback a tape which has had Dolby NR applied to the recording process, the highs will sound artificially boosted - which they are. Therefore, the loop must remain closed for Dolby to operate as planned.

Dolby B is simply the consumer version of Dolby A. Dolby C applies a steeper eq than does either A or B.

That's the answer, if you feel that's crap, you're free to leave. Now. I don't have time for your crap.

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Gold Member
Username: Magfan

USA

Post Number: 3385
Registered: Oct-07
Jan,
You exceeded the 9 sentence limit.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18290
Registered: May-04
.

I figured he stopped reading anyway. I was getting dangerously close to adding a link.
 

Gold Member
Username: Magfan

USA

Post Number: 3387
Registered: Oct-07
I get it.
A link would have put you So Far Over The Top as to render your answer UnReadable.

Where the heck can I get some blank TDK SA-X cassettes? That was my choice, or the simple SA version.

It must have been about '68 or '69. My buddy (later a Dentist!) bought an EXTERNAL Dolby processor. You had to calibrate it to a specific TAPE for best results. What a PIA.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18292
Registered: May-04
.

Blank cassettes show up on eBay and Craigs List. I'm about to sell my cassette collection but I doubt there are any TDK's in there.

Why do you want blank cassettes? For other than simple archival purposes, cassette was/is a pretty lame format. I have a three head Nakamichi that I wouldn't use for any real listening purpose.

I do have years and years of recordings of Prairie Home Companion, including the show he did when he retired the first time.

Great stuff for a limited audience I suppose. But a lot of the performers on those tapes have passed away now. So that's what tape is good for, recording the people who die before you do.

If you want to record a tape, it's best to have a tech set it up for one specific tape and then you stick to that tape for all your serious recordings needs. Have the set up checked every year as tape formulations change.

Most of the shops I worked in offered the service for free as a close to a machine sale. I would think though it would be pretty difficult to find a tech who could set bias and tracking on a tape deck today.



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Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18293
Registered: May-04
.

"I get it.
A link would have put you So Far Over The Top as to render your answer UnReadable."


Just think if I had used a link to a general search engine response!

LOL!


.
 

Gold Member
Username: Magfan

USA

Post Number: 3388
Registered: Oct-07
Setting up either a R-2-R or Cassette is probably NEARLY a lost art. I know my Tandberg needs several special tools to set spring tension, since it is a SINGLE motor drive with NO pressure pads, the feed reel having a BACK SPIN applied to it thru a series of clutches and belts.
It is a MEchnical MONSTER to fix.
My brother informs me that when he had a studio, he had special AZIMUTH tapes for head alignment. I don't know how good he was at that procedure, since He hasn't much patients or detailed mechanical apptitude.
The deck was apparently a 1/2" OTARI. or it May have been a 1" model, but OTARI for sure.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18294
Registered: May-04
.

Several reasons Tandberg didn't make it in the US market. Absolutely great performance but a what a b*tch! to work on.

If you take it to your brother, I wouldn't mention it came from a socialist country.


.
 

Gold Member
Username: Magfan

USA

Post Number: 3389
Registered: Oct-07
I would like to get it someplace where somebody would fix it and make it work again.
Its been sitting a LONG time.
And yes, I've had the Top Cover off ONCE and went NO FURTHER. A real mechanical nightmare.


I won't let my brother work on my lawnmower. My training is Uber meticulous and I go to root cause. I'm the only person you know who runs SYNTHETIC OIL in their mower. All parts / fasteners must be accounted for. I even HAND SHARPEN my mower blade using a FILE. When I saw how the mower shop DESTROYED blades with a bench grinder in about 30 seconds, I vowed never to let 'em fix ANYTHING of mine.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18295
Registered: May-04
.

Sorry, leo, I won't respect your lawn mowing skills until you tell me you finish your blade sharpening with a barber's strop. When you can shave with your mower blade, that's a job well done.



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Gold Member
Username: Magfan

USA

Post Number: 3390
Registered: Oct-07
I had briefly considered that approach.
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