Tom you're 100% correct. The use of LN tape formulas, higher speed and lower track count were much more intelligent solutions though they were concomitantly more expensive as well.
I can tell you from experience that the SR technology blew all the other Dolby (Dubly) processes away completely. I used it just as the ADAT revolution began and it was astounding how quiet and transparent it was. If it had not come about at the exact moment of low cost digital multiple-tracks it was poised to be a revolutionary leap. I still have my SR unit and man that sucker is out of this world.
P.S. if you are around a radio tomorrow check out the World Cafe with David Dye. He is doing a new series called Latin Roots and yours truly is doing the inaugural segment. I think you will dig it...
Sent from my iPhone
On Jan 11, 2012, at 4:30 PM, Tom Fine <[log in to unmask]> wrote:
> Dolby became necessary when everyone was using 8, 16 and then 24 tracks for rock, pop, some jazz and even some classical recording. I can see it being a huge benefit to keep hiss buildup at bay when you're combining all those tracks. However, it became an obsession in the 70's and 80's. Why was it necessary to be used again on a 2-track master? 15IPS 2-track on low-noise tape is very quiet, and the Dolby can and often does squashes the sound, making "presence" and "high end" tweaks necessary in LP and CD mastering. The Dolby tracking falls off as the tape self-erases, even if you set to Dolby tones at the beginning, as I understand self-erasure that doesn't mean that all components of all dynamics erased at the same rates/ratios, so the Dolby tracking should be adversely effected (further "deadening" the sound and "washing out" the top end).
> There are examples out there from the early days of 16-track where the multitrack was running low-noise tape at 30IPS, no NR, and the 2-track master was recorded at 30IPS, no NR. They are not especially hissy. Dolby did allow economies of tape usage, no doubt there.
> Sonically, it was a real mixed bag. As I understand it (having never used it), SR was a leap forward. I think the whole obsession with hiss was over-rated, but I agree that 16 or 24 hissy tracks mixed together is too noisy. If it were me producing, I would have gone with higher speeds and higher levels first, turning to NR only if nothing else worked. The advent and wide acceptance of Dolby also probably cut off some R&D in the tape world. What about thicker emulsions like 35mm mag-film? Also, what about 12 tracks per 2" instead of 16? That's the same track width as 3-track 1/2" and should make for low-noise recording if low-noise tape was used at higher operating levels.
> -- Tom Fine
> ----- Original Message ----- From: "Richard L. Hess" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, January 11, 2012 4:10 PM
> Subject: Re: [ARSCLIST] Dolby Plugin
>> Hi, Jamie,
>> You caused me to go look at the CAT22 schematic again and I noticed some interesting things.
>> (1) You're right that there are odd diode-ninja things in he drive to the FETs, but there are also two FETs driven from the same line, producing, what would appear at first glance, a steeper attenuation slope.
>> (2) There is another nasty thing--fairly hard diode clipping (which isn't as hard as digital clipping as you know) on the base of the compressor's audio output emitter follower. Joy!
>> I'm glad I've got a bunch of CAT22 cards to carry me into the future.
>> Fortunately, failure modes appear to be MOSTLY coupling caps.
>> On 2012-01-11 3:12 PM, Jamie Howarth wrote:
>>> They also do some weird attack and release ninja with diodes that is really hard to mock up. The while enchilada has strange xfer curves beyond just the compression ratio, bandpasses, and thresholds- which is why they invert-added through the same screwball circuit - building two of these won't match.
>>> Knowing what I know now about this self-nulling circuit and tape compression there's no way it can't be heard mistracking. Comparing a dolby a encode-immediate-decode through wire is audible if the dolby dot levels are even slightly mismatched. Off tape it's hilarious. Of course who likes hiss...
>>> But that's why hot 15IPS or hot 30IPS was the preferred "evil" ... Dolby a changes stuff a lot.
>> Richard L. Hess email: [log in to unmask]
>> Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
>> Quality tape transfers -- even from hard-to-play tapes.