which reel to reel ?

[TIMTAPE]

Originally Posted by ben

Are you referring to the prerecorded tapes or the machines?
I had a Fisher FVHP-720 mono vhs vcr with long play and dolby; also an almost identical Hitachi (VT18?). I think the panasonic D deck nv777 had it too. All mono...

Ben, I stand corrected then. Still I'm surprised machines were made with Dolby, mono and LP. The audio on VHS SP (15/16ips) wasnt too flash but on LP (15/32ips) it was pretty cheesy at best. For a start the audio wouldnt have gone much higher than 5khz, and that's with perfect alignment. How would Dolby have performed in that scenario, and how reliable would it have been?

Cheers Tim

[SteveCG]

Michael,

Just to be clear: The Ferrograph machine I mentioned in my last post is a 1/2 track (stereo) machine, model 722HD. This works at 3 3/4, 7 1/2 & 15 ips; with Dolby B operational on all speeds.

Given what you and others say about Dolby's licencing, we seem to have a puzzle!

[brenellic2000]

Thanks Steve re the Dolby B being operational at 15ips on the Ferrograph - that is a mystery! - and to Maurice for the B77 article. My little Collins Pocket Gem German-English dictionary is struggling valiently.... I'll have to dig out my ASC brochures (in English!).

Perhaps the B77D was trialed in the more affluent German market, but abandoned for the UK market?

Barry

[brenellic2000]

... now this should put the cat among the pigeons:

Don Aldous' review of the Ferrograph 722HD of November 1972 (Hi Fi News) - just after the machine's launch - states:

"At 15ips the noise performance of the recorder with Dolby B compares with the microphone/amplifier chain..." - so one must presume Dolby B was operable at 15ips (the American 'Electronics' magazine report merely implies that Dolby B applies to all speeds), so perhaps early models did have it connected?

Here is an interesting bit in Don's report:
"It should be noted, incidentally, that the Series 7 includes both single and double channel models, with various full, half and quarter track configurations. Additionally two tape speed groups are available: 7-1/2, 3-3/4 and 1-7/8ips and (Suffix H) 15, 7-1/2 and 3-3/4ips. Dolby B is incorporated only in the two channel models." - ie: not on mono machines, as Tim has already mentioned.

Having now read the ASC 6002 brochure (in English) referred to in Maurice's article ... why didn't ASC offer Dolby B!!

Barry

[SteveCG]

Barry: Interesting what you have found out.

In the early 70s as I mentioned earlier in this thread I had a model 724. When Ferrograph introduced their Dolby models I contacted them to see if they would retro-fit Dolby on my year old machine. They declined. Yet having seen where the Dolby cards were placed in the Series 7 there really was no reason why Ferrograph could not have so done - if they had wanted to!

[brenellic2000]

Ah well, that was one major difference between Ferrograph and Brenell - Brenell were small enough and interested enough in their customers to do one-offs whereas Ferrograph were geared up for volume production for BBC and government orders.

Aldous was not impressed by the quality of Ferrograph's Dolby pcbs cards - brittle and subject to failure - but then Revox A700 edge connected output/inputs were prone to breakage too!

TTFN

[Synchrodyne]

Originally Posted by Ted Kendall

I've never seen nor heard of a Dolby B77, save the one McKenzie mention. The big test was actually in HiFi For Pleasure, if memory serves.

I am not sure if the attached is the test report at interest. As it is a promotional reprint from HFP, I imagine that there are no copyright issues in including it here.

Cheers,

[TIMTAPE]

Originally Posted by paolo

In professional recording, the issue of tape hiss didn't really arise until after 4 track.
... for most users of domestic or semi-pro machines, I can't see the reason for Dolby at anything above 7.5ips. Even at 3.75, my PR99 sounds pretty damn good to my ears and considering that the highest of fi that would have been recorded on it is an LP, the quality at that speed is amazing.

Paul

Paul, no one else commented on your post so I will.

Tape hiss was always a problem because (among other things) the tape's dynamic limitations were the weak link in the recording chain. This was well known in the industry. If you were to connect a suitable good quality microphone into your PR99's microphone input, the tape would overload, or its hiss would intrude, well before the mic and preamp's would.

Multitracks with narrower tape tracks exacerbated the problem but they didnt create it. It was there all along.

I have a quote from Stefan Kudelski on this very problem relating to his Nagra 4.2 portables which could run at 15ips full track! (It's on my other computer which I cant access at present) He freely admitted that the tape's signal to noise ratio was inferior to a good microphone plugged into the Nagra's own internal preamp. That's why he built limiters into the machine so that field recorded sound tracks could be limited in dynamics to "fit" onto the tape.

Somebody else in this thread mentioned a quote to the effect that with Dolby A, the tape could now be closer in its noise figures to that of a mic and preamp feeding it.

Tape was perhaps the best analog method of recording audio, but it wasnt the tape that was the real limitation but the analog method of recording. Some digital audio tape machines had tape speeds around 15/30ips, and stationary heads, similar to professional analog tape machines, but even without any noise reduction they were far quieter than the same tape recorded in analog.

Unfortunately, noise is analog and so any recording system that uses analog means will have this noise "built in".

Dolby NR was one of the systems designed to reduce this noise.

Cheers Tim