On 1/13/2011 8:51 PM, George Brock-Nannestad wrote:
> From: Patent Tactics, George Brock-Nannestad
> Hello Michael [Shoshani],
> you never understood high speed commercial dubbing. Well, it was a high speed
> reproduction of the master 1/4 inch tape and dubbing it onto high speed
> recording cassette tape,

The duplicators I saw here in the U.S. often used a 1/2 inch master 
because it was four track -- both sets of stereo tracks were recorded at 
the same time.  The master was in a bin-loop which played over and over 
and over and over.
>   collecting the recorded cassette tape in a cassette,
> putting in an empty cassette and recycling the master. The cassette tape came
> from a pancake and was cut.

They usually recorded the entire pancake from the continually repeating 
bin-loop master.  The recorded pancake was placed on the cassette 
loading machine, and a cue tone told the machine where to cut.  The fun 
part is watching the automatic splicing block splice the tape onto the 
middle of the C-0's leader.  Then the tape is wound into the cassette 
until the tone stops it, and then the automatic splicer tacks the other 
half of the leader onto the tape and is wound back into the cassette and 
it drops down a chute to the pile of cassettes.  I videotaped one of 
these machines and ought to put it on YouTube -- but I bet there already 
is one.

>   It was very quick, but there was no loss of high
> frequencies, because that is all dependent on the gap length, and that stayed
> the same. It was a fully automated process, and LYREC of Denmark made very
> good duplicating equipment. The electronic difficulty was in the bias
> frequency, which was in the Megahertz range, and you had to be very careful
> with your stray capacities.

The interconnect cables were video cables because the frequencies were 
up in the video range.

> Mechanically it was a challenge, but LYREC did
> solve that. LYREC machines are still in operation, I think, and their last
> markets were in India and Russia.  Kind regards, George

I think there still might be some going here in the U.S.

Mike Biel   [log in to unmask]
> ---------------------------------------
>> On Thu, 2011-01-13 at 19:21 -0500, Tom Fine wrote:
>>> But, none of this warm and fuzzy nostalgia will make those piece of
>> garbage pre-duped tapes sold to
>>> the Walkman Generation sound any better. They were disposable junk, and
>> almost all of them ended up
>>> in landfills in the 90's, replaced by much better sounding CD's. I never
>> fell for the trap since I
>>> could dub my own tapes.
>> Same here. I never understood how high speed commercial dubbing worked
>> in the first place; it seems that all the high frequencies would be well
>> out of the reproduction and recording range of the equipment involved.
>> I made my own LP to cassette dubs, carefully setting the recording level
>> to kick just below -0 db on the loudest passages so as not to ride gain
>> constantly.
>> My children will never know such geeky joys. :)
>> Michael Shoshani
>> Chicago