Re: [ARSCLIST] Distance between staggered heads

["Richard L. Hess" <arclists@xxxxxxxxxxxxxxx>]

At 12:20 PM 2007-12-30, Parker Dinkins wrote:
> on 12/30/07 10:51 AM US/Central, Jim Long at JJimLong@xxxxxx wrote:
>
> > Can any ARSC gear head tell me the distance between the left- and
> > right-channel staggered heads on early 1/4-inch 1950's stereo 
> tape recorders,
> > e.g., Magnecord?
>
> I think they varied, but according to
> http://www.websitetoolbox.com/tool/post/bsnpubs/vpost?id=2313089 it was 1.25
> inches for the Magnecord.
>
> Probably it would be best to use a DAW and slip one channel until they
> match. **If** the speed was absolutely correct, you could figure out the
> distance from the offset time.

Hello, Jim,

Parker is correct that as best we can determine, 1.25 inches is the 
correct spacing for Magnecord.

However, I've had several two-track staggered head recordings which 
seemed to work better at 120 ms (on a 7.5 in/s tape) than the 167 ms 
delay that the 1.25 inch spacing would indicate. The math indicates 
that this was 0.9 inch spacing. BUT it was hard to tell on this tape 
as it was two halves of a choir in a synagogue and there was little 
common information between the two mics with a good arrival time pedigree.

Remember, that sound travels about 1.1 feet per millisecond so plus 
or minus 20 ms would be a mic spacing distance of +/- 22 feet which, 
in a large worship space recorded long ago by someone else is 
difficult to tell.

I did run sections at 100, 120, 133, and 167 ms delay and the 120 
sounded the best. 100 ms would, of course be a spacing of 0.75 inches 
and 133 ms would be a spacing of one inch.

I once had my hands on an Ampex PR-10 with four channels of 
electronics, and staggered quarter track record and play heads. I 
think the stagger was under 1.25 inches. This was a home-brew cobble, 
but apparently worked when other 4-track recorders all required 1/2-inch tape.

Also note that instrumentation heads are typically spaced by 1.500 
inches. You'll find this on the 7-track 1/2-inch IRIG tapes as well 
as the 14- and 28-track 1-inch IRIG tapes.

Good luck!

Cheers,

Richard


Richard L. Hess                   email: richard@xxxxxxxxxxxxxxx
Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
Detailed contact information: http://www.richardhess.com/tape/contact.htm
Quality tape transfers -- even from hard-to-play tapes.