[78-L] half track tapes

[Michael Biel]

From: David Lennick <dlennick at sympatico.ca>
> Then somebody invented butterfly heads and the CBC bought
> Studers that had them, and all my nice tapes recorded at
> home on the Revox or Teac had problems if they'd been bulk
> erased because the Studers picked the WHUMP WHUMP WHUMP 
> down the center channel.

You would have flunked my audio production class.  Apparently you
haven't been taught the proper way to bulk a tape.  If you take less
than maybe five seconds in s-l-o-w-l-y pulling the bulker away from the
tape, you deserve the WHUMP WHUMP WHUMP.  I demonstrated the proper and
improper way to bulk and showed how to do it without any WHUMP WHUMP
WHUMP and proved it every time.  But you are off the hook because even
beyond the fact of my retirement, I have bulked my last tape because it
is important to keep my pacemaker away from magnetic fields like a bulk
eraser or metal detector.   
 
> Wollensak memories: My dad went through a few of these, starting
> with a half-track mono machine in 1959 and a quarter track model
> the following year. The pressure pads were always wearing out or
> falling off, so he'd "borrow" a felt hat from my little brother
> and trim away a little bit of the brim to make new pads. That
> hat got pretty narrow within a couple of years.   dl

Are you sure that it was not just that the kid was GROWING!!!  By the
way, Robbins sold a packet of pre-cut press-apply pressure pad for
something like 89 cents.

Professor Biel   mbiel at mbiel.com

 
 Michael Biel wrote:
 > At 09:41 AM 8/8/2009, you wrote:
 >>> Remember the Wollensak with its dial for shifting the playback
 >>> head down a millimetre or two to play half-track tapes with
 >>> equal balance? Any other machines have a feature like that?
 > 
 > From: "Robert M. Bratcher Jr." <bratcher at pdq.net>
 >> Which model is that? 
 > 
 > Wollensak T-1515-4, T-1616, T-1580 (I think that's the number), and
 > several Revere's -- the stereo playback versions of the single knob
and
 > the pushbutton models if they have a suffix "-4". All of their stereo
 > playback machines from 1959 onwards were this way until they started
 > making machines that recorded in stereo, and they also sold an
adapter
 > head-set. The major purpose of the "Head Track Selector" was to
enable
 > the recording on the lower tracks on these machines which only
recorded
 > in mono. This gave you four mono tracks, but they played back in
 > stereo. Since the 2-track tapes were so common back then, the extra
 > notch to lower the head just slightly was quite handy. The BEST thing
 > these things could do was search out the best part of the tape for
 > warped full track tapes. It is still a very valuable technique to
play
 > back old full track tapes. (The second best technique archives use is
 > to have a quad-four head and pick out the ONE track which is the
best.) 
 > 
 > 
 > There may have been a mistake in an earlier posting about which track
 > was weakened when playing a half-track stereo tape on a quarter-track
 > machine. It is the RIGHT channel which is weakened. The Guard-Band
 > space in-between the tracks is wider for stereo then it is for mono
half
 > track. The lower track of the 4-track system will hit half on the
 > guard-band and half on the lower track of the 2-track stereo tape, so
it
 > needs to be slightly lowered. This also has the benefit of moving the
 > upper track away from the edge of the tape which is where physical
 > damage can first happen. It also helps when recording a tape to be
 > played on the full track Ampex portables 600, 601, and maybe the 602.

 > These machines had a slightly curved play head which avoided the
upper
 > and lower edges. They completely miss the upper quarter-track. The
 > record head is flat and records the full width of the tape, but since
 > portables might be working with damaged tape, this helped make the
 > playback of full track tapes more consistant. There might have been
 > head-bump compensation. 
 > 
 >> I had a worn out Webcore Music Man that would shift the playback
 >> head with a lever on the back of the head assembly. Threw it
 >> away when it stopped playing tapes at 3.75 ips & was having
 >> trouble with 7.5 ips. Belts were shot really bad but then 
 >> I got it for free.....
 > 
 > The Wollensak/Revere device moved BOTH the Record/Play and the Erase
 > heads.
 > 
 >> Today, of course, you just look for a Technics 1500 with the
quarter-
 >> and half-track playback heads. Still quite a few of them out there.
dl
 > 
 > Yes for 1.5k to 1.7k on the bay site. 
 > 
 > The Otari 5050 machines had an extra quarter track play head in the
 > second of the 4 head blocks. It was standard equipment until the Mark
 > IV, when it became an option WHICH NOBODY TOLD ME WHEN I BOUGHT MARK
IVs
 > FOR MY SCHOOL. So those last 4 machines have only three heads and
 > screwed me up for playing my home recorded tapes. I had to use the
 > earlier ones we had there. By the way, the record and play heads are
 > exactly the right spacing for Staggered-Stereo playback!! Set one
track
 > on play and the other on Sel-Rep and it will play them!!
 > 
 > Mike Biel mbiel at mbiel.com