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Re: [ARSCLIST] cassette crackle

Mike Hirst wrote:

In future, is there anything that I can do at playback, to reduce or eliminate the problem - maybe a playback deck with a narrower head, or some other solution?
Most of what I will say here concerns open-reel tape because cassettes are so damn small and some of these problems concern mainly older and wider tapes. But I'll get to cassettes in the end.

I know that this is controversal because of the effect on the bass when playing a tape back with a head that has a narrower track than the tape had been recorded with. But using a head with a narrower track can overcome a lot of problems on old tapes.

Some of you other old-times might remember the "Head Track Selector" that Revere/Wollensak had on their early quarter-track stereo playback/mono record machines. My first machine 48 years ago was an ill-fated Wollensak T-1616, and I later used a T-1515-4. The selector allowed you to move the stereo heads down slightly to center on half-track stereo tapes and miss playing part of the guard band with the lower track. Remember that the guard-band on half-track stereo is wider than for dual-track mono. Half of that guard band is in the area where the lower track is on four-track stereo. If you play a half-track stereo tape with a four-track stereo head, the right channel will be lower in level and noisier because of this unless you drop the head lower. The mechanism then allows you to move the heads further down to be able to record and play on the lower track three with the upper head gap so you could record four separate mono tracks.

That's how you were SUPPOSED to use this device. But I found it had two other benefits. I occasionally came across tapes that had been re-used on machines with narrower tracks than it had originally been recorded on. For example, a full track tape might later be used on a half track machine, or a half-track tape might be later used on a quarter-track machine. Although the person doing the new recording might not have noticed it, the original recording might not have been erased by the next machine in the guard band area. By moving the head down to this guard band area, I could recover the older recording. I found a master-dub of the Fred Allen Portrait In Sound broadcast this way.

The other benefit concerned old warped tapes, especially full-track, and this is where the controversy comes in. On many old tapes, especially acetate, what had been a razor-edge straight recording from the original full track head has now become a curvy-wiggle shaped line. If you play this tape back on a real full track head the high frequencies will drift in and out because they will not be totally in azimuith allignment and some frequencies will be nulled out when a positive and negative portion of the same wave hits the head at the same time. I found that if I used the Wollensak instead of a full track machine, I could move the head track selector up and down to find a place where there was no tape warpage and none of waves would be nulled. And as for those who will yell HEAD BUMP, I say that sometimes the increased bass sounds good on the old tapes, and it can be EQed out if you insist.

I have seen some people suggest using a four channel quad head to play back full track tapes and select one AND ONLY ONE of the tracks to use. NEVER mix two tracks together when playing a full track tape. That also goes for cassettes. Never mix the two stereo tracks together when playing a cassette recorded on a mono machine.

My suggestion is to have a machine set up for just playback with a head that can be moved every which way. I remember machines made for playing tapes in disc mastering labs that had a large knob to set azimuith instead of using a dinky little screwdriver that would eventually louse up the little azimuith screw. Add to that another knob to set the height. Have adjustable tape guides and adjustable pressure pads for the guides and possibly even the head. Removable, of course. And have the guides be rotating if possible to avoid any non-moving surface to contact the tape to reduce shedding, either sticky or powdery. When I was in Moscow in 1995, Alexander Tikhonov took me to a studio that did the restoration work for Radio Moscow. He had a special russian-made machine (I don't think it was the Hungarian machines that were almost exclusively used in the Radio Moscow studios, but I would have to check my videotape) that was designed for restoration playing. I don't think it was a modified or one-off machine. No recording electronics or heads, of course. (95% of us have no need to record tape anyway.) It had maybe a dozen different interchangable head blocks for all sorts of different formats with all sorts of different dials on them for adjustments. Never seen a machine more versatile. Studer make one like this??

A last note about cassettes. The narrow tape does not give some of the problems that wider open reel tape has, but controlling the head location is also a problem. The cassette shell adds a whole-nuther set of variables. Nobody has ever made an open reel player for .150 tape, have they? Oh, that little Nagra. What was its tape width? .125 or .150? But that thing would probably cost as much as a luxury car now if you could find it. Maybe some of you who have worked more with cassettes than I have (I HATE them) can recommend machines that have more sturdy and accessable adjustments than the usual crap, and some that retract the pressure pad.

Mike Biel mbiel@xxxxxxxxx

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