Cassette azimuth adjustment

[JacKam_]

Folks, I invented that today (you can write patent application, but do not forget about me) :

A compact cassette with a loop of very thin tape inside. The length of the tape is around 10-20 cm, glued in a shape of Mobius loop. With wrong azimuth the tape would be recorded in some direction, let's say "/" , played out "\" way. Only with head position "|" technician will get maximum volume.

So we record on one side and playing back other side, I expect playback signal much weaker, but still good for measurements.

Simple ? Who wants to make one ? Use C180 or c240 tape.

Jacek

[Radio Wrangler]

Anyone can record suitable test-tones and a swatch of music using whatever tape machine they have to hand and then call it an alignment tape... and ask any price they want for it. Make the price high enough and the 'reassuringly expensive' effect kicks in.

What separates a good one from the others is the matter of where does the confidence that it is accurate come from?

The need for accurate azimuth adjustment comes from the need to make tapes interchangeable between machines, so someone with multiple machines and swaps tapes with a group of friends all need to use the same or identical alignment tapes.

The pre-recorded cassette industry had to get it quite accurate because they wanted their product to be usable on every player on the planet, and each cassette had to be the same.

You can also try making the assumption that head manufacturers used accurate jigs and adjust azimuth by looking at the relative phasing of stereo channels with the highest frequency possible, but that again relies on the azimuth of whatever the tape was recorded on.

Finally, there are ways of viewing the effect of fields on a tape affecting magnetic dust which can be inspected under a microscope.

With large open-reel machines whose head-blocks aren't shrouded by the lower panel a scope with an accurately mounted mirror and a reticle can be used to look at the gap.

Listening to tapes only achieves matching with whatever recorded the tape.

David

[unitaudio]

I always use a well recorded music tape (Frank Zappa, 'Broadway the hard way') recorded on my mate's Nakamichi DR-3 deck. When I recorded the tape the machine was brand new and although that's no guarantee of accuracy, the DR-3 is as near as I can get to a benchmark and while machines set up with this tape aren't necessarily spot on, it always brings a significant improvement.

I've always suspected the majority of tape mechanisms aren't set up particularly well from the factory. A friend of mine bought a Saisho car stereo in the early 90's. I had to reset the azimuth on that, it was miles out. Serves him right for being such a skinflint!

Regards,
Paul

[Restoration73]

Worst were the car stereos with auto reverse - not possible to get optimum in both
directions. Later decks in mini systems with reverse had a head that rotated through
180 degrees, often better. Use a good type 2 or 4 tape if you want the best high end
or white noise. Otherwise a 8kHz tone both channels is useful if you have a dual trace
scope. The tape path should be demagnetised first.

[Karen O]

I seriously doubt that a cassette adapter will be of any service for azimuth adjustment. You may notice a variation in coupling as you adjust the azimuth but it will do nothing to determine whether the head gap is aligned with the 'magnetic furrows' that pass by it on tape.

[mitajohn]

Hi,

Someone of you members who owns a good cassette recorder would be very helpful to record a cassette both sides with a mono signal of 8 or 10kHz and post the cassette to Hampus to adjust his machine. Why not! Is this the purpose of the forum to give help or not!

[Karen O]

It would be a very valuable service to the community if someone made available (at cost) reference cassettes. I don't think any of my machines are adjusted correctly and so I would take advantage of such a service. The only pre-recorded cassette I have is an Alba karaoke demo tape!

Talking of which, that Kara Oke seems to get dozens of gigs, yet she never turns up and the punters end up singing

[Restoration73]

I'm sure there would be a response had this thread been in the "sets and parts wanted";
I have a BIB test tape from 1973 (by Decca) and even the Dolby B is still accurate.
There would have to be a consensus on what tests users actually want.

[TIMTAPE]

The only time I need an azimuth alignment tape is when servicing a cassette deck for a customer which these days isnt that often.

Adjusting azimuth on a machine with a worn (grooved) head can lead to problems. At worst the tape can be damaged trying to navigate the twisted path. Better to relap or replace the head and then adjust the azimuth afresh.

The most handy tool I have in terms of azimuth adjusting I made myself. It's just an extension of the cassette machine's azimuth screw, appearing on the front panel as a small adjustable knob. It makes it easy to adjust the playback head to whatever tape I happen to be playing without having to faff around with finding the right screwdriver.

Pictured is an adjuster I made for a professional cassette deck but it could be done on consumer decks too. The tricky design bit is allowing for the movement of the head when it enters and exits the cassette. I used a small Allen wrench as the basis for the extension rod as it had a ball end. I replaced the cassette machine's adjuster screw with an Allen head screw. The Allen wrench rod and the Allen head screw become a ball and socket joint.
At the adjuster end, the rod tilts in a slightly elongated hole in a thin plate although a more sophisticated bearing could be made.

Much easier to do on reel to reel machines as the head is stationary.

Tim

[sp10mk11]

TimTape
good idea and I like the execution of it aswell, of course if we all had Nakamichi Dragons that do this function themselves...........where is that lottery ticket......

[TIMTAPE]

Thanks.

No, me neither. I've never had a Nak Dragon or the other fancy models with manual or auto azimuth. But I'm a fan or the more lowly 480/482 models which go for little these days. They have essentially the same mechanism in them as the Nak exotics with dual asymetric capstans and the pressure pad lifter.

I added an azimuth adjuster to a 480 too. I made this one really simple, without the flexible coupling. The adjuster is just an extended screw with a knob on the end. It moves up and down along with the head. But fitting it did involve some hacking away of the front panel which some purists might not appreciate!

Cheers Tim

[Tractorfan]

Hi,
It's probably worth degaussing the heads too before aligning them. That can improve the treble on a machine that has done lots of playing back, but little recording.
Cheer, Pete.

[vidjoman]

Don't try to make the head easily adjustable if it's only a 2 head machine. It's going to wreck any recordings you make and they'll be unplayable on any other machine. Can only be done on a 3 head and only on the playback head.

[TIMTAPE]

That assumes new recordings will or can be made on such a machine.

A way to help safeguard valuable one off recordings from the past is to play them only on a machine incapable of recording or erasing.
The machines I have modified with a user adjustable azimuth control have also been modified not to record or erase. No chance of accidental erasure.

Cheers Tim