test calibraton tapes

These mechanical alignment tapes are recorded single track the full width of the tape with a test signal. You look at the reproduce outputs on a dual trace scope and adjust the repro head azimuth so the two output signals are in phase. That aligns the playback head. You then put on a blank tape and record the same signal on both tracks while You adjust the record head azimuth so the outputs are in phase.

These alignment tapes used to be available in the electronics catalogs, but I haven't seen one for years. There must be some company that still produces them, because the electronics shops could not do a mechanical alignment without one. Do a search on the internet.
Regards,
Ray
 
Hi,
you can get calibration tapes here:

http://www.almedio.co.jp/cassette.html
http://www.teac.co.jp/testmedia/cas.html
http://www.jrfmagnetics.com/basftapes.html

but still it depends on what type of deck you have. Nnakamichi decks for example (the earlier ones) use the older equalization standard. That`s why if you have Nakamichi deck you should try to get Nakamichi cal tapes. You need only 4 tapes to calibrate a nack. They are somewhat difficult to find and in used condition. For other types of decks you can get other types of cal tapes but consult your service manual first. Of cource you can get non-nak tapes also for a nakamichi deck but you should use different calibration procedures from what the nak manual says in order to be successful.
Also, you will first have to make mechanical adjustments bevore you calibrate with tapes. It is important to adjust your speed, your tape guides, tension and other things before beginning a calibration with a cal tape. You will need also aditional tools to measure some things. Generally, if your transport mechanics are not ok or out of tune you are not going to get very good results. It is amazing but improper tape tension and bad or worn pinch roller affect quite a lot the performance of a deck ...
Best regards,
Plamen
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
You can only calibrate a Nak with Nak test tapes. Early tapes were out of phase in the high end, they fixed that problem. Teac test tapes work well for most machines. The dolby level tape was a different level than specified for Pioneer and some others. Eq. was the same.

Before attempting a calibration, the condition of the head and transport is critical. T/U tenson and tape path will damage a test tape if they are out. I assume the heads are demagnitized. Once the basics are addressed you set the playback characteristics, then the record. Use a fresh blank of your particular brand to do this. TDK SA was the standard tape most machines were calibrated to. Maxell will be 4~5 dB hotter in the highs with new heads.

You can not make your own cal tapes. The guard bands will mess up the levels as test tapes are full track with the exception of Nak's head height tapes. They are full track with gaps were the head gaps should be, so you tune for "minimum smoke".

-Chris
 
Well, I was always wondering how and with what mashines the test tapes are recorded. Somebody told me that the industry uses Nakamichi ZX-7 mostly for this purpose. But I think that at least they use special heads or special transports. I`ve also seeen somewhere that the machines with wich tey record test tones have special means to adjust the azimuth of the recording heads so that it is in-phase. So I don`t have enough information but I would want to set up such a mashine at home and make CAL tapes. Why not ? Any suggestions ?
Best regards ...
Plamen
 
Hi,
the question is how precise your calibration tapes should be. The original calibration tapes are recorded with a specially tuned equipment. So the test signals are very precise and in-phase.
Let`s face the truth. The industry doesn`t bother anymore to produce high-quality cassette decks anymore. There is also a limited parts support. For example you can´t find new nakamichi replacement heads.
You may say that your deck is being freshly calibrated but the recording heads are not in that condition in order to make such a precise recording. Also the mechanics of a cassette deck gets worn with the time. I`m a great Nakamichi Dragon fan. But personally I don`t think that such a machine can be refurbished exactly to "like new" condition. Because 15 years old heads can´t be like new, even if they are relapped. And if you take a micrometer you will see that the capstan shaft or shafts are also lightly bent or worn. Sure, it can be done to be good enough, but not like new or better than new. Simply because you don`t get the parts anymore.
That`s why the CAL tapes are that much expencive. Also you must keep in mind that even the original CAL tapes are not eternal. They get scratches, the flux gets weaker and they quickly get bad or worn. I`ve heard thet really professional services don`t use a CAL tape too many times. After that they take a new one. Of cource such a CAL tape is still good enough for hobby purposses. It just depends how fanatic you are by doung these thins. :)
Best regards,
Plamen
 
Anyway, if there is a way to make own CAL tapes I would do it. If I only have the information about what type of mashine/heads to use and how to do the proper setup. Somewhere on this earth should be someone who knows this. :)
It is very hard to find useful information about such things. For example everybody is speaking about equalization standards. There are IEC1 and IEC2. But nobody knows the number of these two standards, or the revisions, when exactly they came out so that I find them and read exactly what they state. I`ve done a little research (and I`m still doing) because I wanted to find some more useful information, not only reading service manuals and ad broshures. There is a lot of interesting information in patents. Unfortunately I didn`t manage to find the original Philips patent on the Audio Compact Cassette. I only know that the cassette was patented somewhen back in 1964 and there is a derived specification which is to be followed by all deck or cassette manufacturers. I wanted to use this information in order to design some calibration tools because I`ve got some ideas ... You see you can not find even such simple things. :(
Anyone knowing more ?
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Plamen,
I spent years returning both R-R and Cassette machines to new spec. Nakamichi was by far the most accurate, followed by Teac and others. We would buy new heads for cassette and relap the lappable heads on open reel. Too bad Nakamichi didn't make open reel. Studer was incredible.

Cal tapes are still made properly (MRL). They measure the flux and do not need a "standard tape" to copy. The record azimuth is set by viewing the recorded tape optically with magnetic dust. You can not make your own cal tapes as your head height will be wrong for another deck. That and most three head machines (all 2 head) record out of phase. You can get something "in the ballpark", but there is no substitute for the real thing. I had three sets (different) for cassette and two for open reel (more if you count each speed). I would not have bought them if they were not required.

I hope that explains the why of things,

-Chris
 
Hi Chris,
well this is sure very interesting information. I know about the magnetic dust. There is a magnetic developer sold by Sprague Magnetics. You spray on the tape and when it dries you see the recorded information.

Why would be my head height wrong? After all, that are all these adjustment screws for. I thing you can adjust the heads of any deck to anything you want. And the heads of the special machines must be also aligned towards some kind of standard.
As of the in-phase recording i think this can be also adjusted. There are mashines with manual record head azimuth adjustment. So why not adjust for in-phase recording. Also I think that some of the CAL tapes are recorded full track so there must be a single wide track special head for this purpose. If this is true, there is no need for in-phase adjustment because there is a single signal on a single wide track. Or am I wrong ?

But the question was what kind of equipment and heads they are using to record the CAL tapes. Have you serviced such a mashine ? Are they using a professional deck from nakamichi or Tascam, mashines we know about or just some weird mashines wich nobody has heard about ?

I know that I can not make a true CAL tape with a normal deck, even if it is a Nakamichi one. But today you can get just every type of equipment provided you know what exactly do you want. So, the question was if it is possible to get the same equipment and set it up at home just for the purpose of making CAL tapes and nothing else. By the way, I have Nakamichi CAL tapes and I know how precise they are. Particularly the 1Khz Track Alignment tape is very special and they must have developed a special head for this. or it is recorded full track and then partially erased, who knows.
So, there must be somewhere a service manual, parts list, etc. But it is very hard to get any information which is not in the service manuals ot ad brochures. There are no service bulletins, no specifications, etc. I`ve tried to find a Nakamichi service equipment catalogue, or listing, or just the name of the paper, no way, I`ve heard that there is a Nakamichi Parts Cross Reference Catalog, no way ... I don`t know why this information is so hard to get around. There are so many fans and service people. Does everybody read just service manuals and ad broshures ? Somewhere on this earth must be someone who knows more. Just who ?
For example how do you determine with measurment if a Nakamichi (and also other heads) head is good or bad. How do you measure head's inductance or impedance? Everybody says test it with playing, measure THD, WOW/Flutter, Frequency responce, but I want to put my brain on not just do what other peole say. And, after all, sure you can somewhat measure a head and there is no problem of having a microscope at home for visual inspection ... But where are the electrical/mechanical specifications (like Inductance, Impedance, Gap Length, Tip depth, Track width, Track to track (ctr/ctr) location, Core lamination thickness and such things) of the Nakamichi heads to be found? I didn`t manage to find any mechanical or electrical specifications. Not at all. I also can`t get new heads. And a worn head is out of spec, even if I know how to measure it.

So I may be very eager to do my research but everything leads to a dead end. This is very disappointing. I wish this information could be available to anybody who is interested. I would greatly appreciate if you have more information like spec sheets, service bulletins, etc. and share it somehow with me. Best regards,
Plamen
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Plamen,
Yes, that's the stuff I was talking about. There is also a magnetic "viewer" (dust in a tube) and just free dust (not in suspension).

The machines that make the test tapes are special machines, not a normal deck at all. The angle of the effective gap must be perpendicular to the edge of the tape. Bias level can affect the angle which is why two heads decks are out of phase with themselves. The tapes are recorded full track. The head height tape you are talking about is very accurate. Too bad many techs are not that careful setting up machines. I've heard "close enough for rock & roll" too many times. I have never actually serviced one of these machines. Keep in mind that the flux density,wow & flutter, speed and azimuth are the only important parameters within reason. I doubt these machines sound great.

Calibration training for me occured at Nakamichi head office in Vancouver. Before that at Marantz in Toronto and Yamaha in Toronto. Teac and Tascam training occured at various times in Toronto and Mississauga - all in Canada. Studer and Revox in Toronto as well. So this information is passed on in training seminars only that I know of. My Tascam trainer was Austrian. The info is only as good as the trainer.

You can measure the head inductance. That only tell part of the story. Careful optical examination is very important too. I have received bad heads from many but most from Sony. Generally, a head defect will kill the HF response on one or both channels.

Head engineering details will not be found if the head is made for that manufacturer. There are some replacement head makes that do supply that information. Look in Japan for that. China now, but why bother with those.

You can make "cal" tapes for a Nakamichi, but no one else's machine sets their heads up like that (same as an open reel machine). Therefore the head height is likely off between identical non-Nak. machines. See a problem?

-Chris
 
Yes I see the problem ...
But still I`m eager to know more ... Do you have any written information or at least knowledge of what papers exist. It seems that you have a tremendous knowledge. I deeply respect people like you. I myself have such a deep knowledge on IT systems and I know what it means to aquire it. So I would greatly apreciate if you give me more information somehow. By the way how do you measure head inductance ? And, what else could be measured ?
Thank you,
Plamen
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Plamen,
You may be able to find some info in print. Some Tascam open reel manuals used to give an idea, also Revox and Studer manuals. I don't know how correct Technics are - they did publish some technical guides. Some Marantz cassette manuals may have had some info as well. The journal of the AES must have some excellent articals on this subject. Look in the eighties and earlier.

Head inductance is measured with an ... inductance meter. I use an HP 4263A LCR meter. This is more common with VCR heads than audio heads. There are some much less expensive VCR head meters. They may not work well on audio heads as the inductance is very different.

Your playback level / response tape is the best for determining the status of a head. That and your clear, logical mind. Use your eyeballs first.

Knowledge is hard to come by, I'm also certified on iP phone systems (Avaya iP Office). I know a little networking. There are many incredibly talented people on this board. I hope someone else can add to this.

-Chris
 
:) I also wanted to say that my special interest is for Nakamichi and especially for the Dragon. As of the typical Nakamichi head set-up ... I know that, but I never knew the details. I couldn`t find both the IEC1 and IEC2 standards to read about this. And i think I`m not very fit on this theory. I think IEC2 is actually IEC 60094 - "Magnetic Tape Sound Recording and Reproducing Systems" ...
Which one is IEC1 I don`t know, perhaps the same but earlier revision, but which one, the libraries are very big ... :).
It is interesting also to know what is "open reel alignment" and "non open reel alignment" or ... Why the Nakamichi alignment is open reel like ? I know that the Nakamichi heads are far superior than others and that IEC2 introduces a bump in the high frequency area of the equalization curve because the others have miserable heads and so on. But still I don´t understand what is the difference between open reel alignment and "normal" alignment. I thought that the azimuth should be 90 grad to tape. Anything different than the 90 grad makes the head gap bigger? So what is the difference ? And head height ... Tape should be in the middle of the head. What is here the difference ? Somebody told me that equalization (IEC1 or IEC2) is not only a matter of mechanical adjustment but also a matter of circuitry inside the deck. Perhaps it is simple but since I don`t find literature to read about it I can't also get control of it. :)
As of the mashines ... Yes special ... But what make and model, any Idea ?
As of the replacement heads, I would want to get any but all the sources I`ve tried are no-way. I thought that especially the dragon heads and especially the PA-1L PB head are among the most complex ones and no one has managed to produce a replacement for them ... And it seems that nakamichi doesn`t do them either. So what ? :) It is indeed very interesting to talk with you, thank you very much ...
Best regards,
Plamen
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Plamen,
Only Nakamichi makes Nakamichi heads. Autocal / auto azimuth machines have one head winding that is split into two halves for the auto azimuth circuit. The Dragon uses the "standard deck 1" mech. The 1000ZXL is a far better machine. Same transport but better. Nak heads last for ever it seems.
The Nak system pushes the pressure pad in the cassette away from the head. Gone is the FM tape noise the pad causes. The tape tension is responsible for head contact. It is generated by running the rear capstan shaft slower than the take up side. The heads have no guides on them at all. Just the pad lifter. Open reel machines run on exactly the same principle, some use back tension supplied by a reel brake or motor rather than adjusting the capstan shaft speeds. On a NAk, each head is fully adjustable in free space - just like open reel. All heads set up seperately as well. THe tape path is therefore set up by the mechanism guides and head heights and angles. Same as an open reel.
Other cassette machines use a guide on the head. I had a few head height guides for those, Nak went straight to the gap position on the head.

For EQ, Nak interpreted the spec a little differently. To the energy on the tape. They had a publication on that. To hear the difference you have to play with a Nak, then you know what I mean. Similar to actually driving a BMW or Mercedes to see the difference.

-Chris