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Hi All, The "Look Ahead" system was (is) not only used in the disc mastering process involving audio tape but in the process of making a sound negative for film release prints as well (also a dying technology). The Nakamichi dragon, AFIK, does not use a look ahead tape head but a separate channel that is part of the play head. The fact that Richard Hess noted about one revolution for the auto-azimuth circuit to react is disconcerting.Even though, by design, the Dragon is chasing azimuth, I thought it would be faster than that. Cheers! Corey Corey Bailey Audio Engineering www.baileyzone.net On 5/8/2019 2:45 AM, Tim Gillett wrote: > Thanks Richard, that sounds like a practical use of the tools available. > > Thinking more conceptually about Stuart's point about a repetitively > skewing azimuth and the potential hysteresis problem, I recalled > today the old system used in disc cutting where a "look ahead" tape > head would read the volume levels of the master tape before the actual > repro head received the same signal. It gave the disc cutter lathe's > lead screw servo time to widen or narrow the groove spacing dependent > on track volume. > > A similar system might be used for tracking faster and repetitive > azimuth changes in a tape. A "look ahead" head gathers information > about the azimuth skew. The information - after processing - controls > the azimuth settings of a Nak Dragon style downstream read head. > Since we're only interested in playback, not record, the "look ahead" > head could fit in the space previously occupied by the record head or > even the erase head. Just a thought. > > Cheers, > Tim > > ----- Original Message ----- From: "Richard L. Hess" > <[log in to unmask]> > To: <[log in to unmask]> > Sent: Wednesday, May 08, 2019 6:58 AM > Subject: Re: [ARSCLIST] Tascam 122n MK models > > >> Hi, Tim, >> >> You approached Stuart's challenge from a different direction. I can >> tell you that I've received tapes that "pin" the Dragon's auto >> azimuth capability. If it's a Dragon-worthy tape, I'll readjust the >> mechanical azimuth to get some range on the motor-driven azimuth, and >> then put it back. If it's not a Dragon-worthy tape, I'll put it in an >> MR-1. >> >> Cheers, >> >> Richard >> >> On 2019-05-07 6:13 p.m., Tim Gillett wrote: >>> Hi Stuart , >>> >>> I've serviced a Dragon but not to test the limits of its azimuth >>> correction system. I guess we're talking about severe azimuth >>> changes, beyond what the Nak was designed to deal with. Law >>> enforcement people must have had to deal with such recordings as >>> court evidence and who knows what they may have come up with. I've >>> read of the JBR company and a modified microcassette player they >>> pitched to forensic people. I think it had a play head split into >>> something like 12 tracks. >>> >>> Cheers, >>> Tim >>> >>> ----- Original Message ----- From: "ROBINSON Stuart" >>> <[log in to unmask]> >>> To: <[log in to unmask]> >>> Sent: Tuesday, May 07, 2019 6:19 PM >>> Subject: Re: [ARSCLIST] Tascam 122n MK models >>> >>> >>>> I have never used a Dragon, but what I wonder when I think about is >>>> how long it takes to respond to azimuth changes? Does it for >>>> example respond fast enough to react to tapes that have >>>> country-laning issues? I have had cassettes where record issues >>>> have meant an almost constantly shifting azimuth and I wonder >>>> whether the system can correct for this or if it will end up in >>>> hysteresis always trying to seek the ideal point. >>>> >>>> Stuart Robinson, >>>> Audio-Visual Archival Technician, >>>> School of Scottish Studies Archives, >>>> The University of Edinburgh >>>> >>>> >>>> >>>> -----Original Message----- >>>> From: Association for Recorded Sound Discussion List >>>> [mailto:[log in to unmask]] On Behalf Of Tim Gillett >>>> Sent: 07 May 2019 04:03 >>>> To: [log in to unmask] >>>> Subject: Re: [ARSCLIST] Tascam 122n MK models >>>> >>>> Hi Corey, >>>> >>>> On a dual capstan deck, the reason it's better for azimuth >>>> stability is its uniform back tension. In a standard single capstan >>>> deck, back tension from the supply reel tends to increase as the >>>> tape plays from start to finish. >>>> Changing back tension can change azimuth. An interesting >>>> complication in our situation is that the deck which originally >>>> recorded the cassette we are now playing, may not have been dual >>>> capstan, meaning its recorded azimuth may well change from start to >>>> end of tape side. >>>> >>>> I was in a team digitising thousands of Oral History cassettes >>>> mostly recorded on simple single capstan cassette decks. We used >>>> Tascam Mk III playback machines which, like Naks have a constant >>>> back tension, but controlled electronically, not by dual capstan. >>>> Often the azimuth alignment would slowly drift from start to end of >>>> the tape side, seemingly always in the same direction. If we'd used >>>> Naks I suspect the result would have been similar. >>>> >>>> Ideally, such tapes would be played in a similar deck with similar >>>> back tension changes! Or on a model such as a Dragon, but I wonder >>>> how many of us have access to one of those? >>>> >>>> The other thing is that it's the constant back tension which >>>> *allows* removal or lifting of the pressure pad. This means that >>>> many otherwise fine dual capstan cassette decks would potentially >>>> benefit from the adding of a pressure pad lifter, as per the Naks. >>>> I've modded a few such dual capstan decks (Pioneer, Tandberg, Sony) >>>> with a custom made pressure pad lifter with good results. It's not >>>> always appreciated that the absence of the pressure pad greatly >>>> improves head life, which is one of the main reasons I like Naks >>>> myself. >>>> >>>> The Tascam 122 MkIII retains the pressure pad but it mostly works >>>> againt the record head, not the play, but has a role to play in >>>> maintaining the back tension across the play head downstream of it. >>>> The pressure pad on the record head causes quite a bad wear groove >>>> after not too long a time, but in even the worst wear cases I've >>>> never seen a play head - sitting right next to the record head- >>>> worn nearly as badly or unsalvageable.( The Tascam >>>> 122 head is a beautiful piece of engineering IMO, which unusually >>>> allows full adjustment of the record head independently of the play >>>> head. They're not locked together). In my view the 122 record/play >>>> head assembly should be replaced not when straight line playback >>>> performance suffers, but earlier when the record head becomes >>>> grooved due to the wear from the pressure pad.. >>>> This is especially so when azimuth is routinely adjusted and the >>>> tape is forced to distort inside the "tramline track" of the worn >>>> record head as the head twists with azimuth adjustments. Of course >>>> this applies to any tape head in any machine. >>>> >>>> I noticed on a head from a later model Nak deck, relief slots were >>>> factory cut into the head faces. A nice feature, especially in a >>>> transfer situation where azimuth is regularly being adjusted. >>>> >>>> Tim Gillett >>>> >>>> Perth, >>>> Western Australia >>>> >>>> >>>> >>>> ----- Original Message ----- >>>> From: "Corey Bailey" <[log in to unmask]> >>>> To: <[log in to unmask]> >>>> Sent: Monday, May 06, 2019 11:06 AM >>>> Subject: Re: [ARSCLIST] Tascam 122n MK models >>>> >>>> >>>>> Hi John, >>>>> >>>>> I prefer cassette decks with a dual capstan mechanism for >>>>> playback. The >>>>> reason is that cassettes, particularly old ones, tend to skew and >>>>> a dual >>>>> capstan deck will hold azimuth better throughout the length to the >>>>> tape. >>>>> Some Nakamichi's also have the added feature of a pressure pad >>>>> lifter. If >>>>> you are going to consider a NAK, be sure and buy one that was >>>>> built post >>>>> 1982. Dual capstan decks are expensive, even used which, I think, >>>>> is the >>>>> only way you will find one. The Tascam that you mention is current >>>>> but a >>>>> good used dual capstan machine will out perform it, hands down. >>>>> >>>>> My $0.02 >>>>> >>>>> Corey >>>>> >>>>> Corey Bailey Audio Engineering >>>>> www.baileyzone.net >>>>> >>>>> On 5/5/2019 7:19 AM, John Schroth wrote: >>>>>> Hoping to get some input from everyone. >>>>>> >>>>>> I'd like to add a Tascam 122 cassette deck to our inventory. I've >>>>>> been >>>>>> studying up on the different models, reading conflicting reports. >>>>>> Does >>>>>> anyone have recommendations on which of the models they prefer - the >>>>>> original 122, MK-II or MK-III? >>>>>> >>>>>> Thanks in advance for any input. >>>>>> >>>>>> Kind Regards, >>>>>> >>>>>> John Schroth >>>>>> >>>> >>>> >>>> --- >>>> This email has been checked for viruses by Avast antivirus software. >>>> https://www.avast.com/antivirus >>>> The University of Edinburgh is a charitable body, registered in >>>> Scotland, with registration number SC005336. >>>> >>> >> >> -- >> Richard L. Hess email: [log in to unmask] >> Aurora, Ontario, Canada 647 479 2800 >> http://www.richardhess.com/tape/contact.htm >> Quality tape transfers -- even from hard-to-play tapes.