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.
----- 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.
> 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.
>> ----- 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
>>> 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
>>>> capstan deck will hold azimuth better throughout the length to the
>>>> Some Nakamichi's also have the added feature of a pressure pad lifter.
>>>> you are going to consider a NAK, be sure and buy one that was built
>>>> 1982. Dual capstan decks are expensive, even used which, I think, is
>>>> only way you will find one. The Tascam that you mention is current but
>>>> good used dual capstan machine will out perform it, hands down.
>>>> My $0.02
>>>> Corey Bailey Audio Engineering
>>>> 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
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>>> 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
> Quality tape transfers -- even from hard-to-play tapes.