Exactly the point I was making before. I would bet that there were at
least two different recorders involved here.
Having a variety of narrow track headstacks is a big help in this regard.
--Scott
Scott D. Smith CAS
Chicago Audio Works, Inc.
--ScottOn 3/1/2012 9:29 PM, Jim Lindner wrote:
> I would have to play around with it, but it sounds to me that this tape may have been recorded on first, maybe with a full track head, then re-recorded on with half track heads, and not bulk erased in between the first recording and later recordings. This kind of thing happened in radio production all the time - you just picked up what ever piece of junk that happened to be laying around, used it for what you needed and then threw it back on the pile. Then someone else would pick it up, use it, and back in the junk pile. After a while it was just a hodgepodge of recordings.
>
> It may be that the first recording was recorded in the other direction. When it was re-used, the erase heads took out where the newly recorded tracks were going but the "gap" between the tracks were never erased by the erase head because it was in the wrong position - leaving the residue from the original recording.
>
> For forensic work I sometimes took a very small head designed for multi-track work which had very narrow tracks and mounted it in such a way that I could quickly position it any place i wanted across the tape. I then used only one track from the head, but positioned it where ever I wanted to, so I could listen to areas between tracks and the edge or just part of a wider track, where ever I wanted to.
>
> I cannibalized a deck that was auto reverse to save time flipping the tape, and had my manual head positioning rig so I could easily figure out what was going on. For final playback, once debugged, I could then put it on the right configuration deck or just play it back on the "custom" deck if I needed to. It usually was not about quality, it was about figuring out what was going on. It came in very handy to find all sorts of things. Probably the most profitable deck I ever owned. It cost almost nothing to buy and modify, but it was great for all sorts of billable activity.
>
>
>
>
>
> Jim Lindner
>
> Email: [log in to unmask]
>
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>
>
>
>
>
> On Feb 29, 2012, at 7:41 AM, Gregorio Garcia Karman wrote:
>
>> Hello Richard,
>>
>> let me explain. After having decided that the crosstalk while transferring the problemativ tape on a stereo head is too big, I played back the tape on a Studer A67 fitted with a head that will extract only the signal of tracks 1 and 3. That said, and if we would consider the tape having four tracks 1/2/3/4 and transferring on this head, on the first side I get:
>>
>> Track 1: Signal A
>> Track 3: Signal A + B backwards
>>
>> Then I turn sides, playing back the tape in the other direction and the result is:
>>
>> Track 4 ("new 1"): Signal B
>> Track 2 ("new 3"): Signal B + A backwards
>>
>> I hope I explained it well this time! You can see a screen capture of the resulting protools session here:
>>
>> http://www.ggkarman.de/preservation/wiki/images/0/0d/Screen_Shot_2012-02-24.png
>>
>> As you see, there are two mono signals recorded on the tape. The middle tracks 2 and 3 contain the signal of both channels. If I use a standard stereo block, the crosstalk between both tracks is unacceptable. The only solution to me seems to transfer on 4 tracks and take channels 1& 4, but I have no clue why this is happening.
>>
>> Regards
>> Gregorio
>>
>> On 28.02.2012, at 18:08, Richard L. Hess wrote:
>>
>>> Gregorio,
>>>
>>> We really need to make certain that we are understanding this correctly. I BELIEVE this is what you now mean.
>>>
>>> track 1: Signal A
>>> track 2: Signal A + B
>>> track 3: Signal A + B backwards
>>> track 4: Signal B backwards
>>>
>>>
>>> I do not understand how you can B forwards on track 2 and backwards on track 3.
>>>
>>> I am assuming that you are playing this on a 4-track inline machine like a Teac 3340S
>>>
>>> Let's look at
>>> http://www.richardhess.com/tape/quarterinch_lrg.gif
>>> which is approximately to scale.
>>> (It is normally accessed from
>>> http://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-audio/025-reel-tape/ )
>>>
>>> It could be a DIN tape with a narrow guard band, but I don't think that would explain everything.
>>>
>>> I had been thinking all along it is what Mark D said...but even that does not make complete sense.
>>>
>>> But here is an example of a two-track tape overwritten by a malfunctioning 1/4 track machine.
>>>
>>> http://richardhess.com/notes/2009/09/02/dangers-of-old-tape-recorders-for-playback-using-the-elevator-head/
>>>
>>> I really have to say if you're doing this type of work you need a method of magnetic tape development. Yes, it's pricey...but so is spending time guessing. I would not have figured out the above example nearly as fast without the developer and a calibrated loupe.
>>>
>>> Cheers,
>>>
>>> Richard
>>>
>>>
>>> On 2012-02-28 10:28 AM, Gregorio Garcia Karman wrote:
>>>> Hello Richard,
>>>>
>>>> you definitely spotted the problem at first glance. It should have been indeed 1, 2, 3, 4, in that order and I would say it is clear that it is a half-track tape. There is still the question of the extremely high crosstalk between channels which only occurs on two or three tapes out of the six hundred. I know it would be much easier but I can't develop the tape, so I have to go back to my original question. Which machine would record with such a narrow guard band, or otherwise what could be an alternative explanation?
>>>>
>>>> Huge thanks again
>>>> G
>>>>
>>>> On 27.02.2012, at 15:19, Richard L. Hess wrote:
>>>>
>>>>> Gregorio,
>>>>>
>>>>> This is why I'm such a fanatic about developing tapes and looking at them. The fact that track 3 has B NOT backwards confuses me.
>>>>>
>>>>> Also, I'm surprised you are writing 1/3/2/4 because visually on the tape you'd see 1/2/3/4 and that helps understanding.
>>>>>
>>>>> You could use 1 + 4 to capture, but I'd rather fully understand why as the narrow tracks, especially at the edge, are not the most desirable unless that's all you have.
>>>>>
>>>>> With track 3 B NOT backwards, I'm at a loss to explain.
>>>>>
>>>>> http://richardhess.com/notes/category/audio/magnetic-tape-developing/
>>>>>
>>>>> Develop the tape and post a photo and link to it from the reply message to the list.
>>>>>
>>>>> Do not rule out misaligned heads. Also, some machines used 1/2 and 4/3 as stereo recording and they might have been UK machines instead of the more common US practice of 1/3 4/2 (in all instances L/R and SideA SideB).
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Richard
>>>>>
>>>>> On 2012-02-27 5:39 AM, Gregorio Garcia Karman wrote:
>>>>>> Dear List,
>>>>>>
>>>>>> looking forward to the beginning of a new digitization week: everything is going well in Cambridge thanks in great extent to the support of the members of the list. Huge thanks!
>>>>>>
>>>>>> Now, I have a small group of 1/4 inch tapes in the collection on which I am working (ca 1950s-70s, recorded mainly on Ferrographs) which seems to have a track format, which I haven't met before. On those tapes standard half-track and half-track butterfly Studer blocks consistently produce a dual mono signal with unacceptable crosstalk on both channels (bleeding of about -20 dB referring to the signal on the other channel).
>>>>>>
>>>>>> On the other hand, the output of a quarter-track headblock is as follows:
>>>>>>
>>>>>> track 1: Signal A
>>>>>> track 3: Signal A + B
>>>>>> track 2: Signal A + B backwards
>>>>>> track 4: Signal B backwards
>>>>>>
>>>>>> It would seem that this very small group of tapes would have been recorded on a machine with a very narrow guard-band in comparison to the rest of the tapes I have. What is your opinion about transferring those tapes on a quarter track headblock and keeping tracks 1 and 4?
>>>>>>
>>>>>> I would also be curious about which machine could have had a track format that would agree with the former observations.
>>>>>>
>>>>>> Thanks for your comments!
>>>>>>
>>>>>> Gregorio Garcia Karman
>>>>>> [log in to unmask]
>>>>>>
>>>>> --
>>>>> Richard L. Hess email: [log in to unmask]
>>>>> Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
>>>>> http://www.richardhess.com/tape/contact.htm
>>>>> Quality tape transfers -- even from hard-to-play tapes.
>>>> Gregorio Garcia Karman
>>>> [log in to unmask]
>>>>
>>> --
>>> Richard L. Hess email: [log in to unmask]
>>> Aurora, Ontario, Canada (905) 713 6733 1-877-TAPE-FIX
>>> http://www.richardhess.com/tape/contact.htm
>>> Quality tape transfers -- even from hard-to-play tapes.
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