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.