Hello Shai,
I don't see how a faulty erasing circuit would explain this behaviour, could you expand?
Thanks and cheers
Gregorio
On 29.02.2012, at 19:40, Shai Drori wrote:
> Now that you have explained this I am thinking that maybe the recorder had a fault in the erase circuitry?
> Shai
>
> בתאריך 02/29/12 2:41 PM, ציטוט Gregorio Garcia Karman:
>> 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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