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.