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So perhaps only one machine was defective?

joe salerno


Mike Hirst wrote:
> David,
> 
> I have no information as to what equipment was used. However, it is my 
> suspicion that small mono machines were used. I have digitised some 600+ 
> tapes over the past few months. Only a small percentage exhibit this 
> fault. I think what I need to do is to look at the transfers again and 
> establish what factors are common to those recordings which have 
> crackle. I suspect they are all mono recordings and using only the left 
> channel would be a workable solution.
> 
> It's odd. I sit in a darkened room listening to these things day in and 
> day out. After a while these little glitches start to really get to you. 
>  Reading the messages on this board helps keep me sane. Keep up the good 
> work guys.
> 
> Best Wishes
> Mike
> 
> David Lennick wrote:
>> Dumb question (for various reasons, I can't listen to the file at the 
>> moment). Were these cassettes all recorded on small mono portable 
>> machines? Tapes made on these almost always have a crackly or noisy 
>> right channel when played back on good decks and in stereo. The 
>> solution here is simply to play only the left channel.
>>
>> dl
>>
>> Mike Hirst wrote:
>>> Thanks Richard,
>>>
>>> your advice is, as ever, well informed sagely and intelligent. I 
>>> suspect that I'm not going to find a definitives answer here, but for 
>>> your interest, and for anyone else who may be interested, I've posted 
>>> a 10sec  (wav) clip of the kind of crackle I'm hearing. this sort of 
>>> thing will continue through the full length of the recording and can 
>>> be heard when the tape is played back using multiple recorders, all 
>>> of which have been tested using other tapes, which exhibit no such 
>>> problems.
>>>
>>> http://www.mikehirst.netfirms.com/audio/rhclick.wav
>>>
>>> filesize= 1392640 byte(s)
>>> riffsize= 1764036 byte(s)
>>> format  = Straight-PCM
>>> channel = 2
>>> depth   = 16 bit(s)
>>> blk.size= 4 byte(s)
>>> smp.rate= 44100 Hz
>>> samples = 441000
>>> playtime= 0:10.010
>>>
>>> you will note from the clip that the crackle can only be heard in the 
>>> rh channel. this is typical of the phenomenon, but it can sometimes 
>>> be heard in both channels (with a bias towards the rh ch).
>>>
>>> I have experimented with some of the de-crackle filters I use when 
>>> working with disc transfers and as Richard suggests, the crackle can 
>>> be removed, I am however curious as to where the crackle comes from.
>>>
>>> Richard L. Hess wrote:
>>>> Hello, Mike,
>>>>
>>>> Tom Fine has already posted a number of good explanations.
>>>>
>>>> There are, however, less-common explanations that you may wish to be 
>>>> aware of, just in case.
>>>>
>>>> (1) If there is a mismatch between the record machine record and 
>>>> erase head track position, perturbations in the record bias and/or 
>>>> erase MAY print to a tape like this. DC-(i.e. permanent magnet) 
>>>> erase may also cause something like this, but it is usually more of 
>>>> a "burbling" or what is sometimes called "rocks".
>>>>
>>>> (2) Static electricity and PLAYBACK machine "glitches" CAN print to 
>>>> a tape without the recorder being in record mode. It's uncommon 
>>>> (thankfully),  but it can happen. Static can be generated by fast 
>>>> winding in a very dry environment, and depends on cassette materials 
>>>> including the shell and slip sheets. This is more prevalent with 
>>>> reels than cassettes.
>>>>
>>>> This clicks can usually be removed (depending on their source) by a 
>>>> declick/decrackle plug-in for your favourite DAW. The Magix 
>>>> restoration tools version of this is the best I've yet owned, but I 
>>>> haven't owned either DC7 nor the high-end Algorithmix version.
>>>>
>>>> At 08:53 AM 2008-09-18, Mike Hirst
>>>>> Here's a thing that's been confusing me for some time. I have spent 
>>>>> the past six months working my way through a large number of 
>>>>> cassette tapes mostly recorded between 1985 and 1995. every now and 
>>>>> again I notice light, but significant crackling. This is often more 
>>>>> noticeable in the right channel, but not exclusively so. On some 
>>>>> recordings this is louder, on most recordings this is not evident 
>>>>> at all. This is not restricted to any one brand of cassette, nor is 
>>>>> it associated with any one playback machine and/or soundcard. Can 
>>>>> anyone explain this for me?
>>>>
>>>> Richard L. Hess                   email: [log in to unmask]
>>>> Aurora, Ontario, Canada       (905) 713 6733     1-877-TAPE-FIX
>>>> Detailed contact information: 
>>>> http://www.richardhess.com/tape/contact.htm
>>>> Quality tape transfers -- even from hard-to-play tapes.
>>>>
>>>
>>
>>
>