So perhaps only one machine was defective?
Mike Hirst wrote:
> 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
> 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.
>> 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
>>> 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:
>>>> Quality tape transfers -- even from hard-to-play tapes.