Hi David:

Why does this happen? What is different about the mono deck?

-- Tom Fine

----- Original Message -----
From: "David Lennick" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, September 18, 2008 11:19 AM
Subject: Re: [ARSCLIST] cassette crackle


> 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.
>>>
>>
>