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.
>> 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.