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At 03:59 PM 2008-09-18, Mike Hirst wrote:
>Mr Biel,
>
>I believe you have hit the nail on the head. I've looked back at all 
>the recordings with constant crackle, they are all mono recordings, 
>the clicking is always in the right channel. I have no information 
>as to the equipment used to make the recordings, but everything you 
>suggest matches so closely with what I'm experiencing, that I am 
>confident that you are right.

Yes, Mike did a great job of explaining what I glossed over in a 
generality when I said

"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"."

Mike, I don't disagree with you that this is the cause, but do you 
have any idea why the spectrum of this is so high pitched as compared 
to the usual case where DC components which tend to have more 
mid-range? Normally, we see this as something like the change of the 
"permanent" magnetic field due to changes in tape sensitivity. I'm 
trying to imagine the mechanism that causes the very sharp "tick" 
related to the DC erasure.


>Thanks also to Richard for his helpful suggestions for using 
>declicking filters.

You're welcome, did you receive the de-clicked MP3 of your sample?

>  and to David Lennick for suggesting that I use only the Left channel.

The only challenge in this is that often the left channel has 
suffered some edge damage and the right channel is cleaner.

Even with Nakamichi Dragons as playback machines, the azimuth is not 
always so well set that you can sum the two channels and I almost 
always take one or the other, but being careful to look for dropouts. 
Sometimes it's selected from both channels depending on where in the 
tape and which side.

I would think that the click-removal software would sometimes provide 
a better finished product than some of the inferior left channels I've seen.

The shocking thing, however, is that it's not always the left channel 
that is bad. Sometimes the right channel isn't even there, and I 
assume this is because the record/play head was way out of alignment 
(or that only the left channel of a stereo machine was recorded, but 
the 8-track cassette player usually indicates a bit more width than 
one would get from just a single channel.

For a comparison of cassette tape track widths and p[ositions, please see
http://www.richardhess.com/tape/cass_trk_lrg.gif

Cheers,

Richard

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.