[78-L] Cambridge Process

[Chris Zwarg]

I can correct (not always 100% but usually with a noticeable improvement in listenability) regular "sine-shaped" wow/flutter as caused by an out-of-center record or a dirty/damaged capstan, by adding a frequency modulation that counteracts the spurious one. The process however is pretty cumbersome and not easily explained, and it will not work at all with irregular wow as caused typically by overstretched tape. IIRC, someone has developed a method that uses the ultrasonic a/c-bias tone as a clock and thus can correct all kinds of speed variations in analogue tape recordings, but I have no idea whether this is available commercially - as you need an ultra-wide-range preamp and soundcard to digitize the recording together with the bias tone (which is usually between 50 and 100 kHz), it is unlikely this will ever be practicable with amateur equipment. As I am mainly working from disc sources in my day-to-day workflow, where the a/c-bias method is useless, I have never bothered to make experiments in this field.

Chris Zwarg

At 11:53 16.12.2008, you wrote:
>On the question of processing recordiings, can anyone tell me if there is an 
>available method (preferably  "inexpensive" !) of correcting  wow / flutter 
>on a cassette  tape  recording ?
>
>John Goslin
>----- Original Message ----- 
>From: "Chris Zwarg" <doctordisc at truesoundtransfers.de>
>To: "78-L Mail List" <78-l at klickitat.78online.com>
>Sent: Tuesday, December 16, 2008 10:43 AM
>Subject: Re: [78-L] Cambridge Process
>
>
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