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On 12/5/16 12:56 PM, Marcos Sueiro Bal wrote:

> Could varispeed ameliorate that issue?

No, this is a wavelength problem, not a speed problem.  When the 
wavelength of the recorded bias signal is equal to the gap length, the 
head has no output, regardless of speed.  If you have this problem, your 
only option is to use a head with a different gap length.

Slower playback speed = bias playing back at lower frequency, which 
means it's more likely to survive its passage through the 
bandwidth-limited playback electronics and any filters which would 
normally prevent bias from appearing in the repro output.  Also, bias 
frequencies between 90 and 180 kHz will now be within the bandwidth of 
an A/D converter running at 192k sample rate.  But if the head has no 
output at the bias wavelength, slower speed won't help.

-- John Chester

>
> Marcos Sueiro Bal
> Senior Archivist, New York Public Radio
> 646 829 4063
>
> -----Original Message-----
> From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Richard L. Hess
> Sent: Monday, December 05, 2016 12:11 PM
> To: [log in to unmask]
> Subject: Re: [ARSCLIST] Setting azimuth from program - a caution
>
> Indeed! That is a good trick, but you might have to use 1/4 speed and sometimes the bias wavelength was designed to fit in the head gap null, which makes it more difficult to reproduce on a machine with repro heads that have the same gap length as the design machine.
>
> Cheers,
>
> Richard
>
>
>
>
>
> A trick I learned from Danny Sbardella is to adjust azimuth for maximum output of  the bias tone played at half speed.
>
> Cheers,
>
> Marcos
>