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Adrian Tuddenham[_2_]

isw wrote:

In article
d.invalid,
lid (Adrian Tuddenham) wrote:

Jeff Liebermann wrote:

On Thu, 29 Sep 2011 15:07:40 +0100,
lid (Adrian Tuddenham) wrote:

Does anyone happen to know the official speed of a Dictabelt?

Which maker and what model?
They followed the same speeds at record platters.
ips time
15 15 min
7 1/2 30 min
3 3/4 60 min
1 7/8 120 min

I think you have misunderstood the type of machine I am enquiring about.

[...]
It seems
to be around 6 inches per second or 30 belt revolutions per minute, but
there must be a proper specification somewhere.

30 rev/min = 0.5 rev/sec. At 12" per revolution, that's:
0.5 rev/sec * 12 in/rev = 6 in/sec.
Close enough to 7.5 ips.

It issignificantly below 7.5 ips. I need to know the manufacturer's
specifications as I am developing a playback machine for archival work,
where comparison between the actual speed and the 'official' speed can
yield useful historical information.

Any chance of there being any power-line hum in the recording? If there
is, that's your calibration. If not the fundamental, then maybe
harmonics ...

That sometimes occurs and is very helpful as long as the machine was
running from stabilised mains supplies. Some Dictabelt machines were
battery-powered and some 'in the field' would have been run from
inverters or vibrator packs.

I need to know the manufacturer's standard speed in order to measure
the variations of individual belts from the norm.

--
~ Adrian Tuddenham ~
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www.poppyrecords.co.uk