I know that Tom Fine mentioned that he had an old strobe for checking tape speed. Does anyone know of any that are available? I think I remember Ampex decks in Hollywood that had a small circular strobe that fit on the top of the capstan, but they were of bigger diameter than my Teac 2340R. My A-6100 may have the Ampex diameter, but I don't know. I'd like to be sure that I'm "up to speed", but that probably entails something else as far as the tape being pulled properly by the pinch roller and capstan without slippage.
Thanks for any help. I don't think I've got any problems, but it's nice to be sure. My sense of pitch is pretty good, so when I was listening to the end of a Barclay-Crocker tape in auto-reverse on the 2340R, I started to hear wow. I tried playing it forward on the same deck, and then on the A-6100, and sure enough, it was there on all variations. I have a feeling that a reel used in the duplication, either mine or an earlier sub-master created the problem toward the end of the reel where I've heard similar results in both film and audio recordings. I would guess that the torque is greater at the end of a reel, so more pulling power needs to be applied without binding.
I'm sure you all can supply all the answers, and I would hope that they will be useful to all of us. That's why I love this list....Rod Stephens
--- On Wed, 3/30/11, George Brock-Nannestad <[log in to unmask]> wrote:
From: George Brock-Nannestad <[log in to unmask]>
Subject: Re: [ARSCLIST] Shrunk strobe?
To: [log in to unmask]
Date: Wednesday, March 30, 2011, 2:04 PM
From: Patent Tactics, George Brock-Nannestad
Steven Smolian wrote:
> I recall that there is a small reduction in size to a Xerox copy in each
> generation. Does anyone know what percentage this reduction is?
circular strobes with the same number of bars are inherently identical
irrespective of radial dimension. The Record Collector 40+ years ago had a
strip-shaped strobe that you rolled into a cylinder with the appropriate
number of bars and fixed with a paper clip. You simply rested it on the
label. That also was the same irrespective if you had an undersized copy of
Only if you have a paper strip to the width of a magnetic tape that you
splice into your tape for checking the speed of the tape, then the linear
dimensions of the strip counts.
The only problem with photocopies is the fuzzyness on repeated copying. There
might be a small problem with different magnifications in the two directions,
but at most it would make a cyclic movement of your otherwise stationary
strobe image when you light it with 120 Hz light (such as a fluorescent
light, the older the better). Having the wrong center would be worse: your
impression of the strobe image would be just like it would sound if it were a
> The speeds start at the outside at 107.44 rpm, then 109,08 rpm, and
> successively to 116.13 rpm on the most inner of the 6 sets of dots.
> speed for the wire is 24 ips, at least in one source.
----- these figures do permit some juggling to convert rpm to ips. First you
divide by 60 to obtain revolutions per second. One revolution is one
circumference of the take-up reel, which is PI times the diameter (which you
need to measure, unless it was absolutely standard). Then you know that this
length of wire gets onto the reel per second at the rpm indicated by your
stationary strobe image on the strobe disc.
This was a good capstan-less transport, and they used the large diameter to
ensure that only a few layers of wire came on this reel, so that the diameter
increase (and hence increase in ips) would almost not be audible on the same
piece of wire.
So, in conclusion: the reduction in size in Xerox copiers (to avoid black
margins) is irrelevant (and it was adjustable by the technician anyway).