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ARSCLIST  July 2019

ARSCLIST July 2019

Subject:

Re: Reel-to-Reel tape problem

From:

Jamie Howarth <[log in to unmask]>

Reply-To:

Association for Recorded Sound Discussion List <[log in to unmask]>

Date:

Sat, 13 Jul 2019 00:06:22 -0400

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (177 lines)

If there’s hum in the recording or if you like send me a 192/24 sample right from the playback and I’ll see if we can make a quick utility for you.

Jamie Howarth
Plangent Processes

Please pardon the mispellings and occassional insane word substitution I'm on an iPhone

> On Jul 12, 2019, at 21:58, Tim Gillett <[log in to unmask]> wrote:
> 
> 
> I'm not familiar with the "gliding stretch" of Adobe Audition but if
> it allows you to set (by ear or even better by a reference on the tape
> such as hum) a start speed and  end speed then assuming a linear
> increase in speed between those two end points, I guess it would 
> replicate the original recorded speed.  I'd first make the assumption
> that the original recorded speed didn't deviate due to slippage,
> battery fade etc. Only if the speed was obviously inconsistent after
> the initial correction of start and end points would I attempt further
> corrections.  
> 
> It wasn't just cheap/battery powered  machines which used the rim
> drive system. On the Continent from the mid 1950's,
> Philips, Grundig and perhaps others used rim drive in mains powered
> dictation machines  with essentially constant speed AC drive motors.
> Grundig tended to use their own proprietary tape cassette, and non
> standard reels, but the Philips models I'm familiar with used two 3"
> standard 1/4" reels inside a clear "cassette".  The larger inner hub
> size was used. These machines  come up on Ebay.  Many were
> valve(tube) based machine. Philips continued the rim drive principle
> though to a 1/8" tape in another type of cassette, and then on to the
> tiny "mini cassette", also rim drive.
> 
> https://obsoletemedia.org/el-3581/
> 
> Tim
> 
> ----- Original Message -----
> From:
> "Association for Recorded Sound Discussion List"
> <[log in to unmask]>
> 
> To:
> <[log in to unmask]>
> Cc:
> 
> Sent:
> Fri, 12 Jul 2019 16:41:07 -0400
> Subject:
> Re: [ARSCLIST] Reel-to-Reel tape problem
> 
> Hello, J.D.,
> 
> I tried thinking this problem through a while ago and it hurt my
> brain. 
> You've heard from three experts who all said basically the same 
> thing--with which I concur.
> 
> What I thought I would add is a little thought experiment.
> 
> These machines did not have a capstan and they pulled the tape by a 
> motor attached to the takeup reel. For some reason it has been
> referred 
> to as "rim drive" perhaps because the motor often contacted a rubber 
> surface on the rim of the reel table to provide a "gearing" ratio
> from 
> the motor to the reel table, rather than being directly attached to
> the 
> spindle.
> 
> So, let's assume that we have a constant speed motor that can deliver
> 
> infinite torque (bear with my and hold your "tsk tsks"). If that were
> 
> the case, you could calculate the actual speed by knowing the radius
> of 
> the tape pack at time of recording, the speed of the motor and pi. As
> 
> the takeup reel filled up, the tape speed would increase, so if
> you're 
> listening on a capstan driven machine, the pitch would drop. Let's
> call 
> this calculation (A).
> 
> BUT, the motor does not have infinite torque. As the radius of the 
> takeup reel tape pack increases, the moment arm gets longer meaning
> that 
> the same amount of holdback tension may cause the motor to slow down
> a 
> bit as it can't deliver all the torque that would be required. So
> this 
> adjustment factor could be figured out, but the speed at the end of
> the 
> tape will fall short of what you calculated in (A) above. Let's call 
> this adjustment factor (B).
> 
> So, at this point, the speed at any given point is (A) - (B).
> 
> Now, some odd things enter in that will change this. As the (gasp
> zinc 
> carbon flashlight) batteries discharge, the motor will not be able to
> 
> deliver as much torque as the batteries will deliver less current and
> 
> their voltage will drop compared with fresh batteries, so we have a 
> third factor.
> 
> And if this unknowable was not enough, the holdback tension was
> provided 
> by pressure pads--usually against the heads--so this creates multiple
> 
> additional factors for affecting speed:
> --the calendaring/polish of both tape surfaces will affect the
> friction.
> --the environmental temperature and humidity will affect the
> friction.
> --the cleanliness of the guides/heads will affect the friction.
> 
> So, there you have a quick snapshot of the dynamics of this system
> and 
> why fixing it in post in software is the best alternative.
> 
> I reiterate what Ted Kendall said, "there were myriad reel-drive 
> Japanese recorders around at the time, all of which were different 
> between samples, never mind designs." And I might add, there were 
> differences with the same recorder based on tape type, climate 
> conditions, and battery condition. A fair number of these recordings 
> originated in Vietnam in my experience, but thankfully a large number
> of 
> the ones I have received were recorded with capstan machines. the
> Craig 
> 212 was a classic of the era with a capstan.
> 
> Cheers,
> 
> Richard
> 
>> On 2019-07-12 3:53 p.m., Scott Phillips wrote:
>> These would have been rim drive recorders, without a capstan drive
> roller. There is no fixed speed, it was determined by reel motor
> torque and the diameter of the amount of tape on either reel at any
> moment. Good luck with that, software is about your only available
> practical tool I know of..
>> 
>> 
>> Best regards,
>> 
>> Scott Phillips
>> 
>> 
>> -----Original Message-----
>> From: Association for Recorded Sound Discussion List
> [mailto:[log in to unmask]] On Behalf Of J. D. Mack
>> Sent: Friday, July 12, 2019 1:30 PM
>> To: [log in to unmask]
>> Subject: [ARSCLIST] Reel-to-Reel tape problem
>> 
>> I'm looking for some advice/info. I sometimes transfer reel-to-reel
> tapes to CD or digital files for my customers. Frequently, I receive 3
> inch tapes from the 1960s that start at one speed and gradually speed
> up or slow down substantially as the tape plays. The speed range is
> usually between 1 7/8 and 3 3/4, but never landing on either speed. I
> can correct for this using Adobe Audition's gliding stretch, but it
> takes quite a bit of trial and error. What sort of tape player would I
> need to hunt down to play these tapes correctly without having to
> resort to a software solution? My customers never have any idea what
> brand and model was used to make the recordings.
>> 
> 
> -- 
> Richard L. Hess email: [log in to unmask]
> Aurora, Ontario, Canada 647 479 2800
> http://www.richardhess.com/tape/contact.htm
> Quality tape transfers -- even from hard-to-play tapes.
> 
> -------------------------
> Email sent using Optus Webmail

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