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Slow Speed Tape Machine

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Slow Speed Tape Machine

Postby ken long » Fri Sep 13, 2019 10:56 am

Hello,

Looking for 1/2 track 1 7/8 IPS machines and lower, preferably Revox B77 LS or SLS but recommendations for suitable alternatives considered!

Does anyone know anybody with a cupboard full of these :bouncy:
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Re: Slow Speed Tape Machine

Postby twotoedsloth » Fri Sep 13, 2019 2:43 pm

In the unlikely event that you are in Toronto (Canada) I have a Revox G36.

Best of luck!
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Re: Slow Speed Tape Machine

Postby ken long » Fri Sep 13, 2019 2:56 pm

twotoedsloth wrote:In the unlikely event that you are in Toronto (Canada) I have a Revox G36.

Best of luck!

In the UK but thank you very much for the offer!
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Fri Sep 13, 2019 3:18 pm

twotoedsloth wrote:In the unlikely event that you are in Toronto (Canada) I have a Revox G36.

Best of luck!

I think the G36 only does 3 3/4 and 7 1/2 IPS. An electronically controlled capstan motor had to wait for the A77 and later models. The different sized capstan shafts allowed a wide choice of speeds. I have an A77 SLS which does 1 7/8 and 15/16 IPS, but I too am not just around the corner...

Tim.
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Re: Slow Speed Tape Machine

Postby James Perrett » Fri Sep 13, 2019 6:29 pm

I'd guess that you'd be looking for a logging machine from a radio station. I don't know of any for sale at the moment. As 1 7/8 isn't going to be great quality I usually just use a quarter track machine for that speed and accept a slight decrease in signal to noise ratio.
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Fri Sep 13, 2019 10:47 pm

I know a fellow in Toronto who uses a Racal Store instrumentation machine. 6 speeds from 15/16 to 30 IPS but non standard reels I think.. The Nagra TRVR does 1/2 track 15/16 to 7 1/2. Its direct drive capstan motor alone (no pinch roller and no rubber parts in the machine at all) is impressive. Direct drive Sony's, Akais, Pioneers, Teacs etc don't seem to go lower than 3 3/4 which is a shame.
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Re: Slow Speed Tape Machine

Postby twotoedsloth » Sat Sep 14, 2019 2:49 am

Could you transfer a 1 7/8 IPS tape at 7 1/2 IPS, and transpose it down two octaves?
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Sat Sep 14, 2019 6:23 am

twotoedsloth wrote:Could you transfer a 1 7/8 IPS tape at 7 1/2 IPS, and transpose it down two octaves?

Yes you can, and transferred at much faster speeds than x4 with little or no losses, but without the specialised gear and skills, results can fall well short of the signal on the original tape.

Some take the view that for an already lo-fi recording, any old transfer will do. Others say we should try our hardest not to degrade the signal any more than it already is degraded.
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Re: Slow Speed Tape Machine

Postby James Perrett » Sat Sep 14, 2019 5:17 pm

twotoedsloth wrote:Could you transfer a 1 7/8 IPS tape at 7 1/2 IPS, and transpose it down two octaves?

A good 1 7/8 ips recording could easily contain frequencies up to about 12kHz which means that the 7 1/2 ips transfer would need to be able to reproduce frequencies of 48kHz or more. Most tape machines would be well down in replay level at that frequency.
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Sat Sep 14, 2019 11:00 pm

Yes the repro head is not usually designed for those frequencies and neither the repro amplifier. I still have some old high speed tape duplicator heads for playing back a 1 7/8 IPS recording at 30 IPS. The heads can handle about 800 Hz to 160 kHz or 16 times original tape speed.
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Re: Slow Speed Tape Machine

Postby ken long » Mon Sep 16, 2019 9:23 am

James Perrett wrote:I'd guess that you'd be looking for a logging machine from a radio station. I don't know of any for sale at the moment.

Got a couple C274 this way a while back.

As 1 7/8 isn't going to be great quality I usually just use a quarter track machine for that speed and accept a slight decrease in signal to noise ratio.

Yes I was hoping to get a dedicated machine for this but I do have access to a 1/4 track. That will have to do until something else comes up on the market.

A always, thanks for your suggestions.
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Re: Slow Speed Tape Machine

Postby ken long » Mon Sep 16, 2019 9:24 am

Tim Gillett wrote:The Nagra TRVR does 1/2 track 15/16 to 7 1/2. Its direct drive capstan motor alone (no pinch roller and no rubber parts in the machine at all) is impressive.

Thanks for this, Tim. Will keep an eye out.
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Tue Sep 24, 2019 3:25 am

ken long wrote:
Tim Gillett wrote:The Nagra TRVR does 1/2 track 15/16 to 7 1/2. Its direct drive capstan motor alone (no pinch roller and no rubber parts in the machine at all) is impressive.

Thanks for this, Tim. Will keep an eye out.

You're welcome Ken. Not many were sold unfortunately, mainly to law enforcement surveillance it seems, and their rarity seems to have kept up the price in the collector market. The TRVR only does reels up to 7" though.

Maybe replacing the 1/4 track head in a 1 7/8 machine with a half track head would be a good option.
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Re: Slow Speed Tape Machine

Postby John Willett » Wed Sep 25, 2019 7:10 pm

ken long wrote:Hello,

Looking for 1/2 track 1 7/8 IPS machines and lower, preferably Revox B77 LS or SLS but recommendations for suitable alternatives considered!

Does anyone know anybody with a cupboard full of these :bouncy:

The best place is a radio station.

The only use for an open=reel running at cassette speeds was for ROT (Record Of Transmission) work.

I know LBC in London used to use Revoxes at this speed.

The very low speed meant that they had a complete record of station output for legal reasons - they kept the tapes for as long as the law desired and they were then reused.

But ROT work was the only real use of a machine with such an extremely low speed where cost and a long running tape was the only reason and audio quality was non-existant.
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Wed Sep 25, 2019 9:56 pm

John Willett wrote:The only use for an open=reel running at cassette speeds was for ROT (Record Of Transmission) work
.
Actually slow speed logging was used in many fields of science and industry. If Ken only needs up to 7" reel size, old Grundig, Uher, Philips and Akai machines down to 15/16 ips arent too hard to come by but of course repairs may be extensive.
With the Revox LS and SLS models, watch out for a very worn capstan shaft after heavy use. The wear could be so bad that it lowered tape speed and the ridges created on the shaft could damage the tapes. For such a small diameter shaft, and a heavy load to transport, shaft and pinch roller need to be in excellent condition and adjustment for top performance. Unfortunately, a major aftermarket supplier of Revox pinch rollers appears to have been selling rollers with rubber of different hardness than original Studer/Revox specification. Particularly problematic with the SLS Revoxes especially towards the ends of reels where tapes can start to lose speed erratically.
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Re: Slow Speed Tape Machine

Postby ken long » Fri Sep 27, 2019 9:22 am

John Willett wrote:The only use for an open=reel running at cassette speeds was for ROT (Record Of Transmission) work...

But ROT work was the only real use of a machine with such an extremely low speed where cost and a long running tape was the only reason and audio quality was non-existant.

Also used to record conferences, political, corporate and some occasional domestic examples (although not usually 1/2 track).
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Re: Slow Speed Tape Machine

Postby ken long » Fri Sep 27, 2019 9:23 am

Tim Gillett wrote:Maybe replacing the 1/4 track head in a 1 7/8 machine with a half track head would be a good option.

Think there would be a lot of work with amplifiers and EQ to make this viable.
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Re: Slow Speed Tape Machine

Postby Tim Gillett » Fri Sep 27, 2019 10:34 am

ken long wrote:
Tim Gillett wrote:Maybe replacing the 1/4 track head in a 1 7/8 machine with a half track head would be a good option.

Think there would be a lot of work with amplifiers and EQ to make this viable.

That might be true for record. If it's only for playback it's much simpler. Swap the head and mechanically line it up. There might be 2 or 3 db's increase in output to the preamp but it's unlikely to overload it. Only on the PR99 is high EQ adjustable. A77/B77 high EQ is not adjustable.

I just noticed on a popular online auction site an A77 low speed capstan motor and shaft.
1 7/8 and 3 3/4. (Seller from Spain). With the smaller shaft, if would give 15/16 and 1 7/8. The motor could be fitted to a standard A77 machine which is much more readily available than the LS or SLS models. Some EQ resistors on the repro PCB would need changing. This is an easy mod as the relevent A77 repro board is easily unplugged from the machine. Resistor details are in the A77 Service Manual.
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