Three head cassette decks - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

stevehertz · 21st Jun 2022, 11:45 am

I once did test recordings from a test CD onto a cassette deck (I can't recall which one) and also my Revox A77. Played back, a high frequency test tone (again I can't recall the exact frequency) sounded really pure on the Revox, whilst the same recording from the cassette deck showed noticeable signs of warble and drop outs. But here's the rub, making recordings of real music from a CD onto both machines, I genuinely could not tell the difference. I am an experienced musician with a good ear and a background in using studios and in studio equipment. As an aside, I think that the point I just made about a measurable difference not being audible on real music counts a lot in the world of hifi as any audiophile will hotly deny (or maybe it's the other way round?!

).

I now have a Pioneer CT-93 three head, reference series cassette deck that cost me a small fortune and I much prefer to use it to my Revox because it's so much easier to use (obviously) and as said, sound wise it performs the same to my ears. I keep the Revox because I enjoy the vibe of owning and using a 'tape recorder' occasionally and because I have some important recordings made on it.

stevehertz · 21st Jun 2022, 11:55 am

Quote:

Originally Posted by knobtwiddler

BASF research concluded that - ultimately - dual capstan gives 'better accuracy': https://www.tapeheads.net/showthread.php?t=84823

(post 13, from Willhelm, who worked for BASF)

The best W+F figures I've seen belong to the Dragon and B215 (<0.02% RMS - both dual-DD capstan, approaching what must be the limit for the format). However, both decks also have a reputation for eating tapes if not in tip-top condition.

NB - Some of the BASF tech bulletins are here: http://www.ant-audio.co.uk/index.php...st&qry=library)

The Technics RS-9900 (1978) has been shown to get below 0.02% as well. The model that came after it (RS-M95) went back to single-capstan, funnily enough. They then went back to dual with the RS-M280.

Methinks they had a good look at the Sony 777 decks when they styled the B100 (nothing wrong with that, as the 777s are are excellent. These days they are easier to find than a B100 as well!)

Also, the Pioneer CT-93's stated W&F figure is "No more than 0.022% (WRMS)". So yes it seems that that figure is around the limit for the format. But as with all audio equipment that's mechanical not digital, it depends on how well the machine is maintained. A theoretically poorer cassette deck is quite capable of performing better than a reference model if (say) the pinch rollers are not kept clean.

Radio Wrangler · 21st Jun 2022, 12:04 pm

I've never felt happy about dual capstans.

One piece of tape is gripped by two capstan/pinchwheel sets. The two capstans turn at different speeds...

So there has to be slippage at one or shared between both capstans. Otherwise a loop would be thrown or the tape broken depending on which capstan is faster. Unless one capstan has a slipping clutch to allow its speed to be set by the other capstan via the tape contact. But if so then there isn't a difference in capstan speed. The tape tension is controlled by the added capstan, which will be more precise than spool back-tension. But a slipping clutch is not going to be smooth and will flutter the tape speed at the heads.

I can't seem to find a way this can be done without creating worse problems than it fixes.

Roller guides with a little damping are used on open reel machines to reduce flutter by adding effective mass to the tape but they are large diameter and don't need pinch wheels. Doing this job with something constrained by the size of the spare capstan hole in a cassette is going to need power assistance.

"Dual Capstan!!!" looks great in a brochure, but I thought about it a bit and it didn't seem so great.

David

stevehertz · 21st Jun 2022, 12:10 pm

Interesting stuff David. There's a similar discussion about the pros and cons here:

http://www.tapeheads.net/showthread.php?t=61285

TIMTAPE · 21st Jun 2022, 12:33 pm

Quote:

Originally Posted by Radio Wrangler

I've never felt happy about dual capstans.

One piece of tape is gripped by two capstan/pinchwheel sets. The two capstans turn at different speeds...

So there has to be slippage at one or shared between both capstans. Otherwise a loop would be thrown or the tape broken depending on which capstan is faster. Unless one capstan has a slipping clutch to allow its speed to be set by the other capstan via the tape contact. But if so then there isn't a difference in capstan speed. The tape tension is controlled by the added capstan, which will be more precise than spool back-tension. But a slipping clutch is not going to be smooth and will flutter the tape speed at the heads.

I can't seem to find a way this can be done without creating worse problems than it fixes.

Roller guides with a little damping are used on open reel machines to reduce flutter by adding effective mass to the tape but they are large diameter and don't need pinch wheels. Doing this job with something constrained by the size of the spare capstan hole in a cassette is going to need power assistance.

"Dual Capstan!!!" looks great in a brochure, but I thought about it a bit and it didn't seem so great.

David

I've always understood that the tension limiting factor in dual capstan decks whether cassette or open reel is the tape's elasticity. It's designed to be self regulating.

knobtwiddler · 21st Jun 2022, 12:47 pm

Agree with everything you've said, Steve.

When listening to noisy music, i.e. not classical, I would not expect to see many people reliably pick out a top-flight R-R machine against a perfect-condition cassette when running a metal tape in an A/B/X scenario. Of course, the R-R's superior hiss performance will show with classical. Were both machines perfetly aligned running Dolby S / SR, I'd wager no one could spot it.

Bearing in mind the above, it makes one think about how audible the difference is between modern DACs. I recently got a 4-channel A-D / D-A soundcard that has THD+N at around -106dB (~0.0005%). It cost me £180. In an A/B/X, could anyone discern it from a converter costing 10x as much?

For cassette, things are very different in 2022 than they were in 1992. The point about a modest deck that's been carefully maintained outperforming a monster battleship is bang on.

21st Jun 2022, 11:45 am	#41
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,834	Re: Three head cassette decks I once did test recordings from a test CD onto a cassette deck (I can't recall which one) and also my Revox A77. Played back, a high frequency test tone (again I can't recall the exact frequency) sounded really pure on the Revox, whilst the same recording from the cassette deck showed noticeable signs of warble and drop outs. But here's the rub, making recordings of real music from a CD onto both machines, I genuinely could not tell the difference. I am an experienced musician with a good ear and a background in using studios and in studio equipment. As an aside, I think that the point I just made about a measurable difference not being audible on real music counts a lot in the world of hifi as any audiophile will hotly deny (or maybe it's the other way round?! ). I now have a Pioneer CT-93 three head, reference series cassette deck that cost me a small fortune and I much prefer to use it to my Revox because it's so much easier to use (obviously) and as said, sound wise it performs the same to my ears. I keep the Revox because I enjoy the vibe of owning and using a 'tape recorder' occasionally and because I have some important recordings made on it. Attached Thumbnails __________________ A digital radio is the latest thing, but a vintage wireless is forever..

21st Jun 2022, 12:04 pm	#43
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,902	Re: Three head cassette decks I've never felt happy about dual capstans. One piece of tape is gripped by two capstan/pinchwheel sets. The two capstans turn at different speeds... So there has to be slippage at one or shared between both capstans. Otherwise a loop would be thrown or the tape broken depending on which capstan is faster. Unless one capstan has a slipping clutch to allow its speed to be set by the other capstan via the tape contact. But if so then there isn't a difference in capstan speed. The tape tension is controlled by the added capstan, which will be more precise than spool back-tension. But a slipping clutch is not going to be smooth and will flutter the tape speed at the heads. I can't seem to find a way this can be done without creating worse problems than it fixes. Roller guides with a little damping are used on open reel machines to reduce flutter by adding effective mass to the tape but they are large diameter and don't need pinch wheels. Doing this job with something constrained by the size of the spare capstan hole in a cassette is going to need power assistance. "Dual Capstan!!!" looks great in a brochure, but I thought about it a bit and it didn't seem so great. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

21st Jun 2022, 12:10 pm	#44
stevehertz Dekatron Join Date: Sep 2011 Location: Rugeley, Staffordshire, UK. Posts: 8,834	Re: Three head cassette decks Interesting stuff David. There's a similar discussion about the pros and cons here: http://www.tapeheads.net/showthread.php?t=61285 __________________ A digital radio is the latest thing, but a vintage wireless is forever..

21st Jun 2022, 12:47 pm	#46
knobtwiddler Octode Join Date: Mar 2016 Location: London, UK. Posts: 1,051	Re: Three head cassette decks Agree with everything you've said, Steve. When listening to noisy music, i.e. not classical, I would not expect to see many people reliably pick out a top-flight R-R machine against a perfect-condition cassette when running a metal tape in an A/B/X scenario. Of course, the R-R's superior hiss performance will show with classical. Were both machines perfetly aligned running Dolby S / SR, I'd wager no one could spot it. Bearing in mind the above, it makes one think about how audible the difference is between modern DACs. I recently got a 4-channel A-D / D-A soundcard that has THD+N at around -106dB (~0.0005%). It cost me £180. In an A/B/X, could anyone discern it from a converter costing 10x as much? For cassette, things are very different in 2022 than they were in 1992. The point about a modest deck that's been carefully maintained outperforming a monster battleship is bang on.