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Author Topic: Studer A80 tape spooling in FF and REW mode  (Read 15380 times)

Offline microstrip

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Studer A80 tape spooling in FF and REW mode
« on: June 10, 2010, 06:19:40 PM »
I have now aligned most of the tape mechanism of my Studer A80R.  Several parts were replaced (the advice of some experienced Tapeproject members was really of great help), all tape tensions seem correct ? I can go from any mode to another one without any tape looping or visible stress in the tape tension rollers.
But after I wind or re-wind a tape if FF or REW mode the tape is wound in an un-even fashion, not  with the smooth continuous aspect  that the tape takes after playback. In this mode the tape is very well centered in the spool. 
Does anybody have a suggestion how to fix this ?
Thanks.
Francisco

Offline ironbut

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #1 on: June 10, 2010, 07:17:57 PM »
Hi Francisco,

The first thing you should do is try a different tape. I have a set of tapes that I only use when I'm working on a machine. The tape edges invariably get damaged as I adjust this or that and after a while, the wind of that tape gets worse and worse.
Sometimes it can be the reel it's on too since some just aren't as balanced as others.

For the other Studer guys here, it would be helpful if you could go through the things you've done which may have effected the wind.
Also, be aware that fast winding will almost never result in quite as nice a pack as play. It's the speed that the tape is being laid upon the layer below it which makes it difficult for the air between the layers to escape.
steve koto
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Offline Teeg

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #2 on: June 10, 2010, 08:41:21 PM »
 Like yours, my A80VU packs tape nicely at play speeds but only marginally in FF or REW. Like Steve said, it might be reel-dependent as some do it better than others. The pack is not terrible, just not as good as what you get when running slower.
  Its amazing how fast the A80 spools tape in FF, isn't it? Mine screams compared to other machines but still seems to be quite gentle on the tape.

Tj
 
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Offline JR

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #3 on: July 10, 2010, 02:12:42 PM »
Like yours, my A80VU packs tape nicely at play speeds but only marginally in FF or REW. Like Steve said, it might be reel-dependent as some do it better than others. The pack is not terrible, just not as good as what you get when running slower.
  Its amazing how fast the A80 spools tape in FF, isn't it? Mine screams compared to other machines but still seems to be quite gentle on the tape.

Tj
 

Offline jdza

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #4 on: July 11, 2010, 01:12:25 AM »
Quote
Mine screams compared to other machines

An A80 should not scream. I have 4 A80s that I got about 18 months ago. All of these machines had between 3500 and 4500 hours on them and were well maintained by our state broadcaster. They all screamed in fast wind. Listening to all the A80s on You Tube they all screamed so I assumed that was just how it should be. However both my A810 and A67 were ghostly quiet so I stared experimenting with very unexpected results:

On listening to the A80R I found it much better than the A 810 but extended listening revealed an upper mid glare and grain.I pointed an unwavering Audiophile finger at the tantalum caps in the repro amps. In the meantime I started replacing the small bearings in the tape tension rollers with over the counter nameless bearings.While spooling was now much quieter and all measured parameters OK,I was horrified by the sound of the machine.It now sounded muffled and fuzzy. The effects were really not subtle. I then cannibalised bearings for the best from all 4 machines and was really horrified how gritty some of their bearings felt. Some of the bearings in the pinch roller and stabilising rollers were then replaced with highest quality SKF and NTN bearings with a substantial improvement in sound quality.

Finally I bit the bullet and ordered genuine Studer bearings at huge prices. These have been arriving in dribs and drabs . On installing every single Studer bearing there is a substantial improvement in sound quality-a much bigger difference than say changing cables.The sound now became  much more balanced and smooth.Oh and those tantalum caps?They were replaced with Black Gates and Nichicon Muse and the machine is now at a level where I am too scared to fiddle with anything but the effect was not as large as changing the bearings.

Oh and the fast forward and reverse-Almost as quiet as the A810.You just have to remove that resonating cap from the tape movement roller.
« Last Edit: July 11, 2010, 04:02:56 AM by jdza »
Johan Dreyer

Offline Teeg

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #5 on: July 11, 2010, 07:06:40 AM »
  When I said 'scream' it was not in the audible sense; merely describing how fast it winds tape compared to my other machines.

Tj
T.j. Bassi  
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Offline microstrip

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #6 on: July 11, 2010, 11:48:57 AM »
I then cannibalised bearings for the best from all 4 machines and was really horrified how gritty some of their bearings felt. Some of the bearings in the pinch roller and stabilising rollers were then replaced with highest quality SKF and NTN bearings with a substantial improvement in sound quality.
Finally I bit the bullet and ordered genuine Studer bearings at huge prices.
What are exactly "genuine Studer bearings"? As far as I was told Studer never manufactured bearings, they just ordered bearings from several suppliers. I have recently ordered bearings for my A80 from several Studer parts suppliers and I received ball bearings coming from different manufacturers, but I am still thinking about a fast way to compare their performance.
Francisco

Offline ironbut

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #7 on: July 11, 2010, 12:27:27 PM »
After fooling around with different bearings on the tensioners of my Technics, I believe that some of the more conventional benchmarks for off the shelf bearings aren't as important as other parameters of bearing performance when it comes to tape handling.
I bought some pretty pricey high tech bearings and the degradation of the resulting sound wasn't subtle. In comparison, the stock bearings which had become noisy with some slop from wear had a more open sound much like a large reduction in scrape flutter.
It's my WAG that more that precision/smoothness of the bearing is not nearly as important as the rolling resistance in our case. When I turned the precision bearing by hand, I could feel the increased resistance compared to the old bearings. It could be that in more conventional uses there is a higher load on the bearing which renders the increase in resistance insignificant.
Remember, the load would be a combination of lateral force applied plus the speed that the bearing would need to be turned.
I've tried to think of other applications that a bearing would need to have the least rolling resistance at low rpm's and all I can think of would be equipment that do measurements, the fabric industry or possibly in the medical field. It would be nice to direct source the kinds of bearings that would work best but considering how few times this would need to be done, it would probably be wise to just buy them from someone like Studer while they're still available.

One thing that Fred Thal aways said on the Studer list that bears repeating,.. these machines are systems which have been refined over many years of hard work by some of the best engineers. Expecting that you can exchange a critical component of this system with something that fits and not effect performance is unlikely (paraphrased of course).
steve koto
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Offline microstrip

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #8 on: July 11, 2010, 04:25:51 PM »
it would probably be wise to just buy them from someone like Studer while they're still available.
Thanks, Steve. I feel the same, but where can I get the real A80 Studer bearings?
Francisco

Offline ironbut

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #9 on: July 11, 2010, 05:23:24 PM »
I think you're right that Studer outsourced their bearing to other companies. I'm sure that as long as the bearings met their spec's, they should be good to go. I would imagine that maybe the only thing that might make those bearing different might be minimum tolerances beyond what the manufacturers normally spec (maybe hand selected by Studer for particular characteristics?).
I guess the big question here is what specs are the important ones for a particular location on the machine (and which machine).
I think that's one of the things that Fred was alluding to.

Say, if you had tape path elements A,B and C.
Element B is a bearing.
Element A is a tape tensioning device of some sort and
Element C is a tape tension sensor which feeds back to element A across element B.
The best servo is one that doesn't have to correct speed as frequently or as much. So, the engineers would design all three elements to work together to achieve this goal. A bearing that doesn't meet the specs of the design would require the servo to correct speed much more making the tape speed much less consistent.
Well, this is a simplified version of what the tape goes through. On most machines, there are twice as many elements as these which complicates things tremendously.
On lesser machines like my Technics, the engineering doesn't get that deep but on the master recorders like an A80, it does.

So, I asked before what the important spec would be for a bearing but I would guess it depends entirely on what the bearing is doing in relation to the other elements within the tape handling system.
I don't think who makes it matters.
steve koto
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Offline jdza

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #10 on: July 11, 2010, 10:18:31 PM »
I am sure Studer had specifications to which their bearings were made,whoever the manufacturer. One E Bay seller( Ha Ha -reliable source of info) claims that the Studer bearings were packed with special grease for lower noise. Steve is probably correct though. While I initially suspected noise to be the culprit,the differences noted in going from an unsuitable bearing to the real thing  were sonically similar to going from a belt drive turntable with no fine motor controller to the same turntable with vice like motor(speed) control.Why a worn Studer bearing would sound harsh and grungy must be a noise issue though.

Johan Dreyer

Offline kipdent

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #11 on: July 11, 2010, 11:43:32 PM »
As I said in my recent Service Resources post regarding Athan's work on my A80, I couldn't be happier with the bearings they put in. Where he sources them, I do not know, but I have experienced no untoward sonic effects as Steve Koto mentioned in his Technics "better" bearing story. My guess is that the bearings Athan uses for the Studer A80 are true analogues (no pun intended) of the original bearings employed in the A80.

Kip
Kip Peterson
Vintage-centric system with Apogee Acoustics Scintilla ribbon loudspeakers, Micro Seiki RX-5000 turntable and other odd bits of tube and solid state gear. Now a proud owner of a Studer A80 RC Mk II tape machine!

Offline microstrip

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #12 on: July 12, 2010, 05:59:43 AM »
Do you think the differences should shown in the wow and flutter measurements?
I have just bought two special bearings from the referred eBay source and they seem very smooth, less noisy than the SKF 61900 2Z. Being located in Europe, I would prefer to find a source in EC, otherwise shipping and customs can be an expensive and long process, even for a few ball bearings! 
Francisco

Offline docb

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #13 on: July 12, 2010, 10:19:53 AM »
I would guess that the differences might show more in scrape flutter measurements up around 10-12kHz than they would in the standard wow and flutter measurement range. One thing we discovered in our trying a lot of different ball bearings was that the spendy ceramic hybrid ball bearings designed for high RPMs were not really any better at the slow revs they spin in a tape deck than a good quality ABEC-5 or ABEC-7 bearing and sometimes they were a bit more noisy. My suggestion would be to stick with all steel bearings with an ABEC-7 tolerance rating or if you can't find that, ABEC-5. ABEC-3 can be OK if you find decent ones, too. Also be very careful not to wash out the lubricant when cleaning the tape path. Regular exposure to denatured alcohol in the races will kill a bearing pretty quickly
Dan "Doc B." Schmalle
President for Life, Bottlehead Corp.
Managing Director - retired, The Tape Project

Offline ironbut

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Re: Studer A80 tape spooling in FF and REW mode
« Reply #14 on: July 12, 2010, 04:47:04 PM »
Hi Kip,

I think that's a great example of the right bearing for an application.
Athan specializes in rebuilding motors for the pro audio/broadcast industry.

In the case of reel motors, smooth operation at different rpms and the forces that full reels of tape exert on the bearings are some of the considerations. Heat must be minimized for long life and consistent back tension on the tape during play are othes. If you think about what normally happens at the bearing level, you rewind the tape at a relatively high rpm putting maximum load (full reel) on one bearing to the other (take up then supply reel). Then almost immediately, you put the machine in play where the load is a fraction of what it was. So, not only are you looking for a bearing that produces a minimum of heat but it's also important that it dissipates what heat was produced quickly. The sensors for the adjustment of tape tension/speed are located in these motors also so it's important that the bearings can react quickly or the correction circuits will be constantly hunting for the right correction.
So in this case the bearing need to be able to do some heavy lifting (with what is always an unbalanced load) then switch to a delicate task.

In comparison, the capstan motor is usually attached to a large, heavy flywheel that smooths the speed so the load is ultra consistent. It moves at a slow steady rpm. It also need to be very smooth but for an entirely different reason. You're trying to minimize the amount of noise that the bearing makes so it isn't transmitted to the tape via the capstan. It also need to be able to react quickly during speed corrections.
So a bearing here needs to be able to take a heavy, very consistent load at low rpm's with as little noise a possible.

Someone like Athan has years of experience on which bearings are best in each of these applications within the confines of the particular decks design. Choosing the right bearing would make or break a company who does work on machines that belong to some of the best ears in the world.

On another note, Doc makes a really important point.
Keeping you tape path clean is critical for getting the best sound and maximizing the life of you tapes. But be very careful about how you do this. Dipping a swab into a bottle of alcohol or head cleaner then wiping it on the tape path bearings will eventually ruin them. Actually, I suspect that most noisy bearings are the result of this.
What I do is after dipping the swab, I suck on it,.. no-no just kidding,.. I roll the swab on something absorbent so it's just wet with the solvent and not dripping with it. You're just cleaning the surface of stuff so take it easy. And just to be sure, I clean the parts with bearings last.

Like I said before, just how critical these particular parts are depends of how refined the machine has be designed.
steve koto
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