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Studer A/B67, Damper grease? Recorders, Players & Tape Machines
Old 1 week ago
  #1
Here for the gear
 

Studer A/B67, Damper grease?

Hi,
Im in the middle of restoring a Studer A67 that totaly lacks damper grease in the tape tension dampers. Reading up on the Studer A67 manual Studer advice Kluber L643 grease.

I've been in contact with Revox(yes it's the same stuff in the A700), Studer, Audiohouse, Revox.de, Revox-online, Nagravox and Kluber and so far only Nagravox and Kluber has given positive response as to providing this stuff. There are some drawbacks to their offers though...
  • Kluber offers ONLY a 750gram jar and the cost is like it was made out of ground diamonds.... 10g will be plenty for me so it seems a little over the top to order 75 times my life need of the stuff...
  • Nagravox provides it only as part of their "full monty". Since my A67 is already fully restored except the grease their offer will actually cost more and render more waste than going for the Kluber offer.

Since this stuff seems to be as difficult to come by as "hen's teeth" I have tested other types of grease, so far 5 different ones. None of them gave the result wanted.
I have ordered some silicone grease 300.000CST and will test that too before giving up on finding a replacement.

So Im in a bit of a troublesome situation here and would very much appreciate advice.

I would really appriciate guidance on where I could source a smaller amount of the Kluber L643.

Thanks,
Per
Old 1 week ago
  #2
Gear Addict
 

I don't know what the Studer requires, but it sounds like what is called damping grease, or helical grease. These are special greases used to damp mechanical action rather than just lubricate, and are used on things like camera lens mechanisms to give a smooth, damped resistance feel. Unfortunately, they tend to be very expensive in small quantities, and they have a huge range of damping available, so it is very hard to know what to buy. Vendors don't seem to know how to differentiate it from regular grease.

In the USA, I have bought from Micro-tools
Lubricants – Micro-Tools

and Nye Lubricants makes a whole line of them, but they are hard to find in small quantities.

I would look at Amazon or the big Chinese sell-everything sites, and look for damping grease or helical grease, and try to make a guess as to the strength you need.

I have Nyogel 767A and it is perfect for turntable cueing mechanisms and such. I did not try to figure out if any silicone damping fluid (sold widely as shock fluid for toy cars) would work. You can buy that in many varieties listed in CST (centistokes) of damping.

Last edited by GLouie; 1 week ago at 11:52 PM..
Old 1 week ago
  #3
Lives for gear
For lurkers: those arms/platforms on the Revox and Studer do a lot more than mechanically damp the tape feed. They're also electronic tension controls, and not having them work right can affect speed and tape wrap around the head as well as initial movement.

MCI got by with a less critical damping path by computing tension based on reel rpm. But that was a year or so later than Studer's design.

[I'm sure the OP and respondent know that; this is just for lurkers.]
Old 1 week ago
  #4
Gear Addict
 

Naw, I don't actually know what the Studer needs. And looking up the Klüber L643, it looks like an ordinary silicone grease with PTFE (Teflon) particles for bathroom fixtures, no special damping properties mentioned! Indeed, OP should verify that the damping action sought is correct.
Old 1 week ago
  #5
Here for the gear
 

First of all, thanks for all your thoughts and efforts in trying to help out. It's very much appreciated.


Quote:
Originally Posted by GLouie View Post
I don't know what the Studer requires, but it sounds like what is called damping grease, or helical grease. ....

and Nye Lubricants makes a whole line of them, but they are hard to find in small quantities.

I have Nyogel 767A and it is perfect for turntable cueing mechanisms and such. I did not try to figure out if any silicone damping fluid (sold widely as shock fluid for toy cars) would work. You can buy that in many varieties listed in CST (centistokes) of damping.
You're right the L643 is a helical/damping-grease. I saw that Nye has smaller quanteties on sale so I've asked them for help. Lets see if thay maybe have an eqivalent to the L643?


Quote:
Originally Posted by Jay Rose View Post
those arms/platforms on the Revox and Studer do a lot more than mechanically damp the tape feed. They're also electronic tension controls, and not having them work right can affect speed and tape wrap around the head as well as initial movement.
You're right Jay, the damping is part of the tape path control on A/B67 and RevoxA700. Maybe not speed as much as tape tension in dynamic situations. Since that's the case Im quite keen on getting the correct behaviour of the dampers.
Old 1 week ago
  #6
Gear Addict
 

Nye flat out refused to send me their damping grease sampler kit, telling me a repair technician was not qualified to get one unless I could promise to buy something like $500 USD of product a year. They phoned me directly to tell me so, and directed me to a 3rd party vendor that would sell me a kit for something like $90USD:
tai-lubricants

However Nye does have information about their damping products and several info sheets on their website:

Damping Greases - Nye Lubricants

The 767A I bought is called a heavy damping grease. I have no idea how you quantify the damping in order to compare to other manufacturers, such as the Asian helical greases seen for sale in various weights. All of it is expensive, but if you needed damping, it's the real deal.
Old 1 week ago
  #7
Lives for gear
Pelia, tape tension can certainly affect speed. The sensors in Studer/Revox (and RPM analog computing circuit in MCI) constantly adjust so a consistent pull is applied to the tape going past the capstan. This means the capstan motor doesn't have to work as hard to regulate speed.

Prior to these designs --and maybe 3M's loop-- the only approach AFAIK was brute force, as in the Ampex and Scully pro decks back then. Differences between the heavier pull at the ~3" start of a large reel and the lighter one at ~10" when the reel got full could result in almost a half-step of speed change. As I discovered to my dismay when I tried to splice a note from the end of a performance into a song from the start. And this was recorded on a 350 that had just been calibrated using Ampex's recommended method (i.e., 'fishscale'... we didn't have Tentelometers then).

Those decks had 'large/small' switches on their control panels, which changed a resistor tap feeding both reel motors. But nothing could compensate for the change in circumference while 2500' of tape was rolling from one reel to the other.

Revox A77 also had a large/small function built into its power switch, but for some reason I never encountered the pitch change with it.
Old 1 week ago
  #8
Here for the gear
 

Quote:
Originally Posted by Jay Rose View Post
Pelia, tape tension can certainly affect speed. ....
Im sorry Jay Rose I might have misinterpreted your comment since I commented on the dampers effect on the tape tension, not tape tension effect on speed.

Studer uses two measurements on the machine called A1/A2 to make sure that tape tension springs / torque control of the reel motors and capstan / Damping effect of dampers are balanced out resulting in the right tape tension. A1/A2 should be set within +-1mm. That calibration is easily achieved even without damping at all on an A/B67.

So the only conclusion I can draw is that the damper effect has very small effect on tape speed, I would even venture into saying it's negligible when the system is calibrated within specification.
Old 1 week ago
  #9
Here for the gear
 

Yesterday I tried another silicone paste, very sturdy and sticky stuff. It did improve a little little bit but is nowhere near what it should be.
Old 4 days ago
  #10
Here for the gear
 

Today I tried the CST300000 silicone grease. I compared to a well used B67 and it has slightly more damping(just a little bit) so I guess it will work fine until I get hold of the real stuff, the Kluber L643.

Thanks for all support!
Old 4 days ago
  #11
Gear Addict
 

It would interesting to see if the silicone fluid works better than a damping grease - if it disappears/evaporates/runs off or not. You would have to test it for some time.
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