Restoration: Rek O Kut Rondine 2

[Sam Cogley]

I wasn't dissing the motor. I said "great motor" in my first line. I was designing a turntable many years ago and bought that Pabst motor for it.

I didn't think you were. Just adding some context to the extensive use of that motor in turntables from numerous manufacturers.

 

[Selmerdave]

In theory. But it's rubber and it compresses slightly in contact with hard metals. It's a tiny amount but it's there. It's no longer a single-point, it's a slightly broader surface; a benefit of this "deformation" is better grip on the metal surfaces, thus more consistent transmission of speed from motor to platter.

I think this is shown when idler-TTs are not used, but put in storage, with the idler in contact with the platter. It develops a "flat spot" — caused by compression. (Not the Thorens 124 — it pulls the wheel out of contact when you switch it off.)

Yeah, still not convinced. So you're saying a smaller spindle would cause less of this compression? To whatever extent it's happening it could be varied by the amount of pressure and swamped by any amount of vertical contact. At any rate, ROK recommends the minimum pressure, and with that my 1/200 horsepower motor seems to rotate the platter with no lack of torque let alone indication of slippage.

I'm not saying that one could not prefer one table or another for any number of reasons, but I'm doubtful that ROKs suffer from slippage and that the diameter of the spindle at contact point determines the success of a design.

 

[bimasta]

Understandable assumption because all of the other "Rondine" models were idler drive. I think the Rondine 2 was their first belt drive. That goofy tension pulley was there because the original belt was made of some sort of fiber, not rubber.

Thanks again Malden. You made me feel foolish, but I embraced the rebuke. Now I feel less foolish: all other Rondines were idlers, so I was almost right. As for the belt with "some sort of fiber, not rubber" as you describe it, I had one. It came with the ROK (forget the model, pure beltdrive) I got about 15 years ago. It must've been an attempt to overcome the belt stretching during play. It was rubber, but had fiber-reinforcement in it. Either the rubber was laminated over the fiber, or the fiber was impregnated with rubber. You could see the texture of the fiber-web through the rubber. The result was a rubber surface that provided good grip on the metal surfaces, and a fibrous core that could not be stretched. People are attempting something similar with "thread-drives" on the great old Micro Seiki's — they don't stretch, but I doubt they have the grip. I should have kept that belt — probably lasted forever because it never stretched — but I gave the whole rig to a friend when I couldn't cure the bearing rumble.

Thanks again for all the info.

 

[bimasta]

I didn't think you were. Just adding some context to the extensive use of that motor in turntables from numerous manufacturers.

And I didn't think you thought I was dissing the motor. Diss was just a poor word choice written in haste. Yes, I also saw that same motor in some heavy-duty reel-to-reel tape machines, driving the capstans. Great motor, more power than you ever need, and runs forever — well, except for the bushings probably, but no big deal replacing them, the whole motor came apart easily for maintenance — unlike some of the spot-welded-shut motors you can't get into to lubricate. Thanks for your clarification.

 

[bimasta]

I'm doubtful that ROKs suffer from slippage and that the diameter of the spindle at contact point determines the success of a design.

I didn't mean to imply that, if that was your inference. My first TT was a ROK and I had it 10 years, loved it, only left it when I moved to UK. I never heard speed fluctuation — but I wasn't listening for it when I was 20. I said several times I was only talking about "potential" issues. It's a fact that a "skinnier" shaft (or spindle, but I don't use that word in this context, to avoid confusion with the thing in the middle of platter where the in the record goes, also called a spindle) has less contact-area with the belt or idler, thus a less secure grip. That doesn't mean it does slip, only a higher potential of slipping.

Much of the fascination with analogue is its manifold complexities, which grow the more you know, and the many theories how best to maximize performance. Some of those theories, when I apply them in practice, I can't hear any difference. But I apply them anyway, because they're correct in "theory". This pertains to a tiny cartridge clip, which only weighs next to nothing, up to a 40-pound platter. There are "theories" about each, and if those theories make logical sense to me, I apply them when possible, even if hear no difference. Sometimes I do hear improvement. Other theories don't make sense to me, and I ignore them.

You also asked a good question about shaft-diameter and compression — I'll have to respond later. Thanks.

 

[Sam Cogley]

And I didn't think you thought I was dissing the motor. Diss was just a poor word choice written in haste. Yes, I also saw that same motor in some heavy-duty reel-to-reel tape machines, driving the capstans. Great motor, more power than you ever need, and runs forever — well, except for the bushings probably, but no big deal replacing them, the whole motor came apart easily for maintenance — unlike some of the spot-welded-shut motors you can't get into to lubricate. Thanks for your clarification.

The rather amazing thing is that the Papst wasn't even the top-end RoK motor - the truly enormous Ashland hysteresis motor got that honor.

 

[Selmerdave]

This allows slippage, because the contact-area of the shaft-and-idler is quite small.

This is one thing that I'm responding to. Yes contact surface area matters but the only thing that really matters is whether it's enough, beyond that additional contact is wasted and/or detrimental, and again there is the vertical component. You are claiming that the ROK contact is insufficient and that there is slippage, which is different than the relative claim.

Basically, the Garrard and Thorens are better designs.

And this is the other thing I disagree with, at least with respect to the motor spindle (yes that's confusing). There are tons of differences between these tables, I don't think any of them have a design flaw that results in slippage.

 

[bimasta]

This is one thing that I'm responding to.

And this is the other thing I disagree with

I agree with everything you say Selmerdave — except your misrepresentations of what I said. In every case I was talking about "potential" and used that word several times — I only said some designs have a higher potential of something happening, never said it does happen. As for "better design", I think if Design A has a lower potential for misbehavior than Design B, then A is a "better design". Doesn't mean it's better in practise, or sounds better — only better in theory.

I wrote about the role "theory" plays the analogue world in my first reply to you (#25) so no need to repeat it here.

In sum, I would love to have a Rondine of my own. I'm sure it's a great table, my first ROK was great. Design "issues" don't matter — but it's good to be aware of them so we can make sure "potential" issues don't become "real" issues.

 

[Selmerdave]

I agree with everything you say Selmerdave — except your misrepresentations of what I said. In every case I was talking about "potential" and used that word several times — I only said some designs have a higher potential of something happening, never said it does happen. As for "better design", I think if Design A has a lower potential for misbehavior than Design B, then A is a "better design". Doesn't mean it's better in practise, or sounds better — only better in theory.

I wrote about the role "theory" plays the analogue world in my first reply to you (#25) so no need to repeat it here.

In sum, I would love to have a Rondine of my own. I'm sure it's a great table, my first ROK was great. Design "issues" don't matter — but it's good to be aware of them so we can make sure "potential" issues don't become "real" issues.

All good, but hard to misrepresent your words when I'm using exactly your words. I'd say if the "misbehavior" doesn't happen in either case, it's not terribly relevant and doesn't have much of a bearing on how good a design is other than they are all good enough to prevent that occurrence. But we can agree to disagree there.

 

[bimasta]

But we can agree to disagree there.

Agreed.

 

[malden]

...and now back to our regularly scheduled program....The Adventures Of The Rek-O-Kut Rondine 2...

 

[malden]

Here is my Rek-O-Kut Rondine 2. It's in pretty good shape, and I am hopeful this will go well..

Any updates for your project?