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Rondine rumble

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Rondine rumble

Postby chilimac » 05 Oct 2017 01:20

Hi all, I just joined this forum and this is my first post. Several years ago I found a pair of mid-50s Rek-O-Kut Rondine tables on ebay, and set out to make one good one. One of them was cosmetically near-perfect but had a bad motor. The other was a cosmetic nightmare but the motor was OK. I had the idler wheel re-tired professionally and set about making a fancy plinth, then replaced the old stock pickup arm with a fairly modern Sony arm. The resulting setup looks great, but sonically it turns out to be a rumble generator. I understand this is fairly characteristic of the old Rondines when playing stereo records. I have three other more modern tables, so it's not that I depend on the Rondine except that it's the only one I have that has the 78 speed, and I'd like to get it quieted down.

Is there any community wisdom on what (if anything) can be done to reduce the rumble in one of these? I grew up with one in the mid-late 50s in Wisconsin and thought it was a superior piece of equipment, but maybe it was too old a design to be useful in the modern era. Built like a tank, though, and I'd really like to get it right.
Any suggestions will be most appreciated.
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Re: Rondine rumble

Postby Coffee Phil » 05 Oct 2017 06:57

Hi Chilimac,

Welcome to the forum.

The folks at EsotericSound are the R-O-K gurus. In fact they now own the brand name.

http://www.esotericsound.com/

They offer some modern motor mounting grommets which are the same size and shape as the OEM parts but made of some state of the art rubber. They claim ~ a 40 dB improvement however there is a disclaimer for idler drive machines. They say that some motor rumble will still be conducted through the idler wheel so the improvement won't be as good as with belt drive machines.

They also offer a DC motor / belt drive conversion kit which will get the rumble down to that of state of the art machines and permit you to play records of any speed. It is fairly spendy however.

Is the arm which you removed in decent shape? I have a Rondine 2 which I'm working on. So far I'm planning to mount a Grace 940 arm on it. I did not get the OEM arm with the machine and I'm pretty sure the Grace is much better but I would like the OEM look so make me an offer.

Phil


chilimac wrote:Hi all, I just joined this forum and this is my first post. Several years ago I found a pair of mid-50s Rek-O-Kut Rondine tables on ebay, and set out to make one good one. One of them was cosmetically near-perfect but had a bad motor. The other was a cosmetic nightmare but the motor was OK. I had the idler wheel re-tired professionally and set about making a fancy plinth, then replaced the old stock pickup arm with a fairly modern Sony arm. The resulting setup looks great, but sonically it turns out to be a rumble generator. I understand this is fairly characteristic of the old Rondines when playing stereo records. I have three other more modern tables, so it's not that I depend on the Rondine except that it's the only one I have that has the 78 speed, and I'd like to get it quieted down.

Is there any community wisdom on what (if anything) can be done to reduce the rumble in one of these? I grew up with one in the mid-late 50s in Wisconsin and thought it was a superior piece of equipment, but maybe it was too old a design to be useful in the modern era. Built like a tank, though, and I'd really like to get it right.
Any suggestions will be most appreciated.
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Re: Rondine rumble

Postby chilimac » 05 Oct 2017 11:21

Phil,
Thanks for the response. I figured the motor mounts would likely figure into it. And I like the idea of a belt drive conversion, in fact I was trying to figure out a way to engineer such a thing but it seems to be beyond my ingenuity.
A kicker is that in 1964 I bought (new) a R-O-K N34H belt drive 33/45 machine and used it for many years, but in about 1988 the belt had stretched so far it wouldn't turn the platter. This was in the days before the Internet, so I didn't have a clue where to find a replacement belt, so (grit your teeth) I pitched the whole machine into the dumpster. I'd give anything to have that one back now.
Unfortunately, both of the stock pickup arms on the two Rondines I got from ebay were in bad shape and went directly to the dumpster.
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Re: Rondine rumble

Postby chilimac » 05 Oct 2017 11:46

In other forums I frequent, people like to see pictures. Here's one of my Rondine project just after I finished the plinth. The Sony arm is longer than the stock arm, so I had to rotate things, and I used the triangular switch plate to cover the stock arm mounting hole and provide a master power switch. I have a DIY phono preamp mounted in the base, and the switch controls power to its power supply as well as the drive motor.

39481
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Re: Rondine rumble

Postby KentT » 05 Oct 2017 13:26

Are the motor mounts in top condition? The bearings in top condition? The idler wheel in top condition? Is the plinth system up to modern needs? Get the mechanical system in top condition, and as quiet as you can get it, get the plinth system it's mounted in up to what it really needs, and you should have a quieter, less rumbly turntable than you began with, and you should get it to sing. It's an audio classic, DON'T CONVERT IT INTO A BELT DRIVE. Want a belt drive Rek-O-Kut, get one of their belt drive models from that belt drive series. Rondine upper end models need to be preserved in good order.
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Re: Rondine rumble

Postby jfrace » 05 Oct 2017 14:13

Is the rumble audible through records playing? Some of the ROK's have it, but it's not audible through the records. I have a B-12H, and an L-34, and I can't hear anything audible through them. Sold the L-34 to someone who made me an offer I couldn't refuse, but neither had any issues once cleaned up, relubed, idler redone, and bearing cleaned.
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Re: Rondine rumble

Postby chilimac » 05 Oct 2017 16:18

To tell the truth, I've only used the Rondine one time, to play a 78 rpm record made by my mother at a radio station in 1945. The object was to save the recording to CD and then use editing software to clean it up and get rid of the rumble and clicks. That's where I became aware of the extent of the rumble.

I set the table aside for the last few years but am getting back to it now. I've cleaned out the axle shaft housing and put in fresh oil, and am contemplating pulling the motor out to check the bearings. The motor mount bushings are all in one piece, but being original equipment I'm sure they could be improved. I put a drop of oil on the idler shaft. As noted in my original post, the idler was rebuilt when I first got the unit off ebay, but that was on the order of 15 years ago.

I think my next move will be to plug it in as it stands right now and find out how noisy it is, then do whatever more I can to clean, lube, etc., and see how far I can quiet it down.

But to answer your question, yes, the rumble was very audible when playing a record.

For what it's worth, the frame identifies it as a B-12H.
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Re: Rondine rumble

Postby Coffee Phil » 05 Oct 2017 17:52

Hi Chilimac,

A R-O-K N34H into the dumpster? The H means it likely had the beautiful Papst outer rotor hysteresis synchronous motor. That hurts the heart of a Rek-O-Kut lover, but since you are showing the proper remorse we are a forgiving group.

For this machine it appears it also has the synchronous motor. It would be a shame to pitch that so some effort is warranted to to preserve the present configuration. If you just had the grunt induction motor and since while your machine is beautiful, but hardly "concourse" I would disagree with KentT and get the Esoteric DC motor kit. It will have the correct brand and is sort of tasteful. With your nice arm that would make this into a seriously high end machine. If you have the outer rotor motor I can't bear to see that go into the bin so I would try to work with it for a while. DO get the good grommets and lube the motor and you might try a new phase shift capacitor. Even if the cap is good, tweaking the value may get the motor quieter. Also look at the idler wheel and make sure it is almost perfectly round and does not wobble. The last rebuild may not have been well executed.

Phil

chilimac wrote:Phil,
Thanks for the response. I figured the motor mounts would likely figure into it. And I like the idea of a belt drive conversion, in fact I was trying to figure out a way to engineer such a thing but it seems to be beyond my ingenuity.
A kicker is that in 1964 I bought (new) a R-O-K N34H belt drive 33/45 machine and used it for many years, but in about 1988 the belt had stretched so far it wouldn't turn the platter. This was in the days before the Internet, so I didn't have a clue where to find a replacement belt, so (grit your teeth) I pitched the whole machine into the dumpster. I'd give anything to have that one back now.
Unfortunately, both of the stock pickup arms on the two Rondines I got from ebay were in bad shape and went directly to the dumpster.
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Re: Rondine rumble

Postby chilimac » 05 Oct 2017 18:23

Phil,
The sticker on the side of my motor says "General Industries Co, Elyria, Ohio, Model D10". Nothing about Papst. To me, it's an ugly squat square thing. But it seems to run freely without any noise. I haven't got into it yet to check the bearings.
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Re: Rondine rumble

Postby KentT » 05 Oct 2017 19:59

The General Industries motor is not as quiet rumble wise as the Ashland motor used in the top option of the Rondine Deluxe, the Ashland is the motor to have, the Rondines I cared for in AM and FM station service had Ashland Hysteresis-Synchronous motors from the factory (cost a good deal more then when new)
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Re: Rondine rumble

Postby Coffee Phil » 05 Oct 2017 22:14

Hi Chilimac,

I'm pretty sure that is a four pole shaded pole induction motor. They are certainly decent motors but not the nice outer rotor synchronous motor which I have in my Rondine 2. I would not expect that motor to be very bad for rumble. Now it may couple mechanical hum into the platter but I don't think is should be too bad.

I would say with the idler away from the platter, spin it and listen to the spinning platter to determine if the bearing is OK. If it is like my Rondine 2 there is a ball bearing at the bottom of the bearing well. If the platter is noisy and cleaning and lubing it doesn't help a new ball and polishing the bottom of the shaft may help.

After determining that the platter bearing is OK look at the idler wheel. It may be worth it to get the good grommets from Esoteric. They are not cheap so if you are considering the DC kit you might bypass the grommet step.

While the motor which you have is a decent motor, it is nothing special so I think the DC kit make some sense considering what you have done so far. For the collectable value you can even leave it in place. Just power it off and make sure the idler does not contact the platter. Sure the kit is spendy but in the light of the labor you have put into this machine, it may be the most painless path to the performance you want to justify your effort so far.

Phil




chilimac wrote:Phil,
The sticker on the side of my motor says "General Industries Co, Elyria, Ohio, Model D10". Nothing about Papst. To me, it's an ugly squat square thing. But it seems to run freely without any noise. I haven't got into it yet to check the bearings.
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Re: Rondine rumble

Postby chilimac » 06 Oct 2017 02:56

Here's a pretty significant update. I spent much of the day today tinkering and testing the Rondine. One thing I discovered is that some previous owner decided there was no apparent reason for a run/start/phase shift capacitor, so it's completely devoid of such. It also does not have the power cutoff switch that appears to have been connected to the speed control switch. This is no big deal as far as I'm concerned, since I added a toggle switch for main power.

The much more important results are as follows:

1. After a few minor fix-ups, I set everything ostensibly in order and powered it up, connected to a vintage system (all I've got) of Dyna Pas-3 preamp, BK Systems ST-140 amp, Sherwood Tanglewood speakers. Started with a late 60s recording of the Orchestre de Paris on Angel, Le Marsellaise. Sounded pretty good, but the level not as high as I would have expected, using a Bang & Olufsen MMC 10E cartridge.
There was still some audible rumble present, but I'd just started on the curative process, and I could almost live with what I was hearing. But then I decided to switch to a 78 cartridge and try one of my ancient 78 discs, only to discover that I was getting no sound at all through the system. Back to the LPs, I found that I was dropping the left channel quixotically. Time to disassemble and run some tests!

I swapped turntables and resorted to a Marantz TT2200 direct drive, after swapping in the 78 cartridge. Of course, it worked perfectly.
This led me to think about the wiring in the Sony arm. It's a b****r to trouble shoot as there are two points where you have contacts between rods and socket pins, where it's a PITA to get test probes in. Final discovery is that I apparently have at least one short in the internal wiring in the Sony arm, and that could be a headache, but it's reserved for tomorrow.

The good news is that the Rondine is in passable kip, and with some diligence and a few decabucks might just be rejuvenated.

Adolescent note: I really like operating the giant speed control knob. It's like turning the main gun on an Abrams tank.
Last edited by chilimac on 06 Oct 2017 03:54, edited 1 time in total.
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Re: Rondine rumble

Postby Coffee Phil » 06 Oct 2017 03:19

Hi Chilimac,

With that H at the end your model number I would have thought you had the hysteresis synchronous motor which uses the phase shift cap. All of the General Industries motors as you described which I have seen are shaded pole motors which do not require a phase shift capacitor. I'm wondering if your seller harvested the hysteresis motor for what he viewed was a higher purpose and replaced it with the shaded pole induction motor. At any rate with your motor you may not need such a capacitor.

Phil

chilimac wrote:Here's a pretty significant update. I spent much of the day today tinkering and testing the Rondine. One thing I discovered is that some previous owner decided there was no apparent reason for a run/start/phase shift capacitor, so it's completely devoid of such. It also does not have the power cutoff switch that appears to have been connected to the speed control switch. This is no big deal as far as I'm concerned, since I added a toggle switch for main power.

The much more important results are as follows:

1. After a few minor fix-ups, I set everything ostensibly in order and powered it up, connected to a vintage system (all I've got) of Dyna Pas-3 preamp, BK Systems ST-140 amp, Sherwood Tanglewood speakers. Started with a late 60s recording of the Orchestre de Paris on Angel, Le Marselleise. Sounded pretty good, but the level not as high as I would have expected, using a Bang & Olufsen MMC 10E cartridge.
There was still some audible rumble present, but I'd just started on the curative process, and I could almost live with what I was hearing. But then I decided to switch to a 78 cartridge and try one of my ancient 78 discs, only to discover that I was getting no sound at all through the system. Back to the LPs, I found that I was dropping the left channel quixotically. Time to disassemble and run some tests!

I swapped turntables and resorted to a Marantz TT2200 direct drive, after swapping in the 78 cartridge. Of course, it worked perfectly.
This led me to think about the wiring in the Sony arm. It's a b****r to trouble shoot as there are two points where you have contacts between rods and socket pins, where it's a PITA to get test probes in. Final discovery is that I apparently have at least one short in the internal wiring in the Sony arm, and that could be a headache, but it's reserved for tomorrow.

The good news is that the Rondine is in passable kip, and with some diligence and a few decabucks might just be rejuvenated.

Adolescent note: I really like operating the giant speed control knob. It's like turning the main gun on an Abrams tank.
Coffee Phil
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Re: Rondine rumble

Postby chilimac » 06 Oct 2017 03:49

Phil,
That's pretty much what I figured, too. I was actually pretty pleased with the sound I got from the setup today, with the exception of the low level, which I presume to be an artifact of the shenanigans in the pickup arm wiring. I hope to have a resolution of that tomorrow.

By the way, the BK main amplifier I mentioned was bought as a substitute for my most excellent Dyna MK IIIs, which I temporarily retired about 1990 when the power supply filter caps exploded (really!) I've since done the usual mods with parallel caps and bleed resistors, and retubed the amps - one with GE 6550s, one with Svetlana EL34s - using them in a pair of mono systems, but readily available if the BK craps out.
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Re: Rondine rumble

Postby chilimac » 06 Oct 2017 17:48

Spent all morning troubleshooting the Rondine, including:

1. Discovered the problem in the signal wiring was not in the Sony arm at all, but in an over-complicated termination I'd devised to hook up to the output sockets. I've got male XLR connectors mounted at the back of the plinth, and run XLR cables with RCA ends to the amplifier.

2. Removed the motor and opened it up, cleaned and oiled it. It was actually quite clean. While reassembling the drive assembly, I found that the three motor mount grommets were basically hard as rocks, so before I complete the reassembly and test it again I'm going to order the improved grommets from Esoteric. I'm willing to gamble the cost of them against an expectation that they'll make enough difference in the rumble to make me happy. In any case, they've got to be an improvement over the old Fred Flintstone grommets.

3. Wire-brushed the flat metal plates associated with the motor drive assembly, just because after ~60 years they deserve a touch-up.
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