IDLER WHEEL DESIGN-Just the idler... - diyAudio
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Old 10th July 2009, 03:09 PM   #1
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Default IDLER WHEEL DESIGN-Just the idler...

Ok, so I have a Garrard 301 and a 401. I use the 301 with an after market bearing and platter so it's not a pure 301 anymore. I am constantly tinkering with it trying to pry more and more out of it. The one thing I personally think could be improved on in the Garrard is the idler itself. On the two decks I have the idler seems to be the biggest source of noise. No matter how quiet the motor is once the idler is engaged the noise kicks up.

It's quite a revelation putting a stethoscope on the tonearm after the idler is engaged. It sounds like an earthquake, this can't be good.

SO with that being said I was thinking of making a new idler or at very least improving the bushings on the original idler.

I have a metal lathe so turning a perfectly round piece will not be a problem.

Here is what I am thinking so far:

An aluminum disc machined to roughly the diameter of the original idler. Cutting a groove on the outer surface and placing an o-ring on that. Similar to the Versus rim drive thing. I am somewhat stuck as far as a bearing for this arrangement. You could just drill a small hole and recreate the arrangement of the original idler or something altogether new could be done.

Maybe some sort of ball bearing arrangement??

Any ideas??

David
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Old 10th July 2009, 03:59 PM   #2
johnm is offline johnm  United Kingdom
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Surely a larger metal idler will cause/transmit more noise, not less. The large rubber content of the original is meant to absorb noise/vibration to a certain extent. I think the springs which hold the motor, and which pull the idler wheel assembley could perhaps be looked at instead? Replaced by silicon rubber bands perhaps?

Still it would be worth actually trying it out your idler wheel idea and seeing for sure.
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Old 10th July 2009, 09:11 PM   #3
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But a larger idler wheel will run slower and, perhaps, quieter, isn't it? Hypothetically, imagine the idler wheel is 12" in diameter or matching the platter size then it will run at 33rpm so now it's much slower and, I assume, quieter. Am I missing something here?
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Old 11th July 2009, 02:19 PM   #4
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Unfortunately I think you are. I suspect the noise is not being created by the idler, but transferred from the motor assembly to the platter via the idler. Though more difficult, you may get better results by using a softer rubber for the idler, though I don't know what other affects this may have.
If you have a suitable lathe you may even be able to create a sub platter to fit the spindle below the main platter, then replace the large idler drive motor with a smaller belt drive one and power the platter via a VHS tape belt or similar.
I appreciate this latter suggestion is somewhat radical, but I don't think there's any easy way of eliminating the noise from so large a motor
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Old 11th July 2009, 03:58 PM   #5
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Yes, the majority of the noise is, of course, came from the motor. Aren't all turntables like that? I was talking purely about idler designs regardless of what motor you use. I simply suspect, in theory, an idler wheel of bigger diameter is inherently quieter because it runs slower.

In the case of the Garrard or similar idler designs, the quality of the idler wheel affects the noise level but I agree that even if you have found the perfect idler wheel on the planet, the noise in the motor still exist. Either get a quieter motor or some form of power supply that helps the motor runs smoother and quieter. Motor isolation can only go so far and after all the idler wheel still has to engage the motor pulley or shaft. In my experience, the Lenco motor is very quiet compare to many idler tables and its spring mounting system is also excellent but when you touch the motor by hand the vibration is still there and imagine your idler wheel is your hand... With the existing system currently popular in vintage designs, I don't see how the low noise level can be approaching belt-drive or direct drive. You just have to live it. Until a new system comes along . . . Perhaps the Verus motor is one solution - essentially it's a motor that runs slower. Why can't we have slower running motors so we can use bigger pulleys? That, I don't understand. Anyone out there can illuminate me?

ralphfcooke, I don't see any reason to tinker anything under the platter of an idler drive in order to make it a belt drive. Just use a motor pod outside of the platter and drive it via a belt or tape a la Teres style. This way, it can be easily reversible. Can't get better motor isolation than that. But then again, it's the sound of belt-drive not idler-drive. Regardless of noise level, they just sound different tonally. And idler turntables do have a sound or tone that's irresistibly attractive, full, robust, juicy. No wonder idlerists are so addicted. I don't blame them.
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Old 11th July 2009, 08:37 PM   #6
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I'm not an acoustic engineer, but I suspect the difference between idler - belt - direct drive turntables is less to do with the method of rotating the platter and more to do type and amount with the noise and vibration introduced to the stylus via whichever mechanism is used.

In theory either a massive direct drive (not sure they exist, most seem to be of medium mass), or a massive belt drive (again these are not common, except for home builds) will be significantly quieter than any idler drive, though the latter, in most cases, have much higher mass platters.

It should be possible to create a platter that could be either idler or belt driven, but I wonder how many people, except for a few 'cognoscenti' could detect the difference.

It would also be interesting to try a variation of the 'use one platter to belt drive another' method, but to find a way of running the first one in reverse and using it as a 'full size' idler by wrapping a rubber ring around it.

The bottom line surely has to be that there is a law of diminishing returns, and at some point you end up spending much too much time playing with the engineering and far too little enjoying the music.
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Old 11th July 2009, 10:38 PM   #7
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It's funny that all the methods you mentioned are stuff I've been experimenting. I have a recent post about two platters driving each other via VHS tape: DD belt drive platter via VHS tape The only hitch is that I don't know how to make the platter go in reverse so I can use the platter as an idler wheel to drive the passive platter. I am only interested in using DD turntable as the motor part. I usually have two systems, one for listening to music and one for tinkering. It's fun! By the way, the difference between idler drive and belt-drive is not subtle. Idler-driver has a very particular sound to it. I gave up because of noise issue. I might try that again.
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Old 3rd September 2009, 05:52 PM   #8
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Quote:
Originally Posted by kozzmo99 View Post
Ok, so I have a Garrard 301 and a 401. I use the 301 with an after market bearing and platter so it's not a pure 301 anymore. I am constantly tinkering with it trying to pry more and more out of it. The one thing I personally think could be improved on in the Garrard is the idler itself. On the two decks I have the idler seems to be the biggest source of noise. No matter how quiet the motor is once the idler is engaged the noise kicks up.

It's quite a revelation putting a stethoscope on the tonearm after the idler is engaged. It sounds like an earthquake, this can't be good.
Can you measure the rumble in dB? Those garrard idler-wheelers, despite having a huge audiophile cult, actually have unimpressive rumble figures!! (good enough but not great)

Maybe yours is just working up to specs?
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Old 7th September 2009, 07:41 PM   #9
bulgin is offline bulgin  South Africa
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Default Idler wheel design...

Hi

I have 4 Garrard 301's and a 401. Two of the 301's are set up and in daily use. One of these is a cream greasebearing Schedule 1. I have no particular noise issues as I designed a rumblefree plinth for the oilbearing 301 a long time ago. The greasebearing is plintless and sits on 4 aluminium legs, tipped with conical rubber feet.

I too, keep a stethoscope around for listening to rumbles and what I hear is much less than you described.

Grease and oil I use is Superlube with teflon for the grease bearing and Castrol Final Drive transmission oil with the oilbearing models.

Since I have no excessive noise problems, my only suggestion I can think of would be to damp the platter in some way or other on the inside. I read about this in a mainstream audio mag a long time ago and forgot what was used. Could be wax or some kind of resin.

If there is motor noise, this will likely be transferred through the springs the motor hangs on. I wonder if the motor could be made more quiet by means of synthetic bushes? There are specifc engineering plastics for motor bushings.

Years go, a toolmaker friend and I used to go rock and surf fishing. My friend is a qualified toolmaker. We are both 'technofreaks' and used some of the best fishing reels available. We 'tweaked' our reels by removing the roller bearings and replaced them with turned synthetic bushings in a kind of grey material. The results in silence and further casting distances were astonishing.

bulgin
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