This follows on from the thread: Can you improve the Stock Bearing. IanMac has done an interesting mod on the stock bearing but it should have a thread of its own.


For those who have not followed that thread the short point is that IanMac has essentially used a Teflon, a known slippery material for the thrust-pad. In principal this seems a brilliant and obvious idea and surely can only reduce rumble. The problems, if I understand it correctly, were twofold. First Teflon is not hard enough, and second keeping this material in place would require a new housing. The first problem Ian has solved by using a very hard type, called Peek. Second, his engineering skill have enabled him to make a housing.


Below is a comparative picture.


[IMG][/IMG]




The Mike New bearing is on the left, a stock bearing in the centre and the IanMac on the right.


I've had my IanMac bearing for quite a while now and I have decided I will keep using it. I have done a comparison of four bearings spin down times. When I say 'four' I have tested the IanMac Bearing twice, once as supplied, and then in a bath of oil. Here are the results.


[IMG][/IMG]


Each entry is an average of five readings. Larger numbers are better. I have done the test for each bearing in four scenarios. Twice with platter only at 33 and 45 rpm. And twice with a 5mm Achromat, 180 gram LP and the Michel Clamp. So at 33 rpm with platter only the IanMac bearing takes a little over 20 seconds to stop spinning. This is an improvement over the stock bearing.


Subjectively the IanMac bearing seems to have improved over the weeks I have had it, so maybe there is some benefit to running it in, though I did notice an improvement over the MNB straight out of the box as it were. I am not sure about the oil bath. I think improved slippery oils would help if it was a metal against metal bearing / thrustpad contact. But with Peek I am not so sure.


I have taken some readings in Audacity. I have used the silent groove on The Ultimate Analogue Test LP by Analogue Productions. They look like this in Audacity:

[IMG][/IMG]

I have taken Plot Spectrums from the Analyze menu. But I do not know how to interpret them. Anyone know what they mean and what are the best paramaters to choose.

[IMG][/IMG]


The net result is that I will be using IanMacs bearing from now and in due course will put my MNB up for sale. I will continue to experiment with different lubricants. I have a suspicion though that it may be best without any lubricant.