Bearing Shoot Out.
Trials in an otherwise standard Technics 1200 mkII
From a purely frictional point of view the modified bearing offers far less resistance but only once run in, initially its times were worse than the standard bearing.
The run down times when switching the power off, were as follows (No record on platter and just a felt mat) Average of three readings.
Standard Bearing 33RPM = 14.6 sec 45RPM = 19.6 sec
Modified Initially 33RPM = 7.2 sec 45RPM = 11.5 sec
Modified Run In 33RPM = 18.6 sec 45RPM = 25.2 sec
The run in period was only 24 hrs, run at 45RPM, it may improve further.
I know from experience that thinner oil, eg 100% sowing machine oil will produce longer times but at the expense of the sound, you have to find the right viscosity for the bearing, sympathetic with its design and mounting to get the best acoustic results.
The strange thing was that although it ran really poorly at first it felt really free compared to the draggy feel to the standard bearing with its thick oil, just shows, the feel in your fingers can be deceptive.
So how does it sound?
I did four sessions, standard/modified/standard/modified playing the same four complete albums each time. Equipment was the SL-1200 with Goldring 1042 cartridge, Graham Slee Gram Amp 2 SE phono into Sugden A21A class A amp, Tannoy Cheviot speakers.
I will keep it brief, what hit me straight away was the increased warmth and detail of the mid range compared to the standard. Also the treble was not as harsh, being slightly sweeter. Bass is very slightly faster and tighter.
At the end of the last session I tried putting a pea size piece of Blu Tack under the base of the bearing and tightening it down. When I took it out I had to peel the bearing off the bottom of the deck, boy did it stick. There is 2mm clearance under the bearing and the 10mm pea had spread to the size of a 10 pence piece. The effect of coupling the bottom of the bearing in this way was a gob smacking bass, without doubt the best I have ever achieved in any of my systems. It was tight fast and owe so deep, real grunt. The down side is that the mid range lost its lifelike feel, it had no bounce or rhythmic feel to it, being dull in comparison. So out it came. When I build the new plinth I will try this again, that bass is something to aim for, but I don’t want it at the expense of the mid range.I think for the cost involved in modifying the bearing it’s a no brainer, with a significant improvement to the midrange. Tracy Chapman’s voice and guitar were so life like. To improve beyond this you would have to go straight to the Mike New Bearing at ten times the price.
Update - I tried putting a 40mm dia. disk of closed cell Neoprene foam Rubber under the bearing (approx 3mm thick).
This is like wet suit material and it worked fantastic, nearly as good in the bass as the Blu Tack but without the bad stuff going on in the mid range. I have lived with this for a week now and not found any down side, looks like its staying.
Update - After a few weeks use I stripped the bearing to see what was happening wear wise. As can be seen in picture Tech_024 there was considerable damage in a short time. The end of this shaft is soft DO NOT USE THIS SHAFT WITH A STEEL THRUST PAD. I cleaned up the shaft and replaced the steel shim with a stock plastic shim and increased the oil viscosity to a straight SAE 20 grade.