I've just installed the motor isolation base from Michael Lim from Malaysia. More info here: http://lpturntables.blogspot.com/2010/1 ... -rega.html
This was not extremely simple, but by no means difficult either. It took me approximately 3 hours to install and dial it in (including walking to my local hardware store twice and taking a break for lunch). Since I've only had a couple of hours and a few LP sides to check out, don't consider this a definitive review but a preliminary one.
First, the unit itself is very well made, and much more substantial than the photos convey. The base weighs almost 2 lbs. which should effectively keep it from shifting accidentally and changing the pulley distance.
Next, comments on the install: Michael provides detailed photos and step-by-step descriptions for installing it on a Rega table, but not for a P5. So P5 owners should take heed, but others may also benefit.
Some tips that Michael did not provide, but that did help me:
1. Before making any changes, measure the distance from the edge of the subplatter to the motor spindle (or from the subplatter spindle to the motor spindle if you prefer). This will help you to place the motor at the right distance once you've removed the motor from the plinth. You might also measure the height of the top of the motor spindle from the plinth, but this is less important.
2. Make sure that neither the base nor the motor touch the plinth when you're ready to spin. This is not explicitly stated in the instructions, but is a no-brainer considering what the unit is supposed to achieve.
3. Dress the cables so that they don't transfer vibrations.
The installation requires you to bend down the tabs/flanges on the motor top plate in order to mount the motor onto the base, which is a slightly smaller diameter mounting than the stock. I had difficulty bending one of the flanges as well as the other one, and had to drill out the hole on the flange a wee bit wider in order to make screwing the motor to the base go smoothly and without too much rubbing against the flange. They're not difficult to bend, but they are not easy to bend just right.
You may recall that I mentioned going to the hardware store. Well, the machine screws that were provided were much too long for the job. I purchased two M3 machine screws that were 12mm long and they did the trick.
The reason that Michael has included such long screws is to allow the user to mount the motor with spacers between the base and the motor. This would allow the isolation base to sit on your shelf and the motor to reach the proper height for the pulley WITHOUT any contact with the plinth. However, when I install my double pulley at a later date, I might need to adjust this and also have 16 mm screws in case they are better suited after any height adjustments.
So my initial sonic impressions: The most obvious change was that I observed more ambient information than I recalled earlier, listening to the same LPs just prior to the mod. Overall sound was a bit more relaxed and coherent, and still very musical and retaining previous positive character. There were no negative sonic effects from the mod.
I also noted the following observations, but I feel I need further examination to verify: Leading and trailing edges seem easier to follow now. Micro and macrodynamics seem slightly improved. The noise floor also seemed to drop a touch. This last observation is difficult to say with certainty because my modified P5 had a very low noise floor to begin with.
There may be issues with practicality of this mod. The isolation base, because it is free of the plinth, will make the turntable more difficult to move. Michael has included a rubber mesh pouch that you can attach to the bottom of the plinth for this reason. However, be aware that I felt the need to cradle the base when moving the table. And upon repositioning the table, measuring the distance from the motor spindle to the edge of the subplatter to get the correct pulley distance will be necessary from now on.
One positive benefit from the mod is that it is now much easier to seat the plug from the TTPSU into the motor, as the plastic frame is no longer interfering with a good fit. Bad engineering, Rega!
Overall, I am pleased with what I am hearing so far. I will post some pictures and comments after listening some more.