A Copernican View of the Turntable System

At low volume levels its not that hard to get a 'table to sound good. Its at high volumes where the rubber hits the road. IMO, the turntable should be unassailable at any volume. I found that once I had sufficient mass and rigidity in the plinth, that that helped, but I also have the 'table perched on an Ultra Resolution Technologies platform, which is one of the best passive platforms I have seen, unfortunately no longer available (and stupidly expensive when they were!).

The platform is in turn set up on a Sound Anchors stand that is custom-built to accommodate the platform. In turn the stand is mounted on 3 Aurios-Pro bearings.

My point is that it is hard to really know what is the plinth in all this. The only decoupling that occurs is the platform itself and then between the platform and the stand, that is my 'suspension' so to speak. The platform is quite heavy, rigid and inert as it is a sandwich of a special grade of marble, high tensile steel and a military-grade constrained damping layer.

Vibration and resonance can be quite insidious in a turntable, so with respect to the anti-vibration platform, the platter and now (in the case of this thread) the arm tower, it is likely that it would be really difficult to go overboard on the whole thing.

Points in use under the platter and arm tower, while being mechanical diodes so to speak, are not actually perfect diodes. Like elastomerics, they are more efficient if they are loaded properly! So if the load on them is underpar, they simply will not work so well. Load up that arm tower! Get some mass on it, so the points can do their job.

Dgob, Decouple all that you want. My point was or would have been that it is perhaps not wise to use very different mounting systems for the tt and arm pod, e.g., spikes on one and AT feet on the other. In that situation, the two separate devices are almost sure to have a different response to external sources of vibration, and, in keeping with my private belief system, we do not want the arm/cartridge and the groove on the LP to be moving in different directions, whilst the stylus tries to do its work. Surely you can see that this might not be a good idea. This reminds me of the old SNL commercial spoof, where the rabbi tries to perform a circumcision in a car driving over a rough road.

Chris/Halcro,

Thanks for your suggestions and I will look into having a heavy arm column produced that may work better with the spiked option. The weight limitations with the Mambo column could be where the problems lie and it'll be fun (and, hopefully, rewarding) to try this out. I'll let you know as soon as I can sort this out.

On the issue about both the TT and arm tower being on spikes I think Chris has hit the nail on the head. If you are seeking complete isolation, the different methods are secondary. The question resides in how effective both methods are at controlling resonance and vibration.

Henry, if you get a chance to try out the AT616 footers you might be surprised - I was. This also offers you the potential to truly decouple arm-column and TT, which was where I came in, as it were. Lewm, I hope that answers your scenario.

Atmasphere,

Thanks again. I'm going to load up the arm tower as soon as I find a local engineer able to undertake this for me.

On frequency extention, I'd hasten to add that I am playing this set up at very high volumes and the quality needs to be heard to be appreciated. So as I said, I think for everything to click into place I will follow your, Chris and Henry's suggestion of building a heavy arm tower. The gains I already have with the current approach to decouplling makes this a more than worthwhile endeavour.

Grateful for all your kind suggestions and contributions.

The arm pod I'm having made is roughly the diameter of the AT 616. When I get my TT back, 3 616's will go beneath the TT and 1 beneath the pod. Hopefully it works out. Before, I had the TT and arm board sitting on different isolation systems: TT on 3 AT-605 footers and arm on Herbie's tenderfoots. Sounded good to me--but maybe I'm hard of hearing.

Incidentally, while my TT is in the shop, I've been borrowing a Sony 2251. It sounded woeful at first. I almost gave up and on a lark put the tenderfoots beneath it. Much, much better. Pretty good table overall, in my amateur opinion.

@Chris: how did you put spikes beneath your sp10? I'm assuming there's a board in between? That is, the TT sits on the board and the board is on spikes? Or did you thread spikes directly beneath the chassis?