PT mini-anni instructions

[ProfTournesol]

The plinth needs to act as an energy sink for the sub-chassis via the springs, and also for the vibrations coming up through the floor etc.

[natty_dredd]

I fancy just a large monolith of raw, fine concrete myself.. Smooth surfaces with smooth, rounded corners at the top.

Maybe it could be made in sections with some slots for lifting handles in each section.

Make the plinth out of the same concrete too inside the wooden part, so effectively the plinth is the whole massive concrete thing with some wood stuck around the top to make it look like a separate turntable..

[tim_bissell]

The demise of Apple's 'mobile me' service means I have had to move the PT mini-anni instructions; they are now at:

http://www.lotsov.webspace.virginmedia.com/pt-mini-anni/pages/1.html

Nothing new yet; I should document building my new external speed controller, I suppose...

-- Tim

[thezenroom]

well if you gonna get technical about it then this guy is your man..... after much reading around his site, i decided a 'Permali' (resin impregnated ply) was the dogs (about 20-25 mm thickness being optimal for plinth building- i'm gonna mount a SP10 motor, just the motor, in such a plinth {the sp10 and Pinks are surprisingly similar in sonics i think- well i love them both} ).

http://qualia.webs.com/plinths.htm

http://qualia.webs.com/plinthbuilding.htm

http://qualia.webs.com/newdampingfactors.htm

anyway i hope the Prof and Tim enjoy a good read. and Natty you'll find this guy is not a fan of mass loading......

[ProfTournesol]

Given that the Olympics are such depressing viewing for us at the moment by thoughts have turned back to the turntable. I'm going to source a piece of Foamex and bond it to the bottom of the sub-chassis. The thinking behind this is that any record/tonearm induced vibration that passes past the Achromat is trapped in the sub-chassis. That energy has nowhere to drain, therefore by adding a layer of foamex I'm hoping to absorb some more of it. Any suggestions on a bonding agent?

[tim_bissell]

Given that the Olympics are such depressing viewing for us at the moment by thoughts have turned back to the turntable. I'm going to source a piece of Foamex and bond it to the bottom of the sub-chassis. The thinking behind this is that any record/tonearm induced vibration that passes past the Achromat is trapped in the sub-chassis. That energy has nowhere to drain, therefore by adding a layer of foamex I'm hoping to absorb some more of it. Any suggestions on a bonding agent?

Yup, the world's gone topsy-turvy! I would be inclined to use a nice rubbery energy-absorbing glue such as Evo-stik (impact adhesive; coat both surfaces, let dry, press together) - or cover the the underside of the subchassis with thin double-sided carpet tape - this is similar to the discs of double-sided tape the Funk Firm provide to stick achromats to the platter.

-- Tim

[natty_dredd]

Given that the Olympics are such depressing viewing for us at the moment by thoughts have turned back to the turntable. I'm going to source a piece of Foamex and bond it to the bottom of the sub-chassis. The thinking behind this is that any record/tonearm induced vibration that passes past the Achromat is trapped in the sub-chassis. That energy has nowhere to drain, therefore by adding a layer of foamex I'm hoping to absorb some more of it. Any suggestions on a bonding agent?

Is the underside the best place for this or the edges? Will adding it to the bottom just change the resonant frequency and harmonics, lower them?

Pink Triangle originally had a foam strip around the edge of the subchassis. Those were the very first PT1s anyway with the seperate armboard top plate (maybe champagne mirrored glass) and sliding, square switch.

You have a vectored something don't you rather than Anni? I guess the Anni used balsa to dampen so perhaps underside is effective.

[ProfTournesol]

The idea is to do for the sub-chassis what the Achromat does for the platter. Expensive modeling would give me the optimal amount and location but I can't do any of that stuff even if I was that anal! The idea is to dissipate energy in the sub-chassis that otherwise can't escape.