An experiment, nothing more, nothing less.
In my utterly unscientific mind, the most (or only?) serous drawback of the common suspended chassis design (almost exclusively on belt drive TTs, roughly 3/4 of all TTs out there
) is the concept of relatively light floating chassis so that the springs that it resides on (or hangs from) are still relatively "soft", allowing movement in all directions.
Such suspension is much too easily and too often in the wobble state, and even when the chassis movement is completely invisible to the naked eye, it still floats - all the time. This (IMUUM) robs the sound of the spectre that is affected by the wobble, either by absorption (smaller part) or modulation/distortion (most of it).
I always wanted to anchor down a TT with a decent floating design. PL12 is it.
Few considerations leading to some mods:
- PL12 motor is a 4-pole, kicking like a mule on start, and vibrating quite noticeably during play. The fact that it hangs of 3 springs/rubber "plugs" (version dependant) doesn't help when the top plate that it hangs from is fixed! Garrard motor cage it is not. Hmmm. Motor off the plate. Motor will be attached so that it resides ON the same springs attached to the bottom of the plinth. Hanging "cage" and springs rotated. Plinth height adjusted so that the motor spindle and pulley stay at exactly the same height relative to the platter. All good.
- Original PL12 arm is quite short, so to allow a decent 9" (SME3009?) to fit on the plate and swing the counterweight under the lid, a very slightly deeper and wider plinth had to be devised. Lid will have to be either custom made or salvaged from a bigger donor.
I went for a simple CLD, without investing into the mass because it's unnecessary for this type of the drive. Bottom of the plinth (motor base) is the only full size piece (and 80% of the weight) and it's made of 32mm chipboard. Middle skeleton layer is 20mm ply. Top skeleton layer is 20mm MDF.
And here's the plinth out of the spray boot. Also a BMW Diamond Schwartz + thick clear coat job. Nice? I think so.
In my utterly unscientific mind, the most (or only?) serous drawback of the common suspended chassis design (almost exclusively on belt drive TTs, roughly 3/4 of all TTs out there
) is the concept of relatively light floating chassis so that the springs that it resides on (or hangs from) are still relatively "soft", allowing movement in all directions. Such suspension is much too easily and too often in the wobble state, and even when the chassis movement is completely invisible to the naked eye, it still floats - all the time. This (IMUUM) robs the sound of the spectre that is affected by the wobble, either by absorption (smaller part) or modulation/distortion (most of it).
I always wanted to anchor down a TT with a decent floating design. PL12 is it.
Few considerations leading to some mods:
- PL12 motor is a 4-pole, kicking like a mule on start, and vibrating quite noticeably during play. The fact that it hangs of 3 springs/rubber "plugs" (version dependant) doesn't help when the top plate that it hangs from is fixed! Garrard motor cage it is not. Hmmm. Motor off the plate. Motor will be attached so that it resides ON the same springs attached to the bottom of the plinth. Hanging "cage" and springs rotated. Plinth height adjusted so that the motor spindle and pulley stay at exactly the same height relative to the platter. All good.
- Original PL12 arm is quite short, so to allow a decent 9" (SME3009?) to fit on the plate and swing the counterweight under the lid, a very slightly deeper and wider plinth had to be devised. Lid will have to be either custom made or salvaged from a bigger donor.
I went for a simple CLD, without investing into the mass because it's unnecessary for this type of the drive. Bottom of the plinth (motor base) is the only full size piece (and 80% of the weight
) and it's made of 32mm chipboard. Middle skeleton layer is 20mm ply. Top skeleton layer is 20mm MDF.And here's the plinth out of the spray boot. Also a BMW Diamond Schwartz + thick clear coat job. Nice? I think so.
