Overview:
Long, intense project. It took a total driveline redesign to get it to play right. This project is not something for the "beginner" DIY'er (and would be ridiculous to pay to have done). A dead end if you aren't able to handle lots of different aspects of fabrication, *turntable idler drive geometry, metal working, sheet metal, wood working and, ultimately masonry..
It was just incredibly long and arduous task to get to completion.
It fought me at every stage.
*even in perfect new condition, this decks OE design is troublesome, due to the phasing out of 78's and phasing in of 33/45 - making 78rpm the redheaded bastard stepchild.
now to the original post:
Wow,......
What a long strange trip this project turned into.
To say it was a bitch getting it to finish is laughable at best.
This thing is a bitch of a mistress, truly a dominatrix. She fought me at every possible angle. I think I finally got er tamed though!?!
burpin it up
OK,...
Just today (this past saturday), finished a massive project, far more intensive than I could have considered when I started it.
I've long been fascinated with old american radio broadcast record payers, turntables.
I finally decided to look into them, and fell for a particularly old piece by a legend in audio-deco era radio broadcast equipment manufacturing, Presto Recording Corporation.
They made early radio broadcast and recording gear, recording lathe turntables.
I won an auction for a Presto T-18 Pirouette tt, just about a year ago now.
I thought, no problem, clean and lube the motor, get the idler wheels overhauled, relube the bearing - I'd be styling.
WRONG!
As it turns out, the motor bearing bushings were worn out, and it would act nicely for about 15 minutes, then it would start to wailing, and the wailing grew in intensity to a point of hearing it all over the house. You could not go anywhere in the house and not hear it.
So it would get put away, then I'd forget my frustrations, and I'd stubbornly reopen the motor, which has been lovingly renamed the Borg Death Cube, and I'd try everything all over again. My best results bought me 20 minutes before the vibrations started again.
So, I decided to research contemporary DC motors, and learned of motors that had internal speed sensors, and computer drivers, high-tech modern precision DC motors.
So, I thought;
I'll just replace the old motor!!So I did.
I replaced it with a new motor, within its OE drive-line geometry, which quickly revealed its self-noise (this deck came about at the end of 78's and the start of 33/45, and the tech was not so high fidelity yet - still monaural). The self-noise came from the idler wheels, which were three fat dragster tire footprint paches.
So, the nasty vibration is gone, now i just here fat rubber wearing itself away (and these were newly retread tires). It was still too noisy - and I'd already wrapped up too much time :: rolls eyes:: Yeah, right,..... watch me ramp up spending too much time to the thousands.
So, already having far too much time into this project, I decide to abandon rational thought, and redesign the entire drive-line, referring to a few muddled, addled thoughts, buried deeply in the gray matter.
If I can only fit a Lenco tire, from Switzerland, under my old American table from Paramus NJ, this might just work!
So, I started looking around under the hood, and found a few square inches of unused space, and went for it.
A Lenco wheel is a thin light tire with a knife edge. The footprint patch contact is miniscule compared to the 1/4" wide contact of the OE tires, thats got to create less friction noise, right?
To prove it, I had to build it.
The design, and fitting process has been intense, and has eaten up 100% of my freetime over the past 6 months. Sleepless nights caught up in mental geometry, concept, and execution.
Well, today for the first time, I heard it play music, and this thing has serious mojo.
As an idler drive it has torque like a diesel, and cuts through the thickest most intense movements like they weren't even there - stylus drag is a joke through these passages; a heavy platter and idler drive cut through it like a hot knife through warm butter.
The background is silent, because the motor is suspended and isolated from the plinth by rubber grommet turntable motor mounts, my own custom spring suspension and, constrained layer vibration damping isolation motor pod. The CLD motor pod is isolated from the soapstone plinth, entirely, except at four rubber well nut attachment points that hang the CLD under the plinth, but not hard fastened to it.
The mass of the stone takes care of any other vibration issues. The background noise is black silent.
At any rate,.... one of my longest projects to date. It seemed so simple in my head! ::rolls eyes::
ain't she purty?
12" Jelco tonearm (typical arms are 9"), and a Denon Dl103 broadcast cartridge (can be super hot-rodded).
up the skirt shot - the finished rear access panel, rear of arm pod:
She weighs no less than a hundred pounds, maybe a hundred and low teens wouldn't surprise me.
the listening spot view (well, maybe from a bit lower than the spot):
bearing capture device:
The ring is pulling the bearing housing and top plate downward, creating stability of the top plate and bearing housing. The cross-member is to stabilize, recapture, the thrust plate energy, and return it to the plinth-stone, after a gasket has been applied to stop the friggin oil leak.
motor cld:
all the wires are shielded, the motor frame is shielded. There is a 1/4" sub-top plate shield, and the platter itself is shielded.
Topic: Finished: Presto Recording Corp. - Pirouette T-18 Turntable Project (Read 13755 times)