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I have a 1960s-era Califone, one of the all-metal versions, that years ago I pulled all the amp guts out of, rewired the tonearm, installed a Stanton 500 cartridge and have used for years for 78s and transcription discs. I struggled for a while with rumble but that went away when I replaced the hardened vintage feet.
I'm having an issue with wow, which I recently started checking after my musician wife called something she heard from it "wobbly." Checking both with a phone app and also via software with a 3khz tone shows around .3% consistently.
I have two idlers, one is bigger from another player and slightly too big for the post, which I use a juice box straw to make up the difference. This I get the .3% with, and it's super quiet.
I also have the original idler, which was rebuilt last year by one of the reputable dealers that does so, and it's twice the wow and very noisy, so I don't even try to make it work any longer.
The unit has a lit strobe and it wobbles up and down as the platter turns. I realize this could be just that the sticker on the underside might be off slightly. But my local tech felt like the answer is related to that and not any issues with the idler. If I take the platter off it's flat on the table, and if I turn it upside down and set it on another turntable platter, it appears true.
So I'm a little frustrated and perplexed as to what next steps might be. Purchase and try other idlers? Try to replace the platter? Both?
And just mentioning it, but there's not big $$$ in the cards for me to get a Gates or Garrard or such that would be a "better" table, and other than the wow, I'm very happy with how this sounds, so please don't derail this with "get rid of that piece of crap" posts - it's what I have and I feel I should be able to get better performance out of it. Any suggestions are appreciated.
...can you take the platter off and put it into run mode i.e. the idler against the motor spindle? If you can then put a stationary object right against the idler edge and see if there is any 'out of roundness' with the idler wheel.
A small variation in the idler will be visible but it will be tiny. If it looks perfect then look to the platter as Triode suggested. Make sure it's clean on the contact edge and clean it with a Q-tip or something else with Iso-alcohol. If you don't have Isopropyl Alcohol use Vodka
If you can spin the platter by hand with no power and idler off with nothing contacting the platter, see if it spins freely or if it seems to get hung up somewhere during the spin. Mark the rotation with a magic marker somewhere and see if the 'Mark' you've made comes to a standstill near the same spot over and over again.
You can clean up any magic marker with Iso-Alcohol so don't worry if it's on metal.
BRILLIANT suggestion, which I hadn't thought of...holding the smooth side of a roll of scotch tape against the idler while turning there's a very obvious bump....bump...bump which isn't visible. BUT as I mentioned the idler is slightly too big for the post and I'm using a small plastic sheath to make up the difference so am wondering if this is the reason? The idler will wiggle side to slide slightly. Or, of course, it could just have a knot in the rubber, I realize.
I was going to suggest the possibility of the rubber friction surface being dried out, with the possible solution of boiling the wheel in water to regain suppleness , if that was the problem .
However, although far from qualified to give turntable repair advice, I have never heard of any loose assemblies in a turntable being advocated. It might be that cutting multiple plastic sheathes and assembling with less spindle clearance might help.
Alternatively, A better quality German table, audio quest? I forget the name, used to cast their main platter spindle in slick plastic , and then give it a good hard twist to break it free and create a zero clearance spindle support, saying that the slight drag of such an approach tended to stabilize rotation speed, since the drag was constant.
Of course, drag was not a design used in your table, , but the possibility of casting something between the two surfaces and then sanding away just enough material to spin without wobble might be explored, or possibly some barrier lubrication with substitute for the material removal, and might be more accurate. I have heard that urethane casting is used in some hobbies, but am not certain how it is obtained. postal sealing wax might cast easily , but lubrication against wear might need to become a lifestyle.
with some thought, I am sure you will get it. Every problem has a solution, just some are better than others.
Can you discern the approximate frequency of the wow? That might help to pinpoint whether it's the idler or the platter. You can calculate the rotational speed of the idler based on its diameter and the diameter of the platter surface it contacts.
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