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AR the Turntable platter wobble

davelarz

davelarz

Well-Known Member
Just bought an AR the Turntable. I'm new to suspension tables so learning as I try to dial it in, which has been a little complicated by the fact that my sx-850 is acting up on me so for the moment I'm using a low-end 90's onkyo with issues playing into my back-up speakers (Advent 3's). So I've pretty much given up diagnosing and tinkering and referencing against my Technics p-mount until I get my 850 back.

BUT... I'm noticing some platter wobble that at times seems to be producing an audible murmur with slightly warped records that I don't hear on my old Technics p-mount table. I don't know what is normal with these tables so I was hoping someone could take a looksee. A link to a YT video is below - can anyone tell me if this looks like an acceptable amount of wobble. If not, where do I start to troubleshoot? Thanks

 
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looks extreme. does your armboard move up and down also? flip the outer platter over on the inner platter and run again and look to see if the inner platter is what is causing the heave. Usual cause of warp in outer platters on AR is due to heat build up when buffing them on a wheel.
 
Okay - at work now. You're saying remove outer platter, flip it and put it back on? I will try it - how does that show whether it's inner or outer? I did look at just the inner platter spinning and it looked much more stable to me but I don't know if that matters when it's not bearing the weight of the outer platter.
 
davelarz said:
Okay - at work now. You're saying remove outer platter, flip it and put it back on? I will try it - how does that show whether it's inner or outer? I did look at just the inner platter spinning and it looked much more stable to me but I don't know if that matters when it's not bearing the weight of the outer platter.
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that will allow you to view the running of the inner platter, and the outer platter at the same time. running it without the outer platter on it can skew the results some, as the subchassis won't be level.
 
Got it. I'll do it tonight and report back.

Provided that it is the outer platter, what's the fix? New platter?
 
Certainly looks like the outer platter from the way it moves. Was it an ebay purchase?
I have gotten the occasional refund from ebayers who mis-represented the merchandise.
 
No - AK'er. Who is being very cool about the issues I've been having with it btw. It's had some undue static/distortion in the right channel that I haven't felt like I could completely assess due to my amp problems and running it through a back-up amp that I know has issues. That right channel issue is only with certain records, but with those records I do not hear the same noise on my Technics. I've done a lot to troubleshoot this and had pretty much decided to leave it until I got my 850 back and could reference the AR against my Technics in two similar phono stages on an amp that has recently been serviced. But today I was noticing the wobble issue and really started to wonder if that wasn't the cause of the problem, because I was listening to a record that was murmuring in time with the wobble.
 
I have had a few Dual and Thorens come through here that had warped platters. The platters were thick enough for a machine shop [here in Brooklyn] to true. But your platter is undoubtedly thinner and would not stand-up to machining.
 
So I inverted the outer platter - video below. Looked very much to me like the outer and not the inner platter is the source of the wobble. Also looked closely at the armboard and there is definitely movement there. I tried to take a video but it didn't really show on camera. It is a very mild quiver with every rotation.

Any advice as to where I go from here is definitely welcome. Seller strongly recommended to me when he sold it to me that I upgrade the springs, but something tells me that won't address this issue. Thanks - Dave

 
davelarz said:
So I inverted the outer platter - video below. Looked very much to me like the outer and not the inner platter is the source of the wobble. Also looked closely at the armboard and there is definitely movement there. I tried to take a video but it didn't really show on camera. It is a very mild quiver with every rotation.

Any advice as to where I go from here is definitely welcome. Seller strongly recommended to me when he sold it to me that I upgrade the springs, but something tells me that won't address this issue. Thanks - Dave

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it's possible the warp in the outer platter is enough mass movement that's causing the armboard quiver. Looks like a new platter time. unless you would have access to 2 heavy 12" X 12" flat steel plates. If so, you could sandwich it between them, bake in the oven 275-300 for 6 hours, and then let cool off in the oven while still pressed.
 
You were sold a broken turntable, with little or no recourse. Advice? How you handle this will depend on the type of person you are. Seller recommended new springs when you purchased it, so he was well aware of the defect. You say that seller is a member. Shame on him.
 
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Where are you in Brooklyn, No Trans - I just moved from Brooklyn to Westchester but I work in Manhattan every day. I'm wondering if I could bring you my outer platter someday and you could check it out, maybe see what you could do along the lines of Marc's rec - "unless you would have access to 2 heavy 12" X 12" flat steel plates. If so, you could sandwich it between them, bake in the oven 275-300 for 6 hours, and then let cool off in the oven while still pressed." Let me know, obviously I'd be happy to pay you for the work. Just weighing my options here - stock replacement platters are not easy to come by and the retrofit acrylic jammies are like 300. And yes, I'm going to take this up with the seller and honestly I don't think he's crooked in the least. I feel confident that if where I end up is that I want a refund he will give it to me. Just... I want the tt basically. Love the aesthetics, love the idea of modding it up over time - came with a V15 VMR cart and NOS stylus. There's a lot to like. We'll see...
 
I live in Bergen Beach. But honestly, the only baking I do is banana bread. The great machine shop that I used to use is now closed, as Hugo, the coloful and creative owner, is in his 9th decade. A platter such as yours cannot be cut on a lathe, as its shape [like a donut] will not lend itself to getting fastened to the lathe.
 
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