Thump Once Per Revolution

Re: Thump Once Per Revolution

Postby Dorian » Thu Jan 11, 2018 1:20 pm

dizzio wrote:Hello Dorian. I’m following this thread with interest so I was wondering if you have resolved your problem.

Thanks,
Diz

By way of an update, I listened again on headphones last night and didn't experience the issue. I haven't changed anything since my original post either. It's a real mystery.

I did receive my order of Super Lube and will perform that maintenance step on the weekend.

I have no idea what caused the issue to appear and then disappear.
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Re: Thump Once Per Revolution

Postby Bloodflame666 » Sun Jan 14, 2018 12:14 am

I had the same exact issue. I lubed the platter bearing with white lithium grease and it solved everything.
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Re: Thump Once Per Revolution

Postby Dorian » Sun Jan 21, 2018 1:12 pm

Thanks 666.

So yesterday I cleaned out the old grease and applied new grease to the bearing. I also checked VTF and I was at 1.85. Recommended range on my cart is 1.9 - 2.0, so I increased it to 1.95.

Unfortunately after doing all that I still had the same issue with one of the two records. So figuring it must be the record, I got another copy of it and no more problem - great. However, what I now notice is that I get the skip/thump problem on most records, due to footfalls. :shock:

One thing I neglected to mention in my original post, and realize now I should have, is that I recently added a Symposium Segue ISO platform. The sound significantly tightened up after adding it, but it does seem to have introduced a negative too, being this increased sensitivity to warps and footfalls, which is odd because it's meant to reduce those! I don't want to remove the platform as the sound is much better with it in, but I need to do something about the footfall issue. Video of current setup with the platform is below, any suggestions? I will call Symposium tomorrow and see what they suggest.

https://vimeo.com/252048615
Last edited by Dorian on Sun Jan 21, 2018 4:38 pm, edited 1 time in total.
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Re: Thump Once Per Revolution

Postby jonathanb » Sun Jan 21, 2018 1:14 pm

Perhaps it's time for a wall-mounted shelf for the Prime?
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Re: Thump Once Per Revolution

Postby Gary1955 » Sun Jan 21, 2018 3:31 pm

Dorian, Beautiful set-up!! it looks like your Segue shelf is elevated- are you using Symposium's couplers below? I have various Symposium shelves under my components and an Ultra under my table, which sits flat on the top of the rack. Have you tried using the Seque sitting flat on your rack without the couplers? Also, is your rack/top shelf perfectly level? The other question is with your couplers below the table's cone footers- do they have multiple ball bearings below each?
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Re: Thump Once Per Revolution

Postby Dorian » Sun Jan 21, 2018 4:38 pm

Thanks Gary. The Segue shelf is just sitting directly on the cabinet on it's stock spring feet - see photos below. I don't have a "rack"; just a cabinet. The top of the cabinet is not perfectly level, no, so I adjust the Prime feet to get the platter level. Not ideal but I won't be getting a rack due to 0% WAF. What is frustrating is that I didn't have any skipping at all when I just had the Prime sitting directly on the cabinet! Weird. The footers into which the cones sit are the stock Prime footers and these do have multiple ball bearings, three to be precise.

IMG_0323.jpg
IMG_0323.jpg (236.35 KiB) Viewed 687 times


IMG_0325.jpg
IMG_0325.jpg (258.14 KiB) Viewed 687 times
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Re: Thump Once Per Revolution

Postby Gary1955 » Mon Jan 22, 2018 11:17 am

Dorian, can you remove the footers below the Segue shelf and have the shelf sit directly on the top of your cabinet?
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Re: Thump Once Per Revolution

Postby Dorian » Mon Jan 22, 2018 11:36 am

Gary1955 wrote:Dorian, can you remove the footers below the Segue shelf and have the shelf sit directly on the top of your cabinet?

I don’t think so. I’m going to call Symposium and see what they recommend. Thanks Gary.
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Re: Thump Once Per Revolution

Postby 10ovr » Mon Jan 22, 2018 11:37 am

You mite try Racquet Balls under the platform just to see if it makes any difference ,, viewtopic.php?f=7&t=9032&p=33035&hilit=racquet+balls#p33035
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Re: Thump Once Per Revolution

Postby billo » Tue Jan 23, 2018 6:44 pm

Dorian,
I'm sure you've read the Symposium page many times -
"very soft "ball type" feet represent a non-linear suspension, and the secondary suspension resonance caused by these soft rubber footers will usually interact unfavorably with the ISO's suspension system, and can cause even greater problems with footfall and feedback." Could Delrin be the culprit here? Then brass footers might help. Or could the Symposium inserts in your footers (from a previous thread) be interacting with the ISO?
Other than that the rack could be an LD instead of an MD.
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