Pitch Wobble Mystery Challenge!

This is where record cutters raise questions about cutting, and trade wisdom and experiment results. We love Scully, Neumann, Presto, & Rek-O-Kut lathes and Wilcox-Gay Recordios (among others). We are excited by the various modern pro and semi-pro systems, too, in production and development. We use strange, extinct disc-based dictation machines. And other stuff, too.

Moderators: piaptk, tragwag, Steve E., Aussie0zborn

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literal_screw
Posts: 11
Joined: Tue Jan 08, 2019 6:17 pm

Pitch Wobble Mystery Challenge!

Post: # 52273Unread post literal_screw
Thu Jan 31, 2019 8:14 pm

Hello fellow Trolls, :o

I’m having some issues with pitch wobble that I haven’t been able to resolve and was hoping I could pick your brains and bring your considerable talents to bear.

I’m going through the last 8-10 black units of my most recent shipment of blanks from the fine folks at MyShank, and can’t seem to cut the first side (the less perfect side) without pitch wobble. While lower frequencies, such as male baritone vocals seem to be fine, higher frequencies are affected (acoustic guitars, harmonicas, pianos, as well as ambient sounds.)

I assumed it was simply a warped blank issue because when I did test cuts, which I mostly do on the side of MyShank’s blanks that are mostly always flat, because, well, they’re mostly always flat, what I heard sounded great.

The reason I’m no longer sure the blanks are to blame is because I have some clear units too (also from MyShank) that looked completely flat, but when I started to cut one just now, I experienced a very similar pitch wobble.

Could it be the precision plate needs calibrating, and if so, how exactly would I go about correcting that? Though if it’s the precision plate, why are my test cuts coming out

Could it be that this issue stems from the inner motor assembly not spinning evenly due to a lack of lubrication, and if so what type of oil would I use for this? But again, if its a lubrication issue, why do my tests come out great?

Needless to say I’m a little stuck here as to what my issue or issues are here, much less how to solve them so any help in the short term would be greatly appreciated.

I look forward to hearing your insights and drawing upon your wisdom. Thank you!

Setup Specs:

- VR T560
- SL-1200 MKII
- “New” Resharpened MyShank diamond
- 2mm MyShank blanks
- Stylus weight, 15g-17g
- Counterweight 40g-50g
- Precision plate from Souri

Thanks again!

:wink:

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tragwag
Posts: 1277
Joined: Wed Jun 22, 2011 2:30 pm
Location: Providence, RI USA
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Re: Pitch Wobble Mystery Challenge!

Post: # 52285Unread post tragwag
Fri Feb 01, 2019 2:08 pm

I would try cutting another track, or try test tones and see what you get.
You can check if they're actually frequency dependent or if the track is coloring your theory of the high vs low

Also a good idea to recalibrate all your weights, the counter weight and headweight.
I dont know how the precision plate works, but definitely recalibrate that too.

Whenever I used a 1200 I had slight pitch wobble especially on 12" at the outer edge.
Switched to SP10 and SP15, and never had a whiff of it.

best of luck
making lathe cuts on a Presto 6N, HIFI stereo cuts on vinylrecorder
at Audio Geography Studios, Providence, RI USA
http://www.audiogeography.com

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