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Can anyone help me with pitch instability on new table?

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Posted on May 23, 2015 at 06:17:17
Matthew G.
Audiophile

Posts: 413
Joined: June 9, 2000
 Hi. I've recently acquired a Well Tempered Amadeus GTA. It sounds amazing overall, but I'm hearing all kinds of pitchiness that I've not heard on any previous table (been using a Spacedeck the last few years). I've tried every set up tweak I can think of, and the speed is stable according to a strobe disk. Can anyone think of any causes other than maybe this table is less kind to warped records than the Nott (and before that VPI)? Thanks.

 

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RE: Can anyone help me with pitch instability on new table?, posted on May 23, 2015 at 07:45:00
Mick Wolfe
Audiophile

Posts: 3365
Location: AZ
Joined: October 10, 1999
Contributor
  Since: September 4, 2000
 Post this issue over at the Well Tempered Forum/ Audiocircle. That said, I would try a new belt (thread) and see if that helps.

 

RE: Can anyone help me with pitch instability on new table?, posted on May 23, 2015 at 08:33:06
PAR
 What you are referring to is usually a result of off centre pressings although warps can have a similar subjective effect. Certain designs exaggerate the problem and that seems to be your trouble here. For example, suspended belt drive tuntables have an inherent disadvantage in this respect as an off centre pressing causes the arm to swing in and out. At the same time the suspended subchassis, being free to move (effectively rotate),does so and the distance between the motor (which is fixed)and spindle is slighly changed causing exaggerated pitch variation. Some manufacturers such as SME alleviate the problem by use of a dash pot to damp chassis movement.

I wonder if the suspended arm bearing of the Well Tempered arm is slightly displaced by an off centre pressing giving a similar effect. Just a thought but your old Spacedack has nothing that can be moved in this respect and the in and out arm movement is all that is the result of the off centre pressing. A pitch variation ensues but it is not exaggerated by other factors.

 

RE: Can anyone help me with pitch instability on new table?, posted on May 23, 2015 at 08:58:47
Mel
Audiophile

Posts: 2993
Location: New York City Area
Joined: February 21, 2001
 The strobe disk will not tell you whether the velocity of the turning is stable, except as an average over a time span.

When something like this happened to me, I found that the bearing needed a good lubrication. Problem was solved!

 

that is funny, posted on May 24, 2015 at 19:41:38
Penguin
Audiophile

Posts: 7116
Location: Delaware
Joined: August 5, 2001
 since the Well tempered spins in a cup of oil, there is not much you can do about lubrication. couple things.

Take of the belt (ok thread with the knot), put a piece of scotch tape on the platter, spin it a few times by hand starting from different spots giving it various initial spins and make sure that the platter stops at random spots. If it tends to stop at the same spot, you either have a bad grind on the spindle or bent spindle or something. The well tempered bearing uses two teflon V blocks and an offset thrust made of teflon. having the well filled above the upper v block with either silicon oil or Mobil 1 is important.

If that is all passed then get a record with a 3.15K track and use platterspeed. You should be within specs of the table, I do believe it is less than 0.02% wow and flutter. If you are not within spec then you either have a bad drive thread...make a new one, a bad motor controller or a bad motor.

good luck


dee
;-D

True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut

 

the well tempered is a rigid table, posted on May 24, 2015 at 19:43:28
Penguin
Audiophile

Posts: 7116
Location: Delaware
Joined: August 5, 2001
 No suspension of any sort.

:)

dee
;-D

True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut

 

RE: the well tempered is a rigid table, posted on May 25, 2015 at 01:14:47
PAR
 Although the turnable itself is not supended I referred tp the Well Tempered Arm bearing which is suspended. If tracking an off centre record causes the central point of the arm bearing to swing slightly from the fishing line suspension then this will change the distance from the spindle to arm bearing and thus emphasise the pitch variation. It was just a thought and maybe the design can deal with this, but looking at it then it seems that such a moveent is feasible.

 

You would have the same issue with any of the stick on string arms, posted on May 25, 2015 at 08:56:34
Penguin
Audiophile

Posts: 7116
Location: Delaware
Joined: August 5, 2001
 but that is hardly an issue. All those arms establish a virtual pivot point and they only move side ways just like a gimbal arm would. The vertical motion of the well tempered arm is more interesting. It will move slightly forward when a warp is encountered and increase stylus pressure. But the displacement is so small that it is inaudible. Trust me i lived with what some people call an ill tempered turntable since 1985. Not a bad table, but takes loads of patience to set one up right.


dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut

 

RE: that is funny, posted on May 25, 2015 at 11:11:33
Matthew G.
Audiophile

Posts: 413
Joined: June 9, 2000
 Thanks for the suggestions. The platter passes the tape test. I'm waiting on some thread to make a new belt. If that doesn't fix it, I'll send it in to get a new motor.

 

Dick's sporting goods, posted on May 25, 2015 at 12:03:32
Penguin
Audiophile

Posts: 7116
Location: Delaware
Joined: August 5, 2001
 I think it is a simple under 10 lb test finishing line. 10 bucks will get you set for ever and beyond. If in a rush pull a strand from a dental floss and tie it in a belt. typical 10 lb test line is about 0.007" or smaller diameter.

dee
;-D
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut

 

RE: Can anyone help me with pitch instability on new table?, posted on May 25, 2015 at 17:56:13
flood2
Audiophile

Posts: 2558
Joined: January 11, 2011



Do you have a test record from which you can record the test tone from? Unfortunately it is very hard to isolate the effects of off-centering and a poor accuracy test signal. The Analogue Productions "Ultimate Test LP" has a 3150Hz tone for checking W/F.
You can determine from the FFT what the centre frequency shift is and the side bands will tell you what other frequency components are contributing to the pitch instability.

The other possibility is an arm/cartridge mismatch? If the mass is too high then the suspension excitation will modulate higher frequency tones. Even with a reasonable match, you will see this frequency component showing up on the "shoulders" of the centre frequency.

Regards Anthony

"Beauty is Truth, Truth Beauty.." Keats

 

RE: Can anyone help me with pitch instability on new table?, posted on May 26, 2015 at 17:45:54
Matthew G.
Audiophile

Posts: 413
Joined: June 9, 2000
 Thanks for your response. Unfortunately, I don't have a test record with a test tone, and the Ultimate Test LP is rather pricey, and even if it identifies the problem won't help me fix it. In any event, my ears tell me that something is amiss in terms of pitch stability. I'm hoping a new belt will fix it. I don't suspect any cart-arm issues, but I'll try a different cart just to see. Worst case scenario, I'll get a new motor.

 

Time for crate digging, posted on May 28, 2015 at 06:44:21
Penguin
Audiophile

Posts: 7116
Location: Delaware
Joined: August 5, 2001
 just find a test record with a 1Khz tone. It will work just much less accurate.

dee
;-D.
True terror is to wake up one morning and discover that your high school class is running the country.

quote by Kurt Vonnegut

 

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