skipping problem with Pioneer PL-12D turntable
Nov 17, 2008 at 9:51 PM Post #16 of 26

fzman

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if the problem is an arm-cart mismatch, which it seems to be, then the resonant frequency of the combo is probably right in the range of footfalls and tappings, etc, so the table is effectively an amplifier of those events-- making it extra sensitive to such things. -- have you tried to use a test record to see where the resonance is?
 
Nov 17, 2008 at 10:34 PM Post #17 of 26

steelglam

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Quote:

Originally Posted by fzman /img/forum/go_quote.gif
if the problem is an arm-cart mismatch, which it seems to be, then the resonant frequency of the combo is probably right in the range of footfalls and tappings, etc, so the table is effectively an amplifier of those events-- making it extra sensitive to such things. -- have you tried to use a test record to see where the resonance is?


I have not. How would I go about doing this?
 
Nov 18, 2008 at 11:20 AM Post #18 of 26

memepool

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Quote:

Originally Posted by fzman /img/forum/go_quote.gif
if the problem is an arm-cart mismatch, which it seems to be, then the resonant frequency of the combo is probably right in the range of footfalls and tappings, etc, so the table is effectively an amplifier of those events-- making it extra sensitive to such things. -- have you tried to use a test record to see where the resonance is?


A good suspended subchassis should have much better shock resistance than a constrained layer plinth like the Technics. I can gently tap on the edge of my Thorens while it's playing with no audible effects.

It is a budget deck but it's pretty well made so there is no reason why the suspended subchassis shouldn't work as well as this but they do require more careful set-up and tweaking than a non-suspended design.

So you should maybe also look at the springs on the Pioneer because these should be adjustable. Essentially when you push down on the spindle you want the top plate to bounce evenly up and down and not wobble from side to side.
Getting it to do this and be level at the same time is the trick. Lighter and heavier springs and the amount of damping applied (usually in the form of a bit of foam shoved into the springs) will change the Q (resonance frequency of the supsension) which obviously can interfere with the stylus too.

So you can maybe experiment quite cheaply with changing the springs for heavier or lighter gauge springs which you should find in a large hardware store as they can sag with age.

The fact that your stylus CAN jump perfectly in and out of the same groove though, suggests to me that the suspension must be well levelled and the arm bias set correctly as this is actually quite a feat.

So I reckon it's all quite finely balanced and the arm is simply of too high a mass to work with the springy suspension on the cart which is being exited unduly by the suspension on the deck when it absorbs a knock and bouncing. A less springy cantilever tracking heavier should be under better control.
 
Nov 18, 2008 at 11:30 PM Post #19 of 26

NightOwl

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Altough this is my first post, audio has been a hobby of mine throughout my life and I am old enough to have set up and used many turntables, tonearms and cartridges. Hopefully I can add a bit and help.
Everything memepool has posted is good advice. It is very possible that the springs are too loose or too tight lowering or raising the resonance frequency transmitting vibrations to the arm. The only thing I can add is that you might want to check that the tonearm cable is properly dressed. Not acting as an active part of the suspension (pressing on the bottom of the plinth or not providing free travel and pushing the tonearm).
ADC cartridges are among the most compliant and low mass cartridges ever made and will never work in either your Pioneer or Technics (because of their tonearms) no matter how light a headshell you use.
The Pioneer is a good turntable for what it is, but it was a budget turntable and I would not spend a lot of money on it but, if you wish, would save the funds for a better turntable down the road. I am not a fan of direct drive non-suspended turntables, but the Technics was one of the better-executed models and I doubt that the Pioneer would be much better. The fact that your tonearm jumps straight up and down bodes well for the arm's bearings, but check these anyway before spending money.
The 440ml is a very good cartridge, although you may find it a little bright depending on your electronics. It also may not be the perfect match for either of your tonearms. Funds permitting, you may want to look at a Shure m97xe cartridge down the road, since the stabilizer brush will help offset arm/cartridge mismatches and the efffects of vibrations.
One other thing you may want to try is to put the turntable on a shelf mounted directly to the wall and not on a stand, helping to isolate it from vibration.
You're probably smart enough to have stopped, but please DO NOT continue to track at 3.5 grams. With any stylus profile other than spherical you will be carving new grooves in your vinyl and permanently damaging your cantilever/cartridge suspension. No cartridge should be used at higher than +10% of its recommended range.
 
Nov 18, 2008 at 11:57 PM Post #20 of 26

steelglam

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Quote:

Originally Posted by memepool /img/forum/go_quote.gif
A good suspended subchassis should have much better shock resistance than a constrained layer plinth like the Technics. I can gently tap on the edge of my Thorens while it's playing with no audible effects.

It is a budget deck but it's pretty well made so there is no reason why the suspended subchassis shouldn't work as well as this but they do require more careful set-up and tweaking than a non-suspended design.

So you should maybe also look at the springs on the Pioneer because these should be adjustable. Essentially when you push down on the spindle you want the top plate to bounce evenly up and down and not wobble from side to side.
Getting it to do this and be level at the same time is the trick. Lighter and heavier springs and the amount of damping applied (usually in the form of a bit of foam shoved into the springs) will change the Q (resonance frequency of the supsension) which obviously can interfere with the stylus too.

So you can maybe experiment quite cheaply with changing the springs for heavier or lighter gauge springs which you should find in a large hardware store as they can sag with age.

The fact that your stylus CAN jump perfectly in and out of the same groove though, suggests to me that the suspension must be well levelled and the arm bias set correctly as this is actually quite a feat.

So I reckon it's all quite finely balanced and the arm is simply of too high a mass to work with the springy suspension on the cart which is being exited unduly by the suspension on the deck when it absorbs a knock and bouncing. A less springy cantilever tracking heavier should be under better control.



So, I got the 440 in the mail today and hooked it up. Man, does it sound sweet! Anyhow, the problem still exists with the 440 attached, but it's not as severe, especially when I track it toward the upper end of the recommended range. Given space restrictions, I don't really have the capability to mount the turntable from the wall, but I think I'll try something that Stanley B1 suggested: I'll go to Home Depot and buy a slab of concrete (cost is like $2.00 or something) and put it under the turntable. I'm assuming the thickness of the concrete should absorb a good deal of the vibration. My apartment is in an old house and therefore does suck in terms of susceptibility to vibration, so I know that doesn't help.
 
Nov 19, 2008 at 11:05 AM Post #21 of 26

memepool

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If the Technics plays without jumping and you put the Pioneer in the same place then the Pioneer should be more than capable of this. Did you check the suspension?
I think there are some red headed screws if you lift off the platter that release the suspension. Pioneer don't seem to say much in the manual about this but I would guess there are three or 4 coiled springs which should have some form of user adjustable cups. Usually these are accessed by removing the bottom of the plinth. Some good general info on this here TURNTABLE Set-Up

It's perfectly ok to track the AT440MLA at full recommended downforce or even a little over, in fact it's safer to do so than have it bouncing around the grooves. It's pretty hard to measure these things very accurately without a very good gauge anyway and the Shure / Ortofon ones allow for 10% error. The most important thing is to get the alignment spot on as the stylus tip is a Microline which can needs to be perfectly aligned otherwise it will cause damage. Vinylengine have free protractors which you can download and print out.

Stanley's concrete idea is also a good one. This is basically adding mass to absorb vibration. You can also mimic the constained layer design of the Technics by using several heavy chopping boards ( preferably granite or marble) which places like Ikea sell cheaply enough, and stack these with an absorbant layer between. The best thing is Foculpods which are sorbothane but computer shops sell these kinds of things much cheaper than audio shops. Quiet PC Hardware have little feet made of this stuff. Cheapest of all is to cut a few tenis balls in half and put these in between.

Spiked feet is the other popular method. You can buy these from audio shops and attach them to the bottom of the shelving unit the deck sits on quite discreetly. Also check the orientation of the floorboards and try to position the shelves so that they are perpendicular to lessen the issue.
 
Nov 21, 2008 at 4:10 AM Post #22 of 26

steelglam

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So, I got it to stop skipping! Just wanted to say thanks to everyone for their replies, as it was the combo of a bunch of things that made it work. The low compliance cartridge + the lighter headshell + the concrete blocks to absorb the sound + the stretching out of the springs that act as the suspension. I actually added one more thing to the mix that also seemed to help a lot: I stuffed two cotton balls in the middle of each spring, which acted as a damping effect on the "jumpiness" of the plinth. I just put on a record, jumped in the air, landed hard on the floor, and no skip!! Thanks again!

I also ordered a new belt. I also should pick up some turntable oil to oil the shaft. Anyone have any recommendations?
 
Nov 21, 2008 at 12:39 PM Post #23 of 26

memepool

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Quote:

Originally Posted by steelglam /img/forum/go_quote.gif
I stuffed two cotton balls in the middle of each spring, which acted as a damping effect on the "jumpiness" of the plinth.


cool. The springs should usually have foam in the middle to damp them and prevent ringing, maybe this was perished with age? Like I said finding some similarly dimensioned heavier grade industrial springs would also do the trick, in effect a Linn Cirkus upgrade !

Quote:

Originally Posted by steelglam /img/forum/go_quote.gif
I also ordered a new belt. I also should pick up some turntable oil to oil the shaft. Anyone have any recommendations?


Either a light machine oil like you'd use on something like a sewing machine or else a lot of people recommend synthetic engine oil like Redline or Mobil One. You only need a few ml though. Also get gold of some lint free paper towels and some of those extra long q-tip type cotton buds for cleaning tape heads to get the old oil off the bearing and the sides of the well / sump.
 
Nov 21, 2008 at 5:02 PM Post #24 of 26

steelglam

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Quote:

Originally Posted by memepool /img/forum/go_quote.gif
cool. The springs should usually have foam in the middle to damp them and prevent ringing, maybe this was perished with age? Like I said finding some similarly dimensioned heavier grade industrial springs would also do the trick, in effect a Linn Cirkus upgrade !


Yeah, the foam was in crumbles! It was a sad sight!

I went to Home Depot and Lowes because I was thinking about just replacing the springs, and neither had similar springs nor did they have any idea where I could get them. I called both Pioneer and a couple of electronics dealers in the area, and they don't have any replacement springs, nor did they have any idea where to get them. Do you have any suggestions as to where I could find the type of springs you describe?

Quote:

Originally Posted by memepool /img/forum/go_quote.gif
Either a light machine oil like you'd use on something like a sewing machine or else a lot of people recommend synthetic engine oil like Redline or Mobil One. You only need a few ml though. Also get gold of some lint free paper towels and some of those extra long q-tip type cotton buds for cleaning tape heads to get the old oil off the bearing and the sides of the well / sump.


Sounds good. Thanks!
 
Nov 21, 2008 at 5:55 PM Post #25 of 26

memepool

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Quote:

Originally Posted by steelglam /img/forum/go_quote.gif
Do you have any suggestions as to where I could find the type of springs you describe?


I went on similar quests and found a really old fashioned hardware store in Victoria in London (England) which had every kind of spring and washer you could imagine in thousands of little boxes.... But you do tend to find that kind of thing in London. Shops that only sell screwdrivers, or springs or buttons and have every kind imaginable.
I would have thought any older big city would have these kind of shops but they are usually not on the web unfortunately.
If you don't live anywhere near a big city I would try phoning around industrial suppliers, or companies which actually make things which would use springs and ask where the get them.
 
Aug 29, 2010 at 2:44 AM Post #26 of 26

johndalek

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i still have a pl-12d turntable--bought it in college in the 70's.  i am going to find a new stylus for it, but i know that it's probably impossible to find one of the little weights that was on the side of the tonearm--the counterweight is there, but i think it was an anti-skip weight or something.
 
does anyone have any idea what the weight of that little thing was?  i am quite handy and can make something work, but would like to start out with the correct weight.
 
thanks
 

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