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Tonearm not lowering correctly

 

New member
Username: Nornironpete

Post Number: 1
Registered: Sep-11
Hi guys, first post here. I recently bought a second hand Pro-ject Genie MK3 turntable, my first "decent" deck. I'm very pleased with it and have no problems except for the fact that on lowering the tonearm it travels slightly towards the edge of the disc (the deck has been levelled). Not a major problem and I'm really just wondering if this is the norm . I have gone through the setup step by step and as I said there are no other problems like skipping or jumping. I suppose the obvious culprit is the anti skating weight which I believe I have set correctly for a downforce of 17.5mN in the second groove stub.
Any advice appreciated,
Pete
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16780
Registered: May-04
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Some arms just simply drift while cueing down. There's typically not much you can do about the situation other than lighten the anti-skate slightly or learn to acommodate the drift by settting the arm a bit inside of where you want to cue.

Anti-skate is not a fixed degree of compensation as LP's will require more force against skating over the course of a track from outer to inner grooves. A few manufacturers have decided anti-skating is so inaccurate most of the time that they have gone away from using a typical weight or spring loaded mechanism to make corrections. They have instead simply increased the tracking force by about 1/4-1/2 gram.

This isn't what I'm recommending as this simply makes the stylus dig in deeper on the curvy parts of a track - sort of like adding 200lbs. of sand to your trunk when running the slaloms. The net effect can cause as much disc wear as having too much anti-skating. Contact the Project distributor and ask if there are any fixes they recommend.



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New member
Username: Nornironpete

Post Number: 2
Registered: Sep-11
Hi Jan, thanks for the reply. I can understand the logic behind doing without the anti skating as I had, in my impatience, tried the tt without the weight fitted and it seemed to play fine. However being a slave to the manual I decided to fit it as described. I would also say that cuing was truer without it. Do you think I could do without it altogether?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16783
Registered: May-04
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That's up to you. The "no anti-skate" theory is based on arms designed for such applications. It has been adopted by other users and the results are fairly mixed. As I said, skating effects are constantly changing and highly dynamic. That means even with good anti-skating systems they are imperfect most of the time. How imperfect? That depends on the geometry of the arm and the type of stylus in the cartridge. Straight arms have a different skating effect than do most "J" or "S" shaped arms. Arms with a longer effective length also require less skating compensation due to the path they travel accross the disc's surface. Neither of these have much effect on your arm since it is fairly conventional in its construction. However, the stylus profile on your cartridge will make a reasonably large difference in just how you set up the arm.

You probably have a conventional elliptical stylus which is what would be found in most budget oriented cartridges suitable for the Project table. You should assume Project has established what they feel are the appropriate settings for anti-skating for your stylus type. I'm not familiar with the type of anti-skating compensation used on the Project arm but a spring type loading is better able to deal with the dynamics of the arm's actions despite the fact springs are always loosing their tension from the moment they are put in use. Hanging weights are consistent throughout their life but unable to adequately deal with the dynamic conditions of skating. Either way, you are really just setting the compensation to a given amount and hoping for the best.

With today's medium compliance arms skating has slightly more effect on stylus and record wear. Setting skating is generally not something you can do by ear unless it is really off the scales wrong. In the days when LP's were the primary music source several test discs were produced which provided a single blank groove. You sat the sytylus in the groove and adjusted the skating compensation to the point where the stylus/cantilever were perfectly aligned without pulling to either side. The problem here was the disc didn't address the dynamics of outer vs inner groove compensation nor did it provide the dynamic music program which you are trying to reproduce with the lowest tracking distortion. For a few years Shure sold a very early computer and test disc that allowed retailers to set up tables with a greater degree of perfection but the discs quickly began to wear and needed constant replacement. Most retailers abandonded the system after a few years.

So you see there is no perfect way to do anti-skating. If you have access to a microscope you could check for wear on one side of the stylus every few months but that's seldom a good way to go about the problem today when stylus microscopes are about as common in audio shops as tube checkers. Plus, if the diamond stylus has worn to the point of being visible, you know the discs have also worn and there is no replacement for damaged vinyl.

A pair of high quality headphones - not the type that come with iPods - are today your best resource for critical listening as you adjust skating compensation. Choose several discs with a very strong center vocal image which hits some dynamic peaks. As you adjust for skating, listen for any changes in the quality of the vocals or high frequencies. Test at different portions of the disc as inner and outer groove modualtions will affect skating.

Unfortunately, after all that, there is no recommendation I can make. It's your table and your discs. Nothing you can do will ever be perfect when it comes to anti-skating. So it's up to you to make your decisions about what best suits your system and your way of using it.



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Gold Member
Username: Magfan

USA

Post Number: 2579
Registered: Oct-07
I had a TT with the weight type anti-skate.
It is not perfect at either extreme of tonearm range...all the way IN or OUT.
However, I had a special calibration disc with an inch of BLANK in the middle. I adjusted the antiskate so the needle tracked in the middle of that area and forgot about it. I suspect it was over compensated at one end and under compensated at the other end of tomearm travel.

Spring type antiskate, if you can calibrate it, is potentially better.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16785
Registered: May-04
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I would also suggest you track your cartidge at the upper imits of its tracking force range and then adjust the anti-skating to work with that agreed upon VTF. The two are complementary components and need to be adjusted together. Not necessarily to the exact same valaue - though that is your rough starting point - but as two pieces which together complete the picture. If you know anything about cars, think of this as adjusting both caster and camber to achieve the best handling or toe in and tire pressure.

Tracking at the lower limits will, in virtually every case, result in poor tracing (tracing vs tracking) performance of high frequencies and highly dynamic groove modulations as the stylus tends to bounce around the groove with little control exterted by the tonearm. If your cartridge has a suggested tracking force of, say, 3/4 - 1 1/2 grams, track it at the highest tracking force. If you don't have a scale or beam level for your tracking force adjustments, buy one, They are fairly cheap and are always better than what the manufacturer provides. http://www.needledoctor.com/Shure-SFG-2-Stylus-Force-Gauge?sc=7&category=915

You might even find a digital scale for cheap dollars at any store that specializes in scientific equipment. A friend who teaches high school bought several for his students at less than $20 each. These scales are accurate down to the "0.00X gram". Don't spend the money for such a scale through an aftermarket audio retailer.

But a common problem is most people think tracking their cartidge at its lightest pressure is the right idea to minimize disc wear when, in fact, the direct opposite is all too often the case. Pay attention to how the cantilever of the cartridge settles into the body of the cartridge as you adjust tracking force. When you lower the arm onto a disc, there should be a definite "settling in" to the cantilever. Anything less and you risk record damage and poor sound quality. Anything more and you risk a warped disc hitting the bottom of the cartridge body. You'll find the correct VTF as you go back and forth a bit but, in general, follow the old 1960's Rowan and Martin's Laugh In rule, "Hi again - and glad of it."

From ther you can adjust the anti-skating compensation.




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New member
Username: Nornironpete

Post Number: 3
Registered: Sep-11
I'll definitely try increasing the tracking force, I currently have it set at 17.5, to 20 which is the maximum recommended. I do have a white plastic balance/guage I got with the TT made by pro-ject.
Thanks everyone for the advice, much appreciated.
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