AR XA tonearm reveals its secrets

american simplicity
lenjack
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Re: AR XA tonearm reveals its secrets

Post by lenjack » 19 Aug 2019 02:27

You're probably aware that an SME type can be adapted.

oztayls
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Re: AR XA tonearm reveals its secrets

Post by oztayls » 19 Aug 2019 02:32

lenjack wrote:
19 Aug 2019 02:27
You're probably aware that an SME type can be adapted.
Yes, but not necessary for me as all my headshells are in perfect condition and so are the arm connections. I prefer the AR headshells as they are lighter than anything else, and besides, they look so cool!

lenjack
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Re: AR XA tonearm reveals its secrets

Post by lenjack » 19 Aug 2019 02:57

Agreed.

oztayls
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Re: AR XA tonearm reveals its secrets

Post by oztayls » 19 Aug 2019 03:05

lenjack wrote:
19 Aug 2019 02:57
Agreed.
When you think about it and do the maths, the AR headshells don't work out to be any more expensive than doing the conversion and the price of a good quality headshell anyway. I imagine soldering new wires into the plastic headshell could result in a case of potty-mouth!

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Re: AR XA tonearm reveals its secrets

Post by derspankster » 19 Aug 2019 14:24

I've owned AR XA turntables for over 50 years and love them. What I never liked were the plastic head shells. One of my XA's now sports a Jelco tonearm and the other the original arm with a Technics wand and SME connector. So glad I don't have to deal with the plastic head shell anymore.

fscl
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Re: AR XA tonearm reveals its secrets

Post by fscl » 19 Aug 2019 15:53

oztayls wrote:
19 Aug 2019 01:13
I've just fitted an AT-VM95ML to the XA headshell. It's a little tricky because there are two threads to contend with on each screw. The trick is to hold the cart flat to the headshell when doing up the screw so that you get the screw "synced" with the two threads. Start with the end of the screw flush with the top of the cartridge. It works well and is held tightly to the shell.
Centerline of mounting screws and stylus distance looks a bit more than 3/8".

From lenjack's link

46351
46352

Did you use the overhang dimension / original plastic stylus locator / one of VE's protractors for alignment ?

Fred

oztayls
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Re: AR XA tonearm reveals its secrets

Post by oztayls » 19 Aug 2019 18:22

I’m a bit of a purist so I prefer to listen to my turntables as the designers intended. Rather than modify, I prefer to optimise. The “weight on a string” anti-skate thing is a dabble, and it’s working well on one table. Naturally, it’s completely removable as it’s only held to the arm with BluTack and the drape post is magnetic. On the other table, I’m messing with the method that EV mentions in his articles, ie. the arm dragging against the viscosity of the silicone grease in the arm tube. I guess you would call it “viscous anti-skate”. It’s working very well, but I can appreciate why AR didn’t run with it, as it would have been difficult for most consumers to get right due to variations of climatic conditions under which the table would operate with the greases available at that time, not to mention the host of various carts that would be used, each requiring their own particular CST weight!

As for the stylus distance of 3/8”, I’d have to find my imperial ruler to check this on the AT-VM95ML, but it’s probably irrelevant anyway as I use the Rega Stevenson protractor for this arm.

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Re: AR XA tonearm reveals its secrets

Post by derspankster » 20 Aug 2019 16:50

I've always been of the opinion that the lack of anti-skate on the AR XA was a very minor issue. In the 50+ years that I've used one I can't recall undue stylus wear or any objectionable distortion because of the lack of anti-skate. I am well aware that others have completely different opinions on this and I respect that. I certainly have no desire to open a can of worms over the subject. It's simply my view.

lenjack
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Re: AR XA tonearm reveals its secrets

Post by lenjack » 20 Aug 2019 16:53

oztayls wrote:
19 Aug 2019 18:22
I’m a bit of a purist so I prefer to listen to my turntables as the designers intended. Rather than modify, I prefer to optimise. The “weight on a string” anti-skate thing is a dabble, and it’s working well on one table. Naturally, it’s completely removable as it’s only held to the arm with BluTack and the drape post is magnetic. On the other table, I’m messing with the method that EV mentions in his articles, ie. the arm dragging against the viscosity of the silicone grease in the arm tube. I guess you would call it “viscous anti-skate”. It’s working very well, but I can appreciate why AR didn’t run with it, as it would have been difficult for most consumers to get right due to variations of climatic conditions under which the table would operate with the greases available at that time, not to mention the host of various carts that would be used, each requiring their own particular CST weight!

As for the stylus distance of 3/8”, I’d have to find my imperial ruler to check this on the AT-VM95ML, but it’s probably irrelevant anyway as I use the Rega Stevenson protractor for this arm.
Would you be kind enough to show photos or videos of the antiskate mechanisms on your Ar's?

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Re: AR XA tonearm reveals its secrets

Post by noisefreq » 20 Aug 2019 17:58

I never had any anti-skate issue using SAS or line contact styli, until I installed an aftermarket Pickering JICO D1200 .3X.7 elliptical.
Now I use the "tonearm wires twist" trick to compensate.
Works great on the XV-15.

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Re: AR XA tonearm reveals its secrets

Post by derspankster » 20 Aug 2019 21:45

I have run a variety of Shures, Denons, and Grados with nothing more than a twist of the tonearm wires. Works fine.

oztayls
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Re: AR XA tonearm reveals its secrets

Post by oztayls » 20 Aug 2019 22:38

I totally agree that with a lot of cartridge/stylus combinations, AS is not really necessary. However, with some of my favourites, there is noticeable channel imbalance which a simple anti-skate does solve. I certainly will not create an argument that it's a necessity, because it isn't in all cases. Using a thick oil in the arm post will provide a measure of anti-skate action. On one of my turntables, I'm using CST500 with a dab or two of CST300K, but I'm still working on it. It's fiddly.

The hanging weight method is much simpler to adjust and I made it from little parts in my shed, like ss welding wire and scrap aluminium. To get the loop, I just wound it around a screwdriver. The drape post is made from an oil seal part from my Land Rover's old injection loom, but you could just use some epoxy putty with a magnet on the bottom to hold the wire. For the little weight I used a copper alloy welding tip because it already has a hole down the middle. I just cut off a section and held it against a grinding wheel until I had the weight I needed, which turns out to be 1.4g. The string is just a thin braided fishing line. At the moment I just have it stuck to the arm with a bit of BluTack, but I may soon opt for a reversable hobby glue of some sort.

PS. The black thing on the arm is just a piece of split plastic tubing. This is just for easier fine adjustment of the tracking force.
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lenjack
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Re: AR XA tonearm reveals its secrets

Post by lenjack » 21 Aug 2019 01:18

Beautifully elegant and thought out. =D> :)

oztayls
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Re: AR XA tonearm reveals its secrets

Post by oztayls » 22 Aug 2019 01:04

My XB1 arrived yesterday. I've been looking for a nice one to replace the one I stupidly sold a few years ago. This one is in pretty good original condition, unmolested and has its original box and packaging. The bottom was still held in place with staples and the owner said it hadn't been used for 40 years. The only downside is the Fidelity Research FR-6SE cartridge has a broken cantilever. :( (I’ve only serviced it, but have yet to spruce up its looks.
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Anyway, I digress because I'm pretty excited about what transpired yesterday after I had serviced it and removed the old oil and grease. As you know I've been fiddling with anti-skate on my 2 XAs using two methods, i.e. the draped weight method as per the pics I posted earlier, and the viscous drag method using silicone oil blends. After cleaning out the arm well of the XB1 and finishing the clean out with an IsoPro cotton tipped applicator, it was totally free of oil, so I thought I'd give my new idea a try. I don't know why I had dismissed the idea of using 500K CST (500,000 CST), but maybe it was because I thought it would be way too thick and the viscosity much too high. (I have been fiddling with blends using 500 CST and 300K CST and this was only somewhat successful) I decided to wipe some neat 500K CST onto the arm tube and bearing. This is the same stuff I always use to restore arm set-down mechanisms. The result was that I could really notice the slight drag on the arm as I move it back and forth.
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Playing the first record was a revelation. Not only are the channels perfectly balanced, but suddenly, I could notice a significant improvement in bass and treble extension. There was more drive and punch too. Then I got to thinking about what was going on here. The swinging arm in the tube is basically a viscous clutch and works in the same way as the cylinder in the XA's arm. When the cylinder moves relative to the arm post, initially there is drag created when the bonds of the oil molecules are stretched, but then they "catch up" whereupon the status quo is re-established, and arm stability is restored. Because the arm is moving very slowly, one groove at a time, the drag on the arm is actually very small and the oil molecules are only being stretched minutely. Placing the stylus on a video disc reveals how well the anti-skate is actually working. Instead of the arm racing across the disc to the centre, the arm traverses slowly. According to Peter Ledermann of The Soundsmith in his discussions on anti-skate, this is pretty much ideal. Of course, it’s not absolutely perfect as centripetal force gets stronger the closer to the centre that the stylus gets, but it’s a good average.

The other happening thing is the improvement in sonics that I seem to be hearing with the viscous anti-skate, but then I recall what Ed Villchur and others have mentioned in their arm discussions and perhaps it’s not to be unexpected. EV said that he chose a plastic for the headshell to reduce the mass at the end of the arm and that he could not achieve the same low mass with aluminium. The purpose was to help overcome some of the inertia that is created at the end of the arm as it traverses the grooves, which in turn translates to improved efficiency for the cantilever which can pass through improved vibrations, and ultimately, improved sound benefits. He said that if you can stabilise the headshell, the cantilever will be able to transmit more of the vibrations from the record grooves to the cartridge, and sonics will be improved. What the viscous anti-skate does is further stabilise the headshell. This is also the purpose of the silicone oil moats seen on some expensive arms, so it’s an established design concept. As a by-product of the viscous anti-skate, there is improved damping of the horizontal arm motion which stabilises the headshell and in turn this must result in better transmission of cantilever vibrations into the cartridge.
To my mind, I think the viscous anti-skate is a win win for better sound from the AR. I would like other AR owners on this forum to give this a try and let me know what they think!

Note: For this to work, the arm well and arm post need to be absolutely free of oil, and dry. A fingernail amount of 500,000 CST is all that is needed. A little on the bearing and a thin, even coat on the arm post. Moving the arm from side to side to side across as wide an arc as possible, taking care not to stretch the tonearm wires, will ensure the oil’s even adhesion to the surfaces. Then stick on a record and let us all know if it works for you!

oztayls
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Re: AR XA tonearm reveals its secrets

Post by oztayls » 22 Aug 2019 02:36

fscl wrote:
19 Aug 2019 15:53

Centerline of mounting screws and stylus distance looks a bit more than 3/8".

Did you use the overhang dimension / original plastic stylus locator / one of VE's protractors for alignment ?

Fred
Hi Fred

Confirm that the VM95 distance is 3/8" so AT must comply with the standard you refer to. Unfortunately I don't have the original plastic stylus locator, so I just use the Rega Stevenson protractor for 222mm arms, glued onto an old record. I did make a cardboard stylus locator but of course, it doesn't have a bubble, so there is a small error. It's good for a quick ballpark check though.