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Old 15th April 2008, 03:54 PM   #1
ms977a is offline ms977a  United States
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Default Friends of AR Turntables (F.A.R.T.s)

Hi!

I'm new to this forum but have had an enjoyable past with home-built speakers, a DIY passive preamp, bi-amped system, and an old AR turntable that I have majorly modded. This was all done on a super-cheap budget, and I pride myself on doing things with little money, but maximum gain.

Anyway,

I was toying with the idea years ago of starting up a cult group, "Firends of Old AR Turntables (Old FARTS), but the idea didn't catch on. Since there were no computers, getting a paper-based network going was... a challenge.

After reading a bunch about expensive commercial mods to old ARs, I decided to attempt my own. I have an EE background and some mechanical sense, so I dug in.

I started simple enough, by isolating the AR's outer platter from the inner, by placing about six small pieces of thin self-stick weatherstrip foam and sticky friction tape around the supporting edge of the inner platter. When the outer platter is rested on it, there is a mechanical disconnection that knocks down quite a bit of mechanical rumble from bearing noise. Also, I discovered that when I would spin the patter at high speed with the belt off, the platter had a tendency to wobble side to side. So I repeatedly lifted the outer platter, rotated it in relation to the inner platter, and kept doing this until the platter was in balance and there was no wobble at high speed. I marked the platters with a pencil so I could always put them together in the balanced mode.

After the original foam mat rotted, I stuck about 18 small squares of--you guessed it--weatherstrip foam tape to the top of the outter platter, which the record rests on. My guess is, this further knocks down bearing noise but supports the record effectively.

I also cleaned the main bearing and added powdered graphite to the original AR machine oil that came with the turntable. This all contributes to reduce wow and flutter, and lower rumble.

The main problem with the original AR tonearm is not so much the mass or geometry of the arm, but with the headshell. I took the original plastic shell, and cut the back of it off, that has the mount and wiring. I cut a piece of very light aluminum from an old office easel stand, and fashioned a cartridge shell expoxied to the back of the original plastic one. I drilled several holes in the aluminum to lighten it. I mounted a $50 Grado cartridge and aligned it and the arm using a paper template found in an old magazine article. This alighnment is a pretty critical step. According to the alignment procedure, the cartridge needs to be absolutely perpendicular to the disc at two points in its travel from start to finish on the record. Otherwise, the stylus can't track properly.

Using a light stick, I rested the stylus on the stationary platter and tapped the cartridge and arm with the amp's volume up high. I noted the resonances and started adding strips of sticky friction tape to the arm to reduce vibrations and resonances. This reduces colorations caused by an insufficiently damped arm, and results in a more natural, musical sound.

I also cleaned and treated the arm's bearings as I did the platter bearing, with graphite aded to the oil. Getting the arm bearing properly adjusted goes a long way to getting good performance.

I also added some window glazing compound to the edges of the metal chassis, which adds weight and also reduces any metallic ringing tendencies. This compares to the expensive commercial mods, which feature a molded acrylic chassis instead of the original metal one.

As a result, I think I have a useful turntable that delivers solid performance without spending an arm and a leg, and of course it's always good to recycle and re-use.

I'd be very interested in hearing if others have done similar mods to their old ARs.

Cheers,

Mike H.
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Old 15th April 2008, 04:06 PM   #2
sreten is offline sreten  United Kingdom
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Hi,

You may be better off here : http://www.vinylengine.com/phpBB2/viewforum.php?f=34

/sreten.
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Old 15th April 2008, 04:17 PM   #3
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I suppose I fit into the category that you have created. I was given an AR and so decided to bring it up to a reasonable standard of playback without resorting to Merril Scillia mods.

I found this stuff priceless. At 18 it doesn't break the bank and the 4 sheets of multilayer mats for structure damping will damp a lot of turntable. I also used it on my DVD player. I damped the T bar and the underside of the metal top plate. I also damped the inner platter with it. The outer platter fits well enough for most resonance to be killed by fit with the inner platter, but I use an Isoplatmat to be certain. However I do like my stuff to look nice so the body has been treated to some love and looks quite pretty as well as sounding very good.
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Old 15th April 2008, 05:33 PM   #4
SY is offline SY  United States
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I've had three of them over the years. Once I replaced the tonearm with something decent (in my case, a Weathers, a Mayware F4, and a Grace 707II), the virtues of the basic table could stand out. Isolation from vibration and shock is about as good as anything I've ever used.

10 minutes on a milling machine and the T-bar will accommodate any arm that's not wildly different in mass than the original plus bearing.
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Old 24th April 2008, 04:58 PM   #5
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I can't tell when this thread was active, so hopefully there are still some people around.

I consider myself a card carrying member of
FARTS . Having had two AR-XA's over the last 40 years. Yes the big negative over time has been the Headshell or what I call headshell hell. I recently rectified that situation by modifying the tonearm to accept a cheap Universal headshell. Which also allows for a two null alignment which opens the sound stage and really makes the table sound great. The suspension is a brilliant design,you can literally hit it with a hammer and it will bounce a bit but never miss a beat.
http://www.box.net/shared/okflevxc0s
http://www.box.net/shared/9m0vzh8sg4

http://www.box.net/shared/eiitw6w0k8

This track is not from an audiophile recording, quite the opposite, a free record given away by Maxell when you bought a case of tape you got 3 samplers Classical, Rock and Jazz. I choose it for testing because it is the last track on the side, has some good musical content and if it gets ruined I haven't lost an expensive album.



I have a lot of time on my hands now a days and feeling a little cocky from my success with the tonearm modification, I have been thinking of a DIY tonearm that uses the nice suspension of the XA.
I am looking for a table to play with, don't want to mess up my table. My plan is to take the old tonearm out by sliding the whole think out by the spindle. Make a new shaft with a plate to accommodate Gimbel that will hold the tonearm. My plan is to drill and tap the piece that holds the shaft to accomplish VTA, that alone is an improvement over the old tonearm. But where the shaft no longer had to move this would seem like a logical thing to do. Although I am not so sure the metal will take a drill and tap, we shall see. Another unique feature would be two set screws so the affective length of the tonearm could be easily changed and would make the use of different cartridges possible. Just some idea I am playing with, will probably start some modeling very soon to see if any of these ideas work. I am not quite sure what material the gimbal will be best, I am open for ideas. Also I was thinking of a Carbon Fiber tonearm but also open to ideas. One of the things I am totally in the dark about is antiskating, I have seen enough of them to know how to physically make it but not sure about weights and adjustments, help here would be nice.

Just playing,
Barry
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Old 24th April 2008, 05:33 PM   #6
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Quote:
Originally posted by SY
Once I replaced the tonearm with something decent (in my case, a Weathers, a Mayware F4, and a Grace 707II), the virtues of the basic table could stand out.
I am responsible for quite a few ARs sporting Grace 707s & Maywares (and at least one hadcock) ... the AR i have downstairs will eventually get a Mayware & a new plinth (unless someone gets to it before me)

dave
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Old 24th April 2008, 05:57 PM   #7
SY is offline SY  United States
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It's a great combo. I used to have fun blowing away Linn setups.
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Old 24th April 2008, 07:48 PM   #8
ms977a is offline ms977a  United States
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Hi, Barry. Let me suggest another idea about alignment and VTA, which I assume means vertical tracking angle.

The Grados have a rectangular front surface on the cartidge body that should be perpendicular to the record. This makes an easy reference for alignment. I accomplished this alignment by placing a small mirror on the platter, then resting the stylus on it. Sighting from directly above the cartidge (my homemade shell allows the cartridge to protrude beyond the shell), I can easily see when the cartidge is perfectly perpendicular to the platter.

As far as skating goes, I don't think the anti-skate compensation is worth it. I envisioned a tiny pulley (from a junked cassette?) and a small weight, attached with a light cord to the tonearm. This would give a constant pull away from the spindle. But I never got around to trying it, because once you have the cartridge and arm properly aligned, and if you are tracking as I do at the maximum pressure, there is no loss of contact in the groove. It tracks with no distortion and no skipping.

I also decided to place the turntable on a shelf mounted to the wall. It hovers just above the surface of the cabinet that my equipment is in, so you don't notice it is wall-mounted. This completely isolates the table from the floor.

For now the phono section of my old NAD integrated amp is hissing and burbling, so no analog for now. I guess I need a super-cheap phono preamp. Any ideas?
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Old 24th April 2008, 08:19 PM   #9
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Thanks Ms977a for the nice post. Truth be know where I have only had an AR-XA I am not familiar at all with anti-skating. It just seemed like it was something that most good tonearms have it.

I have a house full of old amps(use them all) and one new receiver, opps how did that happen. My marantz although I love it spends time in the ship once every couple of years, which for its age I guess I can accept, never cost too much, this time it was $55. I decided rather than pushing things around I would buy a backup. The guy where I bring it is good but usually takes 2 months to get it back. I bought this
http://www.ecost.com/Detail/Receiver.../40159585.aspx

From Ecost.com, I remember with shipping it was $112. It is unique for an amp today, it has all the inputs and outputs, including two tapes and monitors which is something I need and a Phono input with gnd. For $112 you can barely buy a phono preamp. The tuner section is as good as my Carver, I was astonished and the amp is nearly as good as my Marantz, well amps are a taste thing, I have used Marantz for so long I am just use to the sound. But it has a clean 100/c which drives my AR-3a which is no easy task and generally is a very nice amp. I have another Onkyo I bought 20 years ago and still gets use everyday in my bedroom and it has never been it the shop. It is re certified(refurbished), but I couldn't tell mine from new. Just a thought don't know if this helps, but it at least would give you something to use while yours is in the shop or you could open up your Nad and try to figure out what is wrong, and replace a few parts to see if it helps.

Oh and I have bought two things from Ecost and they ship super fast, I had mine in 2 days.

Take care,
Barry
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Old 25th April 2008, 02:48 PM   #10
ms977a is offline ms977a  United States
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Barry, that's a great resource (ecost)! The Onkyo amp deal looks great. I also have a backup amp that my sister gave me in my shop, but the Onkyo sounds like a bargain and decent quality too. Sometimes I think the "refurbished" units are actually returns from people who got them for gifts, or didn't like the color, or features, etc. rather than an actual defect. This was the case with a Kitchenaid refurbished mixer I bought for less than half price.

My NAD 3150 integrated amp has a jumper for the preamp, so I just use the NAD as a power amp in a bi-amplified system. I also tap into the NAD phono stage by going through the "tape" section of the NAD. It has a seperate selector switch for "tape" as opposed to "listen," which I set for phono. Then I run the output of the tape output to a passive preamp based on a design I found in Stereophile mag a number of years ago. Except my volume control is a ganged 5k Alps pot cannabalized from an HK tape deck, which happens to track quite acurately at all positions.

I built a Marchand 24dB/octave electronic crossover at 200 Hz which is the Swan IV crossover point. I have a little HK receiver, 20 watts/channel driving 12" bass speakers. The NAD drives the Swan satellites. All in all, it is a very clean, good-sounding system. The bass response is very smooth and tunefull from low 30s up to 200. Certainly adequate for my mostly quiet living room. I no longer feel the need to rattle the walls. My teeth probably couldn't take it anymore.

I'm glad I found this forum, I'll probably be dropping in often as I am retiring next Wednesday. I also think I might spring for the $43. item from Phonopreamps.com. I have sent my NAD amp twice to a shop in Cambridge, MA (the service bench) and I don't know if I want to spend another 70-$80 for the repair to the phono stage. I have an EE background but it's been too long and I don't have the equipment or patience to fix the thing.

Thanks for the feedback,

Mike
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