AR XA modification success!

[Deleted User]

Hello,
About five or six months ago I went looking for a new turntable that was simple to use, easy to handle, moderately priced and sounded good. I settled on an AR XA turntable combined with a modern Shure phono cartridge. After a few weeks one showed up on Craigslist in Arlington, VA that looked in good shape and seemed reasonably priced. The missus and I drove down, had a nice lunch in Arlington and met the seller and checked out the turntable. He played a Beatles record (good sign) and after a few minutes left with the AR nestled in the trunk.
I cleaned out the platter bearing, added some synthetic lubricant, polished all the metal parts and cleaned up the dustcover. I ordered a Shure M97xE cartridge and started listening. Everything sounded fine, good left/right channel separation, good feeling of dynamics, channels seemed balanced and the tracking was excellent (always a Shure strong point). For around $200.00 I had a satisfactory way to listen to records.
Being the "I wonder how it could be better" kind of guy I began reading about great results being done to AR tables by Marc Morin, especially on Audio Karma. I contacted him and asked what he offers. He responded explaining that he can work on four areas of the XA: the suspension, the tonearm, the platter bearing and the drive motor. His philosophy is that the turntable is a well designed system, one part working with the others to allow the cartridge stylus to extract information from a record. Here is what he said:
"I can give you the science behind the work. There is measured mechanical timing, and there is flow to timing. I went with the flow. I'm not a fan of correcting devices as they can only correct after the fact, thus creating no less than two problems. The work to the suspension deals with how the perches work keeping the suspension square reduces the timing flaws. The drive pulley with the internal damping and balance plus added torque reduces timing flaws. The freedom of the platter to spin reduces timing flaws. Rumble, if were to be measured now would exceed -83db. All kudos really belong to the man who originally designed the table. I just found simple solutions to issues it seems people have been overlooking for years. It doesn't take gobs of money to fix simple problems. Rega, Jelco, and other entry level arms wished they could perform as that XA arm can when a few issues are settled."
I can go into what he does to each section of the table if anyone is interested. Suffice to say that he uses sound engineering practices and the results are nothing short of amazing. You know the feeling, the more you listen the more you want to hear. If you have an AR do yourself a favor and contact Marc at BaMorin@aol.com, you'll be happy! Here is my message after I had a chance to do some listening:
"Hello Marc,
The problem with the amp turned out to be one of the output tubes, got it
replaced and everything?s fine. I love the sound the turntable produces,
everything is so much better. I hardly know where to begin. I have been in a kind of audio slump recently as a result of having to move into a smaller
room and making adjustments. The work you did on the AR has broken the gloom and music is sounding wonderful. As luck would have it George Harrison?s Concert for Bangladesh was up rotation and it was as if I had not heard it before. It just plain sounded real, as if I were attending the concert. My theory of sound perception is that if you are able to give enough aural clues to the human brain and if you use a little imagination you can begin creating a believable picture of what something might have sounded like at the real event. The more clues the easier it is to complete the illusion. The changes you did to the turntable, without question, provide a tremendous level of listening "signposts" to what can be revealed in a record.
Thank you very much, it will be much appreciated and enjoyed!
Do you mind if I mention your service on the Polk Audio forum?
Best regards, Ken"

quadzilla

Pictures or it didn't happen.

AudioGenics

Hi Ken. You mention a synthetic lubricant ...

what type and brand are you using for the XA ?

[Deleted User]

Hi AG,
I have always used Rislone as a lubricant, I started using it several years ago after hearing of it on several pro tape deck sites. Marc used Royal Purple Synfilm GT32 in the platter bearing and arm bearing. One of the things he does is measure the bearing wells and spindle for wear. If everything is close to factory tolerance he puts a 60 degree cross hatch pattern on the spindle bearing. Then a 15 degree cross hatch on the spindle give a natural 45 degree spread making an equal load, up and down, on the oil film. The result is a long spin down time (the length of time the platter comes to a stop at 33 1/3 rpm with no belt) three minutes, I believe.
Ken

Fongolio

Three minutes to spin down is amazing. Virtually frictionless. Sounds like you have yourself an excellent unit now. Thanks for sharing about it Ken.

[Deleted User]

No problem, glad to share his work. He reshaped and polished the spindle and pivot ball and replaces the thrust plate. He said my XA had a longer spin down than his ES-1. The spindle should be .375" and mine was .3745" and the bearing is supposed to be .378" and mine was .377". Just blind luck, I suppose.
He puts the same attention to the arm, platter suspension and motor structure. I couldn't believe how good it sounded. On the Harrison recording the sound the cheering crowd made gave me goosebumps.

george daniel

Wow,, a three minute spindown,,thats amazing--thanks for sharing that Ken,,if you can,would you mind sharing some pictures.

Roy Munson

I've had an AR XB with a Shure V15III since the 70's when I purchased it new.

Even though these tables have a following they really are underrated imo.

Glad you're enjoying your AR!

TroyD

Ken,

That's awesome!

What happened to your other table?

BDT

amulford

The AR XA is just a flat out good design. It might not be UBER sophisticated, actually very simple, but it just seems to work.

Good on ya. Enjoy.

[Deleted User]

Hey Troy,
Thanks, I've got the SAS replacement styli on order (never happy, are we?) eager to hear what the improvements are.
Ah, the Maplenoll has become a bit of a project. I decided that the air compressor assembly needed some TLC. In the original design there were two smaller sized PVC storage tanks mounted beside the air compressor. One morning, several years ago, one of the tanks blew up. No kidding, really detonated sending bits of PVC into the wall and spreading emulsified brown synthetic oil goo everywhere. The mounting platform that the air compressor was on was damaged. As a stop-gap measure I sandwiched two pieces of wood as a support. This just looked too "hillbilly" (I can say that since I'm from Western Maryland) to me so I decided to overhaul the air compressor. Of course this turned into a research project, reading about how to turn a 'fridge compressor into an oil cooled air compressor (which is what Maplenoll did). So, I've sanded the chipped black paint off and repainted it a nice hammer finish. I've made a replacement wood platform and a support frame for the cooling fan. But, along the way I lost a component for the temperature sensing switch and have had a devil of a time finding a replacement.
Anyway the AR was meant as a temporary replacement just to be able to play records. But, it is so good sounding and easy to own that I'm in no hurry to do anything with the 'Noll.

[Deleted User]

You're absolutely correct, AM, simplicity personified, just an on/off switch. In the face of all of the super complex turntables with hours of setup time needed the AR approach is reduce the job to the fewest number of parts and make each part as good as you can at a reasonable price. Then what Marc does is take those parts one step further with simple solutions that work. For example, for arm-tube damping he uses those foam ear plug jobbers.

[Deleted User]

Nice write up. Its not everyday you read a review that uses George Harrison source material. Cheers. :cool:

TroyD

Holy crap, Ken, it's a darn good thing you weren't there when it exploded!

BDT

[Deleted User]

Yea, leave it to me to be wounded by flying PVC. At the time the compressor and tanks were in the basement and the gear was directly upstairs. I turned on the compressor to do some morning listening and heard a loud pop. Went downstairs and saw the mess.
As a result I bought a 12gal steel storage tank rated up to 120psi, the highest I want is 45. But now I don't have room for all of that extra stuff in the new listening room.
The post office says the new stylus can be picked up, so off I go! I read a telling quote, "the AR XA is the box that the Linn came in".

stuwee

Congrats on the 'new' AR TT! Great story, except for the emulsified brown synthetic oil goo everywhere part :frown:. And ya had a nice outing for the afternoon with the Mrs's, always a good thing! Very underrated table that most owners have to have it pried from their cold dead fingers :biggrin:

[Deleted User]

Hello,
I've had some additional fun with the AR XA and an Ortofon TC-3000 turntable computer I have. It allows someone to connect a turntable and make quite a few interesting measurements including changing the capacitance load and seeing how that effects the frequency response. After trying several loads I settled on 180pF which is provided by the AR.
Once I had everything all connected I thought I'd do some measurements of the original Shure stylus versus the Jico SAS replacement. The tracking force was adjusted to the same 1.25gm for both styli and loading remained the same 180pF/47k. The first measurement taken is the left and right outputs, the left for the Shure was 3.60mV and the Jico was 5.10mV. The right channel was 3.4mV versus 5.3mV this is done at 5cm/sec. Next is channel balance, the Shure was within 0.4dB and the Jico was within 0.4dB. Next is channel separation first is the left minus right and for the Shure it was 25.4dB and the jico was 28.2dB; right minus left was 17.6dB for the Shure and 24.0dB for the Jico. Then the measurements are for "tracking ability" measured in uM the Shure was given 79 and 75 for left and right, the Jico measured 80 and 79. Next is a frequency response, I'll list the frequency response for left then right channels at each frequency, Shure on the left Jico on the right:
1kHz 0.0dB 0.0dB 0.0dB 0.0dB
5kHz -1.5dB -1.5dB -0.8dB -0.5dB
10kHz -1.3dB -1.1dB 0.0dB +0.1dB
12kHz -1.2dB -1.8dB +0.5dB -0.1dB
15kHz -0.8dB -0.9dB +0.3dB -0.4dB
18kHz +0.8dB -0.4dB -0.6dB -1.3dB
20kHz 0.0dB -1.2dB -0.5dB -2.2dB
The next series of tests deal with how the tonearm and cartridge operate together. The moving mass of the arm/cartridge combination working with the compliance of the cartridge to form resonance frequencies. The Shure stylus had a vertical resonance of 10Hz the Jico was 8Hz. The lateral resonance was 19Hz for the Shure and 6Hz for the Jico. It is usually regarded as ideal to have a resonance between 10 and 15Hz with 8Hz as probably okay. Next is a dB measurement of these frequencies, with the Shure being 8dB for vertical and 5dB for lateral and 9dB and 16dB for the Jico. Here the lower the better for resonance damping. If I used the stylus brush on the Jico the vertical resonance was below measurability and the lateral resonance reduced from 16 to 11dB. I think I'll leave the brush down on my combination.
Keep in mind these are on very new styli and suspensions may not be at their optimum, I've probably played less than 10 records on both styli. This shows, in my opinion, what a wonderful phono cartridge the stock Shure is at a reasonable price and it will mate well with an AR XA. It also shows that the Jico replacement stylus increases the output level by 3.0/3.8dB left/right which should improve signal/noise performance (make sure your phono stage input sensitivity is okay with 5mV inputs). As to channel separation, the Jico is better as well as the important frequency response betwen 1kHz and 15kHz.
I hope this is interesting information.
Cheers!