AR XA² Two Arm Turntable , An exercise of passion.....

[Nashou66]

I have had this Rega RB 300 tonearm on a crappy custom TT I made out of MDF , plywood and a rack system Kenwood TT guts with a wimpy platter. It served me well for a while before I really got into TT's. I also Had an AR XA but never really gave it much of a chance as it needed a lot of work.

One day I decided to set up the AR and searched for info on it, I came to VinylNirvana where I saw so many cool AR builds and parts etc. I new I had to use the RB-300 on one some time in the future. But after more research I found AK and Marc Morins work on these old simple design tables. I realized the original arm is quite excellent once you add jewel bearings polish the pivot pins add a SME style collet/bayonet and some other little tweets to it.

So I began looking for more of these to work on just for fun. But I own a restaurant and
people began to move onto other jobs and I never could find any good quality cooks with common sense and who could handle the pressure of a mad rush with out having their hand held. So I worked more hours and had no time for these projects.

A few months ago before Wuhan reeked havoc on us, I found a cheap AR XA with no tone arm, I had extras here so I went to buy it. Well Once I got it home I realized it was cut for an SME 3009 series II arm.

So my plan was halted there.

Sub chassis pic with the cut out for the SME.

So I always loved the look of dual arm TT's and have been playing around in my head about a
dual arm AR XA TT, but my original plan was with two AR arms as I think they are great for their simplicity.
This fantasy has been with me for at least a decade. So now that I got this hacked sub chassis and
time from the shut down and I finished other more important projects around the house I decided last night to
go for it and chop up some TT's and try to figure out a Dual Arm AR XA Turntable!!!

So I first cut off a section of the hacked sub chassis to kinda play around with ideas.
I also cut off the side supports so when I affix it to the main chassis it wont be too
high and hit the top plate, I decided to use the underside face up.

I eventually also had to cut the small raised support section( still in pic above) to fit a wood mounting plate that will eventually go there. Another hole will be drilled overlapping the larger hole above, and the suspension stuff hole will line up with the main chassis's.

I had to remove some of the main chassis raised edges so the wider new arm board section will fit to it.

A quick mock up ......

I photo copied the original RB 300 arm template so I wouldn't ruin it, did the same on its original TT it was on.
I lined it up to see where I stand on new arm mount length . I can take some off the end later as I have room.

I drilled and tapped 4 screw holes to affix the new sub chassis section to the main one.
I still haven't drilled the overlapped hole in this pic. I forgot to take a pic of that, I will later.

Here is the pic of the overlapped hole I drilled out.

Here is a mock up with the two arms . I'll need to figure out the arm board height . I may make some
brass spacers. Still thinking on what would be best. Heavy or lighter, it depends on the spring compression
once I get a set of the heavier duty springs and try it out as is.

Then I need to figure out the plinth. If I sat and thought it out more I would have put the new extension on the front chassis wing so I could put the RB-300 on the right side of the TT and the AR arm would be in the back.
then the dimensions of the table would look better with a full length of wood on the right
for the added extension arm board, so to say . Now It will have a wide wood arm board along the back of the Table. This will make it probably close to square in shape. Unless I decide to add a wider body all around, that would make a very big foot print not common with these little XA's .

So what do you guys think?

Any other Ideas ?

Not sure how much more time I'll have for this as were getting close to re opening
soon....I hope

Athanasios

 

[Nashou66]

I added the top plate to see what I will have to do with the base etc.

I might cut the top plate more in line with how the "The AR Turntable" is and make a wood top plate .

 

[Nashou66]

Just ordered a set of each spring set from Vinyl Nirvana Just to be sure.

The Rega arm and added chassis is way to much for stock springs obviously.

Nashou

 

[StuartB]

That is really creative and interesting. And very ingenious to do from scratch. I would be worried about the weight distribution and imbalances across the suspension points. You have significantly messed with the original design without adjusting the suspension points. I think it will take more that stiffer springs. I think you will have to think about adding mass to the sub chassis to balance if you keep the seeing’s where they originally are. Cool project for sure!

 

[Nashou66]

That is really creative and interesting. And very ingenious to do from scratch. I would be worried about the weight distribution and imbalances across the suspension points. You have significantly messed with the original design without adjusting the suspension points. I think it will take more that stiffer springs. I think you will have to think about adding mass to the sub chassis to balance if you keep the seeing’s where they originally are. Cool project for sure!

Thanks Stuart, I ordered two sets of springs . One of the very stiff set and the one that Marc would use for mass loading.

So yes, I plan to add mass as I did on my Paprika AR. And I can also maybe play with the different spring rates , Got the stiffer one for the RB 300
end and then the regular ones at the other points or a different combination. I am sure it will take a lot of thinking and trail and error.

But I think its a cool project and I love the AR XA's. So hopefully this XA² project will work out mechanical, geometrically and with the physics.

Athanasios

 

[Nashou66]

So I worked out the plan for the base and wood fill in top plate, I have a friend who I was going to have him make a stainless steel top plate
larger than the original but just decided to go with the wood.

I temporarily used a piece of underlayment for the fill in plate just to get an idea. So far
I think it is coming along fairly well . For the base I used Cumaru decking material.
Its the same wood I used for my Turntable/Record storage cabinet . It very very hard and heavy.
Not easy to work with as it chips and tends to burn when cutting or drilling due to its extreme
density . it also has a natural wax that seeps out over time. So not sure if I'll finish it
with any type of gloss finish etc at least at the beginning.

Hopefully Marc will guide me from above with any ideas
or suggestions.... he already is the inspiration for this endeavor.

Here are some pics of the mock up .

Nashou

 

[AudioFeline]

I had an AR XB in the 1980's. Scored a Grace 707 arm to replace/upgrade the original toneam. Needed to machine some of the subchassis to be able to mount the arm. It was an amazing upgrade from the original (of course, this was pre-internet so there was no information circulating on how to upgrade/mod these nice turtnables). I've moved on to other turnables since, but a couple of years ago I caught up with my friend who inherited the modified XB and it's still delivering the goods.

 

[Nashou66]

Well I got around to putting the base together. Man was it a bitch to line it al up.
I ended up buying 7 corner clamps to add to the only one I had. Used glue to
join them and then added some corner bracing inside to help hold it as I really needed
to fan-dangle those clamps quite a bit going back and forth to get the outside joints lined
up best I could and tight.
This Cumura wood is not flexible at all, or very little. Its like working with stone..
But I think it came out pretty well so far.



Here are my corner pics.

That one corner needed a little more help.

This will probably be the front of the TT

You can see on the inside the color of the wood better. The Left side is just Howards Feed and Wax and the smaller color patch is Howards Walnut Restore
a finish . I will play with a scrap piece with some type of gloss finish on the wood to see if I like it.
But Im more of a natural wood type of a guy. I like to feel some texture to it like the original AR-XA's .

Athanasios

 

[revox-b77]

Very nice work there. Great project too. And you learned that a man can never have enough clamps!

 

[Nashou66]

Very nice work there. Great project too. And you learned that a man can never have enough clamps!

LOL yeah how true !!

here is the pic with the clamps.

And here is a test piece with just clear lacquer

Athanasios

 

[Nashou66]

Got more done. Working with this wood is difficult all around, even finishing it. I figured since this wood is so dense I wouldn't need to do any real prep to it. and the 400 grit paper made it feel silky smooth. However once you apply the spray lacquer it opens up those pores in the wood and they expand.

So One can of spray was not enough. And I went to get more of the gloss and they were out so I went with he brush on
watch version. It needed lots of coats and sanding. There were so many highland low spots that just came out of no where !! lol .

So I could have done better but I an anxious to get this completely done before I open more days at my restaurant.

But here are some pics of the progress so far. I sanded dry with 220 , then wet with 400,800 and 1500. then I used 0000 grade steel wool with a little feed and wax
for lube. Then I used Formbey's Lemon oil with pumice stone powder followed with Oil and Rottenstone powered . Then I used a 3M fine cut auto rubbing compound followed by Meguire's fine cut pre wax cleaner, then a coat of Howards feed and wax.

I then mocked up the top plate again with the temporary Birch underlayment . I plan to make the RB300 riser piece a little smaller in diameter so there is more play
for the bounce of the suspension. I used Vynil Nirvanas heavy duty spring for the RB300 side and the regular upgrade brings for the other two points.

I think I got it pretty well set up using wheel weights I had left over from my other AR XA.

I have 3/4 inch furniture grade ply, not sure of the wood type, might be maple. Not sure if I should leave it natural with just lacquer
ir make add a bit of color to it. And not sure what color to do the AR's metal top plate. the original rough finish is in really good shape. Might leave it for now as is
till I find something I really like.

Pics of the base

Here are the mock up Pics. I added a little Howards Walnut restore a finish to the birch, Might try it on the 3/4 ply I want to use.

I also might move the metal top plate inside the base so it doesn't rest on it, what do you guys think about that?


Athanasios

 

[Nashou66]

Some more progress. I cut the wooden "top plate frame" and fit it to the base just by pressure fitting.

Then I had to cut the center of the frame out to hold the metal top plate.

The hard part was cutting the hole for the Reg Arm and arm board spacer( which I need to get right still) . I didn't want to get it wrong as Id have to make another frame then from scratch. But I think I got it ok. I went with a larger hole than the mock up just so I can have some more wiggle room. It wont look as nice but it will do for me.

Once I figure all that out I'll need to do some clean up work on the Base and top plate frame so the suspension
will not be impeded. Then adjust the suspension some more and then wiring up the arms and motor which I had to rebuild.


So far I think Its coming along nicely.

Athanasios

 

[Audiofreak71]

Some more progress. I cut the wooden "top plate frame" and fit it to the base just by pressure fitting.

Then I had to cut the center of the frame out to hold the metal top plate.

The hard part was cutting the hole for the Reg Arm and arm board spacer( which I need to get right still) . I didn't want to get it wrong as Id have to make another frame then from scratch. But I think I got it ok. I went with a larger hole than the mock up just so I can have some more wiggle room. It wont look as nice but it will do for me.

Once I figure all that out I'll need to do some clean up work on the Base and top plate frame so the suspension
will not be impeded. Then adjust the suspension some more and then wiring up the arms and motor which I had to rebuild.


So far I think Its coming along nicely.

Athanasios

Very nice work , who would have thought a 2 arm XA could come together so nicely. Looking forward to the rest of the build and finished product

Audiofreak71

 

[Nashou66]

Very nice work , who would have thought a 2 arm XA could come together so nicely. Looking forward to the rest of the build and finished product

Audiofreak71

Thanks @Audiofreak71 . The sub chassis isn't the best looking and I think I could have come up with something else and not have to chop up the other sub chassis. But it was already cut so I said what the hell. Also its not neatly done as I do not have metal milling tools. Just a drill press , saws all, a Dremel and other hand tools. I know I could have done better if I had the proper machinery . The base isn't perfectly square so the top plate frame and it has some small gaps.

I'm excited to get it wired up to see how it works together. But the mounting of the RB-300 arm is what will be a trying endeavor . The wood mount I made got messed up and it's not even now, as I tried to sand it down to lower the VTA but that messed up the azimuth . I also noticed I have some more grinding to do on the sub chassis where it sits. I left some raised edges throwing it off.

But its coming along slowly.

Nashou

 

[Andre Garcia]

This is a nice project.
There is a lot of things involved and you need to make it work. Dont surprise if sound horrible at first, probably there is more fine tuning to do.
But well done and congratulation to have the encourage to do it! At the end this TT will be unique.
AG.

 

[Audiofreak71]

Thanks @Audiofreak71 . The sub chassis isn't the best looking and I think I could have come up with something else and not have to chop up the other sub chassis. But it was already cut so I said what the hell. Also its not very neatly done as I do not have metal milling tools. Just a drill press , saws all, a Dremel and other hand tools. I know I could have done better if I had the proper machinery . The base isn't perfectly square so the top plate frame and it have some small gaps.

I'm excited to get it wired up to see how it works together. But the mounting of the RB-300 arm is what will be a trying endeavor . The wood mount I made i messed up and its not even now as I tried to sand it down to lower the VTA but now I messed up the azimuth . I also noticed i have some more grinding to do on the Sub chassis
where it sits. I left some raised edges throwing it off.

But its coming along slowly.

Nashou

Practice makes perfect, you will get it squared away. Definitely can’t wait to see how this turns out, this is a very cool build .

Audiofreak71

 

[Andre Garcia]

Practice makes perfect..
Audiofreak71

Absolutelly!
AG.

 

[Nashou66]

Today I spent most of the afternoon into the evening getting it ready to make sound. Rewired the AR arm with 1877 Phono tonearm wire. Repaired the Rega
RB-300 arm wire as I ripped it out trying to remove the RCA's .

I also forgot to get a terminal block each of the three times I went to Home Depot today ...DOH!!!
So I made my own with some wood and some bare copper wire, I should have used a thinner gauge. It was a bitch to get hot to melt solder.

I still need to make more room for the sub Chassis to move more freely. It's hitting one of the mounting plates by the RB-300 arm extension .

I also need proper RCA's for the XA arm, I am using those throw away( I save mine for such reasons) RCA's that come with VCR's .
And I might use some of the Mogami cable to replace the stiffer Rega cable.

I also used walnut restore a finish and feed and wax for the top plate wood frame. I did not want that to be glossy.

Here are some pics of the work done today.

And a little video of both arms working .

Athanasios

 

[Audiofreak71]

Today I spent most of the afternoon into the evening getting it ready to make sound. Rewired the AR arm with 1877 Phono tonearm wire. Repaired the Rega
RB-300 arm wire as I ripped it out trying to remove the RCA's .

I also forgot to get a terminal block each of the three times I went to Home Depot today ...DOH!!!
So I made my own with some wood and some bare copper wire, I should have used a thinner gauge. It was a bitch to get hot to melt solder.

I still need to make more room for the sub Chassis to move more freely. It's hitting one of the mounting plates by the RB-300 arm extension .

I also need proper RCA's for the XA arm, I am using those throw away( I save mine for such reasons) RCA's that come with VCR's .
And I might use some of the Mogami cable to replace the stiffer Rega cable.

I also used walnut restore a finish and feed and wax for the top plate wood frame. I did not want that to be glossy.

Here are some pics of the work done today.

And a little video of both arms working .

Athanasios

Very nice

Audiofreak71

 

[Nashou66]

My parts to finish the build came in the other day and I began to get ready for installing them.
The feet, Mogami cable and new .1uf cap.

The cap went in and no go, so back went he 1uf cap as it at least will spin the motor, with the proper value cap it doest move.

The night the parts came I cut the corner pieces for the feet mounting. Drilled the holes for the wood threads. and installed the feet.

Then I made the new cable from the wire tree to the SUT. I used some Old audioQuest connectors and
the quad Mogami microphone cable . I was using a cheap VCR audio cable but was getting hum which I assumed was because of that.
I was correct!!! With the Mogami W2893 microphone cable I have no motor hum I was getting before when I turned the motor on.
I highly recommend this cable, its very flexible and narrow so its easy to maneuver behind the rack. And has pretty good specs I think, if there are
others with more knowledge of cable theory I would love to here what they have to say about the specs.


Here are the specs.

These are the feet used.

Installed

Here is an underside pic of what else was done. I used some copper tape to wrap the motor and go over
some of the AC wiring , Not sure if it worked but why not? I had the tape for other projects I never got to when I was
fixing CRT projectors. I also used a ferrite choke . Also you can see where the Mogami cable goes right out the back
if the plinth base.

And the Back side of the Mogami cable exit .

This if for now. I want to make my own dust cover too. That should be a fun project.


PS, Did i mention how quiet that Mogami Cable is!!!!

Athanasios