LP12 arm collar r armboard bolt tension level
- Thread starter Colin131
- Start date
Sounds reasonable. Rega arm mounting bolts are 2nm but that's going in from the top against an alloy foot. Seen a lot of cracked armboards.
13th Duke of Wymbourne
pfm Member
Er yes, there was much discussion on the WAM about LP12 torques (mostly from T O'K). I'd been waiting for months to use the suspension nut torque as an April Fool there but I couldn't because of the WAM demise so I used it here. Sorry.
Well it was hilarious so the wait was worth it.
lencotweaker
Mostly dreaming of record players
Wam is still working. You may have to log out and back in but otherwise it’s still up and running.
13th Duke of Wymbourne
pfm Member
That worked, seems nothing happened while I was away.
My 1984 LP12 had the original mdf armboard but it bent after decades of supporting the weight of the Ittok so the azimuth was way out. The problem with the early steel kite shaped sub chassis is that the arm is completely supported on the end of the armboard dangling in mid air! Also, the bearing can distort the chassis where it’s mounted causing misalignment of the platter.
So I bought a second hand cirkus aluminium sub chassis and an Audio Classique ceramic armboard.
Now the biggest hassle in setting up an LP12 is aligning the armboard in the plinth cutout while simultaneously getting the bounce correct. This involves twisting the springs which I’ve never thought was a good idea and can take hours. So what I did was enlarge the 3 arm collar screw holes in the subchassis to 7mm and the arm rest pillar hole to 10mm, giving some wiggle room. Then all I had to do was set the springs central and in their natural position without any twists etc, set the height, align the armboard in it’s cutout then tighten the bolts. Dead easy, faff free and the bounce was automatically correct.
After this I fitted a new cart and took great care with the set up. The result was far better sounding, very detailed but maybe a little dry / hard sounding and lost quite a bit of its warmth.
So thinking about this thread I tried loosening the arm collar bolts but it didn’t make much difference.
Finally I cured the issues with the sound by cutting out a piece of thin card to the shape of the armboard with holes where all the bolts go through. Now the armboard is basically mounted with a piece of card sandwiched between it and the sub chassis, The bolts are just finger tight (Tony L is a great believer in finger tight bolts on turntables). Sounds just wonderful now, all the original warmth and super detailed. I think this is how an LP12 should sound.
Oh and a blue belt helps a lot too.
Was a complete newbie to LP12s a few months ago but by no means an expert now.
So I bought a second hand cirkus aluminium sub chassis and an Audio Classique ceramic armboard.
Now the biggest hassle in setting up an LP12 is aligning the armboard in the plinth cutout while simultaneously getting the bounce correct. This involves twisting the springs which I’ve never thought was a good idea and can take hours. So what I did was enlarge the 3 arm collar screw holes in the subchassis to 7mm and the arm rest pillar hole to 10mm, giving some wiggle room. Then all I had to do was set the springs central and in their natural position without any twists etc, set the height, align the armboard in it’s cutout then tighten the bolts. Dead easy, faff free and the bounce was automatically correct.
After this I fitted a new cart and took great care with the set up. The result was far better sounding, very detailed but maybe a little dry / hard sounding and lost quite a bit of its warmth.
So thinking about this thread I tried loosening the arm collar bolts but it didn’t make much difference.
Finally I cured the issues with the sound by cutting out a piece of thin card to the shape of the armboard with holes where all the bolts go through. Now the armboard is basically mounted with a piece of card sandwiched between it and the sub chassis, The bolts are just finger tight (Tony L is a great believer in finger tight bolts on turntables). Sounds just wonderful now, all the original warmth and super detailed. I think this is how an LP12 should sound.
Oh and a blue belt helps a lot too.
Was a complete newbie to LP12s a few months ago but by no means an expert now.
The Original MDF arm-board bent because it was only painted on the top surface. The unsealed side absorbed moisture, expanded and the board bent. Later arm-boards which have multiple laminates don't bend.
What you're saying doesn't make any sense. The springs do not have a 'natural central position'. They pull to one side. You rotate them until they pull away from each other and cancel each other out. It's a fairly simple process and usually pretty quick if you've got a flat sub-chassis and have set the hanger bolts correctly. What you've done is more complicated, unnecessary and I can't understand how there is any advantage to it at all. It just sounds like you don't understand how the suspension works.