LP12 arm collar r armboard bolt tension level

[Colin131]

I’ve been tweeking my older pre cirkus LP12 and have found the tension of the arm collar bolts that go into the MDF armboard affect the sound quite a bit. It you do then you tighter the sound is also tighter and more detailed but maybe less musical. Done up ok but looser it’s more musical but you loose detail. Anyone ideas of the exact recommendation? Slightly adjustments seem to make a difference too. This is the arm collar bolts.

I remember in that past Linn used to say the armboard is a loosy connection and you shouldn’t do it up tight, but I think that referred to the smaller armboard to subchassis screws. How about the armboard bolts? They do come looser over time as they sink into the MDF too.

Any advice would be much appreciated. How tight should the armboard screws be too? Only just enough to hold it or done up a bit tighter than that?

 

[Mynamemynaim]

Linn tight ?

 

[Colin131]

Linn tight ?

Then you’d break the armboard wouldn’t you??
Even if you do up tight later on it gets loose due to the armboard being MDF (or plywood if you have an earlier armboard)

 

[John]

Do you have a Linn setup manual? The subject is covered pretty clearly in the 1998 manual.
You can download it from the Vinyl Engine website. You may need a login to do so.

https://www.vinylengine.com/library/linn/lp-12-sondek.shtml

 

[Colin131]

Do you have a Linn setup manual? The subject is covered pretty clearly in the 1998 manual.
You can download it from the Vinyl Engine website. You may need a login to do so.

https://www.vinylengine.com/library/linn/lp-12-sondek.shtml

Thanks. I looked and it says to tighten bolts up to the point that the serrated washers sink into the armboard. I think I’ve been doing it too tight. Will adjust and might have to use a different armboard.

 

[colasblue]

Depends on which type of armboard you have.

With the later and better laminated ones you can definitely overdo it and crack the surface in which case your armboard is toast.

The older particle board ones are different and "Linn Tight" is OK, but if you have one of those just junk it and get a new one and revel in the improvement for little money!

 

[Colin131]

Depends on which type of armboard you have.

With the later and better laminated ones you can definitely overdo it and crack the surface in which case your armboard is toast.

The older particle board ones are different and "Linn Tight" is OK, but if you have one of those just junk it and get a new one and revel in the improvement for little money!

Thanks for the info. I have quite a few different armboards already. The one I like the sound of most is the single layer MDF one with black top and bottom laminated. Probably from about 1989 onwards. I didn’t like the sound of the newer triple sandwich types (too clinical) , but then again maybe I was doing this bolts up too tight.

When you talking about going Linn right is that regarding the earlier MDF type from about 1987 that has no bottom black laminate but is still MDF?

There is also the earlier plywood armboards. I would assume going tight on those is ok too? Those have a less detailed sound than MDF but can sound warm and smooth.

One thing I noticed about the single layer top and bottom laminated MDF boards is there are two types, one is lighter and the other is heavier. I’ve weighed them. Not sure why that would be or which one is supposed to be better?

 

[Beobloke]

If you really think it makes a difference, why not just tighten them until you get the sound you like?

 

[Colin131]

If you really think it makes a difference, why not just tighten them until you get the sound you like?

Can do, but then after a while, not long, the bolts get loose!

 

[Chops54]

Put some Wellseal or similar sealing compound on the threads. This is non setting but will stop the bolts from working loose.

 

[Colin131]

Put some Wellseal or similar sealing compound on the threads. This is non setting but will stop the bolts from working loose.

Thanks. I explained it in a bad way. I’m pretty sure the bolts don’t get loose themselves, they just sink into the wood and seem to loosen after a while. This is normal, and I think you have a tighten up a little. I’m gong to look at it properly tomorrow. Might have to replace the armboard. Maybe the heavier type MDF one is less prone to the bolts sinking in?

 

[Chops54]

What about tightening the bolts up enough to fully compress the arm board and leaving it like that for a while? Once the arm board has reached full compression you should be able to loosen the bolts and retighten as required.

 

[Mr Pig]

On the loose side is better than too tight. If you overtighten the fasteners on the LP12 it sounds pants. I don't have any torque settings for the LP12 but to give you an idea the arm fixing bolts on Rega arms should be 2nm. Which is not a lot.

 

[Chris]

So, to my simple mind, if I had a Keel with/without a Karousel, with or without a Radikal, would I also benefit from a certain amount of tightness/looseness on my arm base bolts and my arm height adjuster bolt, not to mention my cartridge screws ? If I didn´t believe in magic I would say it is all a ginormous piss-take ? Anyone for a Houdini ? I love my 25 quid blue belt.

 

[david ellwood]

The Keel doesnt have arm base bolts, but if it did, Id have them tight.

All this talk of loose connections being more musical is arse imo, Not saying they should be over tightened, just done up properly.

 

[Chops54]

All this talk of loose connections being more musical is arse imo, Not saying they should be over tightened, just done up properly.

I’m with you David but if someone prefers the sound of their turntable with the arm mounting bolts just nipped up then who are we to disagree?

 

[Mr Pig]

If I didn't´t believe in magic I would say it is all a ginormous piss-take?

Why? Nothing magical or complicated about it. If you deform the material you alter the way energy/resonance transmits through it and many people overestimate how much force is needed to make a fastener tight. That's pretty much it.

 

[Colin131]

The Keel doesnt have arm base bolts, but if it did, Id have them tight.

All this talk of loose connections being more musical is arse imo, Not saying they should be over tightened, just done up properly.

I’ve experimented a lot with this recently. My verdict so far is that a bit looser is definitely more musical for these arm collar bolts, into a standard Linn armboard with steel subchassis, - however the sound gets more focused and clear when it’s tighter. It’s a question of getting the correct tightness and small adjustment seems to make a difference from my listening. However of course, over some time the MDF will compress causing the bolts to appear loose and things might change!


The older plywood or particle armboards are more musical still but a bit soft in the treble. Not as detailed or crisp as the MDF ones.

 

[Colin131]

On the loose side is better than too tight. If you overtighten the fasteners on the LP12 it sounds pants. I don't have any torque settings for the LP12 but to give you an idea the arm fixing bolts on Rega arms should be 2nm. Which is not a lot.

Thanks for this. So that includes the arm collar bolts (and I totally agree on that after experimenting) , which others too?

 

[Mr Pig]

Thanks for this. So that includes the arm collar bolts, which others too?

Most of the bolts on the LP12 are best done up to the correct tightness. By correct I mean the tightness that would typically be right for a bolt or screw of that type.

It's quite easy to demonstrate how to judge bolt tightness by feel but it's harder to explain over the net. But feel is the best way to do it. Yes, you can use a torque wrench, if you have one that is accurate at low values, but with little bolts and screws you can feel when it's right more easily with your fingers.

Find something you can practice on. I used to show people on an old bike stem. It doesn't matter what it is, the principal is the same. Thread the bolt or screw in until it 'lands', until it gets to the point where any more rotation is tightening it. From that point the majority of bolts will want about a quarter of a turn but you can feel it. The amount of resistance you'll feel for that quarter of a turn will feel constant and then it will get to a point where the resistance will start to change. Depending on the type of screw and what it's going into either you'll feel that much more force is needed to turn the bolt or, strangely, that it's turning more easily. What is happening is that either you're now starting to try and deform the materials or they are weak enough that they are failing easily. Either way, you are going to far and if you continue you risk damaging something.

As long as you don't strip the thing you can tighten up and undo a bolt lots of times getting a good feel for it. Then just translate that onto the bolts on the LP12 and you're good. It might feel strange at first as you don't think you're doing the bolts up very tight but you are. The tool is multiplying your force.

I said almost all of the bolts on the LP12, there are exceptions. The hanger and plinth mounting bolts on the standard top plate, do those fechers up proper tight! Because if you don't, they can come lose when you're tightening the spring and plinth fastening nuts. Especially if you're using very tight locking nuts. Both the bolts and nuts are steel so will take a good old tighten. If you're using an alloy top-plate I'd thread lock the rods into the inserts for the same reason.