Item Audio "Spoke" for the Linn LP12 anybody..?

[PlattenFantast]

Just saw this: http://www.itemaudio.co.uk/linn_lp12_modification.html

Anybody here tried it? It would seem that this mod is supposed to counteract the possibble rotational movement of the subchassis, only allowing for a clean vertical bounce.

 

[muzzer]

£99 for the kit, or £399 including fitting, is that a typo?

 

[YNWOAN]

Hmm..not seen that before - but it is, effectively, bypassing the suspension.

 

[pure sound]

As records are cut in both the vertical and horizontal planes you need isolation in both planes. Eliminating isolation in the horizontal plane is not the smartest idea but then having a motor pulling against a suspension system in that plane isn't such a great idea either. The limited horizontal isolation that there is will just be reduced further by this.

 

[Paul R]

£99 for the kit, or £399 including fitting, is that a typo?

£99 looks a lot for the bits. £399 looks reasonable including the fitting since it appears to involve complete dismantling and drilling of both the subchassis and top plate.

Ill conceived though, IMO.

Paul

 

[djftw]

Mark (and Andrew), How about a Rubikon with a mount for the Radical motor? That would seem the obvious solution to me - if Linn's spiel about the Radical is not overly influenced by the marketing department it seems to me that the motor should, in addition to the claims they make, be quiet enough that any remaining advantage of having the motor isolated from the sub-chassis would be outweighed by disadvantages of the rotational pull on the suspension. Some top plate modification might be needed to accommodate that too I guess. I imagine radical owners interested in a non-Linn sub-chassis would be a small market thought...

 

[flatpopely]

djftw.

There are some things on the horizon that may be of interest, Some by us, some not.

Stay tuned in the 'Trade' room.

Andrew

 

[sonddek]

This looks like a very cunning and well designed piece of engineering to me. Rotation of the sub-chassis should be pretty much eliminated, while some degree of vertical isolation is still retained. Of course it can't solve the stretchy-belt/heavy-platter problem, but at least it can stabilise the suspension system horizontally. I would love to hear this demonstrated in two otherwise identical decks.

 

[flatpopely]

sonddek, you are 100% bang on; listening to two identical decks, apart from the mods, is the only way to do it!

Andrew.

 

[sq225917]

They are round spars, equally strong in all directions, so any change in horizontal compliance will be matched in the vertical plane. You may as well just get a quiet motor a proper turntable support and bypass the suspension altogether. ;-)

 

[colasblue]

Mark (and Andrew), How about a Rubikon with a mount for the Radical motor? That would seem the obvious solution to me - if Linn's spiel about the Radical is not overly influenced by the marketing department it seems to me that the motor should, in addition to the claims they make, be quiet enough that any remaining advantage of having the motor isolated from the sub-chassis would be outweighed by disadvantages of the rotational pull on the suspension. Some top plate modification might be needed to accommodate that too I guess. I imagine radical owners interested in a non-Linn sub-chassis would be a small market thought...

Its already been done (sort of) and is called the funk kit. Ok it isn't a radikal motor its Arthur's own but its a definite upgrade.

How good VFM any of the LP12 upgrades are is in my view questionable. My new orbe/graham cost less than any of the rated ones, leaves my 2001 LP12 in the dust and I've got a whole TT not just a couple of bits for the old one.

 

[zener]

It looks like its making the top plate stiffer , why not just make a stiffer top plate , I recon the new subchassis has taken care of the need for a flexy top plate , the LP12 is slowly morphin into a solid deck TT

 

[flatpopely]

It looks like its making the top plate stiffer , why not just make a stiffer top plate , I recon the new subchassis has taken care of the need for a flexy top plate , the LP12 is slowly morphin into a solid deck TT

boing said zebedee!

mine still wobbles Jon

 

[zener]

so the secret is to keep the vertical boing and reduce the sideways flex ie stop the bolt from twisting the top plate , which this thing might do. said zebedee

 

[sonddek]

It looks like its making the top plate stiffer , why not just make a stiffer top plate , I recon the new subchassis has taken care of the need for a flexy top plate , the LP12 is slowly morphin into a solid deck TT

I think you have misunderstood the photograph. It looks to me as though one end of each rod is attached to the top-plate, and the other end of each rod is attached to the suspended chassis. The purpose of such an arrangement would be to stop the suspended chassis from rotating in the vertical axis of rotation, which it is prone to do as soon as the belt tries to do its job, i.e. accelerate the heavy platter.

It is an effort to address one of the fundamental design flaws of the sondek, which is that the elastic belt and suspension springs both introduce considerable elastic stores of motor energy, thus obstructing smooth and rapid transfer of motor energy to the platter where it is needed. This device solves the spring problem by stopping the springs from absorbing torque in the vertical axis of rotation.

They are round spars, equally strong in all directions, so any change in horizontal compliance will be matched in the vertical plane. You may as well just get a quiet motor a proper turntable support and bypass the suspension altogether. ;-)

If the rods are attached to the top-plate at one end, and the subchassis at the other, then they will do little to inhibit vertical motion, due to the elasticity and length of the rod. They will however oppose movement of the subchassis in the vertical axis of rotation, since the rods will not stretch horizontally nearly as much as they will flex vertically. It's a clever design.

 

[sonddek]

BTW, considering holes must be drilled in both subchassis and top-plate, £399 doesn't seem altogether unreasonable, especially considering someone invented this. Call it £100 for parts, £100 for disassembly, drilling, reassembly, and £200 for the "research and development". Don't forget Linn charge £2000 for the research and development that went into the Keel, and that's a much less imaginitive idea.

 

[zener]

yes i see , the last photo is of a bolt , that is fitted to the subchassis and connect via the spoke to the top plate bolt. If it sound better then it flies in the face of Ivors ideas Its heading toward a solid plinth.

 

[sonddek]

yes i see , the last photo is of a bolt , that is fitted to the subchassis and connect via the spoke to the top plate bolt. If it sound better then it flies in the face of Ivors ideas Its heading toward a solid plinth.

Ivor did not design the Sondek suspension (if at all) to rotate in the vertical axis. It is an unfortunate side-effect or flaw of the vertical suspension system. This invention completes the basic Thorens/Ariston idea by reducing the side-effect. It may increase the transfer of noise to the platter though.

The point is that this rod system is specifically designed to retain as much vertical bounce as possible while curbing subchassis rotation. It is not intended to turn the deck into a solid chassis system as you suggest.

The rods will actually introduce a subchassis rotation all of their own, since their horizontal length will change during a bounce. However, the subchassis is not meant to bounce far during use, so the effect will be infinitessimal.

 

[dave]

I think you have misunderstood the photograph. It looks to me as though one end of each rod is attached to the top-plate, and the other end of each rod is attached to the suspended chassis. The purpose of such an arrangement would be to stop the suspended chassis from rotating in the vertical axis of rotation, which it is prone to do as soon as the belt tries to do its job, i.e. accelerate the heavy platter.

That's how I'm interpreting the photo. Basically, two vertical posts-one mounted to the top plate and another anchored to the subchassis with a rod passing through both. Vertical suspension movement allowed but not rotational movement. Interesting...

 

[James]

It's the classic panhard rod concept. Regardless of its operational simplicity, I strongly suspect that springs with opposing 'twist' will still need tuning-in to optimise the vertical bounce and for the LP12 magic to surface.