New Solid Aluminium Platter for the SL1200

[MartinT]

The Michell TecnoArm also has holes in the arm tube, only not so visible as they are all on the underside.

[DSJR]

The tecnoArm has "slots" I believe, which may not be quite the same thing in measurement terms. FFS, there's only ONE main resonance in the arm pipe at around 900Hz IIRC. Surely there are ways of finding out where in the assembly this occurs.

I also believe that Les at Avondale dealt with this resonance by a tensioned long bolt fixed at the cartridge end and down the inside of the tube and screwed into the bearing block, thus making the whole assembly inert..

[Stratmangler]

You're mixing up the Technoarm with the Origin Live, Dave - the Technoarm deifinitely has holes.

If you look on the OL site you'll see that one of the models there has slots cut into the underside.

[MartinT]

Yes, deffo holes not slots. I have one here which I must put up for sale.

[DSJR]

Apologies... I believe Noteworthy Audio have ceased trading in their previous form. there were loads of great pics there and I was working from memory.

Yes, the TecnoArm seems to have TWO rows of *holes* at 45 degrees to each other on the arm underside..

[pure sound]

Noteworthy Audio are now Deco Audio

http://www.decoaudio.com/

Peter Empson is still there

[DSJR]

Thanks Guy, I liked the fella's there when I used to call on them back in Jonathon's day and was sad to hear of their apparent demise.

Some great pics there, but I'm feeling very low as many things I knew well have doubled in price in twenty years and income is lower.... Much of the increases seem to have been in the last five years or so as well.

[Avondale Audio]

The tecnoArm has "slots" I believe, which may not be quite the same thing in measurement terms. FFS, there's only ONE main resonance in the arm pipe at around 900Hz IIRC. Surely there are ways of finding out where in the assembly this occurs.

I also believe that Les at Avondale dealt with this resonance by a tensioned long bolt fixed at the cartridge end and down the inside of the tube and screwed into the bearing block, thus making the whole assembly inert..

Quite true and after much investigation, I've come to the conclusion that this is the only way to control resonance - take it up out of harms way. The new arm I'm currently developing uses just this stategy - a high tension bicycle spoke down the centre of a titanium tube. For bright cartridges, a carbon fibre armtube is preferred by some but still using the tension bolt down the centre - it works a treat. The new tonearm will soon be ready for beta testing as Jeff has managed to make several for just this purpose. For those who don't know how it works, here goes:

Lateral bearing; A micro ground and hardened tungsten shaft of some 3mm diameter is supported by two line-reamed sintered sleeve bearings some 40mm apart. A 3mm shaft is quite sufficient to support the arm assembly with very little surface speed and therefore friction. The top of the shaft is constrained by two opposing ring magnets as is the lower end of the same shaft. The result is that the shaft is going nowhere once the magnetic forces have settled out. There is little hard metallic contact between the shaft and the constraining bearings and so spins freely with little friction evident.

Vertical bearing(s): A pair of hardened steel pins some 20mm apart which locate downwards into bearing cups a la the ubiquitous unipivot. Where this design differs from the unipivot is that the vertical pivot point can be exactly on a horzontal line with the stylus tip leading to much better stability when riding warps for instance. Being twin 'unipivots', a contradiction in terms I appreciate, there is none of the 'rock' under dynamic conditions known to plague unipivot designs.

Results: The prototype arm is brilliant at tracking band four of the Hi Fi News torture record. I've yet to find a commercial arm that will cope even with band three let alone band four. Surface noise is in another world...even major scratches are treated with the same confident tracking with no 'aftertones'.

Future: I intend to publish drawings of this arm for home constructors - it's too exciting to just to end up as a blue chip product for some major manufacturer and really deserves to be enjoyed by vinyl lovers all over.

Once I figure how to upload images, I'll post some links to let you all have a shuftie and perhaps be kind enough to give me a spot of feedback.

All the best each,

Les

Here you go: http://img12.imageshack.us/i/p8120113.jpg/ Proud Father of the first tonearm: http://img22.imageshack.us/i/p8120107.jpg/

What I hoped it would look like back in 1999: http://img196.imageshack.us/i/magnetrak.jpg/

[SteveW]

Les..
Sometimes life is stuffed to the gunnels with synchronicity, which as it was the worst Police album I ever had, I hope this isn't the case...but tis g'zactly what I'm lookin for.

Thankyou.

[DSJR]

The "double pin" vertical bearing was used on the excellent Sony PS 8750 (I suspect a real Techie basher in the sonic stakes, but never had the chance to compare directly). I think though that the Sony had upward facing pins...

As I'm sitting down (!) any ideas on proposed retail prices???