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

[sonddek]

So you think using two bits of Sellotape to attach a thread would be better than just using the Sellotape, really, think about it?

What do you think would be harder to pull off sideways, the string under a bit of Sellotape or the Sellotape?

I recommend using a long bit of tape and a long bit of thread under it.Here's my picture again to make clear what I'm talking about:

You can even put a few knots in the thread in case that improves holding power. Apply the thread to the tape in a taut line and fasten the tape to the armboard with the tape reaching right to the corner. If you pull the thread you should see that it holds quite well. I then use the thread to pull the subchassis away from the motor, and fasten it down on the plinth corner and down the side of the plinth. Use a finger nail along the tape around the thread to make sure it has a good grip. This method helps to ensure that elastic extension of the thread occurs only in the short section which bridges the gap, i.e. the few mm between armboard and plinth. The shortness of the span is important as it should reduce the amplitude of resonance in the thread. Hey presto, tuneless pianos fixed.

You should probably unclamp your arm before doing this as that might loosen the tension in the thread. When you cue the arm you should notice much better sub-chassis stability with the thread in place. Cue gently to maintain tension in the thread.

You can experiment with different tensions. Depending on your set up you should find that increased tension produces increased pitch stability but worse timbre and air. I usually find that only a mm or so of displacement is needed for most records, but you'll know when it's not enough as you can sometimes hear an ugly pitch wobble when the sub-chassis wants to move enough to slacken the thread. That's even worse than without the thread. The more tension there is in the thread, the more timbre seems to go to b***ery. So you need the least tension that stops pitch wobble. 2mm of displacement should be a good starting point.

The problem with taut tape across the gap is that it will be fairly stiff in the horizontal shear direction, and therefore should transfer that mode of noise to the sub-chassis more effectively than the thread, which only has one axis of stiffness.

 

[Item Analogue]

The Two offending LP12's have been down to Hi-Fi World for review last week, both armboards ended up with 3 x M3 Csk bolts fixing them to the respective subchassis, and the standard Ittok LVIII was swaped between them with my Benz Micro Glider in it.

I was there for the demo with the Journalist and things went OK, there were clear and positive differences to be heard, I'm not sure what Noel Keywood will think though, but you can bet he will make some quantitative observations. The review is due out in the Jan Issue.

See you all at the news stand . . .

 

[Item Analogue]

It occurs to me now that we have a fixed dimensional relationship between motor and platter, that we could experiment with non strechy drive belts, perhaps some old quater inch mylar audio tape might be an early contender, oxide 'in' or 'out' anyone?

Hope everone is still ok out there

As a pithy previous contributor noted, we'll soon have this LP12 fixed . . .

 

[Paul R]

...have a fixed dimensional relationship between motor and platter...

Except that you don't.

FWIW I have a recording of the Ultimate Analogue test record 'rumble' track with 'free' LP12 and with the sub-chassis restrained by Sonddek threads. It would be interesting to see what the effect of the spokes are. Can you do this? I'll show you mine etc.

Paul

 

[sq225917]

No, You're wrong Paul. I think you'll find it doesn't move at all. ;-)








cont on page 42... lol.

 

[Item Analogue]

Except that you don't.

FWIW I have a recording of the Ultimate Analogue test record 'rumble' track with 'free' LP12 and with the sub-chassis restrained by Sonddek threads. It would be interesting to see what the effect of the spokes are. Can you do this? I'll show you mine etc.

Paul

Hi Paul, I don't have this test recording but I would expect that it would show that some motor noise from the top plate is now being transmitted by the spokes, and likely as not, that wow and flutter is also worse as the cartridge is now better able to extract more energy from the platter during heavy cuts. I would not expect these figures to be of a very much higher order, but I would expect a worsening of a dB or so? I expect Mr Keywood will answer this question in his tech analysis in the forthcoming copy of his magazine.

I would still contest that the Turntable sounds much better even whilst probably measuring 'worse' in a conventional sense. I would urge people to try and free their minds to imagine the mechanical issues I am tring to address, and then try to get to hear one of the modded LP12's.

I have just 'spoked' an Ariston RD11s and an RD 80 too, and am now working on a Thorens TD 160.

Gary H.

 

[sonddek]

I have been giving this excellent spoke idea some thought, and were I to spoke my deck I would want the fixings to be less than a centimetre apart, still tangential, and tied together with a tensioned Kevlar filament. That way motor yank is still countered by tension in the threads, but less noise is transferred to the subchassis.

 

[sq225917]

That's a game of two halves, less vibration transmitted through the thread and probably a little less stable as well.

I'm surprised that we haven't yet seen one of the many Spoked LP12's that must now be out there in the market making an appearance in the turntable speed stability thread. That is its reason d'etre after all is it not? Surprised the designer isn't keen to show the improvements...