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

darrylfunk said:
yes, if you analyse the design.
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Be our guest. You shed no extra light on it last time though. It's a motor whose housing can rotate against a spring. When the stylus slows the record, the spring stretches until the delta in its extension balances the additional motor slowing force. As the platter starts to catch up again, the spring energy is released into the platter again. It probably hunts, or at least accelerates past correct speed. No magic there, and no miraculous ability to avoid subsonic wow either. A powerful motor driving a light platter ruled by a well designed feedback mechanism is certainly a better scheme for avoidance of wow than the Roksan or Sondek with their spongey power delivery.
 
sonddek said:
Be our guest. You shed no extra light on it last time though. It's a motor whose housing can rotate against a spring. When the stylus slows the record, the spring stretches until the delta in its extension balances the additional motor slowing force. As the platter starts to catch up again, the spring energy is released into the platter again. It probably hunts, or at least accelerates past correct speed. No magic there, and no miraculous ability to avoid subsonic wow either. A powerful motor driving a light platter ruled by a well designed feedback mechanism is certainly a better scheme for avoidance of wow than the Roksan or Sondek with their spongey power delivery.
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i will contribute more when you can show me an audio recording of a roksan wowing in comparison to a sondek.....

like i say when you apply a constant couple of grammes of cartridge tracking pressure on a roksan platter the spring doesn't swing the motor back and forth like you have said in your assumptions of how it behaves under a cartridges drag.
 
sq225917 said:
Is the Roksan really anything more than a light motor heavy flywheel deck with an interesting physical clutch arrangement for the motor?
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Yes but that's to ignore the very carefully designed and unique, tuned layered suspension system.

The clutch system is very effective whether evaluated through listening for pitch accuracy, or wow measurements for the deck.

I think until someone supplies meaningful measurements to back up their claims re Sondeck, Xerxes or Technics the arguments will remain unsubstantiated.

mat
 
sonddek said:
I have no idea. It doesn't matter. The job of the motor is to render variations in speed, whatever their origin, so small that they are inaudible. The oscillatory effect of oscillating stylus drag may be underestimated. Placing resonant springy reservoirs between motor power and its intended destination serves to lower the frequency of speed oscillations, but it mightn't make them less musically destructive. If critically damped, power damping springs may sound preferable to hunting or prolonged excursion from correct speed, but that's no substitute for rapid recovery of correct speed (e.g. Technics). A motor unit ought to be powerful enough to ride rough-shod over the stylus's efforts to change record speed. Feeble motors with damped energy transfer aren't a great way of avoiding low frequency wow, even if they are good for suppression of motor noise.
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But with a heavier flywheel type platter you won't get speed variations anywhere near those of a lightweight platter whose motor is constantly compensating for speed changes, so what is going on at the motor end of both turntables is not directly comparible.

mat
 
mmaatt said:
But with a heavier flywheel type platter you won't get speed variations anywhere near those of a lightweight platter whose motor is constantly compensating for speed changes, so what is going on at the motor end of both turntables is not directly comparible.
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Agreed. However, I suspect that deceleration of platters like those on the Sondek and Roksans is more audible than people assume.
 
mmaatt said:
I think until someone supplies meaningful measurements to back up their claims re Sondeck, Xerxes or Technics the arguments will remain unsubstantiated.

mat
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Well yes, I quite agree. As fate would have it, just such a thread exists on this very forum, in the DIY section; unfortunately, neither Roksan nor Technics owners have chosen to take part - so far (hopefully they will change their minds).

sonddek said:
A powerful motor driving a light platter ruled by a well designed feedback mechanism is certainly a better scheme for avoidance of wow than the Roksan or Sondek with their spongey power delivery.
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To be blunt, that's pure conjecture.

None of the measurements I have done have supported the idea that stylus drag is the issue that this thread seems to believe. I am not saying that issues do not exist within TT drive systems, but I am saying that relative to other forces acting within the system, stylus drag is a relative constant. I do think the speed of TT systems is prone to modulation, but I do not believe that variations in stylus drag are the primary source.

However, one should be wary of attaching blanket statements of belief regarding performance to any specific element of the drive system, as no individual part can be truly considered in isolation.
 
I submitted SP10 & EMT DD needledrops earlier on. However, it is an analysis of behaviour under a static (test tone) load & seems to show up characteristics of motor (& rotating parts). I don't think it is yet capable of showing what might occur when a constant tone is reproduced while the 'load' is varying.
 
Sorry, I know you did Guy - I was thinking of 1200/1210.

I agree with you regarding the methodology. When I get a chance I will set up a second arm to play another part of the record. However, I suspect that each cartridge will be able to 'hear' each other via the record, I wonder how much this will corrupt the results.
 
mmaatt said:
But with a heavier flywheel type platter you won't get speed variations anywhere near those of a lightweight platter whose motor is constantly compensating for speed changes, so what is going on at the motor end of both turntables is not directly comparible.

mat
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There's little evidence so far in those measured decks to show platter mass to be a defining factor. And is t5he Roksan really that different from the LP12 platter, how much more than the LP12 platter do people think it is.
 
Just found it, 2.155kg, it's no bloody heavier at all. In fact it's barely half the weight of the LP12 3.75kg outer platter. Time to think again boys, you have a platter about the same weight as a Rega glass platter, so the claims for flywheel simply don't add up.
 
sq225917 said:
Just found it, 2.155kg, it's no bloody heavier at all. In fact it's barely half the weight of the LP12 3.75kg outer platter. Time to think again boys, you have a platter about the same weight as a Rega glass platter, so the claims for flywheel simply don't add up.
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I know the Roksan platter is lighter; that was an intentional part of the design when Touraj was first conceiving the Xerxes and how to improve on an LP12. It does however concentrate its mass around the outside of the platter to optimize the flywheel effect and hence falls into the inertia type category. I'm not an expert but I'm sure that the mass of the Xerxes platter was chosen as part of a balanced design: simply going for the largest mass platter is not necessarily a better solution. The Roksan bearing spindle can be thinner and much less noisy as a direct consequence.

I was previously comparing the flywheel type design to the Technics design not an LP12 by the way.

mat
 
YNWOAN said:
Well yes, I quite agree. As fate would have it, just such a thread exists on this very forum, in the DIY section; unfortunately, neither Roksan nor Technics owners have chosen to take part - so far (hopefully they will change their minds).



To be blunt, that's pure conjecture.

None of the measurements I have done have supported the idea that stylus drag is the issue that this thread seems to believe. I am not saying that issues do not exist within TT drive systems, but I am saying that relative to other forces acting within the system, stylus drag is a relative constant. I do think the speed of TT systems is prone to modulation, but I do not believe that variations in stylus drag are the primary source.

However, one should be wary of attaching blanket statements of belief regarding performance to any specific element of the drive system, as no individual part can be truly considered in isolation.
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Well I don't mind taking part if I am able - what software do I need and where can I get the test LP? I haven't done any needledrops because my soundcard is a crap onboard chip. When I can I might buy a decent soundcard or USB device.

mat
 
A couple of follow up points:

The Roksan platter is lighter than an LP12 platter, but it has higher inertia because the mass is concentrated at the periphery. It is also a four piece design that has been designed to self damp ringing.

I own all three of the decks discussed (Roksan, Linn LP12, Technics SP10) and would say that subjectively, the Technics sounds as pitch stable as the TMS, but no more so, while the Linn is subjectively less stable.

A while back I asked my friend Barry Wolifson who produced the Acoustic Sounds Ultimate Analog Test LP, about cutting a record with a track that included a continuous pitch at say 1kHz, plus a loud low frequency tone that would switch on and off at say one second intervals. This would be great for testing the issues under discussion, and would allow you to look at how much the intermittent low frequency tone modulated the continuous mid frequency tone on a scope. Barry said it would be almost impossible to cut accurately for some reason.
 
MTrei said:
A while back I asked my friend Barry Wolifson who produced the Acoustic Sounds Ultimate Analog Test LP, about cutting a record with a track that included a continuous pitch at say 1kHz, plus a loud low frequency tone that would switch on and off at say one second intervals. This would be great for testing the issues under discussion, and would allow you to look at how much the intermittent low frequency tone modulated the continuous mid frequency tone on a scope. Barry said it would be almost impossible to cut accurately for some reason.
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I can't see why it would be difficult to produce such a disc. It would just be one track with a constant tone and then elsewhere a heavily modulated track with some nice big LF excursions. The problem would come in installing 2 arms on some decks to allow them to play the two tracks simultanously!
 
mmaatt said:
Well I don't mind taking part if I am able - what software do I need and where can I get the test LP? I haven't done any needledrops because my soundcard is a crap onboard chip. When I can I might buy a decent soundcard or USB device.

mat
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Good man :)

You would need to download Audacity (which is free), to do the recording.

I've seen the test LP for sale on-line, Google should find it.
 
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