Good people;
Some of you may have read earlier this spring Art Dudley's account of the Vector mods for the Linn Sondek. For those of you who haven't, check out his recent columns in Stereophile online. Or, the thumbnail sketch 🙂
There is a carbon-fibre top plate that replaces the steel top plate.
There is a carbon-fibre / balsa / carbon-fibre subchassis replacement.
There is a carbon-fibre / balsa / carbon-fibre armboard replacement.
There are various motor configurations, including a cool looking one with idler wheels to avoid tugging at the sub-platter. There is a platter mat.
Mr. Dudley liked some of this stuff. It is expensive, I think about as much as the new Keel from Linn.
All come from from the gentleman who provided the Pink Link upgrades to Linns.
OK, I have several questions and I can't find much that directly bears on this on the existing threads.
There is a company called "Dragon Plate" that makes beautiful carbon-fibre / wood composite plates, and these are not expensive. They could be used to make something similar to the Vector mods (speaking conceptually here).
More importantly to me, they could be used to make similar things for my old Ariston RD11.
Has anyone done this kind of thing, with Linns or (shudder) with an Ariston? I think this would be a fun thing to do this winter with my 15 year old son who is kind of ready for a challenge like this.
Any comments, suggestions, advice? Thanks HUGELY in advance.
Some of you may have read earlier this spring Art Dudley's account of the Vector mods for the Linn Sondek. For those of you who haven't, check out his recent columns in Stereophile online. Or, the thumbnail sketch 🙂
There is a carbon-fibre top plate that replaces the steel top plate.
There is a carbon-fibre / balsa / carbon-fibre subchassis replacement.
There is a carbon-fibre / balsa / carbon-fibre armboard replacement.
There are various motor configurations, including a cool looking one with idler wheels to avoid tugging at the sub-platter. There is a platter mat.
Mr. Dudley liked some of this stuff. It is expensive, I think about as much as the new Keel from Linn.
All come from from the gentleman who provided the Pink Link upgrades to Linns.
OK, I have several questions and I can't find much that directly bears on this on the existing threads.
There is a company called "Dragon Plate" that makes beautiful carbon-fibre / wood composite plates, and these are not expensive. They could be used to make something similar to the Vector mods (speaking conceptually here).
More importantly to me, they could be used to make similar things for my old Ariston RD11.
Has anyone done this kind of thing, with Linns or (shudder) with an Ariston? I think this would be a fun thing to do this winter with my 15 year old son who is kind of ready for a challenge like this.
Any comments, suggestions, advice? Thanks HUGELY in advance.
Hi,
Linn had a huge following that would upgrade the old to the new and then the newer. Linn must have got something right to make folk part with all that money.
I have a sneaky suspicion that a suspended chassis is less influenced by the below deck parts than most other styles of rotator. How much experimentation are you prepared to undertake and will you be able to compare before and after and after and after (when you have just one deck to start with)?
Linn had a huge following that would upgrade the old to the new and then the newer. Linn must have got something right to make folk part with all that money.
I have a sneaky suspicion that a suspended chassis is less influenced by the below deck parts than most other styles of rotator. How much experimentation are you prepared to undertake and will you be able to compare before and after and after and after (when you have just one deck to start with)?
Hi,
I have replaced a steel subchassis on a rebuilt suspended design.
I'd say it was definitely worth doing for a RD11 if it has a good arm.
I'd say the top plate linn mod is the most cosmetic.
I'd use an aluminium sheet based composite with a much thicker core.
(than the max 1/4" thick composite referred to.)
🙂/sreten.
I have replaced a steel subchassis on a rebuilt suspended design.
I'd say it was definitely worth doing for a RD11 if it has a good arm.
I'd say the top plate linn mod is the most cosmetic.
I'd use an aluminium sheet based composite with a much thicker core.
(than the max 1/4" thick composite referred to.)
🙂/sreten.
AndrewT said:
As to your question on "how much experimentation", I can see doing three things.
One, replacing top plate, subchassis, and armboard with something "better" - in my case, following Vector, composite. Why? Because this has been shown to be worthwhile (using that word loosely) by Linn, Pink Triangle, Linn again, and now Vector, in terms of what the Linn community thinks. I also think this would be pretty easy to do.
Two, more of one - change the orientation of the subchassis so that it goes corner-to-corner instead of side to side to get a better static balance. Go for a bigger plinth and a longer tonearm. Make the plinth less resonant - a hollow wooden box with a stainless steel top plate? how quaint - at the same time. Maybe put the motor on the subchassis to avoid torquing the spindle all over the place as the suspension moves - ok need a better motor.
Three - build something like the Teres, using at most the bearing and spindle / subplatter / platter.
Remember, I'm doing this with the Ariston, not the Linn - but I'm also boldly assuming that what works for the Ariston might be of interest to people with old Linns just bought off eBay.
How will I judge whether it sounds better? That will be tough, as you say I only have the one deck. However I think it will be worth it for the fun quotient in any case and there are some serious evident defects with the Ariston as it stands anyway, most notably that its completely undamped metal platter / subplatter / spindle / bearing / galvanized-steel subchassis / stainless top plate rings audibly, and the plinth resonates audibly as well. I could easily get rid of these, and possibly make other things worse.
Or I could get lucky 🙂
What do you think?
Hi,
You could use the dragon plate composite in two layers
with sheet structural foam core for armboard.
For the subchassis IMO aluminium sheet and structural foam is better.
I would not modify the motor system, I would service it.
I would buy some bitumen spray and damp the springs and the top
plate. Improving fixing of top plate to plinth with damp/ reinforce
both. Bottom plate arrangements I'm not familiar with.
Add the carbon fibre veneer to the top plate if you like.
Bottom of my turntable was a simple hardboard sheet. Sprayed
with bitumen damping and adding high strength baking foil, it
now is a "5 layer triple composite with 2 damping layers".
Good for shielding as well.
All the changes that make it less like a Linn I do not recommend,
you can do it, but IMO you'll get something different, not better.
The dynamic behavour of the subchassis is more important than
its static balance, moving things around depends on spring rates
and possibility of moving there points, with a low mass subchassis
its "orientation" will make little difference, though you can make
it asymmetric towards the arm mounting side.
I've rebuilt several turntables, what is important is knowing what
is important, and not overdoing things that are not important.
🙂/sreten.
You could use the dragon plate composite in two layers
with sheet structural foam core for armboard.
For the subchassis IMO aluminium sheet and structural foam is better.
I would not modify the motor system, I would service it.
I would buy some bitumen spray and damp the springs and the top
plate. Improving fixing of top plate to plinth with damp/ reinforce
both. Bottom plate arrangements I'm not familiar with.
Add the carbon fibre veneer to the top plate if you like.
Bottom of my turntable was a simple hardboard sheet. Sprayed
with bitumen damping and adding high strength baking foil, it
now is a "5 layer triple composite with 2 damping layers".
Good for shielding as well.
All the changes that make it less like a Linn I do not recommend,
you can do it, but IMO you'll get something different, not better.
The dynamic behavour of the subchassis is more important than
its static balance, moving things around depends on spring rates
and possibility of moving there points, with a low mass subchassis
its "orientation" will make little difference, though you can make
it asymmetric towards the arm mounting side.
I've rebuilt several turntables, what is important is knowing what
is important, and not overdoing things that are not important.
🙂/sreten.
It is not my intention to intrude in this thread, but I feel my question can be relevant.
I looked at this DragonPlate stuff, which I haven't seen before..interesting!
I have a TD125 without arm and an SME S-II, and I need to make a new armboard...appx 1/2" thick.. any suggestions.. ??
I also have a load of balsa, and different hardwoods with densities close to 1 for the hardest. How about a 5 layer board, - 3 CF and 2 layers of wood.. balsa or the heavy stuff??
I looked at this DragonPlate stuff, which I haven't seen before..interesting!
I have a TD125 without arm and an SME S-II, and I need to make a new armboard...appx 1/2" thick.. any suggestions.. ??
I also have a load of balsa, and different hardwoods with densities close to 1 for the hardest. How about a 5 layer board, - 3 CF and 2 layers of wood.. balsa or the heavy stuff??
Thanks, Sreten, for your detailed response. I have some questions, if you don't mind.
Did you visit Dragon Plate's site? Did you notice they have a foam core based product? I will probably contact them with some questions about this material.
One thing that worries me a bit about such material is the idea of clamping a tonearm mounting to such material and compressing it. Doesn't seem like a good idea.
Not to argue at all with your point of view, but would you mind elaborating as to why you feel that aluminum sheet and structural foam would be better than Dragon Plate carbon/wood/carbon laminate?
Do you have any opinion on the Funk Firm's use of carbon/balsa/carbon in their Linn mods? (here is where my question is coming from: they charge a significant amount for their mods, and I don't think that material costs really come into it; but machining cost or simplicity or related issues might, I suppose).
Here is the article, with pictures of the Funk Firm's mods:
http://stereophile.com/artdudleylistening/107listen/index1.html
One of the things I find interesting in the Funk Firm's Linn mods is the three-point drive system, with the motor actually on the subchassis. I like the three point system from the principle of reducing the tug on the sub-platter. However, my Ariston motor is sufficiently noisy that I don't think I'd want to move it to the subchassis.
Another option with the Funk mods is to move the motor from behind the subchassis - as you face the deck - to the front. Reason given is to stop tugging the subchassis in a direction perpendicular to the stylus. Again, an interesting idea.
When you say "service" the motor, what exactly do you mean? Cleaning and oiling, or something more?
I understand your comment about "making less like a Linn". It seems to me that what I have is a lot like a very old Linn, the sound of which is not particularly venerated any longer and therefore is begging to be "improved"! I've also thought about getting say a Cirkus upgrade...
What I was thinking of in terms of changing the orientation of the subplatter was something like the following. The subplatter long-axis is left-right as you face the deck. I was thinking of making a subplatter with a longer rightward extension - I get your point about needing to reposition the springs as well - both to accomodate a longer tonearm and also to do away with the long armboard that forces the back spring to be tighter than the front in order to achieve leveling, and thus - in my mind, at least - has less than desirable dynamic consequences.
If I then rotated the subchassis counterclockwise by 35° or so, the rightward extension would now sit in the back right corner of the plinth - which would of course have to be enlarged. At that point, the arm could be mounted directly on the subchassis, and the spring tension would be pretty close to the same for all three springs.
Another option to reduce this imbalance - as long as I didn't want a longer arm - would be to avoid all the rotation of the subchassis and instead counterweight the armboard at the front. I've never seen this done, and I've always wondered why it isn't done - ias you say, achieving good dynamic balance is important and I would think that part of that is improving the static balance.
With respect to your comment on bitumen spray on bottom of top plate and top of bottom plate - it would seem that Linn's most recent upgrades provide a bottom plate of aluminum topped with sound deadening material. However, they don't provide a new top plate, and AFAIK their current top plate is not treated. I wonder why?
I've always run my Ariston without the crummy fibreboard bottom plate that was provided. I've read in a number of places that some like the Linn without a bottom plate and some like it better with one.
What are the improvements that a good bottom plate provides? Strengthening / deadening of the plinth? You mention shielding, anything else?
http://stereophile.com/artdudleylistening/107listen/index1.html
sreten said:
Did you visit Dragon Plate's site? Did you notice they have a foam core based product? I will probably contact them with some questions about this material.
One thing that worries me a bit about such material is the idea of clamping a tonearm mounting to such material and compressing it. Doesn't seem like a good idea.
Not to argue at all with your point of view, but would you mind elaborating as to why you feel that aluminum sheet and structural foam would be better than Dragon Plate carbon/wood/carbon laminate?
Do you have any opinion on the Funk Firm's use of carbon/balsa/carbon in their Linn mods? (here is where my question is coming from: they charge a significant amount for their mods, and I don't think that material costs really come into it; but machining cost or simplicity or related issues might, I suppose).
Here is the article, with pictures of the Funk Firm's mods:
http://stereophile.com/artdudleylistening/107listen/index1.html
One of the things I find interesting in the Funk Firm's Linn mods is the three-point drive system, with the motor actually on the subchassis. I like the three point system from the principle of reducing the tug on the sub-platter. However, my Ariston motor is sufficiently noisy that I don't think I'd want to move it to the subchassis.
Another option with the Funk mods is to move the motor from behind the subchassis - as you face the deck - to the front. Reason given is to stop tugging the subchassis in a direction perpendicular to the stylus. Again, an interesting idea.
When you say "service" the motor, what exactly do you mean? Cleaning and oiling, or something more?
I understand your comment about "making less like a Linn". It seems to me that what I have is a lot like a very old Linn, the sound of which is not particularly venerated any longer and therefore is begging to be "improved"! I've also thought about getting say a Cirkus upgrade...
What I was thinking of in terms of changing the orientation of the subplatter was something like the following. The subplatter long-axis is left-right as you face the deck. I was thinking of making a subplatter with a longer rightward extension - I get your point about needing to reposition the springs as well - both to accomodate a longer tonearm and also to do away with the long armboard that forces the back spring to be tighter than the front in order to achieve leveling, and thus - in my mind, at least - has less than desirable dynamic consequences.
If I then rotated the subchassis counterclockwise by 35° or so, the rightward extension would now sit in the back right corner of the plinth - which would of course have to be enlarged. At that point, the arm could be mounted directly on the subchassis, and the spring tension would be pretty close to the same for all three springs.
Another option to reduce this imbalance - as long as I didn't want a longer arm - would be to avoid all the rotation of the subchassis and instead counterweight the armboard at the front. I've never seen this done, and I've always wondered why it isn't done - ias you say, achieving good dynamic balance is important and I would think that part of that is improving the static balance.
With respect to your comment on bitumen spray on bottom of top plate and top of bottom plate - it would seem that Linn's most recent upgrades provide a bottom plate of aluminum topped with sound deadening material. However, they don't provide a new top plate, and AFAIK their current top plate is not treated. I wonder why?
I've always run my Ariston without the crummy fibreboard bottom plate that was provided. I've read in a number of places that some like the Linn without a bottom plate and some like it better with one.
What are the improvements that a good bottom plate provides? Strengthening / deadening of the plinth? You mention shielding, anything else?
http://stereophile.com/artdudleylistening/107listen/index1.html
AuroraB said:
I think a lot of the armboards currently available (eg from Linn for the Sondek, from companies like Origin Live) are MDF.
On this forum there seems to be a lot of interest in multi-layer "constrained damping" composites generally.
I haven't yet stumbled on much beyond discussion of the topic - for instance, I have not yet seen anything as definitive as "I have two Linns, one with the original armboard and one made with a composite of aluminum, carbon fibre, and pork tenderloin, and the latter has much more clearly defined bass and midrange".
I think the DragonPlate stuff looks interesting and not too expensive, and you can order it pre-cut and pre-drilled according to their web site. Might be fun to try. I've been thinking of that myself for my Ariston, but then I think I should be more bold!
Hi,
You will have to pardon my healthy dose of cynicism regarding the
fact the Linn "by common consent" needs to be "improved" by
chucking a large wad of cash at it, £3K for a new Linn subchassis ?
I'll note that the dragon plate stuff is already a 3 layer composite,
and mainly the central ply layer, used as the outer layer in a 3 ply
construction most of the benefits of the carbon fibre will be lost.
The dragon plate stuff is not carbon fibre suitable for a laminate.
High quality blockboard, soft wood core, hardwood ply is a good
scheme for a directionally stiff laminate for Linn style armboards.
(The type where each softwood strip is taller than it is wide,
the lower quality stuff each strip is wider than it is tall.)
Consequently for the subchassis, which IMO should be ~ 1" thick,
(I built one out of 3 layers of 1/2" ply, top full size, the other two
layers in reducing size linked the arm to the main bearing.)
Sheet aluminium as the outer layers will be far more effective.
Core should be lightweight and relatively stiff.
The Funk firm stuff is a cheaper version of the old Aerolam principles.
Having rebuilt a number of turntables one principle is if is is not broken,
do not fix it. Trying to turn one design into another rarely works well.
If the spring rates are equal, such that they are all in different
levels of compression for balance, then by all means move them.
One turntable I rebuilt the whole innnards were set up on a
table and the spring moved round for good level and chassis
behaviour, (moving the springs towards the CofG lowers the
rotational and horizontal frequencies, but too close together
and in yaw the top can "fall off" the springs.)
You can greatly improve the RD11 for peanuts, just some work.
Laminates work very well but are somewhat labour intensive.
I would redesign the subchassis but keep the armboard arrangement.
Possibly something like :
🙂/sreten.
You will have to pardon my healthy dose of cynicism regarding the
fact the Linn "by common consent" needs to be "improved" by
chucking a large wad of cash at it, £3K for a new Linn subchassis ?
I'll note that the dragon plate stuff is already a 3 layer composite,
and mainly the central ply layer, used as the outer layer in a 3 ply
construction most of the benefits of the carbon fibre will be lost.
The dragon plate stuff is not carbon fibre suitable for a laminate.
High quality blockboard, soft wood core, hardwood ply is a good
scheme for a directionally stiff laminate for Linn style armboards.
(The type where each softwood strip is taller than it is wide,
the lower quality stuff each strip is wider than it is tall.)
Consequently for the subchassis, which IMO should be ~ 1" thick,
(I built one out of 3 layers of 1/2" ply, top full size, the other two
layers in reducing size linked the arm to the main bearing.)
Sheet aluminium as the outer layers will be far more effective.
Core should be lightweight and relatively stiff.
The Funk firm stuff is a cheaper version of the old Aerolam principles.
Having rebuilt a number of turntables one principle is if is is not broken,
do not fix it. Trying to turn one design into another rarely works well.
If the spring rates are equal, such that they are all in different
levels of compression for balance, then by all means move them.
One turntable I rebuilt the whole innnards were set up on a
table and the spring moved round for good level and chassis
behaviour, (moving the springs towards the CofG lowers the
rotational and horizontal frequencies, but too close together
and in yaw the top can "fall off" the springs.)
You can greatly improve the RD11 for peanuts, just some work.
Laminates work very well but are somewhat labour intensive.
I would redesign the subchassis but keep the armboard arrangement.
Possibly something like :
🙂/sreten.
Attachments
Hi Sreten,
with the asymetrical spring layout shown, it will be impossible to get the pull from the motor/belt to not twist the subchassis.
The far spring from the motor should be in-line with the platter centre and the other two springs symetrical about that in-line axis.
Alternatively, the nearest spring can be in-line but between motor and platter centre. Again the other two springs should be symetrical about the in-line axis.
Bonzini,
Try to get the weight of platter and sub-platter and arm board and arm arranged to get the centre of gravity directly on the platter centre. Then all the springs will carry the same weight and suffer the same compression and resonate at the same frequency.
I would go for well spread apart springs, but that is just my preference.
with the asymetrical spring layout shown, it will be impossible to get the pull from the motor/belt to not twist the subchassis.
The far spring from the motor should be in-line with the platter centre and the other two springs symetrical about that in-line axis.
Alternatively, the nearest spring can be in-line but between motor and platter centre. Again the other two springs should be symetrical about the in-line axis.
Bonzini,
Try to get the weight of platter and sub-platter and arm board and arm arranged to get the centre of gravity directly on the platter centre. Then all the springs will carry the same weight and suffer the same compression and resonate at the same frequency.
I would go for well spread apart springs, but that is just my preference.
AndrewT said:
Hmmm....
I do not follow or necessarily agree with the above.
There is no point in getting the CofG at the platter center, it requires
additional weighting, the CoG will be somewhere towards the arm.
By definition all springs at the same compression will be equidistant from this CoG point.
I do not know if all the springs are the same or not. If they are not
then the lowest rate, furthest from the CoG should be near the arm.
If they are all the same moving one (the worst affected) will help.
It may be easier to move one and add a smaller balance weight.
How far apart they are affects the rotational frequency of the
subchassis around the platter, very bad on the original DM101,
fixed later by a central spring and softer edge springs.
Given the springs and layout there is probably limited choice.
FWIW I do not consider the drive position of the motor particularly
relevant, except for hum, lots of tosh expounded on this subject.
🙂/sreten.
This is an interesting thread for me as I own an LP-12 and an original Ariston RD-11s from 1973. I am in the process of updating the Ariston and it is now all apart. I have owned my Linn since 1989 and it clearly sounds better than the Ariston as far as clarity, soundstage, and detail. The Ariston is showing it's age. The motor has become quite noisy and imparts an audible rumble to the background. The bearing is still very smooth and quiet but it has considerably more vertical play than the Linn. Also it is starting to leak a bit of oil. First change was replace the motor with an Axis power supply. I removed the motor from the pcb and mounted it with the Ariston hardware plus a 8mm spacer to get the correct height. What a big difference. The motor is very quiet when it is running. It only runs on 25VAC once it is up to speed. I am going to mount the ps inside the table once I am done fiddling. The sound was much better, clearer, better soundstage. Later I am going to build a dedicated power supply for the Axis circuit. The present power supply is about as simple as you can get with only a minimum of filtering. The Axis output circuit is basically a two channel single ended Class A power amp outputting a 50Hz or 67.5 Hz signals 90° out of phase to drive the motor windings. The better the power supply, the cleaner and more stable the output. A poor man's Lingo. Next step is to graft in the Linn subchassis I got on eBay. Unfortunately the Linn and Ariston top plates mounting holes are slightly off and the top plate will requiring some minor machining to mount the new subchassis. I still require an armboard but I saw another thread about using black plexiglass or acrylic. That would look awesome with my plinth. With everything apart I cornerbraced the plinth and refinished it in piano black. I copied a set of Linn hinge mounting plates out of oak. I wasn't going to pay 50 pounds for a set. Hopefully a cheap set will come up on eBay. It now sports a clear Linn deck lid and looks pretty updated. I would also like to make a bearing reinforcement plate to get double thickness rigidity like the Cirkus. This minor change makes a big difference with the Cirkus Linn. I would still lack the slightly longer Cirkus bearing which also improves rotational precision by decreasing vertical play but I have read that the increased structural rigidity to the subchassis still makes a significant improvement. The characteristics of the subchassis and bearing mount clearly affect the sound of the table. The new ridiculously priced Keel is extremely rigid and precise being CNC carved out out billet aluminum alloy. The Cetech carbon fibre subchassis was also reported to be a marked improvement so the new Vector subchassis should provide similar benefits. As for the top plate, I'm not sure how much improvement would be gained. It will definetely be less resonant and it sure looks great. I have seen other people deaden the top plate with Dynamat. I guess you could do the same thing to the subchassis but it is quiet heavy stuff.
Hello, tkwou;tkwou said:
I see that you live in Vancouver, as do I - though right now we're just finishing off a year's leave in France. We'll be back in August. Do you think there's any possibility of getting together for a chat?
I'm really intrigued by your experience of having a Linn next to the Ariston for comparison purposes.
Your motor comments are very interesting. As I recall, my motor has always been somewhat noisy, but for me that's an arbitrary comment since I have nothing else to compare it to. Still, I fancy that I can hear it on the inter-track spaces, especially when wearing headphones. I've thought about buying a DC motor kit from Origin Live or Funk, but both of these are quite expensive in the context of a thirty year old turntable... How did you stumble on the Axis motor idea - just spot one on eBay and go for it, or...?
Can I ask what you're using for an arm? Mine has a G707. What's in my mind these days is building my own, perhaps a uni-pivot and hence my reason for wanting to rethink the subchassis geometry since "conventional wisdom" has it that unipivots and Linn-like turntables don't always get along...
Have you maintained the rubber o-rings on the Ariston platter? I have a mat, made by a Vancouver company (Eon Audio, perhaps?) I'm sure is long defunct, that has the double-sided rubber / rubberized cork approach to things. The rubber side sticks to the aluminum platter to such an extent that it is wise to pry it off every few months. I once left it in place for a few years and had to use a knife blade to pry the mat off the platter to get at the bearing to check it. It also has some sort of plastic (vinyl, perhaps) core. It definitely sounds better than the o-rings which lend a kind of boomy character to playback.
As I mentioned in my lead-off to this thread, I'm as much interested in rebuilding my Ariston for fun and education, and to do something sort of cool with my 15 year old son, as for "ultimate improvements". Plus heck, he might want to take a break from the iPod
AndrewT, Sreten;
With respect to a possible new layout for the subplatter.
First of all, the three springs are of equal properties - more or less, anyway, given their age.
It seems to me that it would be a good idea in principle to have the centre of mass of the platter / subchassis / arm assembly at the midpoint between the three springs.
That should give the best dynamic behaviour of the suspended assembly - each spring would then be at the same tension and see the same "bounce" forces on it, and disturbances would not therefore "rock" the suspended assembly and generate rotational force on it.
At that point, the tug of the belt on the suspended assembly becomes a destabilizing force, particularly because the "pull vector" is not likely to be through the CoM. I would guess that it is in fact above and to one side of the CoM, which should cause a rocking of the subassembly when disturbed.
Who cares whether the subassembly rocks or not? I can only assume that the stylus does, especially if the rocking tends to swing the tonearm from side to side, which I think is likely to be the case given the direction of pull of the belt, and seems to be the reason Funk goes to the effort of either changing the direction of the "pull vector" to be parallel to the tonearm or even eliminating the "pull vector" entirely by putting the motor on the subassembly.
Back to considering just the suspended subassembly for a moment - in effect, with the springs below the subassembly, the relation between the subassembly and the springs is that of a Newtonian pendulum, which is dynamically astable - gravity acts to pull it away from its rest point. If the subassembly were rather to hang from the springs, the subassembly then becomes a normal pendulum which is dynamically stable - gravity acts acts to return it to its rest point.
Given that there are rubber dampers that damp the side-to-side motion of the subassembly, I'm not sure if this astability really matters, but it would seem to me that the subassembly would always tend to "hunt" to whatever degree the dampers permit, which would resolve to a constant source of small forces against the stylus. That being the case, it would be better to hang the assembly from three towers containing springs and dampers - my but this is starting to sound a bit like an Oracle.
Anyway, I'm not sure I'm ready to go with the hanging subassembly approach just yet... but I can see solid physical reasons for laying out the subassembly carefully so that the springs are equidistant from the CoM, and for including in that subassembly the motor.
Have I worn you out
, or do still have the energy left to comment on this?
With respect to a possible new layout for the subplatter.
First of all, the three springs are of equal properties - more or less, anyway, given their age.
It seems to me that it would be a good idea in principle to have the centre of mass of the platter / subchassis / arm assembly at the midpoint between the three springs.
That should give the best dynamic behaviour of the suspended assembly - each spring would then be at the same tension and see the same "bounce" forces on it, and disturbances would not therefore "rock" the suspended assembly and generate rotational force on it.
At that point, the tug of the belt on the suspended assembly becomes a destabilizing force, particularly because the "pull vector" is not likely to be through the CoM. I would guess that it is in fact above and to one side of the CoM, which should cause a rocking of the subassembly when disturbed.
Who cares whether the subassembly rocks or not? I can only assume that the stylus does, especially if the rocking tends to swing the tonearm from side to side, which I think is likely to be the case given the direction of pull of the belt, and seems to be the reason Funk goes to the effort of either changing the direction of the "pull vector" to be parallel to the tonearm or even eliminating the "pull vector" entirely by putting the motor on the subassembly.
Back to considering just the suspended subassembly for a moment - in effect, with the springs below the subassembly, the relation between the subassembly and the springs is that of a Newtonian pendulum, which is dynamically astable - gravity acts to pull it away from its rest point. If the subassembly were rather to hang from the springs, the subassembly then becomes a normal pendulum which is dynamically stable - gravity acts acts to return it to its rest point.
Given that there are rubber dampers that damp the side-to-side motion of the subassembly, I'm not sure if this astability really matters, but it would seem to me that the subassembly would always tend to "hunt" to whatever degree the dampers permit, which would resolve to a constant source of small forces against the stylus. That being the case, it would be better to hang the assembly from three towers containing springs and dampers - my but this is starting to sound a bit like an Oracle.
Anyway, I'm not sure I'm ready to go with the hanging subassembly approach just yet... but I can see solid physical reasons for laying out the subassembly carefully so that the springs are equidistant from the CoM, and for including in that subassembly the motor.
Have I worn you out
, or do still have the energy left to comment on this?Just in relation to my last post, here is a graphic (I scaled it down but have a larger, clearer PNG if anyone wants a closer look) that shows approximately what I'm thinking.
I'm a long way from the turntable right now and I so the only dimension I really know is the spindle - to - pivot distance for a 317,5mm arm which is ~ 305mm.
On the image, it looks as though I've tried to place the platter at the midpoint of the three suspension points, but that wasn't my intent, it was just all the guessing involved as to where the suspension points would have to be to agree with my pet theory that the centre of mass should be at the midpoint of those suspension points.
Also I've shown a hole for the motor on the subchassis just in case it's a good idea
I'm a long way from the turntable right now and I so the only dimension I really know is the spindle - to - pivot distance for a 317,5mm arm which is ~ 305mm.
On the image, it looks as though I've tried to place the platter at the midpoint of the three suspension points, but that wasn't my intent, it was just all the guessing involved as to where the suspension points would have to be to agree with my pet theory that the centre of mass should be at the midpoint of those suspension points.
Also I've shown a hole for the motor on the subchassis just in case it's a good idea
Hi Bozini, happy to chat with you when you get back. I will be away the last couple weeks of August however. The idea has come from a series of projects I started at the beginning of the year when my LP-12 died just after Christmas. I removed the Valhalla and with the help of a friend who is the service tech for Linn in Vancouver I was able to rebuild the board with some improvements for extra durability. Actually the board has been pretty reliable considering it has never been off since 1989. I learned alot about the circuit and felt quite comfortable troubleshooting it. However I had always wanted a my Linn to play 45's and I hate the adapter. My Ariston plays 45's but it's sound quality doesn't do justice to newer 45 LP's. I learned that the newer Valhalla's were based on the Axis supply so I purchased a nonfunctional Axis on eBay. The Axis power supply is a completely different bird from the Valhalla and I didn't have a schematic. I made the assumption that similar parts would fail on the Axis so I replaced all the filter caps, coupling caps and decoupling caps. The ps fired up spun for 7-8 seconds and stopped. Scratching my head I kept working on it to determine what was wrong. In the process a wire dropped on the board and shorted the motor output. What a nightmare? A call to the Linn tech and I learned that the Axis power supply was functioning normally because it goes into "quiet mode" after 7-8 seconds and use the momentum of the platter plus a load sensing servo to maintain speed. A little valuable knowledge too late. Well fortunately a member in this forum had a copy of the schematic and after replacing just about every part on the board it was up and running or so I thought. One of the bias resistors for the output circuit had gone out of spec and went unnoticed because the voltages were measuring within spec. This imbalance caused a decrease in starting torque. It would not start an LP-12 platter without a boost. Disappointed and still wanting my Linn to play 45's, I scrapped that idea and I purchased a broken Valhalla on eBay. I serviced the board and reconfigured it to run at 45 RPM. I then mounted the two board along with a dedicated power supply in an external case with a switch to toggle between the two Valhalla boards. The added ps did improve he focus and soundstage but the motor was still running at 82VAC (lower than spec 86VAC). I read that it sounds even better at 70VAC but then you get starting torque problems. I had always wanted to get that Lingo sound but $1500 for a ps was just too much. The Lingo is similar to the Axis in concept but with much better execution. I still remember when SoundPlus had their Linn septup to allow instant A-B of Valhalla and Lingo. What an incredible difference. An experience that is etched in my mind. In the meantime I now had a functional Axis table and a Ariston with a leaking bearing. Time for another project. I took the Syrinx arm off Ariston and mounted on the Axis while I was updating the Ariston. The Axis sounds pretty good but is no LP-12 with respect to clarity and detail. It is also has very poor isolation. Best sound was acheived sitting on a Target wall mount on top of a Mission Isoplat. What I did notice once the Axis was better isolated was that it imparted a sound stage presentation that reminded me of that Lingo I heard. I wondered if the concept of low voltage supply/lower motor vibration from the motor is a factor in this. The Origin Live DC motors have very little vibration and are known to produce significant improvement in the sound of a Linn. Their motors and power supply are also quite pricey. Anyways the Axis kept popping the surge protector resistor every time I plugged and unplugged it so this lead me to taking a second look at the power supply and finding the out of spec bias resistor. With this replaced I tried it again with the Ariston and it fired up the heavy platter no problem. Time to reconsider the Axis powered Linn again, but since I already had the Ariston apart and it had a noisy motor anyways why not experiment with the Ariston first. That's where I am now. The Axis motor is on the Ariston hooked up to the power supply through wire leads. I am planning the power supply for the Axis board with a regulated HV supply to the output circuit and a regulated low voltage supply to the signal generating circuit. After that I will graft the Linn subchassis to the Ariston.
Hi,
one aspect of the compressed spring astability :
Many turntables have some form of restriction to lateral movement,
this is simply wrong and needs to be removed AFAIC. The rubber
seatings for the springs are to prevent noise and dampen higher
frequency spring modes. Foam cores are sometimes used for this,
I prefer damping the springs with flexible paint / bitumen.
http://www.audioorigami.co.uk/FloppyProject/FloppyDIYMotor.htm
You can use your old pulley if you slow in down a bit.
🙂/sreten.
one aspect of the compressed spring astability :
Many turntables have some form of restriction to lateral movement,
this is simply wrong and needs to be removed AFAIC. The rubber
seatings for the springs are to prevent noise and dampen higher
frequency spring modes. Foam cores are sometimes used for this,
I prefer damping the springs with flexible paint / bitumen.
http://www.audioorigami.co.uk/FloppyProject/FloppyDIYMotor.htm
You can use your old pulley if you slow in down a bit.
🙂/sreten.
Hi Sreten;
Thanks for the comment on springs. I do believe I might try coating the springs with something, as you suggest.
I threw out the foamies that were shoved inside the springs a long time ago. I forget my precise reasoning, but I do remember liking the way the suspension worked better without the foam guck.
So now, the springs look a bit like current Linn springs, except they are bare metal. They are tapered, with the wide bit pressing up on the subchassis and the narrow bit pressing down on the nut and washer at the bottom end of the hanger bolt.
There are rubber grommets that mate the ends of the sprint to the subchassis, the washer/nut at the bottom, and to the hanger bolt, if you see what I mean.
The springs and grommets are also probably somewhat tired out after all these years, so I should probably consider replacing them with something else.
Thanks for the comment on springs. I do believe I might try coating the springs with something, as you suggest.
I threw out the foamies that were shoved inside the springs a long time ago. I forget my precise reasoning, but I do remember liking the way the suspension worked better without the foam guck.
So now, the springs look a bit like current Linn springs, except they are bare metal. They are tapered, with the wide bit pressing up on the subchassis and the narrow bit pressing down on the nut and washer at the bottom end of the hanger bolt.
There are rubber grommets that mate the ends of the sprint to the subchassis, the washer/nut at the bottom, and to the hanger bolt, if you see what I mean.
The springs and grommets are also probably somewhat tired out after all these years, so I should probably consider replacing them with something else.
Hi tkwou;
Thanks for the detailed story on your motor experiments. The Axis project sounds interesting.
Might I ask what you've discovered regarding the diameter of the Ariston vs. Linn subplatters? I seem to recall reading somewhere that the Ariston platter will fit on a Linn subplatter - kind of makes you wonder, doesn't it - but not anything specific about the actual diameters of subplatter.
Somewhere else, I've seen a post suggesting the use of a PC's audio to produce the sine waves necessary to drive an asynchronous motor, presumably in conjunction with a small amplifier. Seems like the best use of Microsoft Windows I've come across in a long time 😱
But seriously, creating a good "Lingo-like" power supply shouldn't be beyond the means of this group, should it?
Anyway, to respond to one of Sreten's earlier suggestions, I think my Ariston's motor is a bit of a piece of crap, no matter how clean and well-adjusted it is. Again going from memory here, but it's always made a lot of noise; I'm not even sure if it doesn't come from the interface between the shaft and the thrust plate (I wish I were there right now to examine it in detail).
So I'm either in the market for a newer, quieter motor or some kind of serious motor maintenance.
I wrote a note to John at Audio Origami today following Sreten's suggestion, kind of summarized this thread, asked for some suggestions. I hope he has a moment to respond.
Thanks for the detailed story on your motor experiments. The Axis project sounds interesting.
Might I ask what you've discovered regarding the diameter of the Ariston vs. Linn subplatters? I seem to recall reading somewhere that the Ariston platter will fit on a Linn subplatter - kind of makes you wonder, doesn't it - but not anything specific about the actual diameters of subplatter.
Somewhere else, I've seen a post suggesting the use of a PC's audio to produce the sine waves necessary to drive an asynchronous motor, presumably in conjunction with a small amplifier. Seems like the best use of Microsoft Windows I've come across in a long time 😱
But seriously, creating a good "Lingo-like" power supply shouldn't be beyond the means of this group, should it?
Anyway, to respond to one of Sreten's earlier suggestions, I think my Ariston's motor is a bit of a piece of crap, no matter how clean and well-adjusted it is. Again going from memory here, but it's always made a lot of noise; I'm not even sure if it doesn't come from the interface between the shaft and the thrust plate (I wish I were there right now to examine it in detail).
So I'm either in the market for a newer, quieter motor or some kind of serious motor maintenance.
I wrote a note to John at Audio Origami today following Sreten's suggestion, kind of summarized this thread, asked for some suggestions. I hope he has a moment to respond.
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