You seem to be suggesting that choosing a good material for a plinth can only be determined by trial and error and once the “system” has been fully assembled. That seems like an extremely dubious proposition to me and furthermore, if true, is of no practical use to most people; how many people are going to make several plinths and then compare how their TT and arm performs on each one (not that you could do a meaningful comparison given the amount of time that would elapse between each trial).
It seems much more likely to me that a good plinth material is a good plinth material irrespective of the other elements of the TT system.
Disclosure: I sell Panzerholz pieces for making plinths. That fact has not influenced my comments above, but you may of course choose to think otherwise.
Yes it returns to it's shape. The orange part of the label reads "Maximum stretch Elastomeric. +/- 35% joint movement."
After a little more reading...
The Difference Between Elastic Materials and Viscoelastic Materials - www.sorbothane.com
GE Max Stretch can probably be considered a Viscoelastic. With a moderate pull, it does return to it's original shape, but slowly.
There's and ASTM specification C920 for caulking that rates it's elasticity. The GE product is rated for 35% joint movement, which is reasonably high. Some Silicones also have this rating, but I think they return to their original form more quickly.
Hugh
The Difference Between Elastic Materials and Viscoelastic Materials - www.sorbothane.com
GE Max Stretch can probably be considered a Viscoelastic. With a moderate pull, it does return to it's original shape, but slowly.
There's and ASTM specification C920 for caulking that rates it's elasticity. The GE product is rated for 35% joint movement, which is reasonably high. Some Silicones also have this rating, but I think they return to their original form more quickly.
Hugh
Silicones Sealants are generally designed to maintain a bond to the Substrate the Silicone is applied onto, hence the various pre application preparations that can be required, Abrading Surfaces, Degreasing Surfaces, Priming Surfaces.
Once the Silicone is applied it expected to maintain a bond especially when used as a Joint Seal when movement is incurred at the Joint, such as Thermal Expansion and Retraction and Structural Movements.
The more the extremes of the movement impacting on the Silicone, the lower the modulus will be selected during the design and selection of sealant materials.
I have also recently discussed aquarium sealant as a material as an alternative applicant where a standard sealant has not shown to be ideal for the environment it is being used in.
This might be ideal for Acrylic as a bonding, it might also have the suggested properties to allow for a micro movement when cured.
Once the Silicone is applied it expected to maintain a bond especially when used as a Joint Seal when movement is incurred at the Joint, such as Thermal Expansion and Retraction and Structural Movements.
The more the extremes of the movement impacting on the Silicone, the lower the modulus will be selected during the design and selection of sealant materials.
I have also recently discussed aquarium sealant as a material as an alternative applicant where a standard sealant has not shown to be ideal for the environment it is being used in.
This might be ideal for Acrylic as a bonding, it might also have the suggested properties to allow for a micro movement when cured.
I can recommend the PVB (Polyvinyl butyral), and although I have some (powder) I haven't tested it yet. It dissolves in alcohols (and other organic solvents, so IPA (95%+water) will work well, it has been reported.
The reason I recommend it is that my brother, who was an architect, gave me samples of reinforced glass (Butacite) which I believe uses PVB. The good news is that the glass sample of 'Butacite' gave a DF of nearly 0.4, whereas 'strengthened glass alone measured 0.033.
I have bought you some PVB powder, so PM me with your address and I'll send it over, my gift.
There are lots of different PU glues, some of them form very strong bonds, but not flexible! One place I worked used PU adhesive, but made a mistake, and had to remove the equipment that used the PU to stick it on a vehicle. It took 3 months to remove the glue!
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When I posted that info about ASTM C920, I wondered if you'd see it on caulking tubes in the UK or Europe. Probably not. I'm guessing you see the word "modulus" instead. True? I don't recall seeing it on anything here.
The Information that you are referring to is looking like a Code a designer and Architect will discuss as it, will have an amount of operational parameters attached to it that are Industry Standards and are easier to communicate in.
A Brand will be selected that falls into the chosen parameters of usage.
I will usually receive a Branded Product and use the Manufacturers Product Data to advise on the usage of the supplied material.
It is more common that at this basic level of description is where the term Modulus will be found.
The PVB is quite interesting as an adhesive, it s value to being used with Glass was an accidental discovery in a lab.
When a Glass Beaker was dropped that contained a dry residual it was not that easy to break the fragile beaker.
A Brand will be selected that falls into the chosen parameters of usage.
I will usually receive a Branded Product and use the Manufacturers Product Data to advise on the usage of the supplied material.
It is more common that at this basic level of description is where the term Modulus will be found.
The PVB is quite interesting as an adhesive, it s value to being used with Glass was an accidental discovery in a lab.
When a Glass Beaker was dropped that contained a dry residual it was not that easy to break the fragile beaker.
Gents, a mixture question here, i have some Avonite, Corian like material to build a plinth and arm support.
I believe in the rigid light route and will first build my LTA support, followed by the Lenco and plinth.
I need to bond various bits of avonite together and was thinking to epoxy glue them with Araldite.
However, if this could obviously be beterred i can find an alternative adhesive if its readily available.
Any conclusions you might offer would be interesting!
Thanks
Mike
I believe in the rigid light route and will first build my LTA support, followed by the Lenco and plinth.
I need to bond various bits of avonite together and was thinking to epoxy glue them with Araldite.
However, if this could obviously be beterred i can find an alternative adhesive if its readily available.
Any conclusions you might offer would be interesting!
Thanks
Mike
Avonite is similar to Corian as said.
There are numerous Industrial Adhesives on the Market for these types of Materials.
Are you planning on producing a Stand Alone Tonearm Pod ?
The information that will be most useful to your planning the project is if you need a Colour Match Adhesive, whether the surfaces to be bonded will be better served as a abraded finish and whether the surfaces to be bonded will adhere best if a force is applied during the curing period, i.e, Timbers and Clamps used.
The above is pretty much for bonding the same type materials, if the want is to produce a CLD Design Plinth, then the Avonite material will need to be identified as a suitable material prior to choosing a method of adhesion.
There are numerous Industrial Adhesives on the Market for these types of Materials.
Are you planning on producing a Stand Alone Tonearm Pod ?
The information that will be most useful to your planning the project is if you need a Colour Match Adhesive, whether the surfaces to be bonded will be better served as a abraded finish and whether the surfaces to be bonded will adhere best if a force is applied during the curing period, i.e, Timbers and Clamps used.
The above is pretty much for bonding the same type materials, if the want is to produce a CLD Design Plinth, then the Avonite material will need to be identified as a suitable material prior to choosing a method of adhesion.
Mike,
Yesterday, I had to use a screwdriver to pry the Acrylic/mdf/Acrylic sandwich apart. The "GE Max Stretch" is an Acrylic/Silicone caulking meant for windows, so it does form a weak but useful bond to acrylic.
So, I'm wondering if an avonite/mdf/avonite sandwich with a similar caulking might work for you. Cats S may have some thoughts on that.
If you're in the US, GE Max Stretch is available from Lowes, although it may be called "Max Shield" there.
I'll be testing another caulking shortly.
Hugh
I am in Uk, looking to rebuild the base of my LTA that sits between its rails and the TT support. Eventually i will build my Lenco into its plinth using similar philosophy, with this same arm.
For now i look for rigid to carry vibration and energy away from the cartridge if it generates it and then dissipate it so it doesn't go back.
The current support is MDF.
I measure the results and see the peak of this tone rising and the noise falling, sidebands reduced, as things are improved, here attached pics of the arm and measurements.
I don't need colour match, only performance.
Best
M
For now i look for rigid to carry vibration and energy away from the cartridge if it generates it and then dissipate it so it doesn't go back.
The current support is MDF.
I measure the results and see the peak of this tone rising and the noise falling, sidebands reduced, as things are improved, here attached pics of the arm and measurements.
I don't need colour match, only performance.
Best
M
Attachments
It took me a long time to be convinced, i was quite happy making things and modifying them and expecting and therefore believing they sounded better.
What i call auto suggestion clicks in and if you spent a week of hard graft making a new widget its bound to sound better than the old one!
Several folks on different threads suggested i measure things and so i adopted a route they suggested.
I play a 1000Hz test tone on the test record and look closely at the peak and sidebands through VA.
To do that i convert the signal to digital by taking the output of my preamp to a AD converter (£20 Behringer 222) and input to my computer using VA which is freeware you can download easily. People were kind enough to give me a tutorial on this which i can copy for anyone interested.
I look at the peak locally around the test tone and as a whole spectrum to see what else is going on.
I understand this is not high resolution testing and the bottom end is probably not fully representative, however its helped me see what affects what, and i attach for your amusement my first test.........i also changed scales since this.
If you do this, be prepared for some disappointments! - and then some progress
M
Those few words say so much! They should be 'writ large' on every audio forum. Excellent.
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as far as I have read, Avonite ® is said to be just acrylic. Corian ® is acrylic filled with alumina (aluminium oxide, hydrated). But although pure acrylic has a DF of about 0.07, Corian® has a DF of only 0.044. However, it might work, as damping is an intrinsic property, there is no way of guessing how effective it might be at damping.
The problem with 'rigid' materials is that they do not damp well. There are exceptions (always is, Panzerholz and polyester/bentonite resin) but there is very little correlation between Young's modulus and loss factors.
But I have found that two materials which show very little damping on their own can have favourable properties when glued together!
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Thanks Bryan,
I shall make something, measure, listen and see what i have! - work starts in the coming days and i will update after, you have the "before" screen shots, "after" will follow.
There is a reasonable stock of Avonite in the garage so, illogically probably, the material is preselected by low cost availability. My entire arm with all the bits is<£50 and thats part of the pleasure, to make something that is quite good and costs beer money as opposed to '00's or '000's..........
Avonite must be filled with something similar to Corian for the colouring, i expect they just forgot to mention that, it is worked in exactly the same way.
Best to all
Mike
I shall make something, measure, listen and see what i have! - work starts in the coming days and i will update after, you have the "before" screen shots, "after" will follow.
There is a reasonable stock of Avonite in the garage so, illogically probably, the material is preselected by low cost availability. My entire arm with all the bits is<£50 and thats part of the pleasure, to make something that is quite good and costs beer money as opposed to '00's or '000's..........
Avonite must be filled with something similar to Corian for the colouring, i expect they just forgot to mention that, it is worked in exactly the same way.
Best to all
Mike
Acrylic/mdf/Acrylic
Here's what I've found with 3 different materials between the Layers. All show very good damping (0.3 to 0.57) at the low frequencies (table attached).
I'm not sure if it's relevant, but there's some 5khz ringing as well. I'm thinking maybe it's the resonance along the thin axis. Is this a real response of the materials to vibration? My Accelerometer suddenly seems dead, so I don't trust the last DF of .07 at 5khz.
If these 5khz bursts are real, the damping is not as good as the LF ones. However, the duration is short (3 to 6 milliseconds).
The GE and DAP caulking are simlar in compliance, so the ASTM spec I was on about earlier only seems to say that it's an Elastometer (or maybe Viscoelastic).
I'll do one more test with a firmer adhesive. I'm thinking this should show less damping. I have a few versions of white glue drying on a piece of Acrylic to decide which one.
Here's what I've found with 3 different materials between the Layers. All show very good damping (0.3 to 0.57) at the low frequencies (table attached).
I'm not sure if it's relevant, but there's some 5khz ringing as well. I'm thinking maybe it's the resonance along the thin axis. Is this a real response of the materials to vibration? My Accelerometer suddenly seems dead, so I don't trust the last DF of .07 at 5khz.
If these 5khz bursts are real, the damping is not as good as the LF ones. However, the duration is short (3 to 6 milliseconds).
The GE and DAP caulking are simlar in compliance, so the ASTM spec I was on about earlier only seems to say that it's an Elastometer (or maybe Viscoelastic).
I'll do one more test with a firmer adhesive. I'm thinking this should show less damping. I have a few versions of white glue drying on a piece of Acrylic to decide which one.
