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Best Arm Board Material ?


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So I'm looking to make an Arm Board for my Denon DD TT. as it will make it easy to swap out tone arms.

 

What do you guys think of what material to use and why ???

 

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I'm certainly no expert here, but if your thinking timber, Maple has extremely low resonance and is a highly recommended timber for plinths, so it may be suitable for an arm board. ;)

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To my ear, it's hard to beat timber.

Or plywood.

 

1) Damping qualities.

 

2) If the armboard is large and depending on method of attachment to the TT (& tonearm) - choose a timber that's not too 'dead', ie. still has some resonant characteristics - tap & listen to it (just like choosing 'tone-woods' for musical instruments). Plywood has the inherent advantage of stability, over many woods that can change over time & with weather conditions. But many timbers, hardwoods esp, can be nice.

 

IME materials like metal or acrylic or granular stones (marble, granite) have resonant character that is not so attractive or benign, sonically.

 

Just IMHO.

Cheers, Owen

Dark Lantern blog - http://darklanternforowen.wordpress.com/

Edited by Owen Y
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@@Peter_F

 

Denon DP-55K

 

Finally got the time to try that Jelco SA-750E  arm I got off you a couple of years ago....

 

I figure that if I can just do an arm board change out, it would be a much much simpler operation.

 

 

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IME materials like metal or acrylic or granular stones (marble, granite) have resonant character that is not so attractive or benign, sonically.

 

 

 

I disagree with this.  The armboard has a critical function, most importantly to provide rigid support to the tonearm through sufficient stiffness and mass, and provide transparency in sound - provide no loss or gain in the sound.  The term benign cops a bad rap in hifi, but in fact it should always be the desired outcome IMO.   The tonearm board should be made from from stable material and solid timber is not stable compared to other materials.     

 

@@Peter_F

 

Denon DP-55K

 

Finally got the time to try that Jelco SA-750E  arm I got off you a couple of years ago....

 

I figure that if I can just do an arm board change out, it would be a much much simpler operation.

In your situation I'd use either HDF or MDF with 1mm laminex on both sides. This will provide incredible rigidness and stability without adding or subtracting to the sound, a perfect result for a DD TT.  

 

Alternatively corian works really well or even billet aluminium.  I recently made my Garrard 401 armboards out of a composite using 12mm corian + 8mm HDF + 1mm laminex.  Mind you though the plinth has composite layers of materials including corian, marine ply and MDF weighing in at 21kgs!  

 

My Thorens TD160 armboards are 7mm HDF + 12mm MDF + 1mm laminex.  My Thorens TD150 armboards are 9mm HDF + 1mm laminex on both sides.  As these are suspended TTs the armboards needed to be light without affecting the suspension but still be very rigid and stable.

 

My SP10 armboards are 8mm HDF laminated both sides.

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I disagree with this.

 

No problem, everyone should have an opinion.

As said IME/IMHO.

 

Every material has resonant properties, even 'rigid' materials (high res freq) & indeed multiple laminates can have a combination of such..

 

But at end of the day, the sonic result is the acid test - which is why dudes like Shindo, Vinylista have achieved high regard for their TT work (incl 301s/401s.).

 

Cheers, Owen

Dark Lantern blog - http://darklanternforowen.wordpress.com/

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But at end of the day, the sonic result is the acid test - which is why dudes like Shindo, Vinylista have achieved high regard for their TT work (incl 301s/401s.).

 

 

 

 

Haha yes but it doesn't make sense to me at all to buy precision and very expensive tonearms which are designed and built for their accuracy only to have an audiophool bugger it up using inferior mounting methods and materials to colour the sound and put a handbrake on its performance.   :unsure:

 

I'm not a tube lover at all so Shindo to me is Shito. :P  

 

Vinylista makes some lovely stuff but I disagree with some of his methodologies and implementation.  I notice that he uses corian for his armboards.  

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And Corian has it's own sonic signature too...

 

Everyone has their own sonic allergies.

 

I love the sound of wood and try to stay away from granite, slate type materials, natural or man made.

 

YMMV

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i) ALL materials have a sonic signature

 

 

PS. Corian is just a cast acrylic resin plastic, Sota used it once in their TTs

 

Yes but some materials will have less sonic signature than others.  

 

Kenwood sucessfully used corian too.   :)

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Yes but some materials will have less sonic signature than others.  

 

Kenwood sucessfully used corian too.   :)

Synthetic concrete, not corian.
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Additionally, some materials have been proven to handle energy well - some reflective, some absorb & re-emit, resonate, others absorb & transfer, 'sink'.

 

Leinster - the DP-55K plinth is 2/3 layer particle/chip board & the arm board is small - so I would go for matching similar laminated board or hardwood.

The trick with a high torque DD mtr + sensitive tonearm/cart, is to mechanically couple to maintain geometry, but at same time try to decouple energy transfer between. You get the picture  ;)

 

Cheers, Owen

Dark Lantern blog - http://darklanternforowen.wordpress.com/

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Thanks Owen,

Once I get the original board off the plinth, I can make  a very accurate template.

I can then make a few "different" boards and see how they sound.

 

As the board is secured to the plinth by 4 screws, I might even experiment with rigid mounting and isolated ( somewhat ) mounting.

 

Hmmmm, i feel a project coming on :)

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Thanks Owen,

Once I get the original board off the plinth, I can make  a very accurate template.

I can then make a few "different" boards and see how they sound.

 

As the board is secured to the plinth by 4 screws, I might even experiment with rigid mounting and isolated ( somewhat ) mounting.

 

Hmmmm, i feel a project coming on :)

 

Exactly the right approach.

(i) Find the right answer to your ears.

(ii) Don't waste any opportunity to develop your own experience/intuition.

 

Thus next time, you likely won't need anyone else's advice ;-)

Keep us posted!

 

Cheers, Owen

Dark Lantern blog - http://darklanternforowen.wordpress.com/

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I will start with a disclaimer: I can't consider myself an expert. 

From what I've read about plinths... MDF is very popular (cheap and easy to work) but is not good acoustically -  it doesn't dissipate energy, so is to be avoided.  Softwood/ply is not very good.  Solid hardwood is better.  Hardwood ply is good - the woodgrain is in different directions, so energy is dispersed in multiple directions. 

 

Why not try some different materials and report back what worked best? 

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  • 2 years later...
On 29/07/2016 at 4:54 PM, stevoz said:

I'm certainly no expert here, but if your thinking timber, Maple has extremely low resonance and is a highly recommended timber for plinths, so it may be suitable for an arm board. ;)

Well, Stradivarius got good results with it! He used maple for the backs and spruce for the top plate. Would he have used MDF if it was available? I very much doubt it. Cedar might be a good choice too as it's easy to find, very stable and resistant to warping.

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8 hours ago, oztayls said:

Well, Stradivarius got good results with it! He used maple for the backs and spruce for the top plate. Would he have used MDF if it was available? I very much doubt it. Cedar might be a good choice too as it's easy to find, very stable and resistant to warping. 

Violins are different to plinths.  In simplistic terms, in a violin there are resonances to enhance.  In a plinth resonances can be bad.

 

 

Edited by audiofeline
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Guest gnnett
6 hours ago, audiofeline said:

In a plinth resonances can be bad.

While this is correct, I always thought that the problem was, within the audio spectrum, plinth resonances (and armboard resonances) will always exist. Over the nominal 3 decade band of audible frequencies, I thought that nothing was "rigid".

 

The statement that one should make an armboard out of "rigid" materials to "eliminate" resonances, would therefore seem to me to be unachievable.  While pursuit of reducing resonance is correct, there will still be resonances to deal with.

 

The most informative resonance measurements I have seen, are those of the tonearms that attach to an armboard. Not the tonearm-cartridge combination, but the arm tube resonance. The "best", most rigid of arm tubes, usually achieve first resonance somewhere in the second decade, none get very far into the third decade, without starting to "rattle". If it is going to rattle, I want it to be a nice rattle. This management of resonances might be achieved by constrained layer damping, material selection, or a combination, even with arm tubes varying in cross section from one of my favourites, the Grace G707, to the extremely well engineered Copperhead. The former a glorious set of compromises and the latter a pursuit of engineering excellence I can only admire, including the way it harks back to Gates broadcast arms. Neither, from my understanding represent absolute rigidity throughout the audio band.

 

While I do not disagree with the aims of an arm board to hold the arm pivot to the platter bearing "rigidly", this will not be achieved without some resonance to be dealt with somewhere in the audio band. I recall living quite happily, for a very long time, with the resonance management afforded by the much maligned arm board of the LP12, although more for the "lossy" fixing, than the actually constrained layer damped construction. Of course Linn have now pursued a more rigid option, go figure. 🙂

 

Cheers

 

Grantn

 

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2 minutes ago, gnnett said:

I recall living quite happily, for a very long time, with the resonance management afforded by the much maligned arm board of the LP12, although more for the "lossy" fixing, than the actually constrained layer damped construction. Of course Linn have now pursued a more rigid option, go figure. 🙂

 

Not much 'figuring' needed, Grant.  :)

 

The pressed-metal subchassis of the LP12 rang - and to prevent (rather, reduce) subchassis vibration from getting into the armboard and so affecting the arm - Linn had a lossy connection of the arm board to the pressed-metal subchassis.  (IE. three pissy little screws.)

 

The problem with this connection, though, was that the arm wasn't rigidly locked to the platter (ie. the bearing) - hence resolution was lost.

 

Then Linn introduced the 'Keel' - a one-piece subchassis & armboard.  Increased resolution was the result - but they were only able to do this because the Keel didn't have the vibration problems of the pressed-steel subchassis.

 

Andy

 

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Great discussion guys, thank you. So as I understand it, the aim is reduce unwanted resonant feedback into the arm and cartridge/stylus?

 

Now, if I want to enhance my old 14xxx series table, without replacing any of its parts, I could:

1. Damp the armboard?

2. Damp the subchassis?

3. Damp the base board?

4. Add a damping material under the feet? Or should the turntable rather be coupled to whatever it sits on to help dissipate unwanted resonant energy through to the floor?

5. Add a damping material to the springs? (I notice that my ERA table of the same vintage has damping material inside the springs. This does not seem to affect bounce)

6. Anything else?

 

 

If changing the arm, and the current arm board can’t accomodate the new arm, the new board needs to be of a material that absorbs as much energy as possible? I realise that energy eventually has to go somewhere, and the best place for it to go is probably into the air.

Let me know if I’m on track here. 

 

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Not quite sure what you're referring to by "old 14xxx series table" but the Qs you've asked, I suspect, will not have a consistent response.  :)

 

11 hours ago, oztayls said:

So as I understand it, the aim is reduce unwanted resonant feedback into the arm and cartridge/stylus?

 

Feedback into the arm from what?

 

Another line of thought, AIUI, is to be able to drain resonances which are created in the headshell - and therefore the arm - by the cart.  :)

 

11 hours ago, oztayls said:

Now, if I want to enhance my old 14xxx series table, without replacing any of its parts, I could:

1. Damp the armboard?

 

Better, I suggest, to make it of a material whose resonances are a. small and b. benign ... rather a material that has a lot of resonances which need damping.

 

11 hours ago, oztayls said:

2. Damp the subchassis?

 

Many people have reported that damping a Linn pressed-steel subchassis took the life out of the deck.

 

11 hours ago, oztayls said:

3. Damp the base board?

 

Why not simply remove the base board?  Linn put it there simply to stop inquisitive little fingers from getting a shock; I was told that Linn employees routinely removed the base boards on their own LP12s.

 

11 hours ago, oztayls said:

4. Add a damping material under the feet? Or should the turntable rather be coupled to whatever it sits on to help dissipate unwanted resonant energy through to the floor?

 

If it's a solid-plinth TT - then, yes, damped feet are essential.  @metal beat has successfully used springs under (some of) his solid-plinthed TTs.

 

11 hours ago, oztayls said:

5. Add a damping material to the springs? (I notice that my ERA table of the same vintage has damping material inside the springs. This does not seem to affect bounce)

 

I think that's a "suck it and see" issue.  :)  ERA may well have - but Linn never did.

 

11 hours ago, oztayls said:

If changing the arm, and the current arm board can’t accomodate the new arm, the new board needs to be of a material that absorbs as much energy as possible? I realise that energy eventually has to go somewhere, and the best place for it to go is probably into the air.

 

That's an interesting conjecture (should the new board be of a material that absorbs as much energy as possible?).

 

I can't comment - I can see pros ... and cons for doing this!  :(

 

Andy

 

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6
18 hours ago, andyr said:

Not quite sure what you're referring to by "old 14xxx series table" but the Qs you've asked, I suspect, will not have a consistent response.  :)

 

 

Feedback into the arm from what? I was referring to unwanted resonances and vibrations, for example from motor, rumble, soundwaves,  etc. 

 

Another line of thought, AIUI, is to be able to drain resonances which are created in the headshell - and therefore the arm - by the cart.  :)

 

 

Better, I suggest, to make it of a material whose resonances are a. small and b. benign ... rather a material that has a lot of resonances which need damping. Gotcha

 

 

Many people have reported that damping a Linn pressed-steel subchassis took the life out of the deck. OK, I have not experienced the so-called "ringing" that some have reported, so I will ignore damping the sub chassis.

 

 

Why not simply remove the base board?  Linn put it there simply to stop inquisitive little fingers from getting a shock; I was told that Linn employees routinely removed the base boards on their own LP12s. Good idea.

 

 

If it's a solid-plinth TT - then, yes, damped feet are essential.  @metal beat has successfully used springs under (some of) his solid-plinthed TTs. OK

 

 

I think that's a "suck it and see" issue.  :)  ERA may well have - but Linn never did. I'll give the spring damping a try

 

 

That's an interesting conjecture (should the new board be of a material that absorbs as much energy as possible?).

 

I can't comment - I can see pros ... and cons for doing this!  :(

 

Andy

Thanks for your thoughts Andy, it gives me a useful guide to try a few things. I've responded above in colour. 

Cheers

Bruce

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  • 1 year later...

Does any one know a CNC shop in Sydney who could make an arm board from a metal material? 
 

Cheers

Edited by ArtCor
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