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What considerations apply to material selection for cartridge mounting bolts?

I have found myself needing some longer bolts to relocate a Shure V15 Type 3 cartridge to a Holbo air-bearing system.

The Holbo tone-arm is a tangential tracker with a rigid rectangular 'launch pad' for the cartridge.  The pad is 3-mm thick which is much more than the fixed SME head-shell my dad bolted the Shure to some 45 years ago.  If it was supplied with longer bolts, they disappeared decades ago!

I will most likely have a similar issue with my Audio Technica VM540ML cartridge which is probably a better fit for the Holbo.  It was supplied with a head-shell 4-mm thick, but the bolts slots are recessed by over 2-mm.

A quick internet search turned up bolts made of stainless steel, titanium, aluminium, brass, plastic and nylon.  Some brass bolts are gold-plated (for corrosion resistance presumably).  As a one-time metallurgist, I know that stainless steels can be non-magnetic, or magnetic.

Plastic and nylon are lightweight insulators and immune to electro-magnetic effects like induced eddy currents.

The lower the material density, the lower effective mass of the cartridge.  Here brass is clearly the worst, being denser than steel and weaker than the other metals.

I presume that the main engineering requirement is to firmly couple the cartridge to the tone-arm but I have no idea how firmly.

The Funk Firm has an opposite view with its Houdini coupler which in effect splits the bolts in half, with an elastic suspension between the cartridge body and the tone-arm.  It seems to allow the cartridge body to swing easily to the left or right side.  Does anybody here use these?

richardbrand
richardbrand's avatar
richardbrand OP
1,408 posts
 

@audphile1 

if cost is not a consideration, does that include buying $250 cartridge mounting screws?

Ahem, cost has just become a consideration!

I only asked the original question because I have to buy two bolts to mount my old Shure V15 cartridge to my new Holbo deck, and the bolts I have are 3-mm too short.  I was also interested to see if any pseudo-science bubbled to the surface.  And then @kevemaher said "Take a gander at  https://korfaudio.com/" which is real science and an absolute eye-opener especially if you have a Shure

Yesterday I did a 70-km round trip to my nearest HiFi dealer and they rummaged through their parts box and found two nuts and bolts, which are thinner than the imperial bolts I have, and a lot too long. The dealer would not accept payment.

So I put the bolts in upside down for now and played my Holbo for the first time.  I would have expected the very high compliance Shure V15 (with a new Jico SAS/B stylus) playing at 1.2 grams, would find it hard to move the tangential arm assembly but it is tracking faultlessly (after an embarrassing failure).

No hardware store or local fastener outlet goes below metric M3 and I believe we need M2.5.

audphile1's avatar
audphile1
8,022 posts
 

@richardbrand 

Enjoy the music!!!

roadcykler
343 posts
 

@audphile1  It absolutely does not objectively affect the sound.

tablejockey
4,405 posts
 

Cartridge mounting screw material affecting sound.

Next year's resolution- don't goof on audiophool claims.

Years not done yet.

I bet if that company did a more colorful hype write up, they could charge DOUBLE, and people would be hitting the buy now button.

I guess if you can afford a fully loaded Dohmann or Tech Das Zero, you buy them.

 

 

 

dover
2,503 posts
 

I guess if you can afford a fully loaded Dohmann or Tech Das Zero, you buy them.

Hahahaha - good luck with that.

Tech Das are M2.6 ( Japanese standard )

Acoustical Solutions M2.5 ( euro standard )

Good luck rooting your pricy cartridge with the wrong size.

Always pays to check the screws provided with the cartridge.

The 2 sizes are not interchangeable.

 

 

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