jonjin

SP10 plinth project

55 posts in this topic

Finally found myself a 12" Ortofon RMG-309 at not too bad a price and should therefore press ahead with making a plinth for the SP10. I've also found some Panzerholz and Russ Collinson himself has some, so this could be quite easy. What I have to decide is the design. I know that conventional wisdom is to make a plinth with maximum mass, but I wonder about a skeletal plinth type that the Garrards use (like this). Too heavy a plinth might be the reason why some people feel the SP10s can sound too neutral or 'dead'. This website also seems to suggest this and backs it up with measurements.

http://qualia.webs.com/plinths.htm

http://qualia.webs.com/dampingfactorvalues.htm

Hmmmmm...

JJ

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Andy, I always have various hifi projects in my head... combinations of what-ifs and wishful thinking mainly. Some reading I've done says the idler and air bearing parralel tracker concept that you have is the best!

Panzerholz is very dense and heavy with high damping factor, higher than slate. It is essentially beech ply with resin pressed under high pressure.

At the moment I'm considering a 2 staged approach. Start with a simple skeletal plinth. If it doesn't sound good, the 2 sections can be glued together.

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http://www.ltlewis.co.uk/b15.htm

Let me know if you're interested in a group buy as one sheet is too much for me.

They can be tricky to cut. This thread has good info on how to do it...

http://www.vinylengine.com/phpBB2/viewtopic.php?t=27852

Between the 2 sections would probably be sorbothane feet only because I have them lying around.

I've also read that Newplast which is basically Play-Doh but oil based makes good damping material!

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depending on price i may be interested , does sound very good for plinths but also very tough i work with oak quite alot and does tend to blunt your chisels and planes quickly .Good quality blades and router bits will be called for i think ,one other thing is the colour alot darker than birch ply

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I have built Kenata style ply plinths for SP10s but have not really been happy with the sound.

I am now using a sold jarrah plinth with a void around the turntable which can be mass loaded with lead shot.A ply bottom is fixed underneath to hold the lead shot in the void.

It seems that jarrah is the best timber for such uses.Dense but not too dense and it has a short grain structure.Grado are now using jarrah for their most expensive cartridge bodies.

If you want to experiment with damping the tonearm from the jarrah you can try different washer materials-lead,acrylic,cork etc but for most tonearms you are best with just the jarrah.

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I have built Kenata style ply plinths for SP10s but have not really been happy with the sound.

I am now using a sold jarrah plinth with a void around the turntable which can be mass loaded with lead shot.A ply bottom is fixed underneath to hold the lead shot in the void.

It seems that jarrah is the best timber for such uses.Dense but not too dense and it has a short grain structure.Grado are now using jarrah for their most expensive cartridge bodies.

If you want to experiment with damping the tonearm from the jarrah you can try different washer materials-lead,acrylic,cork etc but for most tonearms you are best with just the jarrah.

This is very interesting! Can you describe the differences in sound between the Kaneta ply and Jarrah? Which wood did you use for the Kaneta?

I am interested in your idea because the convention has been to have high mass and multi-layered. Eg, Welsh slate is actually composed of layers and taking this one step further would be the Panzerholz which is even higher density. But you seem to have approached this from a different view point with a medium density wood.

Jarrah seems to be available from eBay as untreated reclaimed railway sleepers. This might actually be cheaper than Panzerholz but will require significantly more work.

JJ

edit - slate is higher density than Panzerholz (which makes empirical sense) but I think Panzerholz has higher damping factor

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I definitely think there is a balance to be struck. As you say too damped and it may sound lifeless and boring - bit like an SME deck / arm:)

Are you going to have armboard? That may give you another option for fine tuning. I bought Coco's SP-10 in slate bed and gunmetal armboard. Before adapting the armboard to fit my arms I tried a birch ply one. Gun metal better for vivid, life and emotion. I have no science in why, just know that it works.

Love to see some pics...

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Either go skeletal, uber light and fast carbon/aerloam/nomex, or massy, don't mix the two...

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Either go skeletal, uber light and fast carbon/aerloam/nomex, or massy, don't mix the two...

This makes sense to me too.The laminated ply type is a medium mass approach.

The ply I used was Hoop Pine.A bit lighter than Birch ply but still a premium quality ply.

I will post some photos of my jarrah plinths later.

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One thing to consider is that Lenco's & Garrards are chucking out (relatively) huge amounts of vibration which needs to be sunk somehow rather than conveyed to the base of the arm. I'm not sure the SP10 motor needs to be dealt with in quite the same way. I will try some kind of lightweight foam/nomex/cf type plinth one day!

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Very interesting read JJ, thanks for the links. :^

It seems 'cat squirrel' has done some homework & panzerholz does look quite an interesting proposition for the DP6000 plinth.

I was looking towards an aluminium/acrylic laminate so it will be interesting so read his finds on multi layer composites & there damping factors.

MJ does bring up a good point though on if the SP10 & my DP6000 for that matter, need that amount of damping!

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The plan now is to go modular using Panzerholz. Mainly because I am skint and can only afford one layer! But if you believe the links above, 15-20mm should be best in terms of damping response of the Panzerholz. Obviously, size of the plinth will also make a difference as well. The idea is not to go for high mass but have something which is rigid and non-conducive instead. Panzerholz is basically beech ply with resin injected under high temperature and pressure, so it is essentially a multi-layer composite with 'natural' materials.

Armboard will be the sliding base made of steel ala SME. It should add further decoupling from the Panzer. It also looks nice and should match the silver TT :)

Arm is Ortofon RMG-309 which should match the rest of the neutral system as it has quite a lively and colourful character... luminous as some would say :P

JJ

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The plan now is to go modular using Panzerholz. Mainly because I am skint and can only afford one layer!

JJ

Sounds like you need to sell some S2's:)

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