Layered plinth for SP-10

jlsem · 3rd September 2007, 05:07 PM

Here is a picture of a layered plinth I made for a friend of mine. It is made up of random layers of Baltic birch plywood, solid basswood, and aluminum. It is covered with 1/8" wenge veneer.

John

jlsem · 3rd September 2007, 05:24 PM

I sorry, for some reason the photo won't load. I'll try again later.

John

jlsem · 31st October 2007, 04:34 AM

O.K., the pictures of the plinth I built for my friend Albert Porter are now up on this website:

http://www.soundfountain.com/amb/sp10plinth.html

It can also be seen here:

http://cgim.audiogon.com/i/vs/i/f/1193606055.jpg

A very interesting project with a surprisingly good result.

John

JCLNV · 1st November 2007, 08:08 AM

Very nice work.

jlsem · 2nd November 2007, 04:04 AM

Thanks! The salient feature of that plinth is the grey cast iron block which is coupled by a brass rod to the bottom bearing of the motor and acts as vibration sink. The result was an amazingly quiet turntable - actually more quiet and with blacker backgrounds than the Walker Proscineum. Not at all what we expected.

John

AuroraB · 2nd November 2007, 08:28 AM

Quote:

Originally posted by jlsem
Thanks! The salient feature of that plinth is the grey cast iron block which is coupled by a brass rod to the bottom bearing of the motor and acts as vibration sink.

John

Would you elaborate somemore on this one??

jlsem · 2nd November 2007, 01:23 PM

Any electric motor produces some noise, and a direct drive turntable motor is coupled directly to the platter and is not isolated from the rest of the 'table. The moving coil cartridges used have outputs on the order of 200-600 microvolts, so noise is obviously an issue. The grey cast iron block has a very high specific damping factor (highest among commonly available materials) and the brass rod makes a convenient transfer path for noise and vibration to the iron block, where they magically disappear. This base is admittingly a brute-force solution to the problem, but it worked very well.

John

AuroraB · 2nd November 2007, 01:29 PM

DUH! Of course, direct drive!
I guess my brain wasn't awake yet, this morning....

jlsem · 2nd November 2007, 01:35 PM

I kind of had a feeling that you hadn't realized that this was a direct drive application.

Cobra2 · 2nd November 2007, 07:13 PM

Quote:

Originally posted by jlsem
Any electric motor produces some noise, and a direct drive turntable motor is coupled directly to the platter and is not isolated from the rest of the 'table. The moving coil cartridges used have outputs on the order of 200-600 microvolts, so noise is obviously an issue. The grey cast iron block has a very high specific damping factor (highest among commonly available materials) and the brass rod makes a convenient transfer path for noise and vibration to the iron block, where they magically disappear. This base is admittingly a brute-force solution to the problem, but it worked very well.

John

What noise? What problem?
"What HiFi" + other reviewers did measurements of niose/rumble++, and found it better than most high-end belt-drives (of it's time)...

Arne K

3rd September 2007, 05:07 PM	#1
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	Layered plinth for SP-10 Here is a picture of a layered plinth I made for a friend of mine. It is made up of random layers of Baltic birch plywood, solid basswood, and aluminum. It is covered with 1/8" wenge veneer. John

31st October 2007, 04:34 AM	#3
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	One more once O.K., the pictures of the plinth I built for my friend Albert Porter are now up on this website: http://www.soundfountain.com/amb/sp10plinth.html It can also be seen here: http://cgim.audiogon.com/i/vs/i/f/1193606055.jpg A very interesting project with a surprisingly good result. John

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3rd September 2007, 05:24 PM	#2
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	I sorry, for some reason the photo won't load. I'll try again later. John

1st November 2007, 08:08 AM	#4
JCLNV diyAudio Member Join Date: Aug 2007	Very nice work.

2nd November 2007, 04:04 AM	#5
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	Thanks! The salient feature of that plinth is the grey cast iron block which is coupled by a brass rod to the bottom bearing of the motor and acts as vibration sink. The result was an amazingly quiet turntable - actually more quiet and with blacker backgrounds than the Walker Proscineum. Not at all what we expected. John

2nd November 2007, 01:23 PM	#7
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	Any electric motor produces some noise, and a direct drive turntable motor is coupled directly to the platter and is not isolated from the rest of the 'table. The moving coil cartridges used have outputs on the order of 200-600 microvolts, so noise is obviously an issue. The grey cast iron block has a very high specific damping factor (highest among commonly available materials) and the brass rod makes a convenient transfer path for noise and vibration to the iron block, where they magically disappear. This base is admittingly a brute-force solution to the problem, but it worked very well. John

2nd November 2007, 01:29 PM	#8
AuroraB diyAudio Member Join Date: May 2001 Location: Norway, -north of the moral circle..	DUH! Of course, direct drive! I guess my brain wasn't awake yet, this morning....

2nd November 2007, 01:35 PM	#9
jlsem diyAudio Member Join Date: Jun 2003 Location: Dallas,TX	I kind of had a feeling that you hadn't realized that this was a direct drive application.

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