VPI Classic 3 plinth clone

VPI Classic 3 plinth clone

Postby Crazy Bill » Thu May 18, 2017 11:59 am

Hello all.
I'm building a turntable from scratch. I've been studying plinth construction for a while, then finally woke up and figured Harry's been doing it for a long time and has a pretty good idea how to do it right. ( Had an Aries MK1 from 2000 to 2012 and it surely made beautiful music ). So I've decided to clone a variation of the Classic 3 plinth.
Obviously there's already enough info on the VPI site and elsewhere on how to do it except for the adhesive types. If I had to guess I'd use epoxy between the aluminum/steel plates. Then a woodworking glue to bond the mdf block together, and then epoxy to bond the steel/al plate to the mdf.
Anyone able to shed any light on the adhesives used, or offer any thoughts.

thanks, Crazy Bill
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Re: VPI Classic 3 plinth clone

Postby Letsmakeadeal » Thu May 18, 2017 12:26 pm

Bill - I think they use something that remains somewhat compliant like silicone maybe? I am sure someone like BRF can tell you for sure....
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Re: VPI Classic 3 plinth clone

Postby Brf » Thu May 18, 2017 1:16 pm

Letsmakeadeal wrote:I am sure someone like BRF can tell you for sure....


Not sure about the "for sure" part, but I can give you my opinion on the subject. What you are attempting to do is suppress vibrations through a mechanical engineering technique called Constrained-layer damping. I would suggest Googling "Constrained-layer damping" as this will give you enough information to make an informed choice on a suitable material/glue etc.

Sounds like a fun project. Good luck and keep us posted.
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Re: VPI Classic 3 plinth clone

Postby Letsmakeadeal » Thu May 18, 2017 4:01 pm

At 1.29 to 1.30 of this video it shows Mat gluing on a top steel plate on a Classic. It is a DAP product. If you have good eyes you might be able to figure out exactly...

https://www.youtube.com/watch?v=zJsnuSGZ1Kw&t=16s
Atma-Sphere MP-1 Mk 3.3, Pass X600.5 amps, Eminent Technology LFT VI speakers, Aerial SW 12 subs, True Sound Works Ultimate Apogee Divas, VPI HRX Reference (MagDrive/RimDrive), 12" 3DR tonearms, Miyajima Kansui & ZERO, VPI ADS, Vendetta SCP-1
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Re: VPI Classic 3 plinth clone

Postby Crazy Bill » Thu May 18, 2017 8:22 pm

Thanks Brf and Letsmakeadeal .
I looked at the video and it gave me some insight. Thanks. It does look like a DAP product. ( BTW, my eyes aren't good enough any more to make out which type :oops: )

I really don't think Harry is attempting a constrained layer technique here. The AL/steel plate bonded to the mdf is more of an attempt to using a stiff material with mass. The stiff part obviously comes from the steel/Al, and the mdf adds the mass. From what the reviews say, it works. The plinth as described on the website really does not conform to a typical constrained layer construction.

I'll be following the 1/2 inch AL/steel plate/2 inch mdf formula as presented on the website, with the possibility of increasing the mdf thickness for aesthetic reasons. I'll also be adding a 3 inch diameter cutout of the mdf under the bearing. I plan on adding a sand/oil mixture in that well to add additional damping to the bearing. I think that will help lower the noise floor.

I'm no whizzbang at this stuff, so please keep the advice coming. Much appreciated.

Cheers, Crazy Bill
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Re: VPI Classic 3 plinth clone

Postby Letsmakeadeal » Fri May 19, 2017 12:45 pm

Not sure how Oil and MDF are going to live in harmony? Maybe I am missing something? This may be a feature that you really don't need? If you really want to add more mass damping to the plinth, I would stick with tiny lead shot and no oil...The Classic as it is has an essentially noiseless bearing anyway...
Atma-Sphere MP-1 Mk 3.3, Pass X600.5 amps, Eminent Technology LFT VI speakers, Aerial SW 12 subs, True Sound Works Ultimate Apogee Divas, VPI HRX Reference (MagDrive/RimDrive), 12" 3DR tonearms, Miyajima Kansui & ZERO, VPI ADS, Vendetta SCP-1
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Re: VPI Classic 3 plinth clone

Postby 10ovr » Fri May 19, 2017 7:48 pm

Check out this thread ,,, One of my favorite builds ,,Mite give you some ideas viewtopic.php?f=11&t=968
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Re: VPI Classic 3 plinth clone

Postby Crazy Bill » Sat May 20, 2017 9:50 am

10ovr,
Thanks for the link. I read this a couple of weeks back when I started researching plinth construction. Great build.

Letsmakeadeal,
You're right. No harmony in that combo.
I'm either going to put a pvc pipe in the hole and fill that with the oil/sand mixture, or several coats of a waterproof epoxy would also do the trick. Probably go the epoxy route as its easier.
Right again on it being probably overkill, but I am quite anally retentive about most things, and I can't help myself. I was thinking that since the bottom of the bearing is exposed under the top plate, it certainly couldn't hurt to have it immersed in the sand/oil mixture to attempt to damp whatever vibrations may come from the bearing. Plus there will be no surface oxidation of the bearing housing.

Now a disclosure. I'm only cloning the plinth, not a full VPI Classic table. I had no idea that VPI parts could have been purchased, or I possibly would have gone that route. the guts of the table ( platter, bearing, motor, speed control ) are from the now defunct Choir Audio. I had John make me the platter,bearing,motor and speed control from his CHOIR ONE table, and that's what I will be using. The arm will probably be my Fidelity Research FR66s.

Thanks again, Crazy Bill
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