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-   -   To drill or not to drill? (a VPI turntable) (http://www.diyaudio.com/forums/analogue-source/71003-drill-not-drill-vpi-turntable.html)

m.parigi 4th January 2006 02:01 PM

To drill or not to drill? (a VPI turntable)
 
I've got a recent (18 months) VPI TNT 6 turntable - not the HRX - that came with the JMW 12.5" tonearm premounted.
It looks to me as if like there's no armboard at all, the JMW being mounted directly on the turntable itself.

I've recently purchased on Audiogon an Airtangent tonearm, which is a linear arm suspended on thin air cushion. Since there's no way that it can fit into the space/hole freed by the JMW (which I'm going to uninstall), I have now to decide where to put it.

The most obvious solution would be to drill a 1" hole (that's what is required) on the right side of the turntable and install it in the space that was occupied by the JMW. This solution has at least two disadvantages I can think of:

a) makes me drill a big hole in my beloved turntable, thus damaging it and making it lose some value should I decide to sell it

b) the Airtangent would be operated "sideways", that is with the cartridge going from the front to the rear of the turntable. Positioning on the tracks would be awkward and even placing the periphery stabilizer ring could be a dangerous operation

The other solution, suggested to me by Mike at VPI, would be to fit an additional armboard in the back of the TNT and to place the arm on it. This way the arm would be operated in a more "natural" way, going from the right toward the center of the record, like the linear turntables that were manufactured a while ago.

Disadvantages:
a) I have no idea whatsoever on what material to use, which thickness and how to connect it to the turntable. It looks to me as if I would end up drilling some holes no matter what...

b) I'm concerned that having an armboard hanging out of the turntable would degrade the sound and would pick up some vibrations.

As much as I don't like it, I'm inclined to drill a hole because it looks to me as the best sounding solution.

What do you guys think? Suggestions? Materials?

m.parigi 5th January 2006 06:12 PM

Anybody, suggestions?

valveitude 5th January 2006 07:13 PM

I'll take a stab at it..keep in mind I don't own a VPI, so this is pure conjecture.

Does the platter go right to the edge in the back ? If it does, I would consider a arm "pod" seperate from the table. Look at a Redpoint table. This way you don't touch your table, and gives you a lot of adjustment possibilities.

Casey

m.parigi 5th January 2006 07:42 PM

The VPI plinth has four air bladders that support the feet. In order to keep the reciprocal geometry (distance, height, etc.) shouldn't the arm pod be linked in some way to the rest of the plinth?
It looks to me as if the arm placement is bloody complicated, how does the turntable you mention keep the arm positioning from falling apart?

valveitude 5th January 2006 08:03 PM

Quote:

The VPI plinth has four air bladders that support the feet. In order to keep the reciprocal geometry (distance, height, etc.) shouldn't the arm pod be linked in some way to the rest of the plinth?
Unless the air bladders are leaking, the geomotry of the table should be fixed, true if the table is bumped , it will move independantly from the table...not good. Again, I don't own a VPI, so I dn't know how stiff the "suspension" is. If it floats around like a Linn, it wont work, but if its stable it should.

Quote:

It looks to me as if the arm placement is bloody complicated, how does the turntable you mention keep the arm positioning from falling apart?
Placement is critical. The "pod" idea works because it's mass loaded, possibly with pointy feet..it won't move unless you move it.

Of course you would have to have the table & pod sitting on something stable.

Vinyl-Addict 6th January 2006 03:32 AM

Quote:

Originally posted by valveitude


Unless the air bladders are leaking, the geomotry of the table should be fixed, true if the table is bumped , it will move independantly from the table...not good. Again, I don't own a VPI, so I dn't know how stiff the "suspension" is. If it floats around like a Linn, it wont work, but if its stable it should.



Placement is critical. The "pod" idea works because it's mass loaded, possibly with pointy feet..it won't move unless you move it.

Of course you would have to have the table & pod sitting on something stable.

I built my table with an arm pod but laid everything out on my CAM system. After I machined everything, I made a gauge that simply fits between the plinth base and arm pod. It works perfectly and because the arm pod is mass loaded, it does not move and if I do move it, it takes a minute to get it aligned.
If the VPI is steady on its feet, you can figure out if an arm pod is an option but you'd have to make sure there is enough clearance for an arm pod to sit next to it.:)



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