Upgrade chat...

Looking to possibly upgrade from a VPI HW-19 jr with MK 3 platter. This unit was purchased secondhand in 1998. The MK 3 platter was added a few years back. This unit has provided zero issues over the years. My only complaint with the unit it the notorious Grado hum from the 120v motor. Requirements for next unit are a hinged dust cover, dimensions roughly the same as the VPI, and must be secondhand or demo. 5-6k max money wise. Been looking at the Mobile Fidelity unit. Not sure it would be a step up in performance. Also looking at the Thorens with the semi auto function. Keep the VPI and upgrade it to a mk 4? Any ideas would be welcome.
More of a principle really than advice, my view is there comes a point where it is better to stop thinking of the turntable as all one component and start to think of it as the three or four that it really is: turntable, arm, cartridge, and suspension. Most guys prefer the ease and simplicity of buying this all in one fell swoop. You can do a lot better though by breaking it down and focusing on each part individually. You are with the VPI right at the entry level or beginning of where this approach begins to make sense. 

Here's why. Your $5-6k will buy you a better turntable, for sure. Or it will buy you one hell of an awesome arm. The arm is huge and that arm alone on your table will be a massive improvement. Or you could split the investment between an arm and say a Townshend Platform to put the VPI on. Either one of these alone will be a huge improvement. Together it will be hard to do better with the same money on a turntable package alone.  

It is very hard to imagine just how much performance is lost or hidden in micro-vibrations. Until you hear it. My turntable was on a massive 750lb rack of cast concrete, sand, and granite, with a Black Diamond Racing Source Shelf on top of that. Yet I heard huge improvement with Townshend Pods. https://systems.audiogon.com/systems/8367 You know what yours is on better than I do. Take a look at this and imagine if it did that for me what it could do in your situation. I know guys have told me it was like getting a whole new turntable. 

If you do want a turntable then the safe bet is another VPI. Good solid table, nothing wrong with them, other than the arms are kind of weak. But it is a package, they are very good at giving you incremental value for money. Hard to go wrong.

Dividing it into arm, table, suspension is more work for sure. My experience is, totally worth the effort.
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Yes absolutely, for that money you can buy a brand new Sota. They have excellent dust covers and a great suspension. You can pound on one with a hammer and it will not skip. You want to look at the Sapphire. I would get a used SME arm for it from these guys. http://www.smetonearms.com/index.php?main_page=product_info&cPath=16&products_id=75
Rather than upgrading the VPI to Mk.4, look for a TNT-3/4 platter (7/8" lead-lined aluminum bottom, 3/8" Delrin top layer) or TNT-5 platter (5/8" stainless steel bottom, 7/8" Delrin top) and bearing.

The subchassis of the VPI has a 1" hole drilled for the platter bearing, and some of the TNT bearings are also of 1" diameter (others are 1.25"), so will slide right into place. Either choice under $500.

For the Grado/motor hum, there are shielding materials made than can be wrapped around the motor.

Remove the stock suspension springs, place a set of Townshend Seismic Pods under the subchassis (sitting on the shelf, not the HW-19 wooden outer base).

By the way, the HW-19 Jr,. and Mk.1 and Mk.2 had steel painted black subchassis, the Mk.3 and Mk.4 unpainted stainless steel. The Jr. and Mk.1 have a 1/2" layer of MDF on top of the steel, the Mk.2/3/4 1/2" acrylic.

There is a guy parting out an HW-19 right now (I don't remember where. A Hi-Fi Shark search should lead you to it), the base and subchassis separately. And on USAM there is an HW-19 upgraded with a TNT-5 platter and SAMA (Stand Alone Motor), asking price around $2200.
For a package a used SOTA Sapphire is hard to beat. Made in Delevan. Good people.
Buy a Linn sondek lp 12 and be done....a design that has stood the test of time, and it looks darn good too. 
Follow up. A different vpi unit was purchased that ultimately, unfortunately, did not work out. Moving forward, following advice from bdp24 and others, the super armboard was purchased. I was able to use herbies items to spacer the board correctly on the base. The bearing and platter from the previous armboard will be used. The next issue is the tonearm. The board is drilled for an sme tonearm. I have an audioquest pt-6. Should I seek, from vpi, the mount for the pt-6 or should I seek the sme 309 tonearm? From what I’ve read on the net, the 309 appears to fit this setup. The tonearm appears to sell anywhere from 1700 to 2100 usd. Is this tonearm worth that cost? Or should the board be purchased from vpi to mount the pt-6? Other tonearm ideas are invited and welcome.