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VPI HW-19 Upgrade question SAMA or SDS?

OK, the upgrade bug has bitten again, and I know that ther are a number of folks here that have lots of experience with their HW-19.

I have a VPI HW-19 Mk III that I recently upgraded to a Mk IV with a TNT platter with an inverted bearing. Also, it has a sorbathane puck suspension rather than springs, and I've replaced the rubber feet with cone type spikes. The table dead level sitting on top of a 1-1/2"-inch thick maple top shelf of a very heavy flexi-rack. I'm using an ET-2 arm connected to my shop compressor with four stages of precision air-regulation with the final stage adjustable just before at the entering the ET-2. I just air-up the compressor's 30 gallon tank, then kill the compressor so that it won't start back up, and I can listen for hours (wife think that I've lost my mind every time that I do this, but that's another story). Also, I'm currently listening to an AT33PTG that I have come to really like. The phono section is a Threshold SL-10 upgraded with Black Gates throughout.

The Mk IV upgrade made a real difference from the Mk III. As I quickly found out, the Mk IV presents a fuller soundstage and better base than the Mk III platter/bearing. I view that upgrade as well worth the money, especially buying it used here on A'gon.

Here is my dilemma with funds being limited to purchase only one or the other at this time, but not both - at least for now.

What do you think would be the best upgrade for this HW-19? A new SAMA for $400, or a used SDS for $600 to $800? Used SAMAs never seem to come up for sale, but you can always find a used SDS on Audiogon. I think that there are at least three available for sale here as I write this.

Also, if someone thinks neither mentioned upgrade would be cost effective, and that money would be better spent with an upgrade elsewhere, please say so. I'm trying to keep my mind and ears open - for better sound!

Thank you!
forrestc
emorrisiv
313 posts
 
I got the "black" belt recently and I experienced the same thing concerning "PRAT".

I have been curious about the silk thread.Is there any problem with the motor pulley shape with a thread? Does it give it more PRAT?
ptmconsulting
1,000 posts
 
The only thing to worry about with the thread is the size of the knot. With a thick string it could cause a small thump. Just use a basic over around and through (not a square knot or a bloodknot) with the thinner string.

My pully is V shaped. If you have the flat one it will be OK too, as long as the level of the pulley and platter are OK so it doesn't travel.

Now I haven't heard string directly against the rim drive but I've been told that it has the PRAT of a rim drive without the rumble of a rim drive. I believe it based on what i hear.
emorrisiv
313 posts
 
What kind of thread do you use? Silk? About how long does it need to be? I need to try this.

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forrestc OP
114 posts
 
To answer Emorrisiv's question above, the SDS not only controls the AC voltage to the turntable's motor, allowing full voltage for startup then changes to a reduced predetermined running voltage once the platter has stabilized, it regenerates and precisely controls the AC waveform and frequency. The AC frequency is what controls the speed of the turntable's motor, not the voltage. The output frequency on the SDS is user adjustable in increments of 0.01 Hz, and for this reason, you can set the speed dead-on.

I did in-fact buy a SDS from a seller here on Audiogon, and found it to be a significant improvement over no SDS.

Also, the SDS is obviously not a simple circuit device, it is essentially a full-blown special-purpose single-channel amplifier. IMHO, to do a DIY SDS project, not only will you need to be sharp in circuit design, I'm quite certain that you will need to devote a fair amount of time and effort to the project in order to be successful. Probably the most cost effective solution is just to purchase a used SDS, that is, unless you are looking for a challenging project.

Thanks again for everyone’s input!
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