Here is part of what you wrote today Tmazz
When you upgrade a VPI HW-19 from the Mk II to the MK IV status (which involves installing the heavier Mk IV platter) VPI includes a new set of suspension springs that are tuned to the new total weight of the TT.
I put a heavier platter I purchased from AudioGon on my HW-19 MK III a few months ago.(Inverted bearing I believe from an Aries TT) I even contacted VPI about it, nothing was said to me about different springs only that I would probably new a spacer to raise the height of the tonearm. Should I contact VPI and inquire further
Thanks.........Bill
Bill,
OK, it has been a lot of years since I took college physics, and while I remembered that simple spring system resonance was fairly straight forward relationship with the loading mass, I could not remember the exact formula. Yeah Google! It was pretty easy to find. As it turns out the mass component of the equation is in the denominator so increasing mass will lower the systems resonant frequency (Hey, I remembered it moved it
)
For those of you that still own a plastic pocket protector, here is a link to the formulas ;
http://hyperphysics.phy-astr.gsu.edu/hbase/shm2.htmlSo that changes the point of view of the question, but it basically still remains the same, what effect will the extra weight have on the performance of the suspension system. When designing a spring suspension there are basically two things you have to look for (and trade off between). It has to be loose enough to isolate the platter and arm from any external vibrations that the TT might be subjected to and it must be stiff enough so as not to resonate in a way that will introduce audible artifacts into the TT's output signal.
Basically both of those things have a range of acceptable values and if the change in platters results in a change that still falls within those acceptable ranges the old springs are good to go. The people over at VPI are very good and know their products inside out. I have several conversations with Mike in the service dept. and he has always been right on top of any issue that I asked him about. It is quite possible that moving to a Mk IV platter requires an change in springs and moving to an Aries platter does not. But Mike would certainly be the one to ask. If you do talk to him ask about the new HW-19 isolators that they are selling as a replacement for the springs Set of 4 for $50. One of these days I an going to order a set and see how the sound on mine. It may be better. may be worse, but for $50 what the heck, it would be fun to find out.
As for the arm spacer Mike spoke about, what kind of arm do you have. If you haven't got the spacer yet you might want to think about looking for a VPI Super Armboard. This is a thicker armboard that they came out with when the Mk IV came out that raises the arm so it is compatible with the thicker Mk IV platter. The extra thickness also made it stiffer and less resonant.I don't see them listed on the HW-19 parts page anymore, so I'm not sure if you can get them from VPI, but the do show up every once in a while on A'gon, although mostly drilled for SME arms (others come around but are harder to find.) I picked one up about a year ago, but it is still sitting in the box because I spent so much time dialing in my current cartridge that I don't dare touch it right now. Next time I change it out I will remount the SME IV on the new armboard, but until them it is working just fine, so I don't want to mess with it. (and with any amount of luck, by then I will have also come across a good deal on a MK IV platter and bearing and can change out everything at once. And BTW, if you are running you HW-19 without a PLC or an SDS start looking for one now. I have never heard an SDS in my system, but I can tell you you will be hard pressed to get a bigger improvement for the amount of money you will have to lay out for a used PLC (generally between $200 & $300, but if you keep your eyes peeled you will see one occasionally for under $150).
