So from what you guys are saying if an arm had an eff. mass of say 14g then if you somehow made the counterweight heavier then you would automatically be reducing that number? Not sure I understand... if you have an arm that is 14g eff. mass, then how is that number able to be changed by increasing the weight on the end? Isn't it is what it is by design? Maybe you are just kind of manipulating things is what you are saying, to increase the res. freq. of the two. |
So then in your case, you were able to fix things with a low compliance cart and lightish med mass arm by adding mass to the arm...hmmmm good thinking!
But how about this - what if the tables were turned and someone was dealing with a highish compliance cart and an arm that was a little too heavy for that cart? You can't take away mass from the arm and you wouldn't want to add mass to the headshell either like in your case....maybe a person could find lighter headshell screws for the cart or something....geesh what a ordeal this whole turntable business can be. |
So many times have I read about the 8-12Hz cart/arm res freq guideline its just like it seems to be a law to me because these numbers are the ones always brought up. Now people some times claim 9 or 10 is soem magic number even. I am no analog wiz or do I understand all of this stuff I am just wanting to understand what the hecks going on so I don't wind up putting together something that does not go together and sounds awful or has some weirdproblem. |
I wonder would using lighter cartridge screws help if your arm were a little heavy and cart a little light compliance wise? Or would that make things even worse or with cart screws does it even matter really?
I have seen these really light aluminum and plastic cartrdge screws before and of course steel or stainless steel ones. Someone told me before that these little screws can affect the sound, how though I am not really sure. |
Another thing about that VDH cart which is odd is that its the only low output mc I've seen around with a super soft suspension compliance. The others around are almost the complete opposite - low output mc's with low to med. compliance. 5-15mn weird....eccentric designer maybe? If I am mistaken here please excuse my ignorance and lack of experience. Just trying to get a grip on this stuff. |
This comment really makes me think, as I had no idea.
"Increasing the counterweight mass and then moving it closer to the pivot in order to maintain the same VTF will reduce the eff mass."
This could really help someone I think, in some cases at least. I wonder though how to judge how much the eff mass is reduced when the heavier weight is added and slid forward...would this be figured by somehow reducing or subtracting the actual amount of weight added to the counterweight to begin with from the starting eff mass without the extra weight?? |
Fleib, thanks but not sure I know what you mean. |
Another thing, I have often wondered about is - does it really matter if you use washers under the cartridge screws? I know it adds a little weight but is it a bad idea from a sonic perspective? Thoughts anyone?? |
Great responses everyone, I really thought this thread might help to simplify things for those of us who are not gurus. But boy what a can of worms I have opened, it just keeps getting more and more complicated!...whew..lol Oh well, thats analog and audiophiles for you. |
Wow, a 28gram brass headshell weight and 100gram counterweight add on?! Someone correct me if I am wrong but I think that is an extreme concept and probably not the best one. Instead maybe you could add a couple of stainless steel washers under your headshell screws atop the tonearm end where the cart mounts. If I had to guess I'd say you would be much better off going this direction over adding 128g of solid brass to your arm!
I could be wrong though so maybe someone with more knowledge can share their thoughts also. |
While daydreaming about carts I'd buy if money were no object, I looked at the spec for a low output mc VDH Colibri and found something which is baffling to me -
Weight (metal body) - 7g
Compliance - 35/mn
"Colibri metal body. Total cartridge weight is 7 gram. Suitable for arms with an effective tone arm mass of 10 gram to 14 gram." According to VDH website.
Now, what I am trying to figure out is how in the world a cart with that soft of a suspension go good with anything but a super super low mass arm.
From what you guys are saying exceptions exist but i am sorry this ones specs just appear too extreme not to be curious about. Excuse my ignorance and far be it from me to second guess mr. VDH but the specs imo beg the question. |
So, what you are saying is that most mfg.'s (Lyra, Shelter, Ortofon ect.) use dynamic compliance numbers on their spec sheets but for some reason VDH is using static compliance figures. Correct me if I am wrong here..
Is there a conversion calculator for converting static compliance to dynamic compliance? |
Is this formula correct? If so, it would indicate that both are identical measurements only stated in different units.
1 cm / dyne = 1 g ^-1.s^2 = 10^3 kg^-1.s^2
thus 10^-6 cm/ dyne = 10^-3 kg^-1.s^2
1 um = 10^-6m
1 mN= 10^-3 kg.m.s^-2
therefore 1 um / mN = 10^-3 kg^-1.s^2
the two units are thus identical.
From what I gather on the Colibri test measurement sheet their testing is conducted at roughly 100Hz. (Similar to how Lyra tests) |
All this together would seem to indicate that the stated VDH 35 Micron/mN compliance is the same as saying 35 x 10-6 cm/dyn only in different terms. If testing was done @ 100Hz. I think...
Its kinda like saying .5" is the same as 1/2" Right?
My math could be flawed though, so if that is the case anyone please feel free to correct these statements above. |
Not that I disagree because to be honest I am not absolutely certain but maybe someone can check with a mfg. like VDH or Lyra about that conversion. There are others who believe those numbers can be compared with accuracy.
What on earth would make someone like VDH put a number like that for compliance spec if nobady can understand it?
I hear you though, maybe trial and error means everything but not all of us have the luxury of rolling dozens of arms and carts just to find out which ones work well together. Thats why specs are important to me imo so that I can try to put something together which I think might be close to being right combo the first time. Maybe thats why some people get sick and frustrated of analog before they get a taste of what it can really do. just my 2 cents here and thanks for the knowledgeable people (like Fleib) kind enough to provide their input. |
Fleib and Halcro, your responses were both enlightening, thanks for the indulgence.
All is a bit confusing still, to me anyway. |
So Fleib, if I am understanding what you stated above what this boils down to is being the vdh Colibri static compliance is 35 Micron/mn then we in all likely hood are looking at a dynamic compliance in the 20-22cu range. Numbers being approximate, I assume...tracking specs say 1.35-1.5 g on VDH website so this makes a bit more sense. |
