New Phono Cable and Capacitance

Please forgive my lack of understanding of capacitance and the impact it may have on sound quality. I did read several posts on capacitance load and resistance trying to come to a better understanding on my own. What I think I understand is that the cartridge has a sweet spot for capacitance load and loading outside of that sweet spot can impact frequency response. Is that simplistic point correct? If so, that leads to my question/concern.

I am considering the purchase of a new phono cable. The manufacturer lists capacitance per meter of cable for the various models they sell. My cartridge lists the optimal load as 200-300 picofarads per channel. My phono pre-amp lists input capacitance as 120pf. I cannot find the capacitance for my Denon DP37F turntable in the owners or service manual. If I could find the tone arm capacitance would I simply add that number to the input capacitance of my phono pre to determine if the "load" falls in the sweet spot for my cartridge? Similarly when considering the new phono cable do I just add the stated capacitance of the cable to the input capacitance of my phono pre?

This is probably a gross oversimplification of the concept but my head is still spinning after reading some of the threads I found so gross oversimplification is what I need. My equipment profile is up to date. Any guidance will certainly be appreciated.

Thank you!

 

If I'm following your commentary correctly, it seems you do understand the method here. The total capacitance seen by the cartridge is the tonearm capacitance, the cable capacitance, and the input capacitance all added together. For example, let's say a manufacturer states their cable is 100pF/ft, and you've got a 3ft cable. With your 120pF input capacitance, and a rough ballpark assumption of 25pF for the tonearm capacitance, the cartridge will see: 25 + 100 x 3 +120, or 445pF of total capacitance. This would be excellent for a V15III (which desires 450pF load), but terrible for a more modern cartridge that is made for a 250pF load. If you don't have selectable capacitance on the input of your phono, then your only variable to play with is the cable.

 

I'm going to follow this thread. I think it's time I upgrade my phono cable, but I need to sit down and do all of the math to get the best one for my setup. It just gets a little overwhelming.

 

100 pF/meter is pretty low in general for a phono cable. You can always try to keep it shorter.

 

Great, thank you for that. I appreciate your response. Once I get my tonearm capacitance I am good to go.
Next question. If I'm told or read "445pF total capacitance" may I assume that is per channel?

 

That's a good assumption, yes, it is per channel.

 

Thank you.

 

Just keep in mind, before you end up buying a very high capacitance cable, that it's much easier to add capacitance via loading plugs than it is to take it away. If you ever switch cartridges to something that requires low capacitance, you will be kicking yourself for buying a high capacitance cable. Loading plugs are cheap and easy to make.

 

Great point. Thank you.

 

I believe with your Shure M97xE is better to keep the capacitance bellow 200p. Please see following AC sweep Graph printed from a Spice program using electric model of a Shure M97xE plus a flat response MM Phono Tube preamp. the first graph is with 47K and 450P and the second graph is 47K and 200P

 

I just purchased a Blue Jeans LC-1 cable for my 1210GR, I'm pretty sure it sounds better but I could just be imagining it!

 

Thank you for this detail.