How important is the cable between the SUT and phono pre?


I know when using a cable between a MM cartridge and the phono pre it's very important to take into account the capacitance of the cable for cartridge loading.

I don't recall seeing a discussion on the importance of using low capacitance cables between a SUT and  phono pre.  

I picked up a Denon Au-340 to replace my Denon AU-320 in my system and the AU-320 has built in cables that run to the phono pre, hence my question.

Is there a way to figure out the capacitance requirement for this cable or is it not that important? Will a good shielded cable work fine?

I don't want suggestions on some high dollar cables, that will never happen. I have about 15 or 20 pairs of cables that I picked up over the years, I can always go through the pile and measure the capacitance if necessary.

Thanks

 

BillWojo

billwojo

Some mm cartridges have a recommended capacitive load for flattest response. This capacitance is the sum of the tone arm wiring, cable to the phono stage and the phono stage input capacitances.

If the capacitive load is below the minimum for a particular mm cartridge it will have a high frequency peak. Moving coil cartridges are immune to capacitive loading.

It has a bypass switch but right now I'm just using various versions of the Denon DL 103 cartridges. So 

MC all the way. I have plenty of good shielded cables so I should have what I need. 

Thanks

 

BillWojo

Really, really important. Ultra low capacitance, and low run length < 1.0m are key. You need to try to keep it under 50 pF. Don’t use a "normal" thick audiophile interconnect.

Before I knew how important low capacitance was, I did some cable rolling with high quality "normal" interconnects. All the 1m cables had their sonic signature GREATLY magnified, to the point of obvious coloration. The AQ Fire 1m became overly detailed and aggressive. The AQ Sky 1m sounded overly warm, thick and and bloomy. The 0.5m AQ Niagara, normally inferior to the higher-end Fire and Sky, did better and was relatively uncolored - because of the halved length and significantly lower capacitance. The the dedicated AQ WEL LP phono cable (optimized for lower capacitance), 0.5m, blew them all away. The Bob’s Devices 0.7m interconnects are also really good (but the WEL LP is still better) - I have both their copper and silver cables. They’re optimized for SUT use, obviously.

This was all tested on the same Koetsu cartridge and Bob’s Devices Sky SUT.

MC are said to not be sensitive to capacitance, but the problem with a SUT is that it reflects the capacitance of its output cable times the SQUARE of its turns ratio. That’s enough capacitance that it WILL start to affect the MC cartridge.

Many Cardas interconnects have very, very low capacitance - so if you've got those in your collection, give 'em a try. I believe Bob's uses Cardas ingredients to make his cables.

@mulveling

 

"MC are said to not be sensitive to capacitance, but the problem with a SUT is that it reflects the capacitance of its output cable times the SQUARE of its turns ratio. That’s enough capacitance that it WILL start to affect the MC cartridge."

 

Can you point me to some more information on this? I was searching for information and found nothing to indicate that this was a problem. I've read that the cables from cartridge to SUT didn't need to be particularly low capacitance but nobody talks about the cables from SUT to phono pre.

Thanks

 

BillWojo