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

Hi @imhififan, he's basically explaining a zobel like I mention above, and some generic advice that may or may not fit a circumstance.   However, transformers do not reflect secondary load C to the primary.   

However, transformers do not reflect secondary load C to the primary.   

They absolutely do reflect any capacitance seen on the secondary by the turns ratio squared.  Say you have 150pf (50p cable + 100p input)  at the secondary of a 1:20 SUT.  This will appear as 150*20*20 or 60,000pF or 60nF or 0.06µF to the source.

 

dave

Would love to see a cite with a detailed technical explanation.  I can’t find one, equivalent models I can find don’t show it, and a couple EEs I’ve talked to say it doesn’t.  Repeating a formula is not an explanation.  

For transformer winding capacitance, please read the article on Jensen Transformers Application Notes "AN008" - Audio Transformer by Bill Whitlock

https://www.jensen-transformers.com/application-notes/

 

Thank you for the reference.  Section 1.2.4 is in regard to inter- and intra-winding capacitance and electro-static shielding, which I understand.  While Figure 16 depicts secondary load C as CL, I do not see a reference to it in the text.  This section doesn’t seem to address reflected C.