Cables and Capacitance

[Neil Smith]

Hello, I am just starting out on an F5 build, it is my first DIY project. I have a couple of questions that I appreciate some advice if anyone would kind enough to help.

i. For cable on the signal path I am thinking of a AWG22 multi-conductor, copper core, with tin plating and silicone insulation (high dielectric strength), would this cable choice be appropriate or would you advice a cable with a degree of shielding?

ii. On the PSU, is there a limit on max capacitance, that is, is too much capacitance capacity a problem providing the power requirements of the amp is met?

Thanks in advance.

Neil

 

[JonSnell Electronic]

In time silicon insulation degrades as it is never a solid. In my experience, a fresh loom was manufactured for an amplifier board using similar silicon insulated cables. There was a tight 90 degree bend and after a few years the inner conductors started protruding through the insulator. If balanced digital signals, twisted pairs are preferred rather than screened balanced/unbalanced cables.

All that is required is enough capacitance to bring down the impedance of the supply to a level that stops ripple. Too much is a waste and shows a design with poor knowledge.
Generally speaking if using an LM78/9 type of regulator, 100uF is adequate on the output side for up to 1Amp. Any more and it causes problems within the regulator chip.

 

[DF96]

Unbalanced connections may need shielding. Multi-conductor for what reason?

Too much PSU capacitance merely wastes money, may heat the transformer, may make grounding problems worse. My advice is to calculate the minimum, then just double it.