What value cap to bypass power supply cap?


Is there a way to calculate the value for a bypass cap to parallel a power supply cap? To bypass a coupling cap or crossover cap, I've heard you should use 10 to 20% of the value cap to be by passed. For example, you should use 0.5 microF cap to bypass a 5 microF cap. However, I've heard you should use a standard 0.1 microF cap to bypass power cap, no matter the value (I have power supply caps up to 760 microF).
dracule1
Hi Kijanki, I will need to think about your wiring scheme to make sense of it. I'm not an experienced DIYer.

I think I will use high purity copper wiring with Teflon jacket.

As for the Hyperions, I'm not sure if I can answer that question. However, there was some controversy with phase of the midrange drivers on the 968s:

http://www.iar-80.com/page157.html
Dracule1, the only purpose of this scheme is to increase wire current delivery since capacitors are charged in narrow current spikes of very high amplitude. You can connect them in series but be sure to use as thick wire as possible and to connect load to the last capacitor in the chain.
Let's turn this up a notch ... as long as you have the hood up and soldering iron out .. you may want to construct a Snubber or Tank filter

SNUBBER Pdf

As your diodes convert AC to DC they switch on and off ... this cycling creates a ringing which can be tamed/toned down by placing a Snubber filter between the diodes and the PS caps ... read the PDF for field level box seats behind first base ... as again I’ve merely gotten you in the stadium

Here is an interesting read/point of view from one of my Sensei’s who likes to frequently poke me in the eye with a sharp stick to keep me in align

“Lets talk about FACTS. The AC powered audio devices in fact DON'T USE AC VOLTAGE AT ALL !!!
They are all DC devices and hence they need clean DC not AC. So creating "pure sine" is a most stupid, utterly heretic waste of time.
The AC, after entering our gear, becomes straight away brutally rectified into DC and that is the end of the road for the sine. Then the big electrolytic capacitors accumulate the electrons in a "bottle". These electrons become a source of energy for the active devices in our gear. They are being released slowly as a DC current.
THESE ELECTRONS HAVE NO MEMORY of their "childhood". They do neither remember nor care if they arrived in a form of perfect sine, cosine, square wave, or chaotic ripples. As long as they arrived, their sins are forgiven in the capacitor and they are purified. So in other words - the hi fi gear is indifferent to AC shape.

An absolutely another story is RFI. This frequency is millions times higher than the AC frequency. It behaves like radio-wave and it can penetrate the gear.

The problem is that the RFI can enter gear DESPITE the galvanic separation by transformer and despite filtering effect of capacitors in power supply. The RFI becomes the Trojan Horse of AC grid power system in our gear.

Getting rid of these is a bit tricky. But my advice is - that our intervention is focused on hundreds of kilohertz and not close to 50 Hz AC. So the intervention is very gentle, very low order, and nothing to do with our regular current feeding the gear.

The filtering is achieved by two opposite effects: parallel capacitive shorting and series inductive blocking.
The kindergarten explanation for non-engineers is that for high frequency - a capacitor presents a SHORT, and coil - presents a high resistance (impedance).
So a RFI noise rides by the AC cabling to our house very happy, like a Porsche on the autobahn. But when it arrives to the filter - the road becomes blocked by the coil. Oh shit thinks the noise, getting through is gonna be real tough. But then it notices an alternative route - an easy one - via a cap. It chooses the easy route and ends up in the ground. Dead. That's our noise trap. That applies of course to very dumb Porsches only. This method does not affect the AC performance because the cap is VERY small and the coil has a DC resistance of milli-ohms. Literally - of a foot of thick wire. So the impulse response of the AC source to the amplifier demand is not limited. We say that the supply is NOT CHOKED.

The audible effect depends on many many factors - the circuits in gear, the internal filters commonly built in, the ground quality and arrangement in the house, the type of devices playing together etc. It is IMPOSSIBLE to predict the degree of improvement, but strangely - the results are very consistent

END OF POKE IN THE EYE RANT

Lijanki .. OK I shall petition the federal government and the Treasury Department to put Almarg picture on the hundred dollar bill and your picture on the fifties ... the denomination value has nothing to do with your actual worth ... but only that the $100 are already occupied by Al’s picture

You are both the best at removing any self interest when giving a subjective opinion and Audiogon is lucky to have these two crown jewels in their in their collection

Keep up the good work

Dave
Dave, thanks again. I found nice drawing that shows how rectifier diode behavior introduces EMI:

http://www.powerint.com/en/community/papers-circuit-ideas-puzzlers/circuit-ideas/careful-rectifier-diode-choice-simplifies-and-

Also notice at the "VDC Bus" arrow, that ripple is very big. When ripple gets very small charging current gets very narrow. That's the problem of linear power supplies that in reality are switchers (SMPS) operating at 120Hz but generating a lot of high frequency noise.

Also, SNAP shown at the bottom drawing is not perfectly vertical. Let's imagine that it comes back slowly. If we make vertical line from this small negative peak we can divide it into two times "ta" to the left and "tb" to the right of this vertical line. tb/ta ratio is called "Softness" of the diode. It means that diode pictured here has very little softness. Good diode is fast to switch off (short ta) but slowly snapping back (long tb).
Guys, I feel like a monkey being taught how to speak sign language. Dave, thanks for the watered down analogy of the tank filter. I'll see if this can be incorporated in my amp.