Black gate fake impedance-v-frequency graph

[chuao]

I've been thinking a lot about capacitors lately and I came across this crazy thing in some of the Black Gate product literature. The claim is that if you take these certain capacitors and wire a pair in reverse-parallel the inductance and esr are both magically cancelled.

That seems utterly bogus. The funny part is that there's a graph that goes along with it, for instance figure 5 here:

http://www.octave-electronics.com/Pa.../bg_tech.shtml

Did they just fake it outright? It seems wild that audiophiles would have so little faith in Faraday's law as to believe that...

On an unrelated note, does anyone have a recommendation for a low esr (<0.1 ohm) capacitor in the 100-200 uF, 40 V range? Os-con doesn't go that high on the voltage rating.

[Garbz]

I've head a lot about this Super-E configuration but i've always been skeptical. I've never heard it but I had the intention of trying it on the output of my soundcard until I decided to do away with the single ended supply.

As for a recomendation... How about some black gate caps in super-E config

[ppl]

the Black Gate So Called supper E Configuation is nothing new or exclusive to any one Brand of capacitor. All capacitors have both an inside and an outside foil and on non polar types if one were to connect two non polar or one polar and the other non polar capacitors in parralell with the inside foil of one connected to the outside foil of the other then Inductence will be less than ether of the caps by itself. Polor caps also have an inside and an outside foil however since thay are polerised must be installed only one way however if paralelling with a non polar Type the cap can go in ether way and one can aragnge the leed with the outside foil to connect to the next caps leed of the inside foil

[chuao]

That's what doesn't make any sense to me. The inductance of the capacitor depends just on the geometry of the conductors, and should not depend at all on which way the capacitor is connected. Paralleling two will cut the inductance (and esr) in half, but that's not what the graph shows. It shows them magically cancelled altogether, up to the 10s of MHz.

In my opinion, it's obviously fake. My real question is, how do they get away with that?

[doobooloo]

Well they do have a patent on that thing, IIRC...

[Garbz]

Think of it from a consumer perspective. The people most likely to buy these sort of things are the people who know what they are, how they work, and who aren't stupid enough to fall for this kind of thing.

Just like the Ford Fiesta Sportivo which had that ad here in Australia. It was fine that the car killed the bird, but when they brought a cat into play the ACCC had the ad pulled instantly.

I'm sure if people complain it would be taken.

[antonik]

Originally Posted by doobooloo

Well they do have a patent on that thing, IIRC...

I've read the patent and it is full of marketing stuff. What they claim is irrelevant, as you can reduce the inductance only by close magnetic coupling, which is impossible for two separate capacitors . There were some real attempts to do it, for example "T-network" capacitors from DNM, reducing the impedance by connecting the leads to the middle of the foil roll. The impedance graph most likely is just a fake . Even if the inductance is cancelled the resistive part of the losses can not be cancelled, so the claim that

"In addition, as a result of the elimination of resonance frequency, the impedance and E.S.R. lower infinitely as the frequency increases "

is complete bollocks... as many other things written on that page.

Alex

[peranders]

Notice that those fact doesn't come from Rubycon which makes the Black Gate. -170 dB in distortion, pretty fantastic, don't you think?

[Garbz]

The entire site is a bit whacky. Under black gate NX Hi-Q it says the noise level is "-174kb" [sic]. I never knew kilobits is a measure of noise, that said I never knew kb could go negative too.

[ppl]

Originally Posted by chuao

That's what doesn't make any sense to me. The inductance of the capacitor depends just on the geometry of the conductors, and should not depend at all on which way the capacitor is connected. Paralleling two will cut the inductance (and esr) in half, but that's not what the graph shows. It shows them magically cancelled altogether, up to the 10s of MHz.

In my opinion, it's obviously fake. My real question is, how do they get away with that?

Connecting two identical capacitors in parallel will half the series resistance and series inductance regardless of the capacitors internal geometry. Capacitors of different internal geometries are often paralleled to maintain a flat impedance curve vs. frequency what is important is selecting values that will not self resonate at critical frequencies in your equipment. This technique is used extensively in the industry as im sure your aware its quite common to put a small film cap in parallel to a large Electrolytic with an order of magnitude more capacitance. If the combination is improperly selected then interaction with the other capacitor and PCB trace inductance can form complex LCR circuits and self Resonate at frequencies you do not want.
http://www.jenningstech.com/technotes/cap_parl.shtml
http://www.qsl.net/in3otd/inductors.html
Decoupling in general is discussed in this AVX application note
http://bears.ece.ucsb.edu/class/ece2...decoupling.pdf

I do agree that most of the Literature on Black gates site are of Questionable merit however the lower inductance of paralleling capacitors together is not one of them. Arguably it could be a little much to believe the dramatic reduction on inductance claimed by Black gate however am sure halving it is quite possible. The use of inside to out side foil to get low inductance dates back to the old paper and tin foil types.
ECT sen. http://www.tomography.com/pdf/apnote3.pdf
Fun with a Leyden jar at> http://www.tufts.edu/as/wright_cente...ab_Part_IV.pdf


One item that has me concerned about the supper low ESR and ESL of Black gates is the fact they use pressed on as opposed to spot welded lead termination to the Plates. Typically Low ESR and ESL Electrolytic have Welded Leads. However the dielectric is graphite and they do sound great that’s why I use them at times.