[13405]

[deleted]

 

[drewd]

It's an interesting idea, but, unfortunately, no.

The voltage rating is a guide to let you know the maximum safe voltage, above which the the dielectric may break down, causing the capacitor to fail, potentially catastrophically - look at the top of an electrolytic cap. See the little score marks? They control the direction of the explosion.

The quality of a cap isn't related to its voltage rating. The voltage rating is just what it is - the maximum voltage that the cap is designed for. Black Gate caps have lower capacitance densities because of the design of the cap, that is, the forumulation of the dielectric and the spacing of the conductors. Higher voltage ratings mean that there is either more dielectric material between the conductors or that the dielectric material is of a different formulation. The voltage rating doesn't have a bearing on the quality of the cap.

There ain't no such thing as a free lunch - quality costs, at least with capacitors.

But as grist for another topic, there are several capacitors out there that are much cheaper than Black Gates with a significant amount of the Black Gates' performance.

Poke around Tangent's web site (http://www.tangentsoft.net/audio) for some of his notes on selecting capacitors. He's probably explained it better than I have.

-Drew

 

[ppl]

The Primarry claimed advantage of Black gates over any conventionial Electrolytic is the Electrolyte is Graphite or carbon as opposed to a paste. the advantages claimed are lower inductence, However not mentioned is the fact of possibly increced leakage currents resultent of a almost conductive dielectric. I would also suspect that the larger case sizes reflects the cap may be rated for a lower voltage than the actual capacitor and as sutch be able to obtain comparible leakage currents.

The above is mearly My Humble understanding or misunderstanding of the black gate literature.

 

[Kenny12]

are black gates really that expensive to make or are they just over inflated?

 

[Sycraft]

I'm guessing a little of both. They are a low demand item, and cheapness in manufacturing comes with massive production runs. So it probably does cost more per unit than other caps. They aren't useful to most electronics since they are very large for an an electrolytic (and what makes them great is they are small per their amount of capacitance) and their superiority in specs isn't relivant to most circuts.

However, they also know they are in demand with the group that does use them, so they can charge a whole lot for them.

 

[Kenny12]

:\ double sorry

 

[jcx]

its interesting that cyril bateman's "Capacitor Sound" article in Electronics World magazine seems to have had so little effect on these discussions

basically he suggests any film (including mylar/pet/pte) shows less distortion than any electro

if you must use electrolytics then bipolar types create less distortion, and higher V rating helps also with ~35-50 V being a good volumetric efficiency point, i believe his final electrolytic recomendation was to series 2 bipolar caps if you must block some dcv

black gate make much of the conductivity modifier but cyril's measurements point to the bipolar dielectirc as the key

 

[Sycraft]

That might be because most of us don't recieve Electronics World magaine. If I were to spend all my time just reading journals, I'd never even get through the Psychology journals, never mind the whole social and behavioural science field, never mind all of them.

If it's a good article, link to it, or at least provide quotes and citations as in year and number, not just author and publication.

Also, discussing distortion must be influenced by how a capactior is used. In a PPA for example, all the capacitors are only on the power rails, not in the signal path. I'd bet even on most other amps, elecrotlytics are power only. I mean why would you need or want that kind of capacitince in the signal path. Well, distortion on a DC power rail is quite different than distortion on the signal path.

 

[tangent]

Quote:

why would you need or want that kind of capacitince in the signal path

Output caps.

The corner frequency of an RC filter is 1/(2*pi*R*C). R is the headphones: it can be as low as 16 ohms. Do the math and tell me what kind of C you need to get the corner frequency well under 20Hz.

Now do the same exercise, but for a power amp, where R can be as low as 2!