Wima capacitors for audio?

[Gold]

Careful Paul, the double blind ABX police will be coming for you soon.

I too have also heard caps sound different.

You don’t need golden ears to hear it in the situation I described. I don’t claim to hear those differences in other situations.

It came to mind because the photos of Igor’s build show TDK caps. I tried Wima and wasn’t happy. I tried TDK and it sounded much better. I ended up with others but the differences weren't small and all were PP.

 

[Heikki]

I did a little searching and exposing audio mythology column by John Roberts can be found at RECORDING ENGINEER PRODUCER - Studio and Audio magazine - 1970 to 1992

Here's the one about capacitors. (Page 26)
https://worldradiohistory.com/Archive-All-Audio/Archive-Recording-Engineer/80s/Recording-1984-02.pdf

 

[Newmarket]

I did a little searching and exposing audio mythology column by John Roberts can be found at RECORDING ENGINEER PRODUCER - Studio and Audio magazine - 1970 to 1992

Here's the one about capacitors. (Page 26)
https://worldradiohistory.com/Archive-All-Audio/Archive-Recording-Engineer/80s/Recording-1984-02.pdf

Thanks for posting those links.
Unfortunately in the JR capacitor article there seems to be a couple of pages (27/28) missing in the middle of it.

 

[JohnRoberts]

I'm not sure how much meat was missing (there may have been some drawings). I don't think that was the only time I wrote about capacitors in that column, mostly to demystify them... Even back then we had objective metrics for voltage coefficient et al.... We do have better capacitors available today, but don't expect huge audible improvement.

JR

 

[CJ]

these Siemens caps make good antennas also.
i believe they are like WIMA's without the coating.
anybody try polycarbonate? very temp stable, expensive, and i do not know how they handle audio. could be good if you want stable EQ curves in a tube based box.

 

[Newmarket]

these Siemens caps make good antennas also.
i believe they are like WIMA's without the coating.
anybody try polycarbonate? very temp stable, expensive, and i do not know how they handle audio. could be good if you want stable EQ curves in a tube based box.

View attachment 93640

Polycarbonate dielectric caps' became basically unobtainable some years ago IIRC as main manufacturer (BASF ? Don't quote me !) ceased production.
In have a vague idea that someone may have made some recently but not certain.

 

[Newmarket]

Looking at this thread in general - and whilst not wanting to discourage exploration -I have to say that I can't think that opening up old MI kit and taking capacitor ideas from them is not really the best way to approach the subject.

 

[Matt Syson]

CJ's comment about the (photographed) capacitors making good antennas contains an important aspect.
The foil on the 'outside' Will capacitively couple with other conductors nearby, wherther wires, circuit traces, metallic chassis or other capacitors and components. Thus 2 similar capacitors will behave quite differently depending on which of the 2 foils of each are inside/outside. This effect is also seen on other capacitors, even electrolytics where for example the OUTER foil possibly SHOULD be grounded if that is what you are wanting OR should be considered a 'hostile' emitter (aerial/antenna). So consideration of circuit impedance and proximity of ALL components. In an EQ circuit where you may have a row of capacitors for example, you could easily get quite different results depending on the physical orientation of all the caps.
Matt S

 

[Perm0]

Polycarbonate dielectric caps' became basically unobtainable some years ago IIRC as main manufacturer (BASF ? Don't quote me !) ceased production.
In have a vague idea that someone may have made some recently but not certain.

Your vague idea is correct;

https://groupdiy.com/threads/polycarbonate-film-caps.77251/
I did an enquiry with sayd company but they gave me a "F*** off" quote at $ 180,- for a single cap, they do high quality parts for avaiation and millitary / space stuff.
Even audiophiles would probably call this "expensive"

If you happen to have some polycarbonate caps, try them for filtering on your tweeters, I think these sound great in general.
KC, the non metalised ones are even nicer, but they come in small values only.

 

[JohnRoberts]

CJ's comment about the (photographed) capacitors making good antennas contains an important aspect.
The foil on the 'outside' Will capacitively couple with other conductors nearby, wherther wires, circuit traces, metallic chassis or other capacitors and components. Thus 2 similar capacitors will behave quite differently depending on which of the 2 foils of each are inside/outside. This effect is also seen on other capacitors, even electrolytics where for example the OUTER foil possibly SHOULD be grounded if that is what you are wanting OR should be considered a 'hostile' emitter (aerial/antenna). So consideration of circuit impedance and proximity of ALL components. In an EQ circuit where you may have a row of capacitors for example, you could easily get quite different results depending on the physical orientation of all the caps.
Matt S

You will note that the lead connected to the outer side of the wrap is marked by a dark line. If this lead is connected to ground or a low impedance node (like the output of an op amp) this outer wrap serves more like a shield than antenna.

JR

 

[BluegrassDan]

Using WIMA polypropylene in my latest build. The values are too large for film and foil so I used the MKP4 metalized.

They seem to do what they’re supposed to.

 

[CJ]

I believe that Fender puts the bar on those blue molded caps toward the plate circuit, inner foil to the grid of the next stage, is outside foil to lo z , inner foil to hi z.

 

[abbey road d enfer]

I believe that Fender puts the bar on those blue molded caps toward the plate circuit, inner foil to the grid of the next stage, is outside foil to lo z , inner foil to hi z.

That makes a lot of sense.

 

[Tubetec]

I heard that the line on foil caps signifies how it should be connected in circuit too , so is it the relatively lower impedence of the plate circuit on the outside foil helps prevent external interference creeping in ?

 

[abbey road d enfer]

I heard that the line on foil caps signifies how it should be connected in circuit too , so is it the relatively lower impedence of the plate circuit on the outside foil helps prevent external interference creeping in ?

It must be analysed in the context of the circuit. Let's say we have a coupling capacitor of a convenient value for sub-20Hz response: one side goes to the plate of a tube and the other to the grid of another. The impedance of both sides will be almost equal at audio frequencies, so whatever the direction of the cap, it won't make a difference, except at VLF, but there capacitive effects are negligible.
Now let's take the case of a cathode decoupling (bypass) capacitor. One side goes to "ground" (0V) and the other to the cathode. If the outer foil goes to ground, no interference can be transmitted. On the contrary, if the outer foil is connected to the cathode, electrostatically-coupled interference, although partially dumped to ground, will reach the cathode. The tube will amplify it in common-grid mode, which is a high-gain mode.

 

[zamproject]

I heard that the line on foil caps signifies how it should be connected in circuit too

Since I check foil side for about 50 caps in a 12 tube syth restoration, I'll be careful about line or whatever mark is on the can to indicate that...at least for MKT1813 series

 

[Analog_Fan]

Tolerance is definitely not enough information.

As Abbey said, class 2 ceramics have high voltage and temperature coefficients—the former of which can generate measurable harmonic distortion, and the latter of which can make the exact value in-situ temperature dependent.

class 1 ceramics (C0G, NP0) on the other hand are exceptional performers in these regards.

For 470pF and 560pF, C0G ceramics would be an excellent choice, and would probably be my preferred choice (polystyrene film would also be excellent)

believe the WIMA film caps start at 1nF.

 

[Analog_Fan]

In the EQ circuits I have experience with the brand of like material capacitors matters. In the Igor Sontec TDK PP caps sounded much better than Wima mkp or fkp.

My DIY Voltage Controlled Filters i made contain WIMA 1nF FPK2 2.5% 7 mm x 4.5 mm.
But the "noise" of a VCO isn't that busy as in a song, it's a sine, saw, triangle, pulse wave or a combo of them.
haven't tested other things, my former dealer has a bit of Styroflex stockpile left, but never tried them, it would look like an afterthought on the PCB.
Also was scared that i couldn't get more of them from him.

 

[Gold]

I have lots of gear loaded with Wima capacitors. I’ve never thought they needed to be changed out because they are ‘bad’. I replace like with like when I work on Neumann equipment. I’ve had no problem using them in other situations as well.

 

[soapfoot]

Worth mentioning that outside foil marking on capacitors, if it's even present anymore, is sometimes unreliable. The best way, if it's important, is to devise a rig to test it yourself.