How? Measuring ESR takes some specialised equipment and thorough metrologic methods.jensenmann said:
Which Capacitors for Audio?
- Thread starter Junction
- Start date
Help Support GroupDIY Audio Forum:
jensenmann
Well-known member
I have an ESR meter and a cheapish component tester which does ESR as well.
But as you beat me to it I quickly took some measurements of a few Wima MKS2 6,8uF and they were all around 0,4 Ohm. I have no 10uF here at the moment.
But I remember very well the bag of 10uF Wimas I measured and all were around 17 Ohm. I remember it because the value was so high. That made me think that they are all in the same ballpark. Obviously a bad batch. I stand corrected. Good to know....
But as you beat me to it I quickly took some measurements of a few Wima MKS2 6,8uF and they were all around 0,4 Ohm. I have no 10uF here at the moment.
But I remember very well the bag of 10uF Wimas I measured and all were around 17 Ohm. I remember it because the value was so high. That made me think that they are all in the same ballpark. Obviously a bad batch. I stand corrected. Good to know....
scott2000
Well-known member
So does this mean these film/foil /wima caps are in fact good to use for power supply bypassing??
over dozens of measurements, I see just the opposite. That’s in line with the datasheets that are available also.
I noticed alot of mics use radial *cylindrical* film caps on tube mics. Could one use a wima box style cap in its place?
rock soderstrom
Tour de France
Sure, why not? As long as the technical specifications (capacity and max voltage) are correct, everything is fine.
Box caps tend to be higher above the PCB , no reason they wont do the job , the issue with them is will they fit physically your usage ,
Oval axial caps are what I tend to choose , there wider than they are high and tend to fit in confined spaces better .
Oval axial caps are what I tend to choose , there wider than they are high and tend to fit in confined spaces better .
Last edited:
I could lay it flat across the pcb and bend the leads. Or is that a no no?
Of course, but often box caps have very short leads.
Thats probably ok , but you might need to secure it down to the board to prevent any tendency to vibration .
Im generally building tube mic circuits hard wire style , so if the cap comes off the anode resistor , the lead outs are heading in opposite directions ,which tends to suit me .
Thats a good point Abbey made , you might only have 5mm lead outs on box caps .
Im generally building tube mic circuits hard wire style , so if the cap comes off the anode resistor , the lead outs are heading in opposite directions ,which tends to suit me .
Thats a good point Abbey made , you might only have 5mm lead outs on box caps .
just dont wanna blow anything up. ill give it a shot. i like to order through mouser or digikey, but all they offer are capacitors that the datasheet says are used for "general purpose" or "motor drive" or "high freq switching"...never anything for audio. Things like this...
https://www.cde.com/resources/catalogs/MWR.pdf
Which i never hear in any audio circles talk about...they always talk about wima or solen or sonicap...
Or this one...
https://www.vishay.com/docs/26022/mkp1839.pdf
The specs seem to fit, but are these brands any good for the output capacitor on say...a tube mic?
I generally use 200vdc rated coupling caps in tube mics , mainly to save space ,
normally your dealing with less than 100v at the anode , if you apply power without a tube in there chances are you could exceed the rating , if the the heater goes open circuit you could also be in the same situation . Ive tested a few modern foil caps well above their ratings in terms of volts and they held up just fine .
normally your dealing with less than 100v at the anode , if you apply power without a tube in there chances are you could exceed the rating , if the the heater goes open circuit you could also be in the same situation . Ive tested a few modern foil caps well above their ratings in terms of volts and they held up just fine .
Which brand and model?
I dont really have a preference for any particular brand , its more about form factor and what physically fits in the space I have to work with .
I cant remember which brand I tested , it was 400vdc rated , held up fine at 500v , at 1000v it arced internally , but to my surprise it was still perfect after .
I cant remember which brand I tested , it was 400vdc rated , held up fine at 500v , at 1000v it arced internally , but to my surprise it was still perfect after .
rock soderstrom
Tour de France
Ero MKT 1813 250V are popular for tube microphones as they have a relatively small size, are quite cheap and do nothing wrong sonically IMHO.
I'm sure there are endless other brands and types of capacitors that could be used.
I like to use the old green NOS Ero MKT 1813s because I can get them quite cheaply in my area and I like the way they look. I just bought 10 of them again, price per piece 1€, sometimes you can get them even cheaper.
I think you can still buy this type of capacitor brand new, they are yellow now if I remember correctly.
Last edited:
There are discussions about the different types of film capacitors. They all seem to boil down to the type of dielectric.
The most common polyester (PE) and polypropylene (PP) have similar dielectric constants, but differ by their dissipation factor, better for PP. That's one of the reasons why some designers prefer them. A low dissipation factor is a welcome property in power applications, however there is no definite proof it results in better audio performance.
It certainly has an effect when the capacitor is used in a resonant circuit, but when used as a coupling cap, there is no predictible effect, unless it is undersized.
Dielectric absorption (DA) is another parameter that influences distortion, but is rarely specified.
Most Wima capacitors that are considered good solid performers are PE.
Dedicated "audio" capacitors resort to fancy dressing, like gold foil or Listz wire but the effects on performance are elusive.
In the particular position of plate to transformer coupling, even an electrolytic can deliver perfect performance, whatever preventions some may have.
Polystyrene (PS) is a very high quality dielectric, but only available in relatively small values (<33nF).
Polycarbonate (PC) is also a very good performer, but seems to be unavailable.
Indeed there are various other dielecrics (among them paper) but they are not pertinent to this application.
The most common polyester (PE) and polypropylene (PP) have similar dielectric constants, but differ by their dissipation factor, better for PP. That's one of the reasons why some designers prefer them. A low dissipation factor is a welcome property in power applications, however there is no definite proof it results in better audio performance.
It certainly has an effect when the capacitor is used in a resonant circuit, but when used as a coupling cap, there is no predictible effect, unless it is undersized.
Dielectric absorption (DA) is another parameter that influences distortion, but is rarely specified.
Most Wima capacitors that are considered good solid performers are PE.
Dedicated "audio" capacitors resort to fancy dressing, like gold foil or Listz wire but the effects on performance are elusive.
In the particular position of plate to transformer coupling, even an electrolytic can deliver perfect performance, whatever preventions some may have.
Polystyrene (PS) is a very high quality dielectric, but only available in relatively small values (<33nF).
Polycarbonate (PC) is also a very good performer, but seems to be unavailable.
Indeed there are various other dielecrics (among them paper) but they are not pertinent to this application.
Last edited:
https://www.hificollective.co.uk/catalog/evox-rifa-cmk-polycarbonate-capacitors.htmlThese guys have a few values of PC caps available , mostly in the 100v range .
I always wondered why polycarb caps have become difficult to source , the material itself is widely used for all kinds of things , its incredibly strong and resiliant .
I always wondered why polycarb caps have become difficult to source , the material itself is widely used for all kinds of things , its incredibly strong and resiliant .
The answer is here Polycarbonate Capacitor & Replacement Alternatives » Electronics Notes
Industrial strategy...
Around the turn of the century Bayer ceased production of the dielectric film used I believe. few other suppliers.
Might want to investigate Polyphenylene Sulphide (PPS) dielectric for similar electrical characteristics.
Me being in audio design mostly microphones I strongly recomend to read this Reliable Capacitors
