Capacitor help please!

[TheSloth]

I know almost nothing about capacitors, but have it on fairly good authority that the frequency correction network on my old ESL63's uses an old Electrolytic-type capacitor which is not particularly good for this function, and should be replaced with a Polypropylene version at the same capacitance (220uF).

Excepting the vast difference in size between these two types, what brands am I looking for? This cap is in the signal path, so quality is of the utmost importance. Voltage rating shouldn't be lower than 250V. It doesn't necessarily have to be a single 220uF cap - two 100uF caps will do the trick, and might be easier to place in the housing.

Thanks for your help guys!

Pic of offending cap:

[justin]

Polypropylene capacitors of that value are huge, and very expensive. Solen makes a 220uF 400V, it's $50 at partsconnexion...it's about the size of a coke can

[TheSloth]

I knew they were big, but didn't realise they were that big! People that have done this with 1 220 have mounted it outside the housing, but you can actually fit 2 100's, just not both in the same place. So I suppose 2 100's in parallel it is. Is Solen the way to go?

[TheSloth]

Also, is there something other than a Polypropylene cap that would be better than an Electrolytic cap in a smaller package?

[philodox]

Solen is really the only way to go for values that large... I wonder if it is worth it in this position though? Perhaps a high quality electrolytic like an Elna Silnic II or a Blackgate would be a better choice?

[TheSloth]

Solen is really the only way to go for values that large... I wonder if it is worth it in this position though? Perhaps a high quality electrolytic like an Elna Silnic II or a Blackgate would be a better choice?

This is was posted in a discussion about this:

"From a theoretical standpoint this tweak should lower the distortion in the midrange and treble, and also make the sound 'faster'. This is because of the non-linearity and polarity of the electrolytic capacitor."

Is changing to another (better brand) electrolytic going to change that?

[philodox]

No idea, perhaps someone else can comment. I just know how hard [and expensive] it is to get high value film caps.

[aerius]

There was another company other than Solen which made large value film caps, can't remember the name though since it's been a few years. My personal cheapskate solution is to use motor run capacitors which can be found on ebay as well as industrial supply and airconditioning places. The one downside is they're bigger than the Solen caps, a 75uF cap is about the size of a Coke can.

As for Blackgates, they might be better than a standard electrolytic cap, but in terms of performance they ain't anywhere close to a film cap. We're talking orders of magnitude, not little dinky percentages here. Electrolytics are evil, kill them wherever you can.

[TheSloth]

There was another company other than Solen which made large value film caps, can't remember the name though since it's been a few years. My personal cheapskate solution is to use motor run capacitors which can be found on ebay as well as industrial supply and airconditioning places. The one downside is they're bigger than the Solen caps, a 75uF cap is about the size of a Coke can.

As for Blackgates, they might be better than a standard electrolytic cap, but in terms of performance they ain't anywhere close to a film cap. We're talking orders of magnitude, not little dinky percentages here. Electrolytics are evil, kill them wherever you can.

Thanks for the suggestion. The Solen's really aren't that big for this installation, and at the worst could be mounted externally and clamped to the base.

Final question - what are polystyrene caps?

[aerius]

Final question - what are polystyrene caps?

Pretty nice capacitors which I don't think are made anymore, said to the be 2nd best after Teflon. Available only in small values under 1uF as far as I know, mostly in the pF & nF range. Generally found in phono stages & pre-amps.

[philodox]

The big solens are motor run... the same as the ones you use and were used in my McAlister amp. Still, even with the motor run caps 220uF is a lot. Most companies [asc, aerovox, etc] make 80-100uF max and you have to custom order to get a higher value.

[TheSloth]

The big solens are motor run... the same as the ones you use and were used in my McAlister amp. Still, even with the motor run caps 220uF is a lot. Most companies [asc, aerovox, etc] make 80-100uF max and you have to custom order to get a higher value.

220uF is the biggest listed at parts connexion, so they do have it. But it is very big and would have to be mounted externally and then wired in. Don't like the idea of that, given my 'expertise'. I think I might try a non-polar Black Gate cap and see if it does anything first. Partsconnexion has a 220uF, 160V Black Gate NH model - that sounds like the best option to me. The maximum input voltage allowed by the clamping circuit is 55V, so the voltage shouldn't be an issue come to think of it.

[Dusty Chalk]

I, too, know nothing on the subject -- but there are a couple of very knowledgeable guys on audiokarma.org -- post in the DIY section.

[TheSloth]

Well I'm going to go with the Solen 220uF, externally mounted. It's tried and tested in this application, so that gives me some comfort. I'll need to run some extra wiring to the external mounting - any suggestions for what to use?

[aerius]

Since I don't have to mail-order it, my personal favourites are magnet wire and Cat6 network cable. Sometimes I'll also use RG-6 TV cable, I strip off the outer coating and shield and use only the inner wire along with its thick foamy insulator.

[TheSloth]

Since I don't have to mail-order it, my personal favourites are magnet wire and Cat6 network cable. Sometimes I'll also use RG-6 TV cable, I strip off the outer coating and shield and use only the inner wire along with its thick foamy insulator.

I was thinking of using some anticables speaker cable actually. It's solid core, and quite inflexible which in this case is actually a bonus.

I just had a look inside my pair, which is slightly different from the ones pictured - it's got a better resistor so that doesn't need replacing, but it does have the nasty cap. Here's a picture to make you cringe aerius:

But don't worry, soon it will be no more...

[philodox]

I was thinking of using some anticables speaker cable actually. It's solid core, and quite inflexible which in this case is actually a bonus.

That stuff is actually identical to the magnet wire that aerius mentioned AFAIK. I will chime in with another vote for Cat6. It is solid core copper and comes in different colours... oh, and also super cheap.