Differences in Capcitors and Capacitor materials

[danowood 2,167]

I am becoming more aware of the differences in capacitors, their materials, and uses, and brand names.  The purpose of it's use etc.  types and use in electronic circuitry, amplifiers, and speaker crossovers cause an array of smorgessboards that are overwhelmingly confusing. There are several different types, polarized, non-polarized, ceramic, Polypropylene, foil- oil bathed, on and on.  There are different types of crossovers, passive, active, etc.  Really becomes confusing.  For the purpose of using in a passive crossover, whereas most crossovers are used in passive configuration such as the one I'm working on.   Such and article is this:  http://www.10audio.com/sonicap_oimp_multicap.htm  and for those that understand the principal workings of a capacitor (which amdmittingly is over my head) this tidbit  http://www.audioholics.com/education/loudspeaker-basics/the-loudspeaker-crossover/the-loudspeaker-crossover-the-brains-of-your-system-part-ii-page-2.  Finally Brand names seem to play a role in the best game play.  Different brands are made differently and supposedly have different sounds, each bemoaning theres are superior.  And of course a big difference in prices from 2 or 3 dollars compared to as mush as up to 75.00 for a capacitor, with both having the same uf ratings.  The ones in the installation I'm re furbishing are I believe are Jensen capacitors which to my knowledge aren't available any longer (however, there is a Jensen in Denmark that claims to make them and are very proud of their handmade capacitors, charging 50 to 75 bucks a pop).  Solen makes reasonably price capacitors but do the offer a comparable sound quality to The German made mundrof, rtx, and many others.  Anyone here have experience as to what is reasonably the best to use in a passive xover, that are not overly expensive as the above mentioned brands.  It would not be wise to use capacitors that costs far more than the speakers used in a system, it would not improve their performance beyond what  speaker can perform I suppose. 

 

 

[SteveFord 1,131]

AuriCaps are pretty darned good although they may be out your price range depending upon what size you need.

[danowood 2,167]

Auri caps are good, and the price range on them aren't terribly bad, just not sure with the Jensen speakers if it's getting the value of the caps out of it.  I also am looking at sonicaps premiums which are a little less costly but are suppose to be good quality.  Do you have any idea of the comparisons?  8uf for tweeters and 2.7uf for mids.

[Nahash5150 10,999]

Just keep studying Dan - look up tutorials and articles related to the subject and you'll absorb more info on them.

 

Keep this in mind though - there is nothing mysterious about a capacitor. They block DC and pass AC signal. Basically, it is a device with two plates very close to each other. Of course the plates can be flat or rolled together to increase surface area. It's only job is to take on a charge and if the opportunity arises, it discharges that charge. The charge and discharge operation has what is know as a 'time constant'. That is, its rated charge capacity (usually in micro-farads) tells you how much energy it can hold and release - the more it can hold, the longer it takes to charge or discharge. This charging and discharging is dependent on resistance as well (more resistance makes the time constant larger), which is what crossovers depend on significantly.

 

Frequencies that reach or exceed a capacitor's 'corner frequency' will pass through the device with little resistance. This is because the frequency is CHANGING FASTER than the capacitor's time constant, so the energy on one plate is mirrored on the other with little resistance. Now of course there are much more complicated things that happen, like phase shift, current and voltage leading, and noise. But if you can force yourself to understand that a capacitor is nothing more than a device that looks like an open circuit to DC, and a very large resistor or short circuit to some frequencies, then you'll be on the road to understand crossovers and the like. There are low-pass filters, and high-pass filters, band-pass filters, resonant circuits and a multitude of configurations like 2nd and 3rd order crossovers and all that stuff. All they do is attempt to control the passing of frequencies - either to make a desired band of frequencies pass without any loss or to make some frequencies almost non-existent to a portion of the circuit. For instance, a tweeter is always at the end of a high-pass filter. All the filter does is cause lower frequencies to see a high resistance and high frequencies above its 'corner' to see almost nothing (that is, they pass into the tweeter without any loss). Therefore, the 'crossover' point is the corner frequency of the capacitor AND the resistance involved (the RC network), and sometimes an inductor (which behaves similar to a capacitor with frequency, that is, its 'resistance' changes with respect to frequency (=impedance=Z)).

 

Now, the capacitor types are made for certain kinds of applications (space, cost, voltage, frequency, etc). Electrolytic capacitors are capable of very large capacitance, and are usually polarized because of their chemical make up, and are used mostly for power supplies and 'decoupling' - that is, smoothing out DC ripple (noise). They are used in crossovers too, but usually in their bi-polar variety. The problems with electrolytics is that they degrade over time, they're very sensitive to temperature and tend to make more noise than other varieties. their tolerance is also in the 20% range, making them frowned upon in good crossover designs.

 

Film capacitors are preferred for audio because they are low noise, durable and accurate. Basically a film capacitor is a pair of plates rolled together and separated by plastic. Yup, that's it - plastic. The problem is that they are expensive and sometimes too bulky for an application. Beware of film capacitors that are larger than 1uF - they get HUGE!

 

As far as manufacturers - this is just another complication that you will NOT find consensus on. Think car makers and who makes the best cars and you have a good comparison. They all seem to have their strong attributes as well as weak ones. Some are made in China are are complete garbage - so stay away from Ebay. However - Panasonic, Nichicon, Elna and Kemet are your big companies with good reputations.

 

Passive crossovers are normally much less efficient that active crossovers. Active crossovers tend to deal with the signal while it is small (pre-amp stage) and the signal sees almost no power loss because now the power amp only has to amplify the desired signal to the speaker. The PROBLEM with active crossovers is that it doesn't care about the speaker it is driving, and a speaker is a super-complex load. So active crossovers will turn you into a 'tweaker' to find the best sound. Passive crossovers, while they cause power loss because they are seen by the large signal stage, are usually designed specifically for the speakers, so that the ultra-complexity of the speaker as a load is compensated. And I think only Zumbini is one of those brave souls that use active crossovers with passive crossovers with success - it can be done, but you have to have an ear for it. Take for instance the crossover point for subwoofers used with mains - it's an ever-enigmatic value because all speakers are different - even clumsy subwoofers that handle only like .5% of the audio band. 

[PDR 1,195]

Wow, that was a excellent read hash, thanks.

 

The guy that designed my OB speakers is big on using "quality capacitors". A lot of people have said to him....Dude, the maker doesnt matter if the values and types are the same. He disputes its.....me I dont know enough, I'm an electronics sheeple....and took a Behringer speaker off the shelf, made an identical  x-over, but with better parts, put a switch on them, and sent them on a road show. Told people to switch, or to have someone do it for you so your blind, and see the results. You can read about

it HERE.

 

When he sent the parts out for my x-over there were Sonicap, Erse capacitors and Mills resistors. But there was another

Cap that was suppose to "make" it better.....a Jupiter Bees Wax....it was an upgrade meaning more $. Did I spend the extra money?....yep, cause others said it worked?, partially.....I just didnt want to wonder......so now I dont...lol.

 

You can see the Bees wax cap....its large.....in this pic.

 

 

 

 

[Hibernator69 47]

 

 

But if you can force yourself to understand that a capacitor is nothing more than a device that looks like an open circuit to DC, and a very large resistor or short circuit to some frequencies, then you'll be on the road to understand crossovers and the like.

 

Great summary. I'm guessing a short is a pass region, but is a large resistor similar to the open circuit for DC?

[Nahash5150 10,999]

 

 

 

But if you can force yourself to understand that a capacitor is nothing more than a device that looks like an open circuit to DC, and a very large resistor or short circuit to some frequencies, then you'll be on the road to understand crossovers and the like.  

 

Great summary. I'm guessing a short is a pass region, but is a large resistor similar to the open circuit for DC?

 

The impedance of a capacitor is an exponential function, Z=1/2piƒC, so its resistance changes in a smooth curve fashion depending on frequency (reactance or impedance). The 'short' is the indeed the pass region, when the corner, or crossover point, is the SHARPEST part of the curve toward more or less impedance depending on application. The crossover 'orders' make that sharp turn soft or really sharp.

[xavionics 2,398]

Terrific lesson Nahash!

 

I, too am a newbie to this stuff. But my experience so far is this:

 

A year or so ago, I recapped the x-overs in a pair of KLH Model 5's for a friend. We used Dayton Audio Caps to keep costs down. The results were amazing. 

 

Shortly thereafter I re-capped my Klipsch KG-4 crossovers with Sonicaps. They opened up the high end to a degree I would have never guessed.

 

[SteveFord 1,131]

This should keep you off the streets for a bit:

 

http://www.audiocircle.com/index.php?topic=54218.0

[RichP714 3,169]

http://thecarversite.com/yetanotherforum/default.aspx?g=posts&m=113337#post113337

 

"Capacitors affect the signal passing through them in a way invisible to distortion measurements.?"

 

Several writers have advocated passing pulse signals through two different sorts of capacitor, and subtracting the result, claiming that the non-zero residue proves that capacitors can introduce audible errors. In fact such tests expose only well-known capacitor shortcomings such as dielectric absorption and series resistance, and perhaps the vulnerability of the dielectric film in electrolytics to reverse-biasing. No-one has yet shown how these imperfections could cause capacitor audibility in properly designed equipment.

 

A startlingly close parallel in the history of science is the almost-forgotten affair of Blondlot and the N- rays. [3] In 1903, Rene Blondlot, a respected French physicist, claimed to have discovered a new form of radiation he called "N- rays". This was shortly after the discovery of X-rays by Roentgen, so rays were in the air, as it were, and so was a desire to keep up with the Germans. The N-radiation was apparently mysteriously refracted by aluminium prisms; but the crucial factor was that its presence could only be shown by subjective assessment of the brightness of an electric arc allegedly affected by N-rays. No objective measurement appeared to be possible. To Blondlot, and at least fourteen of his professional colleagues, the subtle changes in brightness were real, and the French Academy published more than a hundred papers on the subject.

 

Unfortunately N-rays were completely imaginary, a classic product of the "experimenter-expectancy" effect. This was demonstrated by American scientist Robert Wood, who quietly pocketed the aluminium prism during a demonstration, without affecting Bondlot's recital of the results. This was widely reported by the famous reporter/explorer William Seabrook, and the N-ray industry collapsed very quickly. It was a major embarrassment at the time, but is now almost forgotten. For more on N-rays, see the new N-ray page

This demonstrates with brutal clarity that it is quite possible for large numbers of sincere people to deceive themselves when trying to perform subjective assessments of phenomena.

[Nahash5150 10,999]

 

 

This should keep you off the streets for a bit:

 

http://www.audiocircle.com/index.php?topic=54218.0

 

 Cool! Even more capacitor manufacturers. I'd still caution though - beware the voodoo. There's nothing mysterious about a capacitor! Just avoid the cheap shit, and use what the application is in more reasonable demand for (ie, try to use film capacitors for the signal path). 

[danowood 2,167]

Decission finally made, after recomendations from an engineer from Sonicraft I have decided to go with the Auri cpas for the tweeters and the AudioCap theta's for the mids on the crossovers.   The Auri's were about 18.00 a pop each and the Thetas were 48.00 a pop each.  I also paid a couple extra bucks each for Level 2 matching within .5% of each other.  Last phase is to recap these puppies and install new gold plated bannana plugs on the cups and put these things back together and then out the door.  Will include final pics when done with them.

 

 

 

 

 

[Nahash5150 10,999]

Looking good!

 

Wow - those are expensive caps! 

[Gene C 1,753]

Nice job Dano. Did you just spray the cabinets with urethane coating? 

[danowood 2,167]

sherwin williams medium Rub Lacquer.  Thats mostly what I use.  I haven't lightly steel wooled them down yet and then appied wax.  The pic of the speakers in the garage is from the fog of lacquer spray, but it doesn't affect the finish much.  It's a low sheen lacquer finish.  It's shinnier than it would normaly be, but I shot about 7 or 8 coats, steel wooling them down between coats.   I'll either brown bag rub them down or use steel wool lightly rubbing  them down to dull the shine a little more then wax them down.  Thanks for your back slap.  Hi five!!

[danowood 2,167]

BTW LOL being a bachalor for the past 21 years have it's advantages sometimes. I get away with cluttering the house up, and working on things inside that sometimes I should be doing outside, but then again, I'm the one that has to clean it all up when I'm done        But at least I don't have to hear the nag     Won't be long, after I get my family room finished, I'll bring in the house cleaners, they're cheaper than a wife    

[PDR 1,195]

Wow, those really look great!!

 

I have to wait till the girls go on a trip before I get the whole house for a proper speaker build..... 

[Retriever 1,143]

Nice job!

But I've been supressing for days,

The difference is "a" between capcitor and capacitor. Sorry just had to go there!

[danowood 2,167]

Nice job!
But I've been supressing for days,
The difference is "a" between capcitor and capacitor. Sorry just had to go there!

 

  you have discovered one of my many weaknesses and the lackadaisical use of spell check    Kinda like the difference between supressing and suppressing I suppose......

[Gene C 1,753]

Nice job!

But I've been supressing for days,

The difference is "a" between capcitor and capacitor. Sorry just had to go there!

 

  you have discovered one of my many weaknesses and the lackadaisical use of spell check    Kinda like the difference between supressing and suppressing I suppose......

LOL! Calling the kettle black says the pot.  

[Retriever 1,143]

I'm still laughing!

 

I Could have gone for an esoteric discussion on capacitors but NO Mr smart a$$, just had to go there. I can be a royal butthead!

[Nahash5150 10,999]

Some of the most dissturbing spelling and gammer errors I've seen have been made by editors from New York. They seem to throw all conventions out the window when they yooz email.

[danowood 2,167]

Just received the capacitors today.  I could tell just by the weight of the package that these weren't no ordinary capacitors.  Probably over kill, but impressive all the same.  Look at the difference from the Jensen capacitors that were in it compared to the replacement ones.  On the left are the 2.7uf and on the right are the 8.0's.  Dang, going to have to make up something different as the Jensen capacitors were tucked under the connecting board on the back of the cup.  There is no way these are going to fit on the cup, without some ingenuity, and probably will need to attach a piece of Plexiglas to the back of the cup to mount the capacitors.  Any ideas?

 

[Retriever 1,143]

Holy size increase! I haven't shopped capacitors in a while are those polypropylene caps?

Voltage rating must be high enough for a tesla coil!

[danowood 2,167]

I couldn't attest to material used but am sure it's a film capacitor, but it must be some trade secret as to what they use for dielectrics, tantalum, silver mica, snot?  My guess is probably double layered.  Don't know.  They seem to be snobbishly into high end only.  http://soniccraft.com/  In further research (the Capacitor has PET #####)  PET stands for Polyester.  Another article has a lot of info on it in regards to the types:  http://en.wikipedia.org/wiki/Types_of_capacitor#Film_capacitors