Capacitor Myths

[Pete B]

This is from a foreign language site, and I'm not positive but I believe it was authored by Tom Nousaine:

I have conducted several experiments in break-in covering periods as long as 150 hours. What happens is that you can measure a fall in system or driver resonance by several percent along with an increse in compliance of a like amount immediately following an extended break-in period. However if you allow the driver/system to rest for several hours you'll find that the unit returns to its 'fresh' values.

Further if you model either set of parameters you'll wind up at the same enclosure requirements for either condition (a lowered Fs and an increase in compliance will be off-setting.)

The "most" you can say about extended break-in is that at most a system/driver may "warm-up" but even then its sound will not change.

On the other hand, the only negative thing about 'warm-up' is that it can be dangerous in that you can damage the speaker by putting too much currrent into the voice coil for an extended period and/or rip suspension components with too much power.

Noise signals are by far the most dangerous. I was involved in a trial testing the EIA 426B power handing standards and found it was possible to actually melt a plastic cone using their long term noise signal.

If one is to try-nature with break-in I'd strongly recommend against using noise (as is often suggested) and especially against using the off-polarity test using a pair of systems placed face-to-face out of polarity to reduce the ambient noise of break-in with a noise signal. It's just too darn dangerous; full or partial band signal with equal amplitude over the entire bandwith, unless you 'like' the smell of softening voice coil glue.

At DLC Design where they use DUMAX to test linearity of loudspeakers they sometimes need a short break-in period to allow a speaker that has been stored on its back to restore its natural rest position .... and this takes less than a minute.

What's the "safest" (as in using a condom for contraception even if you've had a vasectomy) break-in signal? The most comfortable condition is a woofer driven with a sine wave near its resonant frequency in free-air with enough power to allow excursion to attain perhaps half to 2/3 stroke for a relatively short period while you remain in attendance.

But even so if there really were an important "break-in" period wouldn't your speakers simply just break-selfs-in during normal use? The only time this might be an important issue is when the break-in period might exceed the product-return time limit.

I once tested a product where the owner manual suggested that the speaker would 'improve' over 150 hours of use. I called a local dealer and asked what the store return policy was. As it turned out that was 7-calendar days (meaning that a speaker purchased on Monday had until Saturday to get returned but if you bought on Tuesday you had a full week) so that meant that in order to 'reach' the speaker's full potential a new owner would have to use/break-in the product for 6.25 days non-stop to find out if they 'sounded' as good as he was lead to believe..

This condition is but one of the real reasons that break-in has become an audio urban legend. I understand both the conditions where this might be important. First it tends to reduce buyers remorse; but it also tends to limit customer choice.

[Pete B]

I was searching for some words from Ken Kantor on equipment break-in that I read some time ago. I can't seem to find it at the moment, and I came across this thread, which seems to support that he and I are in agreement as far as capacitors go:

http://www.classicspeakerpages.net/dc/dcbo..._id=&page=#4107

[RoyC]

Hi Pete,

It was Ken's post, as well as your comments in an Advent thread, that motivated me to start experimenting with series resistance in some of my restorations. My experience has been very consistent with what you have posted in this thread. It is interesting how a little well-placed resistance can subtly alter the tonal character, especially when directly compared to the same circuit without said resistance.

We are conditioned by sellers of expensive caps, speaker wire, cables etc to believe that ANY resistance is evil, (and that there is magic in their construction materials:-)), even though resistance is a necessary part of any circuit design. Most of the old AR crossovers were wired with 20ga or smaller tin coated wire (today's "marine" wire). It works quite well in those old speakers and has lasted a very long time. Heck, after much experimentation, I still prefer the originally recommended 18ga speaker wire to connect all of my restored AR speakers to their amps.

I'm also in agreement that the capacitor does not "break-in" as much as our perception does.

Roy

[Pete B]

Found the link with Ken's post on break-in:

http://www.classicspeakerpages.net/dc/dcbo...28&mesg_id=2658

[Pete B]

Hi Roy,

Nice when theory and reality agree, isn't it?

Sure, higher gauge wire can be used to soften the damping from a high damping factor amplifier.

All the best!

[kkantor]

Thanks, Pete!

Here's a link to that article that should be working:

http://www.aural.org/audio/articles/audio_fetishes/. I've been meaning to do better scans someday, but....

-k

[Guest Sean]

Parts will "break in" or "settle" at a sweet spot based on the dynamic thermal / mechanical / electrical demands placed upon them. As such, many speaker components are never FULLY "broken in" or optimized, even after MANY years of "normal" use. That's because "normal" use is typically well below the point of stressing any of the components out to anywhere near their rated capacity or level of best performance. As such, losses remain higher than they should be and performance potentials vary as the dynamic conditions dictate.

As far as caps go, it's not hard to actually watch them breaking in / forming IF one knows how to properly form them. Here's a simple trick that most anyone can do with some simple and relatively inexpensive tools.

Take a cap and connect it to a variable high voltage power supply. Gradually bring the voltage up to appr 10% - 20% of the capacitor's rated operating voltage. Let it stabilize and make note of the voltage reading.

Depending on the type and value of cap used, one can typically go back a few hours or a day or two later and see an increase in measured voltage. At this point, the cap has fully formed to that specific level of opertional voltage. Increase the voltage applied via the variable power supply another 10% - 20% and let the voltage stabilize. Make note of the voltage and let the caps continue to form at that rated voltage level.

Upon returning a few hours / days later, you'll find that the applied voltage has once again crept up above the previous setting. Continue to do this until you reach rated operating capacity, or very near it. Obviously, you've got to allow a bit of headroom to compensate for the aforementioned voltage creep as the cap forms, but you get the idea.

As far as running caps up to their rated voltage goes, most caps can take a measurably higher percentage of voltage above their factory rating. When it comes to mass production, most all manufacturers are measurably conservative in their ratings. They do this for multiple reasons.

First of all, no manufacturer wants to be responsible for selling parts that don't meet their own published ratings. Parts that are operated near their rated capacity that continually fail do nothing but risk the reputation of the manufacturer. Who would want to design / build a product based on parts from a manufacturer that continually lied about the spec's and performance capacities of the components they manufacture???

On top of that, manufacturing parts to a level above their rated spec pretty much guarantees a low rejection rate in terms of factory quality control and a low failure rate in the field. The fewer parts rejected at the factory means a higher profit margin due to less wasted production and parts usage. Fewer failures in the field mean less warranty claims, which also raises profit margin.

As such, i would venture to say that most caps can be run up to their rated voltage capacity with little fear of failure. This takes into account that the caps are relatively new, properly ventilated and the voltage is gradually ramped up.

What all of this does in terms of sonics is quite audible and beneficial. The caps are no longer as lossy, so dynamic range is increased. Dynamic peaks are no longer sheared off due to dielectric losses in the cap, as the caps are formed to well beyond any applied voltage level that they are likely to encounter during normal use. In effect, the caps are no longer forming dynamically as the voltage level varies, they are fully formed prior to installation.

On top of that, sonics become much more consistent. This has to do with the fact that the dielectric is fully formed. By forming the caps in advance on a steady state basis, they are no longer trying to form with sporatic operating voltages that are anything but consistent. Obviously, i'm talking about caps as used in a speaker system, as other uses may have steady state voltage levels.

To some, this may sound like a lot of conjecture and "fairy tales", but to those that have actually taken this approach and made direct comparisons, both electrically and acoustically, the results speak for themselves.

It is for this reason that the boutique / DIY audio industry exists, as many of the "doing it by the book" industry professionals that manufacture mass produced products turn a blind eye / deaf ear to this situation. On top of that, this type of procedure takes more time & labour to perform, so most manufacturers do NOT want to deal with it.

If you've got the time, knowledge, tools and inclination to do so, one can easily apply the above info to their systems and come out WAY ahead. Both in terms of aural satisfaction and in terms of bang for the buck.

Starting with a proven design and solid componentry ( AR9's, etc... ) and getting rid of all of the weak links / applying some "love" above and beyond the demands of mass production can really make a drastic difference in one's system. Since you're supplying the parts, labour and skill, one can do this without having to spend $10,000+ for new speakers to achieve those levels of performance. Sean

>

[Carlspeak]

>People here often mention capacitor and speaker break-in,

>here is what Paul Barton founder of PSB speakers has to say

>about it. I don't know where this was first printed,

>otherwise I would give credit:

>

>Finally, and perhaps most controversially, Barton talks about

>the supposed break-in effect of components that has become so

>popular in audio today. Break-in refers to running components

>for a long time (sometimes hundreds of hours) to the point

>where their components "settle" into their proper

>operating mode. Barton doesn’t doubt that some components do

>change subtly, but he thinks that the major improvements

>people think they’re hearing aren’t in the components at all.

>Barton doesn’t doubt that people are hearing these changes,

>but thinks that what they’re hearing is actually brain

>break-in.

>

>Barton has examined his own speakers to test this. He has

>taken a Stratus Gold loudspeaker, built and measured some ten

>years ago, and re-measured it today. The deviation is slight,

>perhaps 1/4dB at most. Although that deviation can possibly be

>heard, it is certainly not a huge difference that one may

>attest to hearing. Instead, Barton surmises that the

>difference in sound that people are hearing over time is

>conditioning of the brain. He cites experiments done with

>sight that indicate the brain can accommodate for enormous

>changes fairly quickly and certainly within the hundreds of

>hours that audiophiles claim changes occur in. Could this

>apply to hearing, too? Barton thinks that more often than not,

>what happens is that the changes in perceived sound that are

>attributed to component break-in are simply the brain becoming

>accustomed to the sound. He warns listeners not to fool

>themselves.

>

I have been thinking about Paul Barton's comment above regarding "brain break-in" and it's apparent application to evaluation of loudspeakers (and perhaps also new caps)over time.

At first I agreed fully with this as a short term effect (e.g. listening for a period of 1/2 to 3 or more hours in a single session). I have experienced this phenomenon wherein something objectionable in the speaker's performance gradually became acceptable and unnoticed after a while.

But, I also wondered about repeated breaks in between listening sessions of 1 or more days and what effects going back to the same music with the same loudspeakers would have regarding the evaluation of break-in. Would the brain's acceptance of a loudspeaker's sonic deficiencies gradually become acceptable SOONER or, even immediate during a new listening session?

This led me to investigate psychoacoustics. Wikipedia's description of it includes the following:

"....There are true psycho-acoustic effects introduced by the brain. For example, when a person listens to crackly and needle-on-vinyl hiss-filled records, he or she soon stops noticing the background noise, and enjoys the music. A person who does this habitually appears to forget about the noise altogether, and may not be able to tell you after listening if there was noise present. This effect is called psycho-acoustical masking. The brain’s ability to perform such masking has been important for the adoption of a number of technologies;..........."

The first sentence above is in full agreement with my personal experience. However, it's that second sentence in the quote above that answered my question regarding repeated listenings over time. So, psycho-acoustical masking may be at the crux of our notion of speaker/capacitor break-in. That is, if Wikipedia and other 'answer' sites are truly correct.

It's all about the music

Carl

Carl's Custom Loudspeakers

[Pete B]

Interesting comments about EIA power testing, I remember reading about Electro-Voice having problems testing some of their Pro drivers where they'd done such a good job on the voice coil and motor that the carbon fiber cones would catch on fire during testing. I find this hard to believe but it came from a reputable source.

[Pete B]

Thanks for the link Ken, oh I remember reading that article years ago, have not seen it in some time.

[dynaco_dan]

Hi Pete;

If I remember correctly, on the Crown web site, there is an article about the recorded temperature from a woofers voice coil, over 150 degrees celcius.

I've written many times, of my many, really too many, experiences seeing charred woofer voice coils, well over 100.

[Pete B]

Recall on EV speakers:

http://www.cpsc.gov/cpscpub/prerel/prhtml88/88047.html

[Pete B]

I began using Intusoft's SPICE back in the early 1980s, and their newsletter was always an informative read. I just found them online, here's an old issue concerning capacitors. I'm not saying that the detais covered there are important for capacitors in Hi-Fi speakers, but I believe it's good for those not working in the field to see the details that is available to us:

http://www.intusoft.com/nlhtm/nl65.htm

http://www.intusoft.com/nlhtm/nl76.htm#A_N...Model_For_SPICE

http://www.intusoft.com/nlhtm/nl44.htm#modeling

http://www.kemet.com/kemet/web/homepage/kf...No5%20Sep94.PDF

http://www.kemet.com/kemet/web/homepage/kf...No2%20Jul98.PDF

[Pete B]

There's been some mention here of measuring the old large compulytic caps using a multimeter. I want to point out that most measurement systems only apply a very small AC voltage to the device under test when simply testing for capacitance value. Some of the better systems allow a DC bias voltage to be applied which helps to determine if the capacitor still meets its voltage rating. Old electrolytics should be reformed, simply to restore the oxide layer if possible and to determine if the part meets its voltage rating.

I'm coming to the conclusion that they should probably just be replaced since they are well past their expected life.

[Diamonds&Rust]

I'm coming to the conclusion that they should probably just be replaced since they are well past their expected life.

It's nice when scientific evaluation and subjective listening finally find an area of agreement. We may not agree on much, or the value of many things, but I think we have reached a common conclusion at least on this one, small, aspect of restoring these speakers.

I'm glad that you and I finally came to a common conclusion even if we used entirely different methods arriving there.

IF people are going to try to use new NPE capacitors, what are your thoughts on the desirable voltage rating of those new NPEs?

(for that matter, if you have a thought on the desirable voltage rating of film caps, that would be interesting to know as well)

Bret

[Pete B]

http://www.classicspeakerpages.net/IP.Boar...?showtopic=2790

[Pete B]

I'm not trying to bash Marsh here, in fact I thought his early paper with Jung was well done - I've not followed his later work.

Anyway I just thought I'd point this out, not an error but their certainly was prior work that was not referenced. Note figure 7 here:

http://www.capacitors.com/picking_capacitors/consider.htm

It is the way their MutiCap is constructed, you would think it was revolutionary the way it's hyped.

Note figure 2B on page 1 of the images for this 1966 patent:

http://patft.uspto.gov/netacgi/nph-Parser?...p;RS=PN/3287789

Pete B.

The link above to the 1966 patent no longer works; here it is again. Note figure 2B:

http://www.google.com/patents?id=Vg1oAAAAE...5&ct=result

And Figure 7 here:

http://www.bychoice.com/cap_design_consideration.pdf

[Carlspeak]

A relatively new AES paper is available for downloading regarding crossover capacitors (myth or reality?). It was written by 3 gentlemen from the UK and was presented at the May 2008 AES convention in Amsterdam. One of the authors was from a university and the other two from the company that owns Clarity Caps.

It's evident from the paper's outcome they had an agenda to promote their MR Range line of high priced caps which are claimed to tame mechanical resonances. A 4.7 uF MR Range cap is priced over $100 at Madisound - OUCH!

The paper included a few measurements and the results of listening panels. They did state there was a clear difference between NPE's and film caps. Mechanical resonance effects were harder to discern which required a 'filtering' of the listening panel.

FWIW,

http://www.aes.org/e-lib/browse.cfm?elib=14444

[Guest bocoogto]

Very good posting and interesting responses. The guy who went through the trouble of setting up a relay to switch capacitors really proved how, if the values are correct, make no audible difference. Not to hijack a very good thread, but it reminds me of speaker cables.

I've done comparisons using toggle swiches to test various speaker cables. You can use anything from 16 gage zip cord to 12 gage Monster cables and anything else you'd like to compare. Whichever cable you switch on or if you switch them all on at once, there is no audible difference. One difference you can hear is if you use a 50' piece of 18 gage "speaker" wire with 4 ohm speakers (AR3's), there is a noticeable difference in level due to losses from resistance of the wire. Yet, people spend thousands of dollars on exotic speaker cables. From experience, I've come to believe that if your "oxygen free" or whatever style of cable you're using sounds different from 16 gage zip cord, the cable is coloring the sound you hear, not the other way around.

[Mazeppa]

Kudos to the OP and contributors, excellent thread. Still trying to wrap my head around most of it, but very helpful to the electronically challenged trying to develop some realistic "rules of thumb" to apply to speaker recapping.

[DavidR]

I ran across this capacitor article and I immediately thought of this thread. I find some of the author's comments about some makes of caps rather subjective (and brand loyalty biased). I suppose a really poorly made PP cap with low quality materials vs a well made, tightly wound with very good materials might make an audible difference but on the whole a well known name brands with good quality control would be hard to actually hear a difference between them.

http://www.humblehomemadehifi.com/Cap.html

I'm not trying to stir up the cap debate; just found this and thought this is where and how a lot of the 'cap wars' debates come from - subjectivity and brand loyalty.

[Carlspeak]

Another CSP thread that deals directly with HHMHF's ratings....

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=5828

[DavidR]

Nice synopsis Carl. I too realized his 'favorites' were the higher voltage rated caps.

[oldarnut]

This discussion reminds me of the age-old speaker cable controversy. It seems that the majority of audiophiles subscribe to the superiority of designer speaker cables--often in the area of several hundred dollars for a pair of cables 10 feet long or less. All this is in spite of the often-tested fact that humans cannot hear the difference between designer speaker cables and 16 gage zip cord.

Anyone who has looked inside their speaker cabinets knows the leads from the terminals on the back of the cabinet to the crossover and to the drivers is always 16 gage stranded wire and sometimes smaller than that. Inside our amplifiers, seldom is wire as big a 16 gage used between the output stage and the speaker terminals--and the wire is almost always solid, not stranded---which is a no-no to designer speaker cable fans.

Then, there are the 120 volt wall outlets that cost hundreds of dollars each, megabuck power line regulators, special power cords, etc. All of this connected to a power grid that is almost all solid copper or aluminum wire.

We've all experienced the phenomenon of making a small change in our audio system and hearing a fantastic improvement. Remember the CD cryogenic freezers, antimagnetic turntable mats, discussions over "true phasing," and other revolutionary audio discoveries that are only a memory today?

Somehow, the capacitor and speaker cable magic hangs on. Now, the designer cable fraud continues whenever you buy a computer or home theater audio or video cord. High priced HDMI, optic audio cables, printer cables, etc. are aggressively pushed at the retail level, and often the customer spends the extra cash.

[der]

I'm right there with you Old AR Nut. Guess I'm an Old AR Nut too!

der