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Carlspeak

Effect of film dielectric on capacitor ESR

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Detail performance tests were run on four ERSE capacitors to look at the effect of dielectric on ESR. Two 2.0 uF and two 3.9 (4.0) caps were tested. Each group had a polypropylene dielectric (Pulse-X brand with black color & gold printing) and a Polyester dielectric (yellow color with black printing).

What I found with these two levels of capacitance was a significant difference in ESR between the dielectrics in the 100 to 10000 hz range with PET generally trending higher in the freq. range evaluated. Below is a plot of the data obtained with a WT2.

IMO, the polyester ESR performance approaches that of an electrolytic. This may be of some value to those recapping that don't want to alter the voicing of the speaker or, where a slightly reduced response is needed in a particular frequency range.

The link below gives a good explanation of why ESR is different between the dielectrics.

http://www.cartage.org.lb/en/themes/sciences/physics/electromagnetism/electrostatics/Capacitors/Applications/PhysicalConsiderations/PhysicalConsiderations.htm

pp vs pet cap tests.pdf

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Thanks I guessed what it was, I got close :) This audio stuff is sure different then the RF world I come from.

And I thought since I was adapt at digging around in the innards of really old radio's and knew all about the parts and theory of operation, electro-mechanical speakers and such, I understood this audio stuff......har-dee-harr-harr :unsure:

By the way do you know about this outfit; http://www.humblehomemadehifi.com/index.html

check out the section that reviews capacitors. according to it the Axon True Cap is better then Solen,

and number of others and they are really cheap, and for a customer look really cool. I have a pair of them

on the low side of the XO's on the Monitor 10B's after 300 or so hours the bass response is better then

it ever has been.

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Yes, I am familiar with Tony Gee's cap ratings. I wrote a paper a few years back about his ratings. At the time I found a high correlation between his ratings and the voltage rating of caps he was reviewing. I surprised him with this finding and he subsequently agreed to conduct a special rating of 3 caps at my request. All that's history now. I haven't followed his ratings recently. However, this paper has over 1300 downloads since it's addition here at CSP. There was high suspicion that Tony's ratings could have been influenced by his prior knowledge of the cap's size and cost. Read the paper, check out his current ratings and judge for yourself...... :rolleyes:

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

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When I read somebody reciting the litany of the Crossover capacitor I can almost hear the Organ, or the Bells announcing the reading of the Gospel; The Gospel of Dueland Cast........Thanks be to Dueland. But what these communicants remind me of the most are wine snobs at a wine tasting, and their closed eyed descriptions of the wine they are tasting.

Crossover capacitors do make a difference. In the case of the Polk Monitor 10B's the Sonicaps, and Axon's have made a gigantic difference, but I was replacing 20+ year old non-polarized electrolytics and in one speaker a pair of fried mid-woofers, and a crossover with one cap that had detonated. I also replaced the 20+ year old Monster Cable speaker wire,with 12AWG cable with proper banana plug terminators.from Monoprice. I had good advice form you and others and I am very pleased with the results.

As an exercise in the ridiculous I decided to see what it would have cost if I had more money then brains. Recapping with the above mentioned Dueland Cast capacitors would have cost me $7,381.02.

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The hobby of audio is definitely one place where the law of diminishing returns prevails. I did an informal assay of speakers years ago and plotted price vs performance and found that at about the $2000 level and beyond, what you got for rapidly escalating $ spent was minor tweaks that were less and less apparent.

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There is one thing I want to know. If I ask this question over on Audio Karma a flame war will ensue, the level of snarkyness there is almost as bad as an Apple forum. Is there a break in period for Audio film capacitors. As you know I installed Sonicap Gen 1's for the tweeter side of the XO's and Axon True Caps for the "woofer" side. of my Monitor 10B;s after about 350 hours of use I do notice a big difference in the sound. This was a very subtle thing It took awhile to notice it. I suppose it took this long for the improvement to be enough for me to hear it. On the Polk forum I was told the Sonicap break in was somewhere around 400 hours. The Axon's seem to be coming on right now. This is a not subjective thing I have been listening to the same music on these speakers for over 20 years. At first they where powered by a Sansui integrated stereo amp, then a really nice JVC integrated amp, a crappy Sony AV receiver which blasted the right channel 10B when the right hand set of PA's failed, and now with the Onkyo TX-NR709. When I first fired up the refurbished 10B's on the Onkyo they sounded great, the bass was a bit snappish,and I didn't notice any improvement in the upper reaches, but the 10B's worked. Listening to those same bench mark albums after all the hours of play time on the refurbished XO's the 10B's sound fantastically better then they ever have.

By the way should this ever come up in you speaker repair business the new replacement Polk MW-6503 driver sounds the same as the original pair I have in the other 10B. The only difference you can see is the wires for the voice coil no longer are attached to the speaker cone but go directly to the spade connectors. I sure wish I could get replacement midrange and tweeters for the Warfedale W-35's compared to the 10B's they don't fair well.

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I believe there is a break in when new caps are installed. Whether this is electrical, mechanical, emotional, psycho- acoustical, or, a combination of those, I can't say for sure.

I was told by engineers at Mundorf that they 'cook' caps on request (for a few $$ more!). So, they seem to believe in it, as well as some of their well pocketed customers. :)

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On 8/12/2012 at 4:07 PM, Carlspeak said:

Detail performance tests were run on four ERSE capacitors to look at the effect of dielectric on ESR. Two 2.0 uF and two 3.9 (4.0) caps were tested. Each group had a polypropylene dielectric (Pulse-X brand with black color & gold printing) and a Polyester dielectric (yellow color with black printing).

What I found with these two levels of capacitance was a significant difference in ESR between the dielectrics in the 100 to 10000 hz range with PET generally trending higher in the freq. range evaluated. Below is a plot of the data obtained with a WT2.

IMO, the polyester ESR performance approaches that of an electrolytic. This may be of some value to those recapping that don't want to alter the voicing of the speaker or, where a slightly reduced response is needed in a particular frequency range.

The link below gives a good explanation of why ESR is different between the dielectrics.

http://www.cartage.org.lb/en/themes/sciences/physics/electromagnetism/electrostatics/Capacitors/Applications/PhysicalConsiderations/PhysicalConsiderations.htm

pp vs pet cap tests.pdf

I ordered some ERSE Mylar Caps, simply because I needed to spend some more money with them, to meet their minimum order requirements on a recent order. Just for the hell of it, I measure both value and ESR of 2 of their yellow Mylar Caps. Honestly, I was a bit surprised how High the ESR was !

The Values were right on the money, but ESR was high. In fact, I have measured some NPE that were lower than the ERSE Mylar. 

I have some speakers I am re doing, and they use a mix of both Poly and NPE's. I plan to order and use ERSE Mylars to replace the 30 year old NPE's, figuring the high ESR of the ERSE Mylars will not change the voicing, when I replace the old stock NPE with them. Plus, I will get the 250 volt rating of the ERSE Mylars !!!!!

The ERSE Mylars will fit, right on Top of the old NPE's. I will leave the old NPE Caps on the board, cut the wires as close to the old caps as possible, and solder the new ERSE Mylar caps right to them. 

 

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Just replaced the electrolytic Bennic caps in pair of Spica TC-60 crossovers with Audio Grade Polypropylene.  Did it after reading that Spica designer, John Bau, approved of that upgrade. Engineer, long time music lover and amateur audiophile.  Always held a healthy skepticism toward "golden" eared experts that claim to be able to hear the airiness of a gnats wing flapping.  Although, do understand that good design and proper component selection makes a difference.   Well, my subjective ear test after the crossover mod was quite surprising.  Chose the following as the first test due to listening to both shortly before the crossover mod.

First, Dire Straits "on every street".  First noticed that the right speaker seemed louder.  After a couple tracks realized the right speaker just sounded better, "cleaner" for lack of a better word.  By the end of the last track had to conclude everything sounded cleaner.  Individual notes came through.

Next listened to Pink Floyd "Dark Side of the Moon" vinyl master recording.  Simply a new experience.  The Sax on "Money" clear and clean.  All tracks revealed something new.  

I am in no way a "golden" ear, but there were real differences wanted to share for anyone thinking about replacing electrolytic capacitors in a crossover. 

 

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