Quiet_Hollow Posted July 28, 2012 Share Posted July 28, 2012 1990 La Scala w/ AL-3 network* 68uF 150V (woofer) 0.04 Ohm each 13uF 100V (squawker) 0.08 Ohm 2uF 180V (tweeter) 0.43-0.45 Ohm each I don't know what Klipsch's own acceptable values for these were at the time of manufacture, but even with these 22 year-old speakers enduring two arctic-style WI winters in cold storage and my goofy experiments with random amounts of EQ, all these caps measure VERY GOOD. * in-place, discharged, the electrolytic shunt split, with an Anatek Blue ESR meter, all drivers disconnected. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 28, 2012 Share Posted July 28, 2012 are your measurements influenced at all by injection frequency? it seems odd that the smaller the cap, the higher the ESR. Wondering if thats due to using a DC signal to measure the esr. Basically, would the results change if the 68uf cap was tested at 200hz, the 13uf cap if tested at 2500hz, and the 2uf cap tested at 6khz. Approx mid point of AL-3 operating range. So are the ESR testers for DC circuts the same as ESR tester for AC circuts? I know for impedeance measurements.....there are testers that have selectable injection frequency. Quote Link to comment Share on other sites More sharing options...
BEC Posted July 28, 2012 Share Posted July 28, 2012 I think that tester uses 100khz for testing. Why would we expect the 100khz test frequency that tester uses to tell us anything of importance about a cap used in audio? But, it correct, the 2uF caps are pretty bad. I assume that those are the two in series in the tweeter circuit. So we have effectively almost 1 ohm in series with the 8 ohm tweeter. Loss due to ESR would be 1 divided by 8 or about 12.5 percent of the signal lost. Bob Crites Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 28, 2012 Share Posted July 28, 2012 I think that tester uses 100khz for testing. Why would we expect the 100khz test frequency that tester uses to tell us anything of importance about a cap used in audio? But, it correct, the 2uF caps are pretty bad. I assume that those are the two in series in the tweeter circuit. So we have effectively almost 1 ohm in series with the 8 ohm tweeter. Loss due to ESR would be 1 divided by 8 or about 12.5 percent of the signal lost. Bob Crites definitely something spooky.....if it used 100khz as an injection frequency...I would have expected the readings to have a pattern reverse of what is presented......lowest esr at 2uf and highest at 68uf.....so yes...a 100khz tester is just as useless as a DC signal injecter. Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted July 29, 2012 Author Share Posted July 29, 2012 You guys crack me up!! With all due respect... But, it correct, the 2uF caps are pretty bad. I assume that those are the two in series in the tweeter circuit. So we have effectively almost 1 ohm in series with the 8 ohm tweeter. Loss due to ESR would be 1 divided by 8 or about 12.5 percent of the signal lost. A quote from AnaTek the manufacturer: "A good 1 ufd, 200 volt metallized polypropylene capacitor can have an ESR of less than 50 milliohms. Yet it's capacitive reactance at 100 Khz is approximately 1.6 ohms, at 50 Khz it is 3.2 ohms. The result is that the meter will indicate 1 ohm or more for such a capacitor even though there is nothing wrong with it." That my meter measured each 2 uF cap at less than 0.5 Ohm given the circumstances is okay. 2 uF is approaching the DUT limit of the test circuitry and many polyfilms average ~1 to 1.5 Ohm @ ~100 kHz because the actual ESR is so low that most consumer meters only pick up the capacitive reactance anyhow. These ones measure below expected acceptable values. Heck, even the 68 uF electrolytics smoke that. [:|] I could be using a meter that measures polyfilms even more accurately perhaps... Buuuut "hypothetically speaking" even if their combined ESR was indeed 1 ohm, a 12.5% voltage loss is only -1 dB...and that would definitely be pushing the resolving limits of my ears in the tweeter passband. [] definitely something spooky.....if it used 100khz as an injection frequency...I would have expected the readings to have a pattern reverse of what is presented......lowest esr at 2uf and highest at 68uf.....so yes...a 100khz tester is just as useless as a DC signal injecter. It's not spooky....it's in the math. See: Doug Jones' Tech Notes Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 29, 2012 Share Posted July 29, 2012 Heck, even the 68 uF electrolytics smoke that. I could be using a meter that measures polyfilms even more accurately perhaps... yes...it looks like your meter is using DC signal injection......so it's more accurate at larger mfd values. I do not believe those 2uf caps have that high of an esr. Quote Link to comment Share on other sites More sharing options...
BEC Posted July 29, 2012 Share Posted July 29, 2012 I wish those cheap ESR meters worked. I bought one of those first. Took me just a few hours to decide it was worthless to do anything other than find really terrible caps. Then I bought a B & K Model 885 meter. Anyway, I found with careful comparison testing that I could hear the difference when ESR was about 0.5 ohms in a tweeter circuit when comparing to a good cap which typically measures below about 0.01 ohms ESR. Quote Link to comment Share on other sites More sharing options...
Johnny's Jill Posted July 29, 2012 Share Posted July 29, 2012 hypothetically speaking" even if their combined ESR was indeed 1 ohm, a 12.5% voltage loss is only -1 dB...and that would definitely be pushing the resolving limits of my ears in the tweeter passband. The -1db spl shift is not the only consideration, adding series resistance in the circuit can also shift the crossover point depending on its location. By adding 1 ohm series resistance to the tweeter circuit in a 1st order network, you can effect the crossover point by several hundred Hz. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 29, 2012 Share Posted July 29, 2012 OK, I just checked the assemble manual for the ESR meeter involved....all the readings are based on a 2khz test signal. Quote Link to comment Share on other sites More sharing options...
BEC Posted July 29, 2012 Share Posted July 29, 2012 OK, I just checked the assemble manual for the ESR meeter involved....all the readings are based on a 2khz test signal. Says here 100khz "effective frequency". Whatever that means. http://www.anatekcorp.com/esr_compare.htm Quote Link to comment Share on other sites More sharing options...
Quiet_Hollow Posted July 29, 2012 Author Share Posted July 29, 2012 Hmmm, I've heard this song before [^o)]...I'm gonna have to get back with you guys on this. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 29, 2012 Share Posted July 29, 2012 OK, I just checked the assemble manual for the ESR meeter involved....all the readings are based on a 2khz test signal. Says here 100khz "effective frequency". Whatever that means. http://www.anatekcorp.com/esr_compare.htm the manual says in one section that it uses an equiv to a 100khz frequency.....but then in another section it says it uses 2khz bursts,,,,,,,not sure what that means. Quote Link to comment Share on other sites More sharing options...
BEC Posted July 29, 2012 Share Posted July 29, 2012 Probably short duration pulses at the rate of 2khz. Width of each pulse equivalent to 100khz. Don't know, just guessing. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted July 30, 2012 Share Posted July 30, 2012 In at under $200 this ESR meter provides 4 different input frequencies. I have had one of these for a while now and it really has been a gem for me. http://www.ebay.com/itm/TH2821A-10KHZ-LCRZ-Meter-W-precision-Resistor-0-1-100K-1M-/140795340719?pt=Vintage_Electronics_R2&hash=item20c80e67af Quote Link to comment Share on other sites More sharing options...
Guest " " Posted July 30, 2012 Share Posted July 30, 2012 In at under $200 this ESR meter provides 4 different input frequencies. I have had one of these for a while now and it really has been a gem for me. http://www.ebay.com/itm/TH2821A-10KHZ-LCRZ-Meter-W-precision-Resistor-0-1-100K-1M-/140795340719?pt=Vintage_Electronics_R2&hash=item20c80e67af Yes...I like that one...Test the 68uf cap at 100, or 120HZ, test the 13uf cap at 1K, and the 2uf caps at 10K Quote Link to comment Share on other sites More sharing options...
BEC Posted July 30, 2012 Share Posted July 30, 2012 That meter looks like spec wise that it might be all right. At least the people who made that one understood that you have to use a 4-wire lead set to measure low ohms with any sort of accuracy. Bob Crites Quote Link to comment Share on other sites More sharing options...
djk Posted July 31, 2012 Share Posted July 31, 2012 A question for Bob: How much different does the ESR measure on a 2µF cap on the B & K Model 885 with 1Khz vs 10Khz? The TH2821B is a lot less money than the A version, and the only real difference (for a home shop) is the A version will run either 1Khz or 10Khz, where the B version only has 1Khz. The B version is $144.50 and ships from the USA for $12 vs the A version is $180 and ships from HK for $50 ($156.50 vs $230 total)). There may be a customs fee due on the one from HK too. http://www.aidetek.com/New_products_info/Datasheet/tonghui/TH2821B_u47.pdf Quote Link to comment Share on other sites More sharing options...
BEC Posted July 31, 2012 Share Posted July 31, 2012 Dennis, On my meter, at least for checking new caps, 1khz or 10 khz shows little differnece. I checked into this early on using my ESR meter and found for the few companies that stated an ESR spec, 1khz seemed to be standard test frequency. After all, the manufacturer doesn't really know where the cap is used, so they test conservatively at 1khz. A test at 10khz will typically show slightly lower ESR. For old caps, frequency of test seems to make more difference but in every case I checked, the more conservative seemed to be at 1khz. So, I decided to use1khz for all my testing. Bob Crites Quote Link to comment Share on other sites More sharing options...
djk Posted July 31, 2012 Share Posted July 31, 2012 I just ordered one, $154.69 total including shipping, shipped from the USA. http://www.ebay.com/itm/270348182317?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649 Quote Link to comment Share on other sites More sharing options...
BEC Posted July 31, 2012 Share Posted July 31, 2012 Dennis, Let us know how that meter works out. I would probably go for one like that next time I need one if that works good. Just wondered if you can figure this out from the info they supply. Does this meter directly measure ESR, or does it just infer it from dissipation factor? That meter seems to assign C/D to the two readouts. On mine, I can select C for one readout and at the same have either D, Q or ESR displayed on the other readout. Perhap this meter can do that also. It is very handy to measure C and ESR at the same time. Bob Quote Link to comment Share on other sites More sharing options...
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