Pete B Posted April 27, 2015 Report Share Posted April 27, 2015 The question remains: Is the actual meas. value within 10% at the freq. normally used for that value cap? I suspect what Roy found is well known in the cap industry and they 'should' be building them to that standard.For example, a 6 uF NPE cap (common tweeter cap) should measure 6 uF + - 10% in say the 2-6 kHz range?Yes, but they are not going to do that for you. A designer should know this and adjust accordingly, I usually try to get the value close around the 3 dB or 6 dB crossover point because that is whereit has the most impact on the transfer function. Link to comment Share on other sites More sharing options...
Pete B Posted April 27, 2015 Report Share Posted April 27, 2015 Here is a serious capacitance meter for about $5K from Agilent - just noticed that it is refurbished probably lists for 10 to $20K:http://www.ebay.com/itm/HP-Agilent-4288A-Capacitance-Meter-NEW-In-Box-1KHz-1MHz-CAL-CERT-WARR-/121616477329?_trksid=p2141725.m3641.l6368It is probably geared more for RF capacitors and that is why it has a 1 MHz test frequency.They probably have another model for electrolytics, and another for microwave caps that tests a GHz frequencies,they probably also have a 20 to $50K model that does it all.These are real meters, what you all are using, and I am using are toys.My Fluke DMM which is an excellent DMM, measures caps by timing the time constant and only goes to 5 uF.Above 5 there is a special method - I don't even use it. Link to comment Share on other sites More sharing options...
iso Posted April 27, 2015 Report Share Posted April 27, 2015 I think the whole DF diversion has complicated the the discussion. DF is directly related to ESR (ESR is easier to understand because the units are ohms) and like ESR varies with fequency.Read more about it here....http://en.wikipedia.org/wiki/Dissipation_factorI agree... but for some reason distributors of NPE´s seems to think that DF is the spec we should know, even ESR information is widely available for polar PSU capacitors. I googled Bennic, Janzen, Erse, Visaton, Intertecnic and Alcap NPE´s. None of them provided ESR information. Intertechnic talked about loss angle and others talked or most even specified DF. Luckily if you know DF you can calculate ESR and vice versa.Don...Manufactures have used different NPS and also film caps as OEM... sometimes you may find even different caps in in L and R speakers. One speaker of my AR5 pair had 24 uf and 72 uf Compulytic (which were the best ones available in 70´s) and 4 uf tweeter cap was black axial (looks quite similar than old Elcaps). Other speaker used only72 Compulytic for woofer. 24uf and 4uf caps were those black ones. Some marques like Kef have sorted NPE´s in 2% band´s to compensate coil tolerances to achieve closer match of crossover slopes. They felt that it is important that 3rd order Butterworth slopes match closely to -30dB region in the stop band. Close matching of capacitance and ESR is important with steep 18 dB and 24 dB slopes. Crossover area is the most important region, like Pete mentioned. However less precision is needed when slopes get gentler. On such positions like AR2ax mid... ESR is not too critical as there is 6-7 ohms pot viper in series to cap ESR. Capacitance tolerance is not too important either, as the load capacitor sees will change when you turn the pot. So... the answer to your question is tough one... it all depends how the original design was made. Also to whom you ask the question about audible changes may make difference... some peoples can not tell difference between two quite dissimilar speakers if they are perfectly happy when listening just music. Some golden ear might hear difference between 2 amp and 1,6 amp mains fuse. I fear that this did not help you too much... but anyway welcome to this forum.Best RegardsKimmo Link to comment Share on other sites More sharing options...
donquixote99 Posted April 27, 2015 Report Share Posted April 27, 2015 My first takeaway is that with mild slopes you don't have to sweat cap matching so much, but with the 18 or 24 dB slopes this is more critical. My other is that if there's a pot in the path, what you can do by moving that rather swamps variation in cap value and ESR.Thanks for response and for welcome! Link to comment Share on other sites More sharing options...
DavidDru Posted April 29, 2015 Author Report Share Posted April 29, 2015 David,The point of the last batch of posts in this thread is that these npe's cannot be measured accurately with a meter unless it has multiple user-adjustable test frequencies (which is not likely). I'm certain your tech's meter is not unlike those in the shops I work for. These meters only measure at certain frequencies (nothing to do with "volts"). Your MET cap measured well because it is a film cap, and as such, is not affected much by the frequency at which it is tested. Every new 12uf npe I have here (Erse, Bennic, and Parts Express) have measured between 13.5 and 14.1uf on 5 meters. I doubt Erse will be of much assistance other than to refund the few bucks these caps cost you.RoyErse sent me new 12uf NPE caps that they tested with their equipment and confirmed as identified to be. I get them and they again test for me with my simple multi-meter high at 14.2.Apparently my testing ability is not going to work out for these NPEs. So do i just trust they are of the proper value measurement and use them?I emailed them back and suggested they test them with a simple multi-meter instead of whatever high end equipment they are using. This would show them what my challenge is along with probably a most of their customers.It has to be this frequency thing. Link to comment Share on other sites More sharing options...
DavidR Posted April 29, 2015 Report Share Posted April 29, 2015 Does this go for polarized electrolytics as well or just non-polar?I've replaced some small caps on PCBs such as my oven readout/display 68uF 35V and several on my Bose active EQ 1uF 50V, 10uF 35V and 470uF 35V and all the replacements were well within spec. Link to comment Share on other sites More sharing options...
owlsplace Posted April 29, 2015 Report Share Posted April 29, 2015 Erse sent me new 12uf NPE caps that they tested with their equipment and confirmed as identified to be. I get them and they again test for me with my simple multi-meter high at 14.2.Apparently my testing ability is not going to work out for these NPEs. So do i just trust they are of the proper value measurement and use them?I emailed them back and suggested they test them with a simple multi-meter instead of whatever high end equipment they are using. This would show them what my challenge is along with probably a most of their customers.It has to be this frequency thing.New business op for Carl and RoyC -- certified pre-tested caps Roger Link to comment Share on other sites More sharing options...
DavidDru Posted April 30, 2015 Author Report Share Posted April 30, 2015 Does this go for polarized electrolytics as well or just non-polar?I've replaced some small caps on PCBs such as my oven readout/display 68uF 35V and several on my Bose active EQ 1uF 50V, 10uF 35V and 470uF 35V and all the replacements were well within spec.not sure. All I got from them in addition to the cheap NPE's has been the Pex Metal Poly film caps (yellow ones) and they measured great with my multimeter. Link to comment Share on other sites More sharing options...
RoyC Posted April 30, 2015 Report Share Posted April 30, 2015 not sure. All I got from them in addition to the cheap NPE's has been the Pex Metal Poly film caps (yellow ones) and they measured great with my multimeter.David,I have a number of Erse 12uf npe's, and they measure very much like yours with my meters. WT2 software, however, shows them to meaure within rated value (as do the 12uf Bennics) at a very broad range around 1000hz. I would use them, and would only be concerned if one of 'em produced a number way out of line with the others.The higher the cap value, the greater the discrepancy (to the high side) will be with these meters because they are measuring values over 2uf at such low frequencies. Caps below 2uf are being measured at higher frequencies (800+ hz) and tend to measure closer to rated value.I found the "operation manual" of one of my meters. It is in broken English (probably translated from Chinese). Here is some of it:Many capacitors (especially the electrolytics) have wide capacitance of condenser. If the test result is bigger than the nominal value, there is no necessary to be surprised at it.....Usually the test result is seldom smaller than rated value.Roy Link to comment Share on other sites More sharing options...
RoyC Posted April 30, 2015 Report Share Posted April 30, 2015 New business op for Carl and RoyC -- certified pre-tested caps RogerHmmm...."Individually tested, including one-on-one counseling to discourage "drifting" and encourage "settling" in quickly. Shipped in cotton in its own foil lined box to prevent contamination by stray electrons."...starting at only $50 for 1uf rated value. Roy Link to comment Share on other sites More sharing options...
der Posted April 30, 2015 Report Share Posted April 30, 2015 They'll never sell. Not expensive enough.der Link to comment Share on other sites More sharing options...
DavidDru Posted April 30, 2015 Author Report Share Posted April 30, 2015 Is that one day shipping? I might be interested. Link to comment Share on other sites More sharing options...
Carlspeak Posted April 30, 2015 Report Share Posted April 30, 2015 Hmmm...."Individually tested, including one-on-one counseling to discourage "drifting" and encourage "settling" down quickly. Shipped in cotton in its own foil lined box to prevent contamination by stray electrons."...starting at only $50 for 1uf rated value. RoyHey! I want some of that action! :-) Link to comment Share on other sites More sharing options...
der Posted April 30, 2015 Report Share Posted April 30, 2015 I bought caps from Carl and am happy with them. No foil lined box though. Damn!der Link to comment Share on other sites More sharing options...
donquixote99 Posted April 30, 2015 Report Share Posted April 30, 2015 I have lots of ideas for cashing in on the overpriced boutique parts and tweeks market. Trouble is, if you get $ for shoveling BS you naturally take to believing it. Then where would I be? Link to comment Share on other sites More sharing options...
RoyC Posted April 30, 2015 Report Share Posted April 30, 2015 Hey! I want some of that action! :-)There's plenty to go around, brother. We must never overestimate the reasoning of an "audiophile" with a need to believe. Roy Link to comment Share on other sites More sharing options...
der Posted April 30, 2015 Report Share Posted April 30, 2015 Yes - I myself will soon go into production on ultra low loss interconnects, speaker cable and equipment power cables. Just $799 an inch for the speaker cable. Terminated in any fashion you wish.der Link to comment Share on other sites More sharing options...
DavidR Posted April 30, 2015 Report Share Posted April 30, 2015 Yes - I myself will soon go into production on ultra low loss interconnects, speaker cable and equipment power cables. Just $799 an inch for the speaker cable. Terminated in any fashion you wish.derAre those cables 99.999999999% OFC and cryogenic treated along with 5 layers of shielding ? Link to comment Share on other sites More sharing options...
der Posted May 1, 2015 Report Share Posted May 1, 2015 Are those cables 99.999999999% OFC and cryogenic treated along with 5 layers of shielding ?But of course. Link to comment Share on other sites More sharing options...
DavidDru Posted May 6, 2015 Author Report Share Posted May 6, 2015 The folks at Erse say they test caps at 120hz - 1k H2.I am guessing this is too high for most standard multi-meteres to do? Link to comment Share on other sites More sharing options...
owlsplace Posted May 7, 2015 Report Share Posted May 7, 2015 The folks at Erse say they test caps at 120hz - 1k H2.I am guessing this is too high for most standard multi-meteres to do?I bumped into a post from 2008 on DIYaudio. If you have a spare $4K you can get a refurbed HP / Agilent 4192A LF Impedance Analyzer used to take the measurements.The take away is that the rise in ESR at low frequencies for npe caps is part of the xover design, or should be anyway. Whether you will find the aural differences between film and npe caps objectionable or beneficial in classic-era speakers exhibiting age-related sound degradation problems will probably depend on personal preference.Here is the link: http://www.diyaudio.com/forums/parts/117452-non-polar-electrolytic-vs-polypropylene-film-capacitors.htmlRoger Link to comment Share on other sites More sharing options...
Carlspeak Posted May 7, 2015 Report Share Posted May 7, 2015 The folks at Erse say they test caps at 120hz - 1k H2.I am guessing this is too high for most standard multi-meteres to do?My Tenma LCR meter has a 1kHz/120 hz switch. Link to comment Share on other sites More sharing options...
DavidR Posted May 11, 2015 Report Share Posted May 11, 2015 I just got a shipment from Erse of Pulse-X 250V PP and 150uF and 200uF NPEs.Pulse-X 82uF: 82.3 and 65.3 - 67.7. The second one just kept bouncing all over the place. Certainly a bad cap.150uF: 169.4 and 166.9200uF: 210 and 212The NPEs were at or outside the 5% tolerance.Erse told me their meter is out for calibration. Link to comment Share on other sites More sharing options...
der Posted May 11, 2015 Report Share Posted May 11, 2015 Oh no, something else to worry about! Are my caps out of tolerance? No, I'm going to let it slide!der Link to comment Share on other sites More sharing options...
DavidDru Posted May 11, 2015 Author Report Share Posted May 11, 2015 I just got a shipment from Erse of Pulse-X 250V PP and 150uF and 200uF NPEs.Pulse-X 82uF: 82.3 and 65.3 - 67.7. The second one just kept bouncing all over the place. Certainly a bad cap.150uF: 169.4 and 166.9200uF: 210 and 212The NPEs were at or outside the 5% tolerance.Erse told me their meter is out for calibration.Interesting. Link to comment Share on other sites More sharing options...
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