vacs2000 Posted September 12, 2002 Share Posted September 12, 2002 Hello Yesterday evening I replaced the stock Aerovox oil capacitors to one of my Cornwall 1977. There are one 2 and ne 4 uf caps. The values I put in are 2.2uf (but after Jensen comments they measure very close to 2uF) and 3.9uF. I left the speaker play 12-15 hours up to now. I am not so impressed. Some of the high freq are not so profound (see missing) with the Jensen one. I will wait for a week if the brake-in is a true argument. Keep you inform george ------------------ --------------------- Fisher 400-CX pre-amp Fisher 100 (EL37) monoblocks (3) Fisher 101R tuner Fisher 100-MPX Sony SCD-333ES Ampex 1260 reel to rell Garrard 401/SME3012R/Grado Speakers... ------------------------- Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 12, 2002 Share Posted September 12, 2002 George, Now, do some real science and replace the stock caps with Hovland Musicaps in the other speaker and compere the two. If you decide you don't like the Jensens, I will buy the 2.0 uF off of you to test. I have been wanting to measure the losses on one of them. Al K. This message has been edited by Al Klappenberger on 09-12-2002 at 06:12 PM Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 19, 2002 Share Posted September 19, 2002 Hi everybody, George was good enough to send me one of the 2.2 uF Jensen paper in oil caps that he tried to use in his Cornwall crossover. I put it on my impedance bridge and measured it. These things are unquestionably a total rip-off! The thing measured 2.099 uF with a quality factor of only 200! In contrast, I have measured many Hovland MusiCaps and have never found one yet that measured below 2000. More musical, baloney! They are simply so lossey that all you highs go away as heat inside the capacitor! This is equivalant to connecting a .38 ohm resistor in sereis with a Hovland MusiCap. My advice -- DON'T USE THEM! Al K. Quote Link to comment Share on other sites More sharing options...
Parrot Posted September 19, 2002 Share Posted September 19, 2002 Al, What does "quality factor" mean? Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 19, 2002 Share Posted September 19, 2002 Paul, "Quality factor" is the same as "Q". It's defined as the ratio of capacitive reactance (pure capacitor effect) and series loss as represented by a simple resistor. a 2.2 uF cap has 1 / (2 Pi F C) ohms reactance. At 1000 Hz, that is 72.34 Ohms reactance. A Q of 200 means there is .362 Ohms of loss inside the cap. That is, 72.34 / 200 = .362. A similar Hovland Musicap will have an internal loss equivalant to a .036 Ohm resistor. I think that's why Hovlands have thicker wires coming out of them. The wires become a significant part of the loss. With the Jensen, who cares about the leads. they can be small because the loss in the cap is so much! AL K. Quote Link to comment Share on other sites More sharing options...
John Warren Posted September 19, 2002 Share Posted September 19, 2002 your findings will be discounted as irrelevant. you are a bad, bad, bad man. Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 19, 2002 Share Posted September 19, 2002 John, I know! It's kind of like saying there is no God! Al K. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 19, 2002 Share Posted September 19, 2002 These Capacitors are popular as coupling caps in tube audio circuits. Would these internal losses have the same effect in tube audio circuits? (would they contribute to a lack of musicallity? dulling, muting?) All I know is that they are real popular with high-end tube amplifiers, and always part of a upgrade option. And they are spendy little bastards, but so are Hovlands. No life, Great. This message has been edited by mike stehr on 09-19-2002 at 09:59 PM Quote Link to comment Share on other sites More sharing options...
JohnA Posted September 19, 2002 Share Posted September 19, 2002 Why would you want to replace one paper and foil in oil capacitor with another one? If for no other reason, the Jensens are a mystery to me. John Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 20, 2002 Share Posted September 20, 2002 mike, One reason the Jensen caps may be used in tube amps is becasue they are rated 400VDC. The Hovlands I use are only rated 100VDC. For crossover networks, you could use 25VDC caps and be safe. Also, in an amp you in an "active" circuit. This means losses are not a problem. You just turn the volume up a bit to compensate. In a filter, like in a crossover network, the frequency response and input impedance get loused up! Losses are usually highest at the points of maximum group dealy, That happens near the crossover itself. Specifically, about the 1 or 2 dB down point on the skirt of each filter. By the way, Hovlands come in higher voltage rating versions too. They just cost even more! Al K. Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 20, 2002 Share Posted September 20, 2002 Thanks Al. Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted September 21, 2002 Share Posted September 21, 2002 The Jensens used in tube amp cap circuits are usually the copper foil versions, which are a different animal than the cap you are measuring (besides having a 630v rating). Be careful of blanket statements here. Also, be careful of using measurements to denote sonics. As most know, measurements can be great as a design aid but can be circumspect when judging sound quality. I am sure the Aerovox measure more than mediocre as well. Indeed, a generic 2002 high negative feedback Circuit City solid state amp measures better in some ways than a quality tube amp. Just out of curiosity, what did you measure the Aerovox oil "losses" to be? As someone that has heard MANY high quality coupling caps from MIT RTX film and foils to Hovland, I can say that Jensen "Copper foil" 630v oils are extremely good sounding, probably more natural than any cap I have tried to date. I will say that I have never heard Jensen Aluminum foil 400v oils either as a coupling cap or in a speaker crossover. kh Phono Linn Sondek LP-12 Valhalla / Linn Basic Plus / Sumiko Blue Point CD Player Rega Planet Preamp Cary Audio SLP-70 w/Phono Modified Amplifier Welborne Labs 2A3 Moondog Monoblocks Cable DIYCable Superlative / Twisted Cross Connect Speaker 1977 Klipsch Cornwall I w/Alnico & Type B Crossover Links system one online / alternate components / Asylum Listing f>s> This message has been edited by mobile homeless on 09-21-2002 at 02:15 AM Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 21, 2002 Share Posted September 21, 2002 Mobile, I am certain that the loss I measured in this particular Jensen cap is a function of the old paper in oil dielecric material. The question of copper versus aluminum foil is insignificant in comparison. The foil could be made of superconductor and the paper and oil would still show major losses. Paper in oil is simply OLD TECHNOLOGY. Its "sonic quality" is simply the loss if energy! That's fine in a active circuit, but NOT in a passive filter! Again: Do NOT use paper in oil capacitors in a crossover network, especially in my design! You will be wasting your money. Al K. Quote Link to comment Share on other sites More sharing options...
vacs2000 Posted September 22, 2002 Author Share Posted September 22, 2002 Hi again, Someone some messages up asked why to replace one oil capacitor with another. Well first I have to say that 2-3 years ago I had replace the stock capacitors on my Spendors BC1 with Hovland. I switch back in a week. They were too bright. SO when it came to the Klipsch crossover since the original unit was using oil capacitors in an era where you could find decent non-oil capacitors I thought (and still think) that I would give a try with the Jensen oil since I had a very nice experience with my Fisher 100 monoblocks when I recapped them with Copper/oil jensen (it was a night/day difference). Since I recap the one Cornwall with the Jensen and after the first impressions either I am starting to be used on the Jensen sound or whetever else but it is getting better eact day. It "rings" much less than the stock one give a sweeter sound. Still I am not sure that it is a 100% needed upgrade but I am getting more pleased with them. Also (and BTW) these Jensens have a orientation band on one side. I tried to contact Jensen in DK to ask about it but they never got back. Anybody with an idea on this?? thank you george ------------------ --------------------- Fisher 400-CX pre-amp Fisher 100 (EL37) monoblocks (3) Fisher 101R tuner Fisher 100-MPX Sony SCD-333ES Ampex 1260 reel to rell Garrard 401/SME3012R/Grado Speakers... ------------------------- Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 23, 2002 Share Posted September 23, 2002 ? Quote Link to comment Share on other sites More sharing options...
djk Posted September 23, 2002 Share Posted September 23, 2002 "For crossover networks, you could use 25VDC caps and be safe." Sure, if you have a 3W amp. In loudspeakers reactive loads may impose voltages up to three times higher than the ones that excited them. The rail voltages in the 100W NAD 2200 are +/- 100V, same as a 200W Carver M1.0T, don't even think about using low voltage caps with amps like these. Plus, the voltage must be de-rated with frequency and construction. A 160VDC cap will take 90VAC at low frequency. But only take 8VAC at 20Khz in the 6.8µF size(MPR and MPW, 85*C metalized polypropylene capacitors). A stacked film snubber capacitor with soldered copper leads will typically take 3X the voltage at high frequency (25VAC) even though it has measurably higher DF and lower Q. "The question of copper versus aluminum foil is insignificant in comparison." Paper and foil in oil caps are much better in high current applications than metalized film caps because of the lead attachments. You can solder a lead to the foil. Everybody has seen the metalized film wrapers PopTarts come in, try and hook a wire on to it. Dr Bruce Edgar recommends DC rated oil caps as opposed to AC rated types because the leads are attached differently and thus sound different. "I am certain that the loss I measured in this particular Jensen cap is a function of the old paper in oil dielecric material." In addition to lead termination issues you also have the dielectric to contend with. You might think whatever has the lowest dielectric absorption is best, but is it? From this standpoint polycarbonate should be one of the best. But they sound bad. This material appears to be very non-linear. Ceramics are very non-linear too. Not to mention piezo electric. So which is better? A high loss capacitor that is linear? Or a low loss type that is non-linear? I know of no meter or test that will tell me a capacitor will sound good. "The paper in oil is extremely clean, best of the group. That may be one reason why some people prefer the sound of the paper capacitors. Although not recorded, oil capacitors in general appear to be very linear. These caps also appear to have relatively stable characteristics with change in frequency." http://members.aol.com/sbench102/caps.html "Note that there are also other mechanisms that can alter the sound" ibid The now defunct Audio Amateur had many a good article on passive parts and their effect on the sound. Required reading for those who really want to learn. This message has been edited by djk on 09-23-2002 at 02:49 AM Quote Link to comment Share on other sites More sharing options...
Al Klappenberger Posted September 23, 2002 Share Posted September 23, 2002 I stand by what I said earlier. 25V caps would be safe in most cases. Higher voltage is always better though. A quick computer analysis on the Klipschorn AK-3 network shows about 25V RMS worst case at 10W input assuming 2:1 reactave loads. A biger problem is that currents approach 2 Amps at that level. ======================== If you put low loss caps in a network and the sound becomes bright, put the attanuation in as a "T" pad outside the filter. Don't distribute the losses throghout the filter components! Doing this degrades the filters passband corners. Better yet, use an autotransforemer to rebalance the levels between drivers. High loss components can kill a filter! An external attenuator does it no harm. Al K. This message has been edited by Al Klappenberger on 09-24-2002 at 05:57 AM Quote Link to comment Share on other sites More sharing options...
Jmm Posted May 9 Share Posted May 9 I have to agree that Jensen caps are very lossy. Metalized film is too bright. Quote Link to comment Share on other sites More sharing options...
Bacek Posted May 9 Share Posted May 9 And this years Golden Shovel award goes to ... Jmm, congratulations 😀 . 2 1 Quote Link to comment Share on other sites More sharing options...
Deang Posted May 9 Share Posted May 9 Good thread. If Jensen was still around I would still be building with them. 1 Quote Link to comment Share on other sites More sharing options...
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