Sorry to see so little mention of the Jantzen Cross Caps. In my purely subjective listening tests I liked them a lot. They are very affordable, too. It's mainly what I use now. To my ear they are better than a lot of much more expensive caps.
Also North Creek are nice, as are the Obbligato from Hong Kong. I've been known to toss a metal can motor run cap from the local HVAC shop into the mix as well.
Also North Creek are nice, as are the Obbligato from Hong Kong. I've been known to toss a metal can motor run cap from the local HVAC shop into the mix as well.
You can certainly hear the difference between non-polar electrolytics and film types. This may be partly to do with the way that exact capacitance is kinda vague with non-polars. 20% error is common.
With film types, I see diminishing returns.
We're not getting near answering the Mundorf question here, but I can relate my experiments with three capacitors in a simple 2.2uF + 47R resistor highpass crossover to a metal dome tweeter. The lowpass was just an inductor on simple little Mordaunt Short compact reflex speakers on stands. Here's a ca. 1997 photo to prove I don't make this stuff up!
An externally hosted image should be here but it was not working when we last tested it.
This was a very good front end of high-end Rotel preamp and power amp, my current RCD-965BX but iced with an expensive Rotel DAC. The DAC brought a stunning bass register and a silky top end. Wish I still had it actually.
The music was Karolina Kruger's "Se pa meg", IIRC. A very good and delicate female vocal.
What I noticed was a sibilance on her voice, but interestingly, it was not appearing in the centre of the stereo image, but rather out of phase on either side of her vocal. Sibilance, or a hissing on "S" sounds really, is about 7kHz, as it goes. The crossover must have operated about 3 kHz.
Opening up the speakers, I found 2.2uF non-polar electrolytics. I swapped them some smallish Solen (250V?) MKPs I had lying about. This made a very noticeable difference, and the sibilance disappeared. Being interested by now, I bought some very fat 630V 2.2 uF Audio Grade Polypropylene Capacitors at Maplin. Swapping these in and out, I decided that the big fatties from Maplin had a lot more top end than the Solen's. A lot brighter. Well, that's what I know.
With film types, I see diminishing returns.
Let me try here:
Capacitors, the GOOD, the BAD & the UGLY - The Classic Speaker Pages Discussion Forums
Steve, there is another difference between NPE's and film types besides tolerance. NPE caps have a nominal ESR of about 1/4 to 1/3 ohm. Film types nominal ESR is in mili-ohms*. Thus, all things being = (other than cap type), film types will yield a bit more SPL.
* this is clearly visible in the data tables at the link above.
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Yeah, I saw that page before, Speaker Doctor. A few interesting odds and ends there.
Is ESR necessary and sufficient to characterize caps for xover use? That is mainly what I read about on that page.
H'mm, I can name a lot of other real world capacitor mechanisms not accounted for by ESR.
This is the critical question because if science adherents cant provide a practical and comprehensive program to science the way through the selection process, then I am forced to conclude that this is all simply philosophy.
Philosophy, meaning another subjective, socially constructed epistemological system that has no more fundamental claim to truth than any other.
I'm looking for a practical and fully sufficient scientific program for selecting xover caps here. One that will fulfill the promise of this claim: "If you can't measure a difference, you can't hear a difference."
Is ESR necessary and sufficient to characterize caps for xover use? That is mainly what I read about on that page.
H'mm, I can name a lot of other real world capacitor mechanisms not accounted for by ESR.
This is the critical question because if science adherents cant provide a practical and comprehensive program to science the way through the selection process, then I am forced to conclude that this is all simply philosophy.
Philosophy, meaning another subjective, socially constructed epistemological system that has no more fundamental claim to truth than any other.
I'm looking for a practical and fully sufficient scientific program for selecting xover caps here. One that will fulfill the promise of this claim: "If you can't measure a difference, you can't hear a difference."
Joe, there are a number of cap factors that can affect the sound of the cap. ESR is certainly one of the important ones.
Just look at some of the bad cap tests at the link - the far right data column, and note how drastically the fundamental uF value varies with freq. vs good caps. With those kind of swings, you can guess what's happeining to the transfer function. Then there's, dissipation factor and a few more.
With regard to your idillic cap computer program, I doubt wel'll see one any time soon.
Just look at some of the bad cap tests at the link - the far right data column, and note how drastically the fundamental uF value varies with freq. vs good caps. With those kind of swings, you can guess what's happeining to the transfer function.
Then there's, dissipation factor and a few more. With regard to your idillic cap computer program, I doubt wel'll see one any time soon.
Well it depends what it is you want to test for. It is usually accepted that a decent quality polyprop cap will have a very low series resistance and will introduce only a very low amount of distortion too.
If you wanted to you could measure the distortion of your power amplifier when it's driving a test load, then add in the cap to the signal path and remeasure. If you've got a very good measurement system and a blameless style amplifier then you might be able to measure something. Douglas Self has a nice article in one of the Linear Audio publications about capacitor distortion. I don't have it to hand right now, but he basically found that good quality polyprop caps have distortion so low as to be negligible compared to other things within the system that could introduce distortion.
From my point of view the only thing you really need to test for is making sure that the cap is within spec and has the correct value. If it does then the only other thing you could do is measure the frequency responses of the individual drivers with the filter in place and check that they match up with what was predicted.
If the ESR of the cap is higher then it should be, or if you are using crap lytic caps, this is an area where things can be different. A caps resistance tends to zero as frequency increases and once it gets low enough if it has a high ESR this ESR could start to become dominant and screw up what the filter is actually supposed to do - I have had this happen when I bought a really shoddy NP lytic.
Providing though that the measured filter is doing exactly what you predicted it would, then you don't have a problem. A high ESR will show up as frequency response aberrations, mainly as a small reduction in the SPL and a change that will be most apparent where the filter is the most effective. This obviously tends to be far worse on things like notch filters, which often require being tuned with very good accuracy because they get rid of problems either within the passband or help to shape the transition band, which is crucial for good driver integration.
Even basic polyprop caps tend to have ESRs that measure only in the 10s of milliohms, which is hardly a cause for concern given the application.
So you have a sounds good measurement , do tell .....
Sorry to see so little mention of the Jantzen Cross Caps. In my purely subjective listening tests I liked them a lot. They are very affordable, too. It's mainly what I use now. To my ear they are better than a lot of much more expensive caps.
Also North Creek are nice, as are the Obbligato from Hong Kong. I've been known to toss a metal can motor run cap from the local HVAC shop into the mix as well.
Havac oil cans ,
I have a few , thinking of giving them a run , never tried the jantzen , in the Past we got caps from MIT, Solen and hoveland..
I never place xover in bass cabinet , I usually measure for it , xover layout and isolation is very important ...
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Yeah, but I wonder if it could modulate the signal? Just asking. Some folks have reported the problem. Guess it's easy enough to test for.
A few years back a buddy ran some caps thru 20Hz-20Khz sweeps on a computerized LCR meter. I was cool to see how different cap types reacted at different frequencies. Electrolytic was worst, Teflon best (most linear). Big difference in size and price, tho.
Xover layout is only necessary so far as to make sure that the inductors don't interfere with one another and the loudspeakers magnet. But isolation for the capacitors is not in any way necessary, unless they are in some way faulty. I would also expect any loose windings from the inductor to be far more of a concern.
Of course it will but at such a low level as to be negligible.
If I were in better health at the moment I'd strap a cap to the cone of a woofer and wire it up to drive a loudspeaker, connect the oscilloscope across the cap and shake the crap out of it and see what happens. It would be interesting to see just how much/little happens.
First you should define which measure and which instruments (with an 8 bit DSO you can hardly see any difference...).
Second it should be scientifically defined the perception threshold.
Google 'Kunchur' and give a read to Prof. Kunchur research (real science and not technicians' dogmas).
You have a very romantic, but false, vision of the industry.
Big companies want to make big money.
'Lot of people' in the audio world are very small numbers for them.
Very scientific...
Similar to the approach of people that judjed Galileo...
Not so simple... you're overlooking a lot of things, DA for instance... and also considering them there's more.
Take three very good quality film/foil industrial caps from reputable manifacturers:
Wima FKP2
Vishay/Ero KP1830
Evox-Rifa PFR5
They're all polypropilene/aluminum foil caps, in practice the best you can buy from current production.
Wima and ERO have indentical declared measures, PFR quite worse:
FKP2 (DF 0,0003, DA 0.05%)
KP1830 (DF 0,0003, DA 0.05%)
PFR5 (DF 0,04, DA n/a)
Well, socket a position in a filter and swap among them, they all have a very different sound signature (both in timbre and soundstage), if you can't hear that you're deaf.
BTW I'm sure that with the right (and sadly too costly for every hobbist) instruments and well defined tests those difference are measurable.
Well as far as I am aware microphonic effects happen in a cap because the layers of the foil get compressed and this generates a voltage, much the same as how an electret micophone works. One could argue that if the entire cap is shaken and all the layers move in unison then nothing will happen.
You sound like you're sceptical, 5th element.
If I was to devise a test circuit for microphonics, it would probably look like the below with a tweeter.
No idea if it would actually pick up anything. Haven't tried it. But you need to polarise a capacitor for it to behave like a microphone.
Edit. Thinking about it, I'm not quite sure if an 8 ohm series resistor on the test capacitor might not be a good thing too.
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Ringing in caps are not from outside mechanical forces alone , voltage and resonant frequency, when measureing i usually do transfer function sweeps, 29-40k look for ringing at different voltage levels ....
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