Is there any sonic downside when combining close value caps to hit a target value?
Specifically, if I combine "higher subjective quality" PP film Caps i.e. 4-15uF plus 2-18u to hit 96uF are there any negative effects of using the two different values?...
I could also use 2 lower level 47uf to get close as well but prefer the subjectively "higher end" caps..
Appreciate comments...Thanks
Specifically, if I combine "higher subjective quality" PP film Caps i.e. 4-15uF plus 2-18u to hit 96uF are there any negative effects of using the two different values?...
I could also use 2 lower level 47uf to get close as well but prefer the subjectively "higher end" caps..
Appreciate comments...Thanks
No issues with doing it that way. I would try to use different values to obtain target value in a HP series application just to avoid capacitor related anomalies (stray losses, resonances and inductance) from adding up in one frequency area. This is really more of an OCD thing for me because there is no reliable way of measuring or hearing this scenario of differences between combined values. I wouldn't think twice combining any like values in a LP or parallel circuit.
Will these be mounted on a PCB, or hard-wired?
It can be difficult to properly connect so many leads to the same circuit nodes.
It can be difficult to properly connect so many leads to the same circuit nodes.
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Hardwired - plenty of room in external crossover box
All hardwired...
I am sure all this is probably a non issue but I also wonder if using
6 - 15F or 5 - 18uF plus a 5uF would be an even better choice?? I have plenty of room...I wish copper film/foil was an option but cost and availability in these sizes is a problem.
Leaning towards Jantzen Superior Zs in the mid ribbon crossover..Replacing a series (75uF + 20uF) Dayton combo that combine for 95uF...
Thanks to all for your thoughts...
All hardwired...
I am sure all this is probably a non issue but I also wonder if using
6 - 15F or 5 - 18uF plus a 5uF would be an even better choice?? I have plenty of room...I wish copper film/foil was an option but cost and availability in these sizes is a problem.
Leaning towards Jantzen Superior Zs in the mid ribbon crossover..Replacing a series (75uF + 20uF) Dayton combo that combine for 95uF...
Thanks to all for your thoughts...
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@ rayme - cost only an issue for copper foil caps and then they are the size of coke cans..Not practical
If you are trying to accurately achieve a specific capacitance, I would recommend to buy a capacitance meter. Many caps have a tolerance of at least 5%.
1. Nobody serious about sound quality would use a passive crossover without considering a bi-amped alternative and dialing-in the XO freq and slopes during iterative testing.
2. My impression is that in today's SOTA thinking even electrolytic caps are indistinguishable from rip-off priced caps. For sure, any ordinary big value film caps (I bought a bunch of 20uF at a local surplus store for $6 each two weeks ago) are as good as you can go.
3. I was surprised how matched were my bunch. But ordinarily, you'd always want to have at least three in your hand to pick the best matched two. Prolly testing in-situ with REW (electric output not acoustic) better than an even an expensive LCD meter.
B.
2. My impression is that in today's SOTA thinking even electrolytic caps are indistinguishable from rip-off priced caps. For sure, any ordinary big value film caps (I bought a bunch of 20uF at a local surplus store for $6 each two weeks ago) are as good as you can go.
3. I was surprised how matched were my bunch. But ordinarily, you'd always want to have at least three in your hand to pick the best matched two. Prolly testing in-situ with REW (electric output not acoustic) better than an even an expensive LCD meter.
B.
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Really? Nothing wrong with well-designed and implemented active systems but you imply that people for whom biamplification & active filters are impractical for various reasons are excluded from being 'serious about sound quality'. Which is certainly not true.
No fan of over-priced components I, but that's a bit of a blanket statement re electrolytic capacitors, since many have significant ESR that should be incorporated into a competent filter design; remove it (e.g. by substituting many film cap types of equivalent value) and you'll risk throwing out the transfer functions unless you add the relevant resistance back into the circuit. This is often an issue when refurbishing older speakers.
Right; a lot of film caps, especially those produced in bulk, tend to be of very close tolerances. The Wima etc. types I've measured have been ridiculous -way tighter than the nominal QC / QA rating, and often less than 1% deviation.
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"biamplification & active filters are impractical for various reasons are excluded from being 'serious about sound quality'."
We each choose what corners to cut, of course. Sorry if I seemed too elitist.
But passive XO are 100 years old and (despite manufacturers of turn-key speakers making kluges with 18-elements) really have outlived their usefulness in a world where quality DSP and Class D amps are inexpensive for the DIY crowd.
The theory of passive XO is an over-simplified model of how drivers and rooms work. No way to predict the final settings in your room with your ears - yet that is what you are "buying" when you do the XO math and fixed component values follow.
We each choose what corners to cut, of course. Sorry if I seemed too elitist.
But passive XO are 100 years old and (despite manufacturers of turn-key speakers making kluges with 18-elements) really have outlived their usefulness in a world where quality DSP and Class D amps are inexpensive for the DIY crowd.
The theory of passive XO is an over-simplified model of how drivers and rooms work. No way to predict the final settings in your room with your ears - yet that is what you are "buying" when you do the XO math and fixed component values follow.
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Not elitist -just wrong. 😉
The OP is not asking about active filters and DSP, so this does not seem an appropriate place to open that particular long-standing debate up yet again. However, briefly:
-Passive electrical filters are relatively old, but age is neither here nor there. 'Kludges with 18 elements' would imply incompetency in design and / or implementation. No doubt loudspeakers exist that have 18 elements or more in a passive filter, but produce poor results due to weaknesses in design, or being set up in a sub-optimal acoustic. That does not automatically mean all such designs / implementations fall into said category though. Just that some do. In the same vein, the fact that inexpensive DSP and class D amplifiers exist does not mean people who wish to use something else are cretins: just that they have a different set of priorities. I could point to quite a few rather poor inexpensive active filters / DSP and class D amplifiers (in the same way there are poor examples of pretty much everything), so before we run away with assumed universal superiority, a little perspective & consideration for context is usually beneficial, as opposed to blanket assumptions.
-The 'theory of passive XO' is not based on a simplified model of how drive units and rooms work. There is no singular 'theory of passive XO' per se in any case. When designing any type of filter, you use (or should use) data. If a designer uses insufficient data, then that's their lookout / 'error'. An active filter does not predict in advance room modes or acoustics etc. any more than a passive filter does. You obtain those via measurement, and then use what measurements you have taken to develop your filter design, whichever approach you wish to take.
Active filters have several advantages, flexibility, and especially rapid flexibility being one of them, and I doubt anybody would disagree with that. However, we should not assume this automatically means alternatives are invalid or necessarily inferior either, because that simply isn't the case.
The OP is not asking about active filters and DSP, so this does not seem an appropriate place to open that particular long-standing debate up yet again. However, briefly:
-Passive electrical filters are relatively old, but age is neither here nor there. 'Kludges with 18 elements' would imply incompetency in design and / or implementation. No doubt loudspeakers exist that have 18 elements or more in a passive filter, but produce poor results due to weaknesses in design, or being set up in a sub-optimal acoustic. That does not automatically mean all such designs / implementations fall into said category though. Just that some do. In the same vein, the fact that inexpensive DSP and class D amplifiers exist does not mean people who wish to use something else are cretins: just that they have a different set of priorities. I could point to quite a few rather poor inexpensive active filters / DSP and class D amplifiers (in the same way there are poor examples of pretty much everything), so before we run away with assumed universal superiority, a little perspective & consideration for context is usually beneficial, as opposed to blanket assumptions.
-The 'theory of passive XO' is not based on a simplified model of how drive units and rooms work. There is no singular 'theory of passive XO' per se in any case. When designing any type of filter, you use (or should use) data. If a designer uses insufficient data, then that's their lookout / 'error'. An active filter does not predict in advance room modes or acoustics etc. any more than a passive filter does. You obtain those via measurement, and then use what measurements you have taken to develop your filter design, whichever approach you wish to take.
Active filters have several advantages, flexibility, and especially rapid flexibility being one of them, and I doubt anybody would disagree with that. However, we should not assume this automatically means alternatives are invalid or necessarily inferior either, because that simply isn't the case.
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OP is considering spending a lot of money on rip-off caps when (1) I point out prolly a waste of money for such caps and (2) better alternatives.
The XO of the rightly treasured BBC LS3/5a had 18 elements. Looks to me like the twilight of that technology... some time ago.
All models are simplifications. Duh. As far as I know, there are no XO sims that account for direction index or room acoustics or even the most basic information from the Spinorama or even the way the parameters of drivers (some of which are in the T/S/Olson model shift about over short and long time-frames and with frequency, age, weather, and wear.
Systems with DSP allow for immediately shifting and sorting of a whole bunch of sound parameters as you get used to the sound. XO allows for slow-motion shifting and sorting too but you need a soldering iron to do it.
Don't believe I previously used your word "cretins". But I wonder if I am beyond temptation?
B.
The XO of the rightly treasured BBC LS3/5a had 18 elements. Looks to me like the twilight of that technology... some time ago.
All models are simplifications. Duh. As far as I know, there are no XO sims that account for direction index or room acoustics or even the most basic information from the Spinorama or even the way the parameters of drivers (some of which are in the T/S/Olson model shift about over short and long time-frames and with frequency, age, weather, and wear.
Systems with DSP allow for immediately shifting and sorting of a whole bunch of sound parameters as you get used to the sound. XO allows for slow-motion shifting and sorting too but you need a soldering iron to do it.
Don't believe I previously used your word "cretins". But I wonder if I am beyond temptation?
B.
So in one post you are implying a filter with 18 elements is a 'kludge' and in the next you mention the 'rightly treasured' LS3/5a has precisely that number of components. Which makes for a bit of a contradiction. The LS3/5a is indeed rightly treasured by many, since it remains excellent for its intended purpose, though technically speaking not great for anything else -which is fair enough because anything else isn't what it was designed for.
It doesn't matter what you think about expensive caps. Or what I think about them for that matter. The OP asked a question about those, not active filters and DSP. Presumably if he was interested in that, he would have asked about it.
You seem to be implying that the only valid crossovers are active types, and derived purely from empirical listening, which, human hearing and brains being what they are, is not exactly a good way to go about designing a filter if fidelity to the source is the goal. If you wish to (yet again) discuss this view I suggest you open a dedicated thread, since it is irrelevant to the purpose of this one.
Nobody said you used the word 'cretins'. If I had, I would have inserted it into quotation marks (a habit of mine when quoting people). However, you certainly give the impression that you regard anybody who doesn't blindly accept your rather questionable assertions as idiots. While that may not be your intention, it unfortunately reads rather in that way to some other people.
It doesn't matter what you think about expensive caps. Or what I think about them for that matter. The OP asked a question about those, not active filters and DSP. Presumably if he was interested in that, he would have asked about it.
You seem to be implying that the only valid crossovers are active types, and derived purely from empirical listening, which, human hearing and brains being what they are, is not exactly a good way to go about designing a filter if fidelity to the source is the goal. If you wish to (yet again) discuss this view I suggest you open a dedicated thread, since it is irrelevant to the purpose of this one.
Nobody said you used the word 'cretins'. If I had, I would have inserted it into quotation marks (a habit of mine when quoting people). However, you certainly give the impression that you regard anybody who doesn't blindly accept your rather questionable assertions as idiots. While that may not be your intention, it unfortunately reads rather in that way to some other people.
For the OP, a couple of thoughts:
-Some take the view that, if you build a total capacitance value out of several paralleled caps, you will need at least 1/3 and preferably 1/2 the total to be made up of the preferred cap type. Note I'm not expressing an opinion myself on the matter, just noting that is one take that some have, and seem to be happy with.
-A potentially cheaper approach, if you want to do something with capacitors, is to charge-couple some quality, but not necessarily expensive film types. JBL have done this in their top models for years, and there is at least a degree of engineering sense behind this. I've tried it a couple of times & it does seem to have an effect, although YMMV very much applies.
-Some take the view that, if you build a total capacitance value out of several paralleled caps, you will need at least 1/3 and preferably 1/2 the total to be made up of the preferred cap type. Note I'm not expressing an opinion myself on the matter, just noting that is one take that some have, and seem to be happy with.
-A potentially cheaper approach, if you want to do something with capacitors, is to charge-couple some quality, but not necessarily expensive film types. JBL have done this in their top models for years, and there is at least a degree of engineering sense behind this. I've tried it a couple of times & it does seem to have an effect, although YMMV very much applies.