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Old 21st October 2014, 02:53 PM   #1
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Default Multiway speaker crossover capacitors - differences

Hi!

I'm on the verge of building my very first multiway (3-way to be exact).

I have the option of using two different types of capacitors in the crossover of the loudspeaker and I am on the fence about which ones to use.
The other ones are roughly 50% cheaper and are 400v and the pricier ones are 800v. Same manufacturer.
I won't say brand names because when it comes to quantifiable differences between electrical components I think it doesn't matter who actually made the product (correct me if I am wrong in assuming this).

I have tried to read about the sonic differences between capacitors but that has just made this decision making process much more difficult. In addition to a headache.

There seems to be no conclusive study on the matter. No "real" testing done to actually determine once and for all if there really is a difference.

I have read various tests between different capacitors being used in crossovers but none that would actually eliminate the reviewers bias.

So here I am. I am almost 64-83% sure I will use the cheaper ones because of the hefty price difference but I will reconsider, maybe save a while and go for the pricier capacitors if I am convinced to go the for the "better" capacitors.

...

After the intro. The questions.

1. Will it make a difference in the "sound" of the finished speaker if I use a 250v, 400v or 800v etc. capacitor in the crossover of the speaker ?

1.1 How would you describe the differences? In the tone, does the tweeter sound more pronounced or something you just can't quite put your ear on.

2. If indeed it does make a difference, does it matter do you use it with the tweeter, mid or bass-section of the crossover?

3. Can it really matter who makes the capacitors? There are about (exaggerating for the sake of the story ) as many manufacturers as there are people who argue about the sonic differences of capacitors.

3.1. Assuming the answers to question 1 is "yes". Who makes the "best" capacitors?


---

That's about it.

I realize this topic has been covered to some extent before, even on these forums, but I just want to raise this question one more time because this topic still needs to be discussed... I think


I am a novice to much of this stuff so please don't be take it the wrong way if I completely miss the mark on some things or the questions don't quite make sense. I am still learning. Constructive criticism is always welcomed.

Thanks in advance.

KM
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Old 21st October 2014, 04:07 PM   #2
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Quote:
I won't say brand names because when it comes to quantifiable differences between electrical components I think it doesn't matter who actually made the product (correct me if I am wrong in assuming this).
It can do -depends on type / materials & the tolerances to which they're made (more of which in a minute). Not all are created equal unfortunately.


Quote:
1. Will it make a difference in the "sound" of the finished speaker if I use a 250v, 400v or 800v etc. capacitor in the crossover of the speaker ?
Possibly, possibly not. Again, this rather depends on the type of cap and tolerances to which they're made. If voltage rating is the only difference, then probably not -thing is, it likely isn't the only difference.


Quote:
1.1 How would you describe the differences? In the tone, does the tweeter sound more pronounced or something you just can't quite put your ear on.
I wouldn't. Subjective assessments have their place (or can do) but language being what it is, what I mean by a phrase isn't necessarily what others mean. What I can say is that if you take, say, a tweeter cap, and have a significant difference in value due to +/- 10% production tolerances, the filter behaviour will change, and this may become audible. For the rest? Well, some are great believers in the sound of capacitors, some are not. I'm partly on the fence -in general, I believe that quality circuit design and tight component tolerances are more significant once you hit a reasonable qualitative level. Beyond that -supercaps, or variations with bypass caps, film & foils etc. may (may) make a difference, but I rather doubt this is ever night & day, and will be circumstance dependent, not least in terms of the drivers, circuit design and the quality of the source material, components & amplification. A ClarityCap MR / Mundorf Supreme Silver-Oil for example aren't going to turn a rubbish driver into a Scan Speak Revelator, or compensate for a poor circuit design.


Quote:
2. If indeed it does make a difference, does it matter do you use it with the tweeter, mid or bass-section of the crossover?
If you want to use an expensive / supercap, the series cap on the tweeter (& midrange in 3 - 4 way designs) is the place I'd look at first. If they're going to make an improvement, that's where you're most likely to get some benefit from them.


Quote:
3. Can it really matter who makes the capacitors? There are about (exaggerating for the sake of the story ) as many manufacturers as there are people who argue about the sonic differences of capacitors.
With major qualifications, yes. See above. Look for the tolerances & get them as tight as possible. If it's a wide tolerance, then unless you are able to have them matched, they're not worth it because there is a chance your filter design will get screwed up.


Quote:
3.1. Assuming the answers to question 1 is "yes". Who makes the "best" capacitors?
No such thing as 'best'. Use what you can afford, to the closest tolerances you can get (usually stated). Beyond that, YMMV.
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Last edited by Scottmoose; 21st October 2014 at 04:13 PM.
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Old 21st October 2014, 04:26 PM   #3
system7 is offline system7  United Kingdom
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If there was any significant difference between grades of audio polypropylene capacitors, some one would have found it.

Filter component tolerances only affect the speaker at the -6dB crossover point. I can think of some crossover null methods that would reveal any level difference quite accurately.

MKT (polyester) capacitors have measureable problems. But MKP (polypropylene) do not. A 250V rating is not only cheaper and smaller, but has huge voltage margin. I see no reason to use mains power supply grade (630-800V) capacitors.

Ferrite coils are far more imperfect non-linear components and air-cored might work better. The only issue with wirewound resistors is to make sure they don't get too hot and change value, so the higher ratings are better. Inductance is insignificant.
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Old 21st October 2014, 04:58 PM   #4
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Originally Posted by system7 View Post
If there was any significant difference between grades of audio polypropylene capacitors, some one would have found it.
Quite. Still, many feel they have heard differences, so YMMV on that score. I'm happy on my fence. It's comfortable here.


Quote:
Filter component tolerances only affect the speaker at the -6dB crossover point. I can think of some crossover null methods that would reveal any level difference quite accurately.
Just so, but differences really should be minimised as far as possible and since this can be achieved for minimal additional effort / expenditure, there's no reason not to. I'd rather have, say, my series tweeter caps matched to within a 2% tolerance than something that was anointed by Chachapoyan virgins but exhibits a 20% difference. Especially in higher order filters.


Quote:
MKT (polyester) capacitors have measureable problems. But MKP (polypropylene) do not. A 250V rating is not only cheaper and smaller, but has huge voltage margin. I see no reason to use mains power supply grade (630-800V) capacitors.
Assuming they're well made & closely matched, should do fine.

Agreed re problems on MKTs (& electrolytics for that matter. Probably more the latter). That said, they can get an excessive kicking -while a decent MKP or film+foil should beat them, they're not automatically the catastrophe they're often made out to be. Even Troels had his doubts: SEAS-W11CY001

Quote:
Ferrite coils are far more imperfect non-linear components and air-cored might work better.
With minor caveats, seconded. In general I've found a high quality cored inductor to be fine for most LF duties (assuming you don't near core saturation), while saving a whole lot of money & space. Air-cores all the way for midrange & tweeter circuits though.
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Last edited by Scottmoose; 21st October 2014 at 05:06 PM.
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Old 21st October 2014, 07:22 PM   #5
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The OP didn't mention HHMHF cap evaluations by Tony Gee. So, don't know if he's aware of them.
Here is a link to a 4 yr old .pdf paper (>3000 downloads) that discussed Tony's subjective cap scores and their somewhat significant positive correlation with caps VDC ratings.

Capacitor voltage rating vs performance - The Kitchen - The Classic Speaker Pages Discussion Forums
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Old 22nd October 2014, 01:09 PM   #6
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Originally Posted by speakerdoctor View Post
The OP didn't mention HHMHF cap evaluations by Tony Gee. So, don't know if he's aware of them.
Here is a link to a 4 yr old .pdf paper (>3000 downloads) that discussed Tony's subjective cap scores and their somewhat significant positive correlation with caps VDC ratings.

Capacitor voltage rating vs performance - The Kitchen - The Classic Speaker Pages Discussion Forums
I have infact read both. The HHMHF reviews and the paper that you are reffering to.
These were the starting point for my quest in finding the proper capacitors for this project. I had to look more closely on the subject matter simply because of the huge price difference of different types of capacitors. I could not use the capacitors that the designer had initially used because they simply were out of my price range.
That lead to the question that was there a difference to be had using so called super caps instead of the cheaper regular capacitors(which are still quite expensive).

To scottmoose.
The tolerance of the ones that I am most likely to order is between 3-5% and the super caps are between 2-3%. According to the manufacturer.
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Old 22nd October 2014, 01:17 PM   #7
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Quote:
Originally Posted by system7 View Post
If there was any significant difference between grades of audio polypropylene capacitors, some one would have found it.

Filter component tolerances only affect the speaker at the -6dB crossover point. I can think of some crossover null methods that would reveal any level difference quite accurately.

MKT (polyester) capacitors have measureable problems. But MKP (polypropylene) do not. A 250V rating is not only cheaper and smaller, but has huge voltage margin. I see no reason to use mains power supply grade (630-800V) capacitors.

Ferrite coils are far more imperfect non-linear components and air-cored might work better. The only issue with wirewound resistors is to make sure they don't get too hot and change value, so the higher ratings are better. Inductance is insignificant.
Thank you for the input.

Both the super caps and the regular ones are MKP (polypropylene).
They are rated for 400vdc (regular) and 800vdc (super).

Can I ask what do you mean by mains power supply grade ? The manufacturer specifically advertises, not just this one but a whole heap of other capacitor manufacturers, that these are so called audio grade capacitors?

Again, thanks for the input and the patience. Everyday is a school day.
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Old 22nd October 2014, 02:16 PM   #8
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Quote:
That lead to the question that was there a difference to be had using so called super caps instead of the cheaper regular capacitors(which are still quite expensive).
Possibly. However, if any do exist then you will almost certainly require a very high resolution system for them to become apparent. You haven't given any details of the speaker, drivers, amplifiers & source components / material, so only you can know on that score.


Quote:
To scottmoose.
The tolerance of the ones that I am most likely to order is between 3-5% and the super caps are between 2-3%. According to the manufacturer.
All probably fine (BTW, there's no real definition for 'supercap' -I just use it as a convenient handle for anything of about Mundorf Supreme price or higher).
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Old 22nd October 2014, 02:33 PM   #9
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IMHO, the OP should go with the 400V caps. IF there is any difference, it will be very small and thus, not justified by the significant added expense.
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Old 22nd October 2014, 03:15 PM   #10
TMM is offline TMM  Australia
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Originally Posted by Gabriel83 View Post
Can I ask what do you mean by mains power supply grade ?
Caps used for mains voltage filtering/suppression and lighting applications.

Lighting capacitors are usually metalized polypropylene due to the high current requirements. 10uF+ 250V caps are common. The only real disadvantage is that they usually have bulky plastic casings, intended to be bolted to a metal chassis by an electrician. Sometimes the metalized slug can rattle inside the plastic housing but it's usually not hard to just pop the housing open and drop some glue in there.

Then there are EMI/RFI Suppression Caps, used to filter the mains supply going into equipment. These have different safety grades (X1/X2, Y1/Y2), as they are designed to fail in a way that would not endanger the user (e.g. cause the metal casing of some equipment to become live). While the safety grades are irrelevant for audio use, if you buy an X/Y cap you know it's a polypropylene, 250V+ rated. Mostly small values available (e.g. 0.1uF).

Both types make a good source of cheap polypropylene caps due to supply and demand.

Sonically there is absolutely no difference between PP mains caps and PP 'audio-grade' caps. Almost any PP cap is virtually an ideal cap when used in an audio application. Even comparing other inferior capacitor constructions (e.g. Electrolytic) the only audible difference you will find in practice is associated with excessive ESR. This can alter the transfer function of a crossover. The typical scenario is someone has some very old and tired electrolytic caps with astronomical ESR in their crossover. They replace the old caps with new "Ultra-super-audiophile-grade Polypropylene" capacitors and their tweeter suddenly gains 5dB as their old cap had an ESR of 10ohm while the new one is 0.01ohm. They perceive the increased tweeter output as 'extra detail' or whatever and go around claiming that Ultra-super-audiophile-grade capacitors are the only choice for a speaker crossover and electrolytics are crap. They could have replaced it with a new electrolytic, ESR=0.05ohm and perceived the same increase in 'detail'.

Unless you are using caps that are completely unsuitable for a speaker crossover (e.g. multi-layer ceramic caps), capacitors don't distort appreciably unless you push them very hard. Hard enough that the distortion would be buried by the distortion caused by the speaker drivers.

In a lot of cases (usually, tweeter HPFs), an electrolytic capacitor is absolutely fine. The ESR is usually low enough that there is no audible change in the transfer function and current requirements are lower so it will last a long time. Usually it's the woofer crossover where you need film caps as the current requirements exceed what electrolytics can handle. Another case where a film cap would be beneficial over an electrolytic is where thermal stability is required. I.e. a notch filter or a conjugate impedance network. PET/polyester is a good middle ground between electrolytics and PP.

Last edited by TMM; 22nd October 2014 at 03:42 PM.
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