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What would happen if I rewired my speakers with a larger capacitor?
almostmitch
post Mar 16 2013, 18:13
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So I came across these old speakers and I was going to try to bring some life back into them by building new boxes and rewiring them.
I noticed there's a capacitor (as you can see in the images) and wondered what would happen if I swapped it with a larger one?
Could they just handle more power? Or would it cause the speakers to blow quicker?
Also, does anyone know any restoration tips for speakers that could maybe help boost performance?






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Porcus
post Mar 16 2013, 19:14
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You want a 3 μF cap. This figure controls the crossover frequency, and you do not want to change that. Edit: surely, crossover frequency also affects power handling, but I assumed that you do not want to hamper the frequency response.

The 30 V rating is how much the capacitor itself is supposed to handle. Should be enough. (Edit: it is serial.)

This post has been edited by Porcus: Mar 16 2013, 19:17


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almostmitch
post Mar 16 2013, 19:20
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Ah yes, shortly after I posted this I realized it had to do with the crossover. Would a place like Radio Shack have something like this?
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Porcus
post Mar 16 2013, 19:23
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They do have such component dot com, dunno about the stores. But ... eBay?


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Wombat
post Mar 16 2013, 19:33
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The 3µF electrolytic cap is a 6dB highpass in front of the tweeter. It prevents your tweeter playing back low frequencies. So if you talk about "larger" as value of the capacitance, highering it makes it playback more low frequencies.
To me this crossover doesn´t look like it was carefully measured and developed. I guess this cap is more or less only in for preventing to blow the tweeter.
You even may have better overall frequency response with some other value in there. You may try values like 2,2µF to 4,7µF. You can use MKT, MKP or other cheap film caps even because they are not exetly expensive.
Would be fun if you can get hold of any measuring equipment. A complete crossover with a value for the bass may make sense and can better the sound a lot.

This post has been edited by Wombat: Mar 16 2013, 19:36
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almostmitch
post Mar 16 2013, 19:58
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Yeah I know I could find it online I just didn't want to spend a lot of time on this so I wanted to see if anywhere would have it in store.

QUOTE (Wombat @ Mar 16 2013, 13:33) *
The 3µF electrolytic cap is a 6dB highpass in front of the tweeter. It prevents your tweeter playing back low frequencies. So if you talk about "larger" as value of the capacitance, highering it makes it playback more low frequencies.
To me this crossover doesn´t look like it was carefully measured and developed. I guess this cap is more or less only in for preventing to blow the tweeter.
You even may have better overall frequency response with some other value in there. You may try values like 2,2µF to 4,7µF. You can use MKT, MKP or other cheap film caps even because they are not exetly expensive.
Would be fun if you can get hold of any measuring equipment. A complete crossover with a value for the bass may make sense and can better the sound a lot.


Could you tell me what kind of effects on the sound different values would have? In short, if you were me and were going to replace these would you stick something different in or just find an exact replacement?
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Wombat
post Mar 16 2013, 20:10
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QUOTE (almostmitch @ Mar 16 2013, 20:58) *
Could you tell me what kind of effects on the sound different values would have? In short, if you were me and were going to replace these would you stick something different in or just find an exact replacement?

It makes no sense to just replace the cap with a higher voltage cap. If under some circumstances this 30V limit is really reached i gues the tweeter is already blown.
My guess is that the sound changes only minimal with different caps becaus such bass chassis as you seem to have there already add much non-linearity in the mid-bands, lets say 500Hz-5000Hz. Mostly boosts there. Some coil in series can tame that. Since we don´t have any data or measuremnts this is all pretty speculative.

If you use lower values like 2,2µf it may simply make your tweeter play back less music content that is in the mid-high area. This is often the area that makes the decision about a speaker sounding scratchy (to much mid-highs) or soft.

This post has been edited by Wombat: Mar 16 2013, 20:10
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Apesbrain
post Mar 16 2013, 20:26
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Not to be a dick, but unless they have sentimental value why bother with this? By the time you've bought materials and invested your time, you'd be better off spending $40 on a pair of these > (Brief review).
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Soap
post Mar 16 2013, 21:03
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Also not to be a dick, but the best possible outcome is if you succeed in making what appears to be a low-end set of speakers sound identical to when new. Without far more information at your disposal than you've passed along so far you can do no better than perfectly reproducing the volume and port specs of the original enclosure.


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Jens Rex
post Mar 16 2013, 21:43
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Not to be a dick, but refurbishing old hardware is a fun, satisfying and learning experience.
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almostmitch
post Mar 17 2013, 03:42
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QUOTE (Wombat @ Mar 16 2013, 14:10) *
QUOTE (almostmitch @ Mar 16 2013, 20:58) *
Could you tell me what kind of effects on the sound different values would have? In short, if you were me and were going to replace these would you stick something different in or just find an exact replacement?

It makes no sense to just replace the cap with a higher voltage cap. If under some circumstances this 30V limit is really reached i gues the tweeter is already blown.
My guess is that the sound changes only minimal with different caps becaus such bass chassis as you seem to have there already add much non-linearity in the mid-bands, lets say 500Hz-5000Hz. Mostly boosts there. Some coil in series can tame that. Since we don´t have any data or measuremnts this is all pretty speculative.

If you use lower values like 2,2µf it may simply make your tweeter play back less music content that is in the mid-high area. This is often the area that makes the decision about a speaker sounding scratchy (to much mid-highs) or soft.


Ah thanks. I didn't exactly know what the different specs caused. In that case I will just replace it with an identical one.

QUOTE (Apesbrain @ Mar 16 2013, 14:26) *
Not to be a dick, but unless they have sentimental value why bother with this? By the time you've bought materials and invested your time, you'd be better off spending $40 on a pair of these > (Brief review).


I have plenty of all necessary materials. The speakers were free and I won't have to spend more than $5 for this project. After today, the project as a whole is nearly done as all I have to do is paint the boxes and and mount the speakers. I believe you thought I was going to spend a significant amount of either money or time on this, but that is not the case.

QUOTE (Soap @ Mar 16 2013, 15:03) *
Also not to be a dick, but the best possible outcome is if you succeed in making what appears to be a low-end set of speakers sound identical to when new. Without far more information at your disposal than you've passed along so far you can do no better than perfectly reproducing the volume and port specs of the original enclosure.


Which is what I decided to do. I realize these speakers are not of high quality. However, I hooked them up while in their original enclosures and they sounded good enough for me to take this small project on. In a days time I built custom enclosures for them that match the specs of the originals. I will be using these for less concentrated listening (parties, get togethers, etc.) in my dad's new man cave and they will look damn cool in these new boxes.

QUOTE (Jens Rex @ Mar 16 2013, 15:43) *
Not to be a dick, but refurbishing old hardware is a fun, satisfying and learning experience.


Thank you. It was all 3 of those today.
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DVDdoug
post Mar 17 2013, 04:02
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Make sure to get a non-polarized electrolytic capacitor. These are special for speakers. Standard electrolytic capacitors are polarized and they do not work with AC speaker-signals. There are other types of non-polarized capacitors, but they tend to be more expensive when you get over 1uF.

You might not want to wait before doing this project, but if you are thinking about doing something like this again, you might want to get a book on speaker building, so you can understand what you are doing. There are complex interactions between the woofer, box size, and port dimensions. If you get the speaker (driver) parameters, there is software for predicting bass performance. The general idea is to get bass that's smooth & deep, not boomy one-note bass, orwimpy bass (as much as possible with the drivers you have).

Again, you might not want to do anything advanced with this project, but if you want a full crossover (to keep the bass out of the tweeter, and the highs out of the bass, etc) you can either build or buy one. Here are some examples.
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db1989
post Mar 17 2013, 04:09
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QUOTE (Apesbrain @ Mar 16 2013, 19:26) *
Not to be a dick, but…
QUOTE (Soap @ Mar 16 2013, 20:03) *
Also not to be a dick, but…
QUOTE (Jens Rex @ Mar 16 2013, 20:43) *
Not to be a dick, but…



It neatly summarises many discussions that occur here and finally obliterates the grating lack of Cleartype on the subtitle. Gentlemen Ladies and gentlemen, be proud of what we have achieved today.

This post has been edited by db1989: Mar 17 2013, 13:51
Reason for edit: plz not to be taking away my feminist card
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almostmitch
post Mar 17 2013, 04:22
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QUOTE (DVDdoug @ Mar 16 2013, 22:02) *
Make sure to get a non-polarized electrolytic capacitor. These are special for speakers. Standard electrolytic capacitors are polarized and they do not work with AC speaker-signals. There are other types of non-polarized capacitors, but they tend to be more expensive when you get over 1uF.

You might not want to wait before doing this project, but if you are thinking about doing something like this again, you might want to get a book on speaker building, so you can understand what you are doing. There are complex interactions between the woofer, box size, and port dimensions. If you get the speaker (driver) parameters, there is software for predicting bass performance. The general idea is to get bass that's smooth & deep, not boomy one-note bass, orwimpy bass (as much as possible with the drivers you have).

Again, you might not want to do anything advanced with this project, but if you want a full crossover (to keep the bass out of the tweeter, and the highs out of the bass, etc) you can either build or buy one. Here are some examples.


Thanks Doug, good to know. I had just started looking for a replacement capacitor but I wasn't even seeing any that were 3uf 30v, or even close to that. I wonder if I should just leave the old one in. But yes, I'm all too familiar with enclosures and their effect on bass. This is why I decided to just match the specs of the original enclosure. As for crossovers, the only reason I would want to add one is if I build it myself, and I wasn't really planning on spending much time on this. Could you tell me if you've ever built one how how easy it was? Also, how cheap could I get it done? Lastly, would the benefits in sound be worth the extra work to install a crossover in this case? My hunch is no, but you probably know something I don't.
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DVDdoug
post Mar 17 2013, 07:01
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QUOTE
I wasn't even seeing any that were 3uf 30v, or even close to that.
Electrolytic capacitors can age a bit. I think the value (uF) drops when they age, but it's probably still OK. If the capacitor was "dead", you wouldn't hear any sound from the tweeter. Here is a 3.3 uF capacitor. That should be close enough. These things usually have a 10 or 20% tolerance anyway... A high-end crossover would use 1% or 3% film capacitors, but 10% - 20% tolerance is common in the "average" crossover. As someone else said, the voltage rating is just the maximum rating for the part. 30V or more is fine for a replacement part.

QUOTE
As for crossovers, the only reason I would want to add one is if I build it myself, and I wasn't really planning on spending much time on this. Could you tell me if you've ever built one how how easy it was?
Realistically, upgrading the crossover is probably not worth it. I assume that these are cheap drivers and a "better" crossover may not improve the sound. For the price of a crossover, you could upgrade to better tweeters, and that would probably make a bigger difference in sound. And, I'm not recommending that either... We don't know anything about the sensitivity of the current woofer or tweeter, and a differnet tweeter might put-out too much or too-little sound relative to the woofer...

I've actually never built a crossover. I've built several speaker systems, and I've built a lot of electronics stuff too, but I've always just purchased the crossover. The simplest crossover is one capacitor and one inductor (coil) for a 2-way system. That's easy to "build" since you just have to wire the parts in series with the drivers. Probably the most common type is a 2nd-order crossover with a capacitor and an inductor for each driver. That's not too hard to build either, if you know how to solder. You have to mount the components to something... You can use a perfboard, but if you want to make it "nice" you need a printed circuit board. By the time you've paid for a blank circuit board, you aren't saving much money by building it yourself.
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Porcus
post Mar 17 2013, 11:27
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QUOTE (db1989 @ Mar 17 2013, 04:09) *
Gentlemen,


Not to be a pussy, but I hope ladies are also welcome on those very same terms?


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db1989
post Mar 17 2013, 13:50
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Of course, and I somewhat regretted “Gentlemen” after making the post, but I didn’t want/was too lazy to edit, and I had assumed (bad move!) that all three of my fellow artistes were male. Sorry, ladies! Now I’ll make that edit. tongue.gif
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Apesbrain
post Mar 17 2013, 15:41
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QUOTE (db1989 @ Mar 16 2013, 23:09) *
Ladies and gentlemen, be proud of what we have achieved today.

Well, I didn't expect to laugh so hard this early in the morning. Thank you for that. (And, yes, I am proud, very proud.)
almostmitch, if you have a chance please post pictures of your completed project.
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db1989
post Mar 17 2013, 17:52
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QUOTE (Apesbrain @ Mar 17 2013, 14:41) *
Well, I didn't expect to laugh so hard this early in the morning. Thank you for that. (And, yes, I am proud, very proud.)
biggrin.gif I didn’t expect anyone to laugh, so thanks to you! tongue.gif

QUOTE
almostmitch, if you have a chance please post pictures of your completed project.
Agreed; it sounds like a fairly easy refurbishment that might be very rewarding. Do you think you’ll try different caps? I was interested to read about the potential effects, so it’d be even more interesting to read whether they have a (audible/measurable) effect upon frequency reproduction/crossover.
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almostmitch
post Mar 17 2013, 21:00
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QUOTE (DVDdoug @ Mar 17 2013, 01:01) *
Electrolytic capacitors can age a bit. I think the value (uF) drops when they age, but it's probably still OK. If the capacitor was "dead", you wouldn't hear any sound from the tweeter. Here is a 3.3 uF capacitor. That should be close enough. These things usually have a 10 or 20% tolerance anyway... A high-end crossover would use 1% or 3% film capacitors, but 10% - 20% tolerance is common in the "average" crossover. As someone else said, the voltage rating is just the maximum rating for the part. 30V or more is fine for a replacement part.

Realistically, upgrading the crossover is probably not worth it.

I've actually never built a crossover. I've built several speaker systems, and I've built a lot of electronics stuff too, but I've always just purchased the crossover. The simplest crossover is one capacitor and one inductor (coil) for a 2-way system. That's easy to "build" since you just have to wire the parts in series with the drivers. Probably the most common type is a 2nd-order crossover with a capacitor and an inductor for each driver. That's not too hard to build either, if you know how to solder. You have to mount the components to something... You can use a perfboard, but if you want to make it "nice" you need a printed circuit board. By the time you've paid for a blank circuit board, you aren't saving much money by building it yourself.


Thanks for this info, very helpful. I figured the capacitors have changed over time and the same exact specs of the original might not be the same specs as a suitable replacement. I think I will pass on the crossover for this project. I always set out to do things and end up spending more money than I planned laugh.gif However, I'm sure sometime not too far in the future I will build one because I do want to know how exactly they work and the science behind them.


QUOTE (Apesbrain @ Mar 17 2013, 09:41) *
QUOTE (db1989 @ Mar 16 2013, 23:09) *
Ladies and gentlemen, be proud of what we have achieved today.

Well, I didn't expect to laugh so hard this early in the morning. Thank you for that. (And, yes, I am proud, very proud.)
almostmitch, if you have a chance please post pictures of your completed project.


Yes, definitely. Pictures will follow in a few days most likely.

QUOTE (db1989 @ Mar 17 2013, 11:52) *
QUOTE (Apesbrain @ Mar 17 2013, 14:41) *
Well, I didn't expect to laugh so hard this early in the morning. Thank you for that. (And, yes, I am proud, very proud.)
biggrin.gif I didn’t expect anyone to laugh, so thanks to you! tongue.gif

QUOTE
almostmitch, if you have a chance please post pictures of your completed project.
Agreed; it sounds like a fairly easy refurbishment that might be very rewarding. Do you think you’ll try different caps? I was interested to read about the potential effects, so it’d be even more interesting to read whether they have a (audible/measurable) effect upon frequency reproduction/crossover.


I think I'm just going to stick to the closest match of the original. Although it's possible it won't be 3uf 30v like the original, so I will try to determine any effects if that's the case. This is definitely something I could come back to and experiment with later. Right now I just want to get these things finished and hear them! smile.gif
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almostmitch
post Mar 24 2013, 23:19
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So I've been slackin' a little, but they're done! Surprisingly good bass performance with these new cabinets.
I used 3/4'' medium density fiberboard so these things are pretty beefy. Inside edges have all been sealed with caulk and I used some basic terminals from Radio Shack on the back.
..and of course I had to throw in some style. I had the stickers and they gave me the idea for the theme.
The Hundreds is a clothing/lifestyle brand that I like, check them out ---> The Hundreds

As for the capacitors, I left them unchanged. No replacements were locally available and I didn't want to pay or wait for new ones. I definitely plan to look more into crossovers and building them in the future.



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