Quick, simple question about crossovers

[VolumetricSteve]

Today I took a two way crossover I found inside an M-Audio Studio Pro 3 monitor and after staring at the PCB layout for about an hour, I was able to construct a schematic diagram of what was on the board.

for the 4 ohm tweeter, there's a 22K Ohm resistor, a 0.1mH Coil, and a 50V 18uF Capacitor

for the 4 ohm woofer, there's a 10K Ohm resistor, a 0.25mH Coil, and a 50V 47uF Capacitor

I read somewhere that Coils do the job of muffling out high-range frequencies, and Capacitors do the job of filtering out low-range frequencies. Holding that in mind, what do resistors lend to the mix?

My diagram:
://i47.tinypic.com/sqibz4.jpg

you have to add html to the link because of a goofy forum regulation

Also, why are the outputs in such weird places? This diagram goes against a lot of what i've read about crossovers, and I'm certain it's correct, I've been looking at it all day.

But most importantly, why do all the simple two-way crossover diagrams just have coils and caps, and this has resistors...for what purpose?


cheers

 

[highfigh]

Today I took a two way crossover I found inside an M-Audio Studio Pro 3 monitor and after staring at the PCB layout for about an hour, I was able to construct a schematic diagram of what was on the board.

for the 4 ohm tweeter, there's a 22K Ohm resistor, a 0.1mH Coil, and a 50V 18uF Capacitor

for the 4 ohm woofer, there's a 10K Ohm resistor, a 0.25mH Coil, and a 50V 47uF Capacitor

I read somewhere that Coils do the job of muffling out high-range frequencies, and Capacitors do the job of filtering out low-range frequencies. Holding that in mind, what do resistors lend to the mix?

My diagram:
://i47.tinypic.com/sqibz4.jpg

you have to add html to the link because of a goofy forum regulation

Also, why are the outputs in such weird places? This diagram goes against a lot of what i've read about crossovers, and I'm certain it's correct, I've been looking at it all day.

But most importantly, why do all the simple two-way crossover diagrams just have coils and caps, and this has resistors...for what purpose?


cheers

You might want to check the resistor values- 22K Ohms will just about kill the sound completely if it's in series with the driver.

A single pole filter is a cap or coil in series and this attenuates the frequencies at 6dB/octave. A second pole can be added to increase the slope of the filter and this is placed after the first component, in parallel. If you look at a high pass filter, the cap will resist AC voltage below a certain point, gradually. A coil resists AC voltage above a certain point, also gradually. If you attenuate low frequencies with a cap and then add a coil, the coil dumps the signal it can pass to ground and performs its normal function above that range. This way, the low frequencies are attenuated at 12dB/octave before they get to the driver. I suspect the resistors are 1 Ohm and 2.2 Ohm and may serve to A) pad the tweeter level so it's more balanced with the output of the woofer and the 1 Ohm may be for keeping the impedance of the woofer above the point where it gives some amplifiers fits.

If the second pole has the resistor in series with it, it would be for tailoring the slope but it wouldn't such a high value as 10K (brown/black/orange) or 22K (red/red/orange).

 

[TLS Guy]

You might want to check the resistor values- 22K Ohms will just about kill the sound completely if it's in series with the driver.

A single pole filter is a cap or coil in series and this attenuates the frequencies at 6dB/octave. A second pole can be added to increase the slope of the filter and this is placed after the first component, in parallel. If you look at a high pass filter, the cap will resist AC voltage below a certain point, gradually. A coil resists AC voltage above a certain point, also gradually. If you attenuate low frequencies with a cap and then add a coil, the coil dumps the signal it can pass to ground and performs its normal function above that range. This way, the low frequencies are attenuated at 12dB/octave before they get to the driver. I suspect the resistors are 1 Ohm and 2.2 Ohm and may serve to A) pad the tweeter level so it's more balanced with the output of the woofer and the 1 Ohm may be for keeping the impedance of the woofer above the point where it gives some amplifiers fits.

If the second pole has the resistor in series with it, it would be for tailoring the slope but it wouldn't such a high value as 10K (brown/black/orange) or 22K (red/red/orange).

That circuit is not right and could not work. Here is a two way crossover with zobel and impedance compensation. The resistors in the high pass filter are are to match tweeter and woofer levels.

 

[highfigh]

That circuit is not right and could not work. Here is a two way crossover with zobel and impedance compensation. The resistors in the high pass filter are are to match tweeter and woofer levels.

I know but it was 5:30 and I didn't feel like going into too much detail.

 

[VolumetricSteve]

Thanks for the help, just knowing now that resistors are used to help level things out is fantastic.....I don't know why that's not written down in more places.

and TLS Guy, I don't know what to tell you, on the one hand, the circuit emulator I was working with sure made it look like the circuit wouldn't work...but I promise you...the schematic there matches what I'm holding in my hands, I'd go as far to post top and bottom views of the board I copied down so you could take a look if you want,on the other hand the amount of time I spent sitting there just looking at it, noting where every leg of every part contacted another, that diagram is the sum of a lot of double and triple checking. I agree with you that it in fact doesn't work, the diagram doesn't make sense to me either, something is clearly wrong but I have a hard time believing it's because I noted a connection incorrectly simply because of how many times I checked it.

However, I should also have noted that in the diagram the white dot between the 100mH coil and the 10K resistor is one of the analog inputs as well as the white dot that's connected to the 13KHz generator. I shouldn't have left the test generator in the schematic.

The resistors used were the 4-stripe kind. One was red red gold gold, the other was brown black gold gold. I googled around for charts showing the values of the stripes (it's been years since i've had to work with them) and the one I found....I thought...was telling me that the value of the should have been multiplied by 1,000 but looking back it only makes sense for that to be much much lower. Maybe 100x or 10x?

but now that I have a solid grip on how simple passive crossovers are made, I might just take the parts out of that board and put them in my own circuit board. Thanks for the input so far.

 

[highfigh]

Thanks for the help, just knowing now that resistors are used to help level things out is fantastic.....I don't know why that's not written down in more places.

and TLS Guy, I don't know what to tell you, on the one hand, the circuit emulator I was working with sure made it look like the circuit wouldn't work...but I promise you...the schematic there matches what I'm holding in my hands, I'd go as far to post top and bottom views of the board I copied down so you could take a look if you want,on the other hand the amount of time I spent sitting there just looking at it, noting where every leg of every part contacted another, that diagram is the sum of a lot of double and triple checking. I agree with you that it in fact doesn't work, the diagram doesn't make sense to me either, something is clearly wrong but I have a hard time believing it's because I noted a connection incorrectly simply because of how many times I checked it.

However, I should also have noted that in the diagram the white dot between the 100mH coil and the 10K resistor is one of the analog inputs as well as the white dot that's connected to the 13KHz generator. I shouldn't have left the test generator in the schematic.

The resistors used were the 4-stripe kind. One was red red gold gold, the other was brown black gold gold. I googled around for charts showing the values of the stripes (it's been years since i've had to work with them) and the one I found....I thought...was telling me that the value of the should have been multiplied by 1,000 but looking back it only makes sense for that to be much much lower. Maybe 100x or 10x?

but now that I have a solid grip on how simple passive crossovers are made, I might just take the parts out of that board and put them in my own circuit board. Thanks for the input so far.

Brown/black/gold/gold- 1/0/1/x.1, so that's 1, second digit 0 and multiplier of 1=10 x 1 x .1 with 5% tolerance and that comes to 1 Ohm.

Here's a chart:
http://ronja.twibright.com/grx/tech/resistor_codes.png

 

[VolumetricSteve]

well then, I feel kinda silly, thanks for the proper number. Do those new numbers make my schematic make any more sense?

I'm looking at the crossover now and....I can't get around it, heh, it must be...either everything I know about schematics is wrong.....or.....m-audio just built something completely insane.

I'll have pictures up later that show the top and bottom of the board just for funzies.

EDIT ****
funzies: same deal, add http back in to the url
://i48.tinypic.com/21e6iko.jpg

://i50.tinypic.com/2mrh1xk.jpg


forgot to mention that one picture is covered in colored dots to show which leads are in direct contact with each other. I know it's still not easy to tell what's where, but it's something.

the top view picture is meant to show which parts are working on the tweeter side or woofer side, Blue is the woofer, red is obviously the tweeter.

 

[highfigh]

well then, I feel kinda silly, thanks for the proper number. Do those new numbers make my schematic make any more sense?

I'm looking at the crossover now and....I can't get around it, heh, it must be...either everything I know about schematics is wrong.....or.....m-audio just built something completely insane.

I'll have pictures up later that show the top and bottom of the board just for funzies.

EDIT ****
funzies: same deal, add http back in to the url
://i48.tinypic.com/21e6iko.jpg

://i50.tinypic.com/2mrh1xk.jpg

forgot to mention that one picture is covered in colored dots to show which leads are in direct contact with each other. I know it's still not easy to tell what's where, but it's something.

the top view picture is meant to show which parts are working on the tweeter side or woofer side, Blue is the woofer, red is obviously the tweeter.

Look in the passive crossover section here:
http://www.the12volt.com/info/diagrams.asp

It should clear up a few things. A 12dB/octave filter will look like an L, where the coil or cap will be in series and the cap or coil will go from the other component's outlet to negative. The resistor will go in series after this if it's a simple design. Some filters are a lot more complex and may have other sections that perform specific functions.

 

[VolumetricSteve]

I found a wonderful calculator that showed me how to make a nice 3rd order butterworth crossover on another DIY site....and I mean, I get all of that and I see that the specific reason some parts are in place are to increase the slope of the attenuation, reduce noise, etc, and most likely I'll end up building a crossover to the 3rd order specs unless there's some reasons I shouldn't trust the results it gave me. However I'm still confused as to how the m-audio crossover worked, as simple as it is, and more over...when I put the stats for my m-audios into the calculator (4 ohm tweeter, 4 ohm woofer, 2.3KHz crossover) the ratings it gave me for the coils and caps were nothing like what are on the m-audio crossover, I tried everything on the list of calculations and nothing came up with 0.1mH, 0.25mH, 18uF, 47uF, 2.2O, 1O


what on earth did they do to build that crossover? (and I know those numbers are right because they're printed plainly on the parts part)



Also, when building my final crossover, should I use some 1Ohm and 2.2Ohm resistors for load balancing purposes? I get the feeling those were chosen specifically to conform to the power handling of the drivers in my cabinets; in other words, it is possible the resistors did something tangible in their crossover that I'd need to duplicate in my crossovers?


Thanks again for your time and help

 

[TLS Guy]

I found a wonderful calculator that showed me how to make a nice 3rd order butterworth crossover on another DIY site....and I mean, I get all of that and I see that the specific reason some parts are in place are to increase the slope of the attenuation, reduce noise, etc, and most likely I'll end up building a crossover to the 3rd order specs unless there's some reasons I shouldn't trust the results it gave me. However I'm still confused as to how the m-audio crossover worked, as simple as it is, and more over...when I put the stats for my m-audios into the calculator (4 ohm tweeter, 4 ohm woofer, 2.3KHz crossover) the ratings it gave me for the coils and caps were nothing like what are on the m-audio crossover, I tried everything on the list of calculations and nothing came up with 0.1mH, 0.25mH, 18uF, 47uF, 2.2O, 1O


what on earth did they do to build that crossover? (and I know those numbers are right because they're printed plainly on the parts part)



Also, when building my final crossover, should I use some 1Ohm and 2.2Ohm resistors for load balancing purposes? I get the feeling those were chosen specifically to conform to the power handling of the drivers in my cabinets; in other words, it is possible the resistors did something tangible in their crossover that I'd need to duplicate in my crossovers?


Thanks again for your time and help

I really don't think you know how to go about designing a crossover.

First you have to look at the acoustic responses of the drivers. Then you have to estimate where the best point for crossover is. You need to take into consideration woofer break up modes, and the Fs of the tweeter.

Now electrical orders and acoustic orders are additive. So if you have a tweeter that roll offs second order and you design a third order filter, then the composite roll off is fifth order. Now acoustic roll offs frequently change order, so your filter must as well. The composite slopes must be symmetrical either side of the crossover, or the speaker will sound dreadful. Very seldom due you need the same electrical slopes for tweeter and woofer.

Now you try when possible to have even order composite crossovers as the lobing pattern is better.

You have to look at the woofer impedance curve which rises with frequency. This often has to be equalized with a zobel so your low pass crossover can have the desired response.

Any break up modes have to be notched out with notch filters.

Then you have to level match, the tweeter. You can not pad a woofer, so your tweeter needs to be more sensitive than your woofer.

You need to accomplish all this with minimal violence to phase and time.

That is some of the basics, but crossover design is difficult and takes experience even though the circuits seem simple.

In fact it is so difficult that very few speakers are actually much good.

 

[Swerd]

Before you go any further with your work, you should take the time to read this link about common misconceptions in crossover design. It's about why using standard online crossover calculators (also known as a textbook filter calculators) can lead to poor crossovers.

I really don't like to dampen anyone's enthusiasm for DIY speaker building, but I think understanding this may explain why you are finding such a difference between your crossover and the calculated values you found with that online method.

 

[VolumetricSteve]

This is all very good to know, and that guide about misconceptions in crossover design was very helpful. I'd actually wondered about the second point he made. Unfortunately, I don't really have much of a way to determine the response of my speakers (drivers).

The weird thing is, the way a lot of tutorials on the matter of crossovers are written...I often get the impression that I've learned a clearly defined chunk of information that is in itself useful and directly applicable. Then, as I read more, I find that's not the case, as there's seemingly always something new to be learned. Then sometimes, new information conflicts with old information and it's not always easy to know what to do.

None of this dampens my spirits on DIY audio; this has always been a passion of mine, I just haven't had a chance to really get into the serious stuff until now. In that regard, I am new to this, "this" being the craft of highly specialized circuitry.

Someday I'd like to be advanced enough to check the frequency responses of my own drivers and tailor crossovers directly to the needs of those drivers. I regret that today isn't that day, however I've gotta start somewhere.


It might help to unveil the whole scope of my project....what I have are some broken M-Audio Studio Pro 3s. The sense in which they are broken only means that a single capacitor on the main power board has bulged out and died. Surely, replacing that cap with one of equal value would return the set to their original state. However, while I was looking at the main board for the primary speaker, I noticed there must have been no less than 60 individual components on that board.

I remembered back to the DIY schematics I'd seen online and thought...between the power supply, the crossovers, and the amplifiers, there can't be more than 30 parts in total. This was the point at which I decided I wanted to take it upon myself to rip out M-Audio's circuitry and try to construct my own.

The entire speaker set only contains two circuit boards, the main board which includes both amps, a power supply, a crossover and a bass boost switch, and then the other board is the crossover for the satellite speaker.

As I recall, these speakers produced a fair amount of hissing even when they were new and I wanted to see if I could fix that. It also seemed reasonable that the power supply should at the very minimum be isolated from the amp/crossover circuits instead of crowded together like sardines.

So, at the very least, I wanted to build a different power supply for it.

Another point of interest in the design of the set was that the capacitors used don't seem special at all, they're just run-of-the-mill electrolytic capacitors, 50V....18u or 47u.....I wonder if sound quality couldn't be improved by replacing them with nicer caps with the same ratings?

The same ought to go for the resistors and coils, yes?

Essentially, what I want to know there is....are the printed values of the components isolated from their function. In other words, could someone see a crappy 50V 18u capacitor, and simply swap it out for a nicer one that was also 50V 18u?

I also wanted to shield and ground the speaker cabinets more effectively, the only part that's shielded in the entire set is the woofer of each cabinet. I wanted to put magnetic/radio shielding in there to see if that helps solve the hissing problem.

I also wanted to replace the opamps with something a bit nicer, the OPA627 is pretty far out of my price range, but I'm open to suggestions.

Thanks for all the input so far.

 

[highfigh]

This is all very good to know, and that guide about misconceptions in crossover design was very helpful. I'd actually wondered about the second point he made. Unfortunately, I don't really have much of a way to determine the response of my speakers (drivers).

The weird thing is, the way a lot of tutorials on the matter of crossovers are written...I often get the impression that I've learned a clearly defined chunk of information that is in itself useful and directly applicable. Then, as I read more, I find that's not the case, as there's seemingly always something new to be learned. Then sometimes, new information conflicts with old information and it's not always easy to know what to do.

None of this dampens my spirits on DIY audio; this has always been a passion of mine, I just haven't had a chance to really get into the serious stuff until now. In that regard, I am new to this, "this" being the craft of highly specialized circuitry.

Someday I'd like to be advanced enough to check the frequency responses of my own drivers and tailor crossovers directly to the needs of those drivers. I regret that today isn't that day, however I've gotta start somewhere.


It might help to unveil the whole scope of my project....what I have are some broken M-Audio Studio Pro 3s. The sense in which they are broken only means that a single capacitor on the main power board has bulged out and died. Surely, replacing that cap with one of equal value would return the set to their original state. However, while I was looking at the main board for the primary speaker, I noticed there must have been no less than 60 individual components on that board.

I remembered back to the DIY schematics I'd seen online and thought...between the power supply, the crossovers, and the amplifiers, there can't be more than 30 parts in total. This was the point at which I decided I wanted to take it upon myself to rip out M-Audio's circuitry and try to construct my own.

The entire speaker set only contains two circuit boards, the main board which includes both amps, a power supply, a crossover and a bass boost switch, and then the other board is the crossover for the satellite speaker.

As I recall, these speakers produced a fair amount of hissing even when they were new and I wanted to see if I could fix that. It also seemed reasonable that the power supply should at the very minimum be isolated from the amp/crossover circuits instead of crowded together like sardines.

So, at the very least, I wanted to build a different power supply for it.

Another point of interest in the design of the set was that the capacitors used don't seem special at all, they're just run-of-the-mill electrolytic capacitors, 50V....18u or 47u.....I wonder if sound quality couldn't be improved by replacing them with nicer caps with the same ratings?

The same ought to go for the resistors and coils, yes?

Essentially, what I want to know there is....are the printed values of the components isolated from their function. In other words, could someone see a crappy 50V 18u capacitor, and simply swap it out for a nicer one that was also 50V 18u?

I also wanted to shield and ground the speaker cabinets more effectively, the only part that's shielded in the entire set is the woofer of each cabinet. I wanted to put magnetic/radio shielding in there to see if that helps solve the hissing problem.

I also wanted to replace the opamps with something a bit nicer, the OPA627 is pretty far out of my price range, but I'm open to suggestions.

Thanks for all the input so far.

Hiss comes from noisy electronics, i.e., resistors/op-amps, not interference going in through a crossover and the woofer is magnetically shielded so it won't affect a TV. Also, a basic amplifier may only need 30 components but these may have some equalization or some other circuitry in there.

 

[Swerd]

This is all very good to know, and that guide about misconceptions in crossover design was very helpful. I'd actually wondered about the second point he made. Unfortunately, I don't really have much of a way to determine the response of my speakers (drivers).

In my experience, being able to measure the response and impedance of your drivers, when mounted in their cabinet, is essential to developing a good crossover. Short of doing that yourself, try to find someone nearby you who has the measurement gear and the know-how to use it properly. There is a very active DIY speaker builders’ forum, Techtalk at Parts-Express.com, where you might find someone willing to help.

It might help to unveil the whole scope of my project....what I have are some broken M-Audio Studio Pro 3s. The sense in which they are broken only means that a single capacitor on the main power board has bulged out and died. Surely, replacing that cap with one of equal value would return the set to their original state. However, while I was looking at the main board for the primary speaker, I noticed there must have been no less than 60 individual components on that board.

I remembered back to the DIY schematics I'd seen online and thought...between the power supply, the crossovers, and the amplifiers, there can't be more than 30 parts in total. This was the point at which I decided I wanted to take it upon myself to rip out M-Audio's circuitry and try to construct my own.

The entire speaker set only contains two circuit boards, the main board which includes both amps, a power supply, a crossover and a bass boost switch, and then the other board is the crossover for the satellite speaker.

As I recall, these speakers produced a fair amount of hissing even when they were new and I wanted to see if I could fix that. It also seemed reasonable that the power supply should at the very minimum be isolated from the amp/crossover circuits instead of crowded together like sardines.

So, at the very least, I wanted to build a different power supply for it.

Another point of interest in the design of the set was that the capacitors used don't seem special at all, they're just run-of-the-mill electrolytic capacitors, 50V....18u or 47u.....I wonder if sound quality couldn't be improved by replacing them with nicer caps with the same ratings?

The same ought to go for the resistors and coils, yes?

Essentially, what I want to know there is....are the printed values of the components isolated from their function. In other words, could someone see a crappy 50V 18u capacitor, and simply swap it out for a nicer one that was also 50V 18u?

I see these are powered speakers. My guess about the source of the hissing sound would be the amp or power supply, but I am not able to comment intelligently about them - so I won’t.

Are the crossover circuits upstream or downstream from the amplifier? If they are downstream, then they work no different than the passive crossover filters in unpowered speakers. If they are upstream of the crossover, they work different in the sense that they need not interact with the variable impedance of the woofer and tweeter. All my previous (and subsequent) comments pertain only to passive crossovers meant to work downstream from the amps.

As to your question about using “nicer” crossover components… using capacitors, inductor coils or resistors of the same value but different construction makes no audible difference. This is a controversial subject, full of audio voodoo, but there is no valid evidence that using different types of capacitors or resistors effects the sound of speakers. I know some people who have examined this in a scientifically credible way, and they concluded that high-priced capacitors and resistors are a waste of money in passive audio crossovers.

On the other hand, replacing your bad cap with a functioning one will have quite a noticeable benefit . Non-polar electrolytic (NPE) caps are very cheap, and are known to sometimes deviate from their printed value or fail over time (15 years or more). Metallized polypropylene (MPP) capacitors don’t suffer from this problem and are available for very reasonable prices from vendors such as Parts Express or Madisound. I would recommend using MPP caps over NPEs unless you need a large cap such as 50 µF or greater, and need to keep the cost low.

For inductor coils, stick to air-core inductors of 16 to 20 gauge solid copper wire. There are some cases where an large iron or steel laminate core inductor can be used for a low-pass filter for a large woofer in a 3-way design. Avoid the temptation to use large gauge wire coils, because they usually create bulky heavy crossovers that are difficult to fit into the speaker cabinets, without improving the sound.

 

[TLS Guy]

This is all very good to know, and that guide about misconceptions in crossover design was very helpful. I'd actually wondered about the second point he made. Unfortunately, I don't really have much of a way to determine the response of my speakers (drivers).

The weird thing is, the way a lot of tutorials on the matter of crossovers are written...I often get the impression that I've learned a clearly defined chunk of information that is in itself useful and directly applicable. Then, as I read more, I find that's not the case, as there's seemingly always something new to be learned. Then sometimes, new information conflicts with old information and it's not always easy to know what to do.

None of this dampens my spirits on DIY audio; this has always been a passion of mine, I just haven't had a chance to really get into the serious stuff until now. In that regard, I am new to this, "this" being the craft of highly specialized circuitry.

Someday I'd like to be advanced enough to check the frequency responses of my own drivers and tailor crossovers directly to the needs of those drivers. I regret that today isn't that day, however I've gotta start somewhere.


It might help to unveil the whole scope of my project....what I have are some broken M-Audio Studio Pro 3s. The sense in which they are broken only means that a single capacitor on the main power board has bulged out and died. Surely, replacing that cap with one of equal value would return the set to their original state. However, while I was looking at the main board for the primary speaker, I noticed there must have been no less than 60 individual components on that board.

I remembered back to the DIY schematics I'd seen online and thought...between the power supply, the crossovers, and the amplifiers, there can't be more than 30 parts in total. This was the point at which I decided I wanted to take it upon myself to rip out M-Audio's circuitry and try to construct my own.

The entire speaker set only contains two circuit boards, the main board which includes both amps, a power supply, a crossover and a bass boost switch, and then the other board is the crossover for the satellite speaker.

As I recall, these speakers produced a fair amount of hissing even when they were new and I wanted to see if I could fix that. It also seemed reasonable that the power supply should at the very minimum be isolated from the amp/crossover circuits instead of crowded together like sardines.

So, at the very least, I wanted to build a different power supply for it.

Another point of interest in the design of the set was that the capacitors used don't seem special at all, they're just run-of-the-mill electrolytic capacitors, 50V....18u or 47u.....I wonder if sound quality couldn't be improved by replacing them with nicer caps with the same ratings?

The same ought to go for the resistors and coils, yes?

Essentially, what I want to know there is....are the printed values of the components isolated from their function. In other words, could someone see a crappy 50V 18u capacitor, and simply swap it out for a nicer one that was also 50V 18u?

I also wanted to shield and ground the speaker cabinets more effectively, the only part that's shielded in the entire set is the woofer of each cabinet. I wanted to put magnetic/radio shielding in there to see if that helps solve the hissing problem.

I also wanted to replace the opamps with something a bit nicer, the OPA627 is pretty far out of my price range, but I'm open to suggestions.

Thanks for all the input so far.

Are you sure you are not dealing with active electronic crossovers here rather than passive?

My advice is to restore those speakers the way the were. I'm pretty certain you will only spoil them.

 

[VolumetricSteve]

Are you sure you are not dealing with active electronic crossovers here rather than passive?

My advice is to restore those speakers the way the were. I'm pretty certain you will only spoil them.

Yes, I am certain they're passive.

No, I won't spoil them. They were broken and free when I got them, and I own functioning Studio Pro 4s....so there's not much to spoil.

The primary objective of this project was to just learn more about this stuff because I wanted to....so if your advice is to pack it up and go home, I refuse to. I respect your advice and everything, but I can't just stop now. I have to start somewhere, a dead/free set of cheap monitors seemed like a good place to me. (In fact I'm not sure it gets much better than that for a first-time around)

The circuit diagram I produced does in fact work, I just needed to put in the proper values for the resistors. I watched the outputs on the woofer and tweeter side, and they match the description of the crossover. They switched at 2.3KHz and the tweeter had sharp attenuation approaching 2.3KHz while the woofer seemed to start to pick up duty a bit higher, it was hard to catch visually but it looked like the woofer started gradually around 5Khz and then really opened up at 2.3Khz, and frequencies below 200Hz were practically non-existent. That simply has to be the right diagram.

Sometime....maybe even today, I'll go get a soldering iron, remove the crossover parts from the main board and re-construct it on a separate board.

Does silver solder really make a difference? I can't imagine for this specific project it would (it also doesn't look like they used it in the boards) but for seriously high end stuff, does it matter?

About capacitors.......if they are marked with a plus sign, that means they're polarized, right? That doesn't make sense if they're used in series with the input..sooner or later there's going to be current going the other way, and if I'm not mistaken, that murders caps.

I saw a + on the PCB board for each capacitor in the crossover, but I didn't see any such marking on the cap itself. It's impossible that it's polarized though.....no discussion, it can't be polarized, right?

More on this later as work is ongoing.

 

[Swerd]

Does silver solder really make a difference? I can't imagine for this specific project it would (it also doesn't look like they used it in the boards) but for seriously high end stuff, does it matter?

No, don't bother with silver solder. Use lead/tin solder that is 60% lead and 40% tin. 63/37 lead/tin is also available and also works well. Silver solder usually has about 4% silver in it and the rest lead and tin. Be sure to use rosin core solder and not acid core solder. Rosin core is for electronics and acid core is for copper plumbing.

About capacitors.......if they are marked with a plus sign, that means they're polarized, right? That doesn't make sense if they're used in series with the input..sooner or later there's going to be current going the other way, and if I'm not mistaken, that murders caps.

I saw a + on the PCB board for each capacitor in the crossover, but I didn't see any such marking on the cap itself. It's impossible that it's polarized though.....no discussion, it can't be polarized, right?

As far as I know, all capacitors in passive crossovers are non polar. Audio signals are AC. Perhaps the mark you saw on the board indicated the attachment point for wires going to the woofer or tweeter. Each driver has a plus and minus terminal and their polarity is important to proper crossover function.

 

[VolumetricSteve]

No, don't bother with silver solder. Use lead/tin solder that is 60% lead and 40% tin. 63/37 lead/tin is also available and also works well. Silver solder usually has about 4% silver in it and the rest lead and tin. Be sure to use rosin core solder and not acid core solder. Rosin core is for electronics and acid core is for copper plumbing.

Makes sense, I thought silver solder sounded kinda crazy.

As far as I know, all capacitors in passive crossovers are non polar. Audio signals are AC. Perhaps the mark you saw on the board indicated the attachment point for wires going to the woofer or tweeter. Each driver has a plus and minus terminal and their polarity is important to proper crossover function.

That's exactly what I thought; that's the assumption I'm going to operate on.

Thanks for the tips.

 

[highfigh]

Makes sense, I thought silver solder sounded kinda crazy.




That's exactly what I thought; that's the assumption I'm going to operate on.

Thanks for the tips.

The caps on the board you showed look like electrolytic.

 

[TLS Guy]

Yes, I am certain they're passive.

No, I won't spoil them. They were broken and free when I got them, and I own functioning Studio Pro 4s....so there's not much to spoil.

The primary objective of this project was to just learn more about this stuff because I wanted to....so if your advice is to pack it up and go home, I refuse to. I respect your advice and everything, but I can't just stop now. I have to start somewhere, a dead/free set of cheap monitors seemed like a good place to me. (In fact I'm not sure it gets much better than that for a first-time around)

The circuit diagram I produced does in fact work, I just needed to put in the proper values for the resistors. I watched the outputs on the woofer and tweeter side, and they match the description of the crossover. They switched at 2.3KHz and the tweeter had sharp attenuation approaching 2.3KHz while the woofer seemed to start to pick up duty a bit higher, it was hard to catch visually but it looked like the woofer started gradually around 5Khz and then really opened up at 2.3Khz, and frequencies below 200Hz were practically non-existent. That simply has to be the right diagram.

Sometime....maybe even today, I'll go get a soldering iron, remove the crossover parts from the main board and re-construct it on a separate board.

Does silver solder really make a difference? I can't imagine for this specific project it would (it also doesn't look like they used it in the boards) but for seriously high end stuff, does it matter?

About capacitors.......if they are marked with a plus sign, that means they're polarized, right? That doesn't make sense if they're used in series with the input..sooner or later there's going to be current going the other way, and if I'm not mistaken, that murders caps.

I saw a + on the PCB board for each capacitor in the crossover, but I didn't see any such marking on the cap itself. It's impossible that it's polarized though.....no discussion, it can't be polarized, right?

More on this later as work is ongoing.

If you are going to rebuild the crossover, I would use polypropylene caps. Electrolytic caps are a bad idea in crossovers. You can get non polarizing electrolytic types, but I still would not use them.

There is no need for silver solder.

I did not realize the speakers were not working. In that case you have nothing to loose.