Hello there! I have a rather big doubt about how to design my speakers cabinet.
I have to build a rather large speaker consisting in a woofer, a mid range and two tweeters, and I know that my mid range (which is 165mm wide) and my tweeters have a suggested cabinet volume of 5 liters, each. The woofer on the other hand is rather large and may be fit in a 1 cubic foot socket with no problem. Now, I am a rookie: my speakers would be rectangular and rather large at the base. I am wondering: could I artificially reduce the volume of the mid and tweeter by closing the braces instead of letting them open? Basically I'd add an L shaped piece of wood to half the volume, obtaining two chambers of 5 liters each.
The fact is that I don't know exactly why the driver has to be placed in a specific box with a specific space behind it: could someone explain that to me? Also, I saw that very few cabinets designers tend to separate components by completely closing the gaps between them; most of them punch holes on the braces. Why's that?
Thanks in advantage for the help!
I have to build a rather large speaker consisting in a woofer, a mid range and two tweeters, and I know that my mid range (which is 165mm wide) and my tweeters have a suggested cabinet volume of 5 liters, each. The woofer on the other hand is rather large and may be fit in a 1 cubic foot socket with no problem. Now, I am a rookie: my speakers would be rectangular and rather large at the base. I am wondering: could I artificially reduce the volume of the mid and tweeter by closing the braces instead of letting them open? Basically I'd add an L shaped piece of wood to half the volume, obtaining two chambers of 5 liters each.
The fact is that I don't know exactly why the driver has to be placed in a specific box with a specific space behind it: could someone explain that to me? Also, I saw that very few cabinets designers tend to separate components by completely closing the gaps between them; most of them punch holes on the braces. Why's that?
Thanks in advantage for the help!
5 liters for a tweeter?! (Or is that 5 liters for mid/tweeter combo?) Who's making these suggestions?
That's how everyone do, as I see. The purpose of separating the volume is not to let interfere each other. Usually the mid suffers a lot from the pressure generated by the woofer, it's called intermodulation, in this case caused by the changes of pressure generated by the woofer, which generally is bigger than the midrange so it moves much more air and IT WINS !!
As two tweeters, they are winners too !
Why 2 tweeters
It's five liters for 2 tweeters and a mid range (the tweeters are connected together).
As I said I am a rookie and I am just trying to rebuild a pair of speakers that has been destroyed by a flood (only the box though). I also wanted to change the midrange because for some reason these speakers were using a piezo-tweeter as a mid range (don't ask me why).
Anyway, I SHOULD actually separate the volumes behind my drivers? Without punching any holes in the divisions?
As I said I am a rookie and I am just trying to rebuild a pair of speakers that has been destroyed by a flood (only the box though). I also wanted to change the midrange because for some reason these speakers were using a piezo-tweeter as a mid range (don't ask me why).
Anyway, I SHOULD actually separate the volumes behind my drivers? Without punching any holes in the divisions?
Also, the fact is that I really have no idea of why you need only so much space behind your drivers. Is that because they need enough room for the sound to reflect? Or because it acts as an acoustic chamber? If the latter is true, why's that if you do anything to dampen the sound reflections inside the box? Also, would having more room negatively impact on sound quality? And having less?
It would appear you should do some reading/learning before you go building anything.
A tweeter won't need a box behind it, and 2 are rarely needed - they are typically the most sensitive driver in a system and are therefore padded down, it would be an unconventional need for multiple tweeters.
You should start with understanding sealed boxes. Try winisd to get an idea of behaviour, it's easy to use. Get a grasp of sensitivities. Read up on the effects of baffle shapes, sizes, and driver positioning (software called 'Edge' is handy). Then some reading of crossovers - the different types, dealing with real world impedances. Phasing. Time alignment. I have somewhat of an understanding and consider myself a beginner.
A tweeter won't need a box behind it, and 2 are rarely needed - they are typically the most sensitive driver in a system and are therefore padded down, it would be an unconventional need for multiple tweeters.
You should start with understanding sealed boxes. Try winisd to get an idea of behaviour, it's easy to use. Get a grasp of sensitivities. Read up on the effects of baffle shapes, sizes, and driver positioning (software called 'Edge' is handy). Then some reading of crossovers - the different types, dealing with real world impedances. Phasing. Time alignment. I have somewhat of an understanding and consider myself a beginner.
Or, you just should consider the frontal emission and forget about the back emission. The chamber behind provokes some reaction due to the higher pressure generated inside, or may resonate at a tuned volume so the speaker finds its balance of motion when oscillating below the resonance frequency ( demonstrated by the two impedance peaks exhibited in a bass reflex box ).
Indeed, the thing is well demonstrated thru analysis of the acoustic impedance seen by the cone. Then the in-room behaviour and eventually the human special sensitive curve
Indeed, the thing is well demonstrated thru analysis of the acoustic impedance seen by the cone. Then the in-room behaviour and eventually the human special sensitive curve
@Phreeky82
Yeah, I definitely need to learn more about enclosures... About everything in speakers to be honest... But I don't know where to start from, apart for research on the Internet and asking around. About the reason for which I am using this setup (2 tweeters, one mid, one woofer): it's because that's the setup the previous speakers had. The crossover is built for that, although I am not sure about the box. I only need to rebuild the box and replace a mid, but the mid range is different (it's a ciare 6.38 MR3, whereas before for some reason the speakers were using a piezo-tweeter as a mid, don't ask me why again, my grandfather had them and they were passed down to me).
Do you know where I could start to understand sealed boxes?
Yeah, I definitely need to learn more about enclosures... About everything in speakers to be honest... But I don't know where to start from, apart for research on the Internet and asking around. About the reason for which I am using this setup (2 tweeters, one mid, one woofer): it's because that's the setup the previous speakers had. The crossover is built for that, although I am not sure about the box. I only need to rebuild the box and replace a mid, but the mid range is different (it's a ciare 6.38 MR3, whereas before for some reason the speakers were using a piezo-tweeter as a mid, don't ask me why again, my grandfather had them and they were passed down to me).
Do you know where I could start to understand sealed boxes?
Sealed boxes are generally the simplest - in fact I'd expect that a midrange in most cases would not need an overly specific box volume, it has a lot more impact at lower frequencies.
You should try and understand the existing crossover though. Draw a schematic to match and try and figure out what is going on - it could be a simple 3 way 2nd order or something, and it may factor in baffle-step correction (which in many ways shouldn't be a big deal switching drivers, depending on how particular you are), however if it has things like impedance correction then it gets much more driver specific.
What model numbers do you know? Anything on the back of the cabinet? On the drivers themselves? The most fundamental thing to get right, IMO, is to determine what sensitivity and impedance you want for the midrange so that it matches the other drivers sensitivity and doesn't alter the crossover frequency respectively.
You should try and understand the existing crossover though. Draw a schematic to match and try and figure out what is going on - it could be a simple 3 way 2nd order or something, and it may factor in baffle-step correction (which in many ways shouldn't be a big deal switching drivers, depending on how particular you are), however if it has things like impedance correction then it gets much more driver specific.
What model numbers do you know? Anything on the back of the cabinet? On the drivers themselves? The most fundamental thing to get right, IMO, is to determine what sensitivity and impedance you want for the midrange so that it matches the other drivers sensitivity and doesn't alter the crossover frequency respectively.
When I have some time I'll draw a scheme and show it here! The fact is that the cabinet has received different drivers, and I am stuck with them, I don't know the models of the woofer and the tweeters but I do know some specifics of the woofer, I know everything only about the mid range because I am actually buying it. If you are an average crossover knower, I might post the image here so you could help me figuring out what's going on!
Alright, I did some research and found out a few things. First of all, I have a rough idea of what the tweeters are now: they should be something from Motorola, two piezo tweeters (decent quality ones) connected in series. The mid range used to be a piezo horn, always from Motorola, but it's no longer working. The woofer is a cheap piece of junk, but it did sound decent nonetheless, although I cannot find any information about it. From my own impressions the information they gave me (32-6000 frequency response) is far exaggerated and should be at most (50-2500/3000). The crossover is designed for cutting bands at around 640 hz and 2000 or so hz (will do some more practical research tomorrow), but the fact is that the mid range used to be a piezo piece. I might need help deciding what I should change in the circuit to allow a voice coil driver to be put as mid-range instead of the piezo horn.
Damn. I never thought designing speakers could be this complicated. They should definitely cost more hah
Damn. I never thought designing speakers could be this complicated. They should definitely cost more hah
Alright! Found out that the crossover is a second order one with an L-pad on the tweeters. Oddly enough, it appears as a normal filter, nothing different from this one which is designed for piezos and normal ones.
Considering this scheme, add an L pad on the tweeter, a resistor in series with C4 (on the line that goes to -), and a resistor instead of C3. C3 instead is placed after the node, with L3, in the line that goes toward the - entry of the mid range.
What do the two extra resistors do in this circuit? Is there a way to figure out the crossing points, considering that:
The L-pad has an 8,2 ohm and a 33 ohm resistors
The other two added resistors are 6,8 ohm resistant
C4 and C2 have a C of 22 mF
C3 has a C of 6,8 mF
An externally hosted image should be here but it was not working when we last tested it.
Considering this scheme, add an L pad on the tweeter, a resistor in series with C4 (on the line that goes to -), and a resistor instead of C3. C3 instead is placed after the node, with L3, in the line that goes toward the - entry of the mid range.
What do the two extra resistors do in this circuit? Is there a way to figure out the crossing points, considering that:
The L-pad has an 8,2 ohm and a 33 ohm resistors
The other two added resistors are 6,8 ohm resistant
C4 and C2 have a C of 22 mF
C3 has a C of 6,8 mF
Hi Herbert,
do you still ahve the old cabinets? Simply rebuild them the same way they were. most important is to keep the volumes behind the speakers as they were - and also the channels.
If I were you, I would not touch the crossovers, get started with teh cabinet.
there are also quite cheap options available for wood, so why not build several versions - so you can compare and see what happens?
Do you know the name and model o the original you try to rebuild?
Maybe it would also be an option to get a DIY kit - which is ready designed and tells you all the measures for the cabinet. With that, at least you can be sure the result will sound well.
do you still ahve the old cabinets? Simply rebuild them the same way they were. most important is to keep the volumes behind the speakers as they were - and also the channels.
If I were you, I would not touch the crossovers, get started with teh cabinet.
there are also quite cheap options available for wood, so why not build several versions - so you can compare and see what happens?
Do you know the name and model o the original you try to rebuild?
Maybe it would also be an option to get a DIY kit - which is ready designed and tells you all the measures for the cabinet. With that, at least you can be sure the result will sound well.
Hello highend!
I still have the old cabinets but they aren't even salvageable. There has been a flood in my town and they sucked up quite a bit of water... At least the drivers weren't touched! That was bare luck. About the volumes and the channels: yes I am keeping the channels the same, but I can't do that for the volumes. The mid piece used to be a piezo horn, whereas now I am replacing it with a normal ferrite driver (ciare 6.38 MR3); the crossover SHOULD be fine with that piece and all the other pieces, the only thing is that I need desperately to attenuate the new mid-range as it has 10 more dbs over the other drivers. About buying more wood and more pieces: sadly right now I am not doing well financially so I was trying to save what I could out of the only average speakers I had, and that's why I am trying to inform myself as much as possible, so I might be able to get something good out of them. Sure they had average drivers in the first place, but whatever, they did sound pretty good with my amp (not only with volume; they had very neat bass and the piezos didn't sound too harsh or bright)
About the original: despite the fact that they did sound well, they were basically a rip off. My grandfather bought them without knowing what he was buying and when I brought the pictures to an expert he said that the cabinet looked like a Jordan one, but the drivers were completely different (and cheaper) than the originals.
I still have the old cabinets but they aren't even salvageable. There has been a flood in my town and they sucked up quite a bit of water... At least the drivers weren't touched! That was bare luck. About the volumes and the channels: yes I am keeping the channels the same, but I can't do that for the volumes. The mid piece used to be a piezo horn, whereas now I am replacing it with a normal ferrite driver (ciare 6.38 MR3); the crossover SHOULD be fine with that piece and all the other pieces, the only thing is that I need desperately to attenuate the new mid-range as it has 10 more dbs over the other drivers. About buying more wood and more pieces: sadly right now I am not doing well financially so I was trying to save what I could out of the only average speakers I had, and that's why I am trying to inform myself as much as possible, so I might be able to get something good out of them. Sure they had average drivers in the first place, but whatever, they did sound pretty good with my amp (not only with volume; they had very neat bass and the piezos didn't sound too harsh or bright)
About the original: despite the fact that they did sound well, they were basically a rip off. My grandfather bought them without knowing what he was buying and when I brought the pictures to an expert he said that the cabinet looked like a Jordan one, but the drivers were completely different (and cheaper) than the originals.
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