Any speaker design gurus?
12-05-2009, 07:29 PM
#1
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Any speaker design gurus?
Center Channel Speaker:
The tweeter is 5.2ohm, and both drivers are 14.5ohm in my center channel speaker. No crossover in there, the tweeter has a resistor/cap and is connected to one of the woofers. The woofers are joined, impedence is 14.4ohm each. Then both woofers are connected together to the spring clips on the back. The impedence is 7.3ohms... I don't get it... :-( I want to put in a 2way passive crossover. But how to match the impedence??
i have them in parallel. tweeter with resistor to one woofer, and then that woofer and the other woofer together to the spring clips. what i'd like is to keep tweeter to crossover and then both woofers in parallel to crossover. So i know what i'll get with the woofers, like 7.3 ohm. but what to do about the tweeter? keep the resistor? and do i get a 4ohm or 8ohm crossover?
http://www.parts-express.com/pe/show...number=260-144
This is the crossover i want to use, and looks like i can use it for the two drivers, since together in parallel they make 7.3ohm (8ohm) on the low pass. But the high pass calls for 8ohm, and the tweeter measures 5.2ohm (6ohm). Would that be safe??
I'm using Oxy Free Copper 16ga wiring inside the speaker.
I'm a speaker design NOOB
The tweeter is 5.2ohm, and both drivers are 14.5ohm in my center channel speaker. No crossover in there, the tweeter has a resistor/cap and is connected to one of the woofers. The woofers are joined, impedence is 14.4ohm each. Then both woofers are connected together to the spring clips on the back. The impedence is 7.3ohms... I don't get it... :-( I want to put in a 2way passive crossover. But how to match the impedence??
i have them in parallel. tweeter with resistor to one woofer, and then that woofer and the other woofer together to the spring clips. what i'd like is to keep tweeter to crossover and then both woofers in parallel to crossover. So i know what i'll get with the woofers, like 7.3 ohm. but what to do about the tweeter? keep the resistor? and do i get a 4ohm or 8ohm crossover?
http://www.parts-express.com/pe/show...number=260-144
This is the crossover i want to use, and looks like i can use it for the two drivers, since together in parallel they make 7.3ohm (8ohm) on the low pass. But the high pass calls for 8ohm, and the tweeter measures 5.2ohm (6ohm). Would that be safe??
I'm using Oxy Free Copper 16ga wiring inside the speaker.
I'm a speaker design NOOB
12-05-2009, 08:07 PM
#2
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The cap is your high pass filter on the tweeter right now (6dB per octave).
The resistor is your impedence match.
So technically you have a crossover. It's common for cheap speakers (almost everything you will find in Fry's or Best Buy type places) to have no real crossover for the woofer and just use natural rolloff on the highs to match with a simple 6dB filter on the tweeter. maybe 12dB if they feel frisky, but most people can't "hear" a good crossover and annoying + loud sells anyway (see Bose)
Yes, they should all be wired in parallel. Your 'nominal' impedence will be 8 ohms. but actual impedence measured at crossover frequency can be anything, and this is what matters for the crossover design. Impedence is a function of frequency and near the Resonant frequency (Fs) can be triple the nominal impedence. designing crossovers by using the nominal impedence is a real crapshoot because you don't know what the impedence curve looks like.
What is the goal here?
If you feel like making your head spin with speaker design theory, check out these forums:
http://www.htguide.com/forum/forumdisplay.php4?f=6
Mission accomplished forum has a lot of great designs. I am in the process of building the Modula NeoD speakers of JonMarsh's design to replace the old speakers I designed and built myself in 1994 or 95 or something. Since then I figured out that I didn't have the tools to do my own design, and I don't feel like buying them, so I've decided to build other people's designs who are more knowledgeable on the subject.
The resistor is your impedence match.
So technically you have a crossover. It's common for cheap speakers (almost everything you will find in Fry's or Best Buy type places) to have no real crossover for the woofer and just use natural rolloff on the highs to match with a simple 6dB filter on the tweeter. maybe 12dB if they feel frisky, but most people can't "hear" a good crossover and annoying + loud sells anyway (see Bose)
Yes, they should all be wired in parallel. Your 'nominal' impedence will be 8 ohms. but actual impedence measured at crossover frequency can be anything, and this is what matters for the crossover design. Impedence is a function of frequency and near the Resonant frequency (Fs) can be triple the nominal impedence. designing crossovers by using the nominal impedence is a real crapshoot because you don't know what the impedence curve looks like.
What is the goal here?
If you feel like making your head spin with speaker design theory, check out these forums:
http://www.htguide.com/forum/forumdisplay.php4?f=6
Mission accomplished forum has a lot of great designs. I am in the process of building the Modula NeoD speakers of JonMarsh's design to replace the old speakers I designed and built myself in 1994 or 95 or something. Since then I figured out that I didn't have the tools to do my own design, and I don't feel like buying them, so I've decided to build other people's designs who are more knowledgeable on the subject.
Last edited by Concillian; 12-05-2009 at 08:12 PM.
12-05-2009, 08:09 PM
#3
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My bookshelves that I use for surrounds are probably going to be easier, but I'll burn that when I get to it. They are 2-ways right now, and probably have a similar design. ie: no real crossover, just wires in parallel and maybe a resistor or something on the tweeter again.)
My towers are going to be MUCH harder. They have a tweeter, 3.5" mid, dual 8". I don't know how it's wired yet, but i'll burn that bridge later too. For that one I'm hoping to use a 3-way cross over and run the 8" woofers in parallel to the crossover. Just hoping the rest works out with the tweeter and mid.
But for now, If I can learn to get this center speaker working, I'll be in good shape.
Oh, the amp is an AVR that calls for 8 ohm speakers, but is 6ohms rated. In the next few months I will be upgrading to another AVR that is 4ohms rated, so anywhere from 4ohms to 8ohms should work. I'm mostly just worried about how to pick out the crossover at this point when the drivers have different loads.
My towers are going to be MUCH harder. They have a tweeter, 3.5" mid, dual 8". I don't know how it's wired yet, but i'll burn that bridge later too. For that one I'm hoping to use a 3-way cross over and run the 8" woofers in parallel to the crossover. Just hoping the rest works out with the tweeter and mid.
But for now, If I can learn to get this center speaker working, I'll be in good shape.
Oh, the amp is an AVR that calls for 8 ohm speakers, but is 6ohms rated. In the next few months I will be upgrading to another AVR that is 4ohms rated, so anywhere from 4ohms to 8ohms should work. I'm mostly just worried about how to pick out the crossover at this point when the drivers have different loads.
Last edited by joltdudeuc; 12-05-2009 at 08:17 PM.
12-05-2009, 08:15 PM
#4
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The cap is your high pass filter on the tweeter right now (6dB per octave).
The resistor is your impedence match.
So technically you have a crossover. It's common for cheap speakers (almost everything you will find in Fry's or Best Buy type places) to have no real crossover for the woofer and just use natural rolloff on the highs to match with a simple 6dB filter on the tweeter. maybe 12dB if they feel frisky, but most people can't "hear" a good crossover and annoying + loud sells anyway (see Bose)
Yes, they should all be wired in parallel. Your 'nominal' impedence will be 8 ohms. but actual impedence measured at crossover frequency can be anything, and this is what matters for the crossover design. Impedence is a function of frequency and near the Resonant frequency (Fs) can be triple the nominal impedence. designing crossovers by using the nominal impedence is a real crapshoot because you don't know what the impedence curve looks like.
What is the goal here?
If you feel like making your head spin with speaker design theory, check out these forums:
http://www.htguide.com/forum/forumdisplay.php4?f=6
Mission accomplished forum has a lot of great designs. I am in the process of building the Modula NeoD speakers of JonMarsh's design to replace the old speakers I designed and built myself in 1994 or 95 or something. Since then I figured out that I didn't have the tools to do my own design, and I don't feel like buying them, so I've decided to build other people's designs who are more knowledgeable on the subject.
The resistor is your impedence match.
So technically you have a crossover. It's common for cheap speakers (almost everything you will find in Fry's or Best Buy type places) to have no real crossover for the woofer and just use natural rolloff on the highs to match with a simple 6dB filter on the tweeter. maybe 12dB if they feel frisky, but most people can't "hear" a good crossover and annoying + loud sells anyway (see Bose)
Yes, they should all be wired in parallel. Your 'nominal' impedence will be 8 ohms. but actual impedence measured at crossover frequency can be anything, and this is what matters for the crossover design. Impedence is a function of frequency and near the Resonant frequency (Fs) can be triple the nominal impedence. designing crossovers by using the nominal impedence is a real crapshoot because you don't know what the impedence curve looks like.
What is the goal here?
If you feel like making your head spin with speaker design theory, check out these forums:
http://www.htguide.com/forum/forumdisplay.php4?f=6
Mission accomplished forum has a lot of great designs. I am in the process of building the Modula NeoD speakers of JonMarsh's design to replace the old speakers I designed and built myself in 1994 or 95 or something. Since then I figured out that I didn't have the tools to do my own design, and I don't feel like buying them, so I've decided to build other people's designs who are more knowledgeable on the subject.
The goal is to take my budget speakers, which, for me sound fairly good right now, and upgrade the wiring inside and put in a real crossover. That's all I'm after right now.
In the future I'd buy some really nice speakers and other things, but since I'm on a budget, I'm just trying to clean up the freqency crossovers to make them cleaner, and change the wiring.
It might be pointless since I'm no audiophile or anything, but I do want to at least have them function properly. I understand that many mainstream speakers are built with resistors and caps as a means for crossovers, but I figured some decent crossovers like the Daytons will probably be a good idea for someone like me who's looking to clean up the signal.
Think it's worth it?
12-05-2009, 08:18 PM
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My towers are going to be MUCH harder. They have a tweeter, 3.5" mid, dual 8". I don't know how it's wired yet, but i'll burn that bridge later too. For that one I'm hoping to use a 3-way cross over and run the 8" woofers in parallel to the crossover. Just hoping the rest works out with the tweeter and mid.
Bookshelves and center channels you can get by with whatever from wherever. IMHO for LR mains on a budget, pick one of the cheaper 2 ways or MTM in the mission accomplished and it'll sound better than what you have. NatalieP I think is the popular inexpensive design. It's an MTM design and I don't think it has any really large inductors (these are what really start pushing the prices up, caps are reasonably priced)
12-05-2009, 08:21 PM
#6
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I'm mainly into video, so audio has never been strong for me, but I'm willing to try a few things now, and learn. I mostly use this for movies. and less for music.
12-05-2009, 10:55 PM
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Honestly? Without proper measurements on the speakers in question, I think you're 50 / 50 on sounding better or worse. Guaranteed better is to replace the (I'm assuming electrolytic) cap with a poly cap of the same value and the resistor (I'm assuming sand cast, will look like a white brick) with a film resistor.
poly caps:
http://www.madisound.com/manufacture...ennic-caps.php
10W Film resistors:
http://www.madisound.com/catalog/ind...Path=404_86_87
This is the kind of thing that would make fairly subtle differences in transients across the crossover frequency. Most likely not even noticeable for video and it wouldn't address the main deficiency in low crossover slope cheap speakers... distortion that is not supressed enough due to low crossover slope.
Beyond that you have to play with steeper crossover slopes. If it worked, it would tend to clean up the human voice ranges on a center channel. It's not the kind of thing I'd expect to be able to get right in one try.
PM me all the values and I can suggest a few inductors and caps to try. I probably have enough lying around that we could try a few combinations and see if they sound better. I don't have a way of measuring distortion so we'd have to play it by ear, so to speak.
poly caps:
http://www.madisound.com/manufacture...ennic-caps.php
10W Film resistors:
http://www.madisound.com/catalog/ind...Path=404_86_87
This is the kind of thing that would make fairly subtle differences in transients across the crossover frequency. Most likely not even noticeable for video and it wouldn't address the main deficiency in low crossover slope cheap speakers... distortion that is not supressed enough due to low crossover slope.
Beyond that you have to play with steeper crossover slopes. If it worked, it would tend to clean up the human voice ranges on a center channel. It's not the kind of thing I'd expect to be able to get right in one try.
PM me all the values and I can suggest a few inductors and caps to try. I probably have enough lying around that we could try a few combinations and see if they sound better. I don't have a way of measuring distortion so we'd have to play it by ear, so to speak.
12-06-2009, 01:21 AM
#9
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Honestly? Without proper measurements on the speakers in question, I think you're 50 / 50 on sounding better or worse. Guaranteed better is to replace the (I'm assuming electrolytic) cap with a poly cap of the same value and the resistor (I'm assuming sand cast, will look like a white brick) with a film resistor.
poly caps:
http://www.madisound.com/manufacture...ennic-caps.php
10W Film resistors:
http://www.madisound.com/catalog/ind...Path=404_86_87
This is the kind of thing that would make fairly subtle differences in transients across the crossover frequency. Most likely not even noticeable for video and it wouldn't address the main deficiency in low crossover slope cheap speakers... distortion that is not supressed enough due to low crossover slope.
Beyond that you have to play with steeper crossover slopes. If it worked, it would tend to clean up the human voice ranges on a center channel. It's not the kind of thing I'd expect to be able to get right in one try.
PM me all the values and I can suggest a few inductors and caps to try. I probably have enough lying around that we could try a few combinations and see if they sound better. I don't have a way of measuring distortion so we'd have to play it by ear, so to speak.
poly caps:
http://www.madisound.com/manufacture...ennic-caps.php
10W Film resistors:
http://www.madisound.com/catalog/ind...Path=404_86_87
This is the kind of thing that would make fairly subtle differences in transients across the crossover frequency. Most likely not even noticeable for video and it wouldn't address the main deficiency in low crossover slope cheap speakers... distortion that is not supressed enough due to low crossover slope.
Beyond that you have to play with steeper crossover slopes. If it worked, it would tend to clean up the human voice ranges on a center channel. It's not the kind of thing I'd expect to be able to get right in one try.
PM me all the values and I can suggest a few inductors and caps to try. I probably have enough lying around that we could try a few combinations and see if they sound better. I don't have a way of measuring distortion so we'd have to play it by ear, so to speak.
I generally feel that if i can put in a dedicated crossover i should hear better separation of the frequencies. If my setup is 6db slope, and i put in, lets say, that 12db slope crossover, what would I hear? would the steeper crossover not be audible you are saying?
I've done it in car audio, and it's been definitely better there.
12-06-2009, 09:57 AM
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If it's right, you will hear a difference from a steeper crossover. 6dB is too shallow for cheap speakers because they have lots of distortion when they play outside of their sweet spot. the steeper crossover will help bury that distortion.
The issue is that you're playing guessing games and you could create a decent sized "hole" or "spike" in the frequency response. It's possible you won't too, and it's possible that the distortion you reduce would make it worthwhile.
In car audio, the important crossover is usually between the sub and the mains. This area is a lot more forgiving due to it not being a voice range. A CC speaker is going to be doing a lot of voices and if you don't get the crossover right certain people will speak and you'll think the volume is too low, then someone with a different voice speaks and you think it's too loud.
Start with your current cap and resistor, and what values they are so you can figure your current crossover frequency. Then we can figure a starting point for a 12dB filter and potentially put a parallel resistor in addition to your series resistor to deal with the impedence peak at tweeter resonance that might be high enough to be audible.
The issue is that you're playing guessing games and you could create a decent sized "hole" or "spike" in the frequency response. It's possible you won't too, and it's possible that the distortion you reduce would make it worthwhile.
In car audio, the important crossover is usually between the sub and the mains. This area is a lot more forgiving due to it not being a voice range. A CC speaker is going to be doing a lot of voices and if you don't get the crossover right certain people will speak and you'll think the volume is too low, then someone with a different voice speaks and you think it's too loud.
Start with your current cap and resistor, and what values they are so you can figure your current crossover frequency. Then we can figure a starting point for a 12dB filter and potentially put a parallel resistor in addition to your series resistor to deal with the impedence peak at tweeter resonance that might be high enough to be audible.
12-06-2009, 10:49 AM
#11
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If it's right, you will hear a difference from a steeper crossover. 6dB is too shallow for cheap speakers because they have lots of distortion when they play outside of their sweet spot. the steeper crossover will help bury that distortion.
The issue is that you're playing guessing games and you could create a decent sized "hole" or "spike" in the frequency response. It's possible you won't too, and it's possible that the distortion you reduce would make it worthwhile.
In car audio, the important crossover is usually between the sub and the mains. This area is a lot more forgiving due to it not being a voice range. A CC speaker is going to be doing a lot of voices and if you don't get the crossover right certain people will speak and you'll think the volume is too low, then someone with a different voice speaks and you think it's too loud.
Start with your current cap and resistor, and what values they are so you can figure your current crossover frequency. Then we can figure a starting point for a 12dB filter and potentially put a parallel resistor in addition to your series resistor to deal with the impedence peak at tweeter resonance that might be high enough to be audible.
The issue is that you're playing guessing games and you could create a decent sized "hole" or "spike" in the frequency response. It's possible you won't too, and it's possible that the distortion you reduce would make it worthwhile.
In car audio, the important crossover is usually between the sub and the mains. This area is a lot more forgiving due to it not being a voice range. A CC speaker is going to be doing a lot of voices and if you don't get the crossover right certain people will speak and you'll think the volume is too low, then someone with a different voice speaks and you think it's too loud.
Start with your current cap and resistor, and what values they are so you can figure your current crossover frequency. Then we can figure a starting point for a 12dB filter and potentially put a parallel resistor in addition to your series resistor to deal with the impedence peak at tweeter resonance that might be high enough to be audible.
Okay, I'll take the sticky tape off, and write down any info i see on the cap and resistor for you.
I was just using the following chart when figuring out where I wanted the high/low cross over to be.
Since I know the drivers in the center are 4.75" and the tweeter is 1" I figured anywhere from 2500hz to 3500hz would be fine.
What I think I'll do is if I have a chance I'll take the tower and bookshelves apart and get the ohm measurements and also any caps/resistors they have. If I can't get that done today, I at least start with this center.
I'll take a few pictures of the drivers for you. The magnets are bigger than I thought they would be.
Just, please, don't judge me for crazy cheap speakers
I know they are definitely dirt low end.
12-06-2009, 01:47 PM
#13
biggest advice i can give?
buy all three front speakers from the same manufacturer. in fact, buy a matched set if you can.
why?
you are creating a front soundstage. you want that to be seamless. if you start to mix and match. or ever worse, make the mistake of making the center channel smaller than the front L/R, watching a multichannel movie will suffer.
then let your A/V receiver handle the crossover between the subwoofer and the mains.
buy all three front speakers from the same manufacturer. in fact, buy a matched set if you can.
why?
you are creating a front soundstage. you want that to be seamless. if you start to mix and match. or ever worse, make the mistake of making the center channel smaller than the front L/R, watching a multichannel movie will suffer.
then let your A/V receiver handle the crossover between the subwoofer and the mains.
12-06-2009, 03:36 PM
#14
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biggest advice i can give?
buy all three front speakers from the same manufacturer. in fact, buy a matched set if you can.
why?
you are creating a front soundstage. you want that to be seamless. if you start to mix and match. or ever worse, make the mistake of making the center channel smaller than the front L/R, watching a multichannel movie will suffer.
then let your A/V receiver handle the crossover between the subwoofer and the mains.
buy all three front speakers from the same manufacturer. in fact, buy a matched set if you can.
why?
you are creating a front soundstage. you want that to be seamless. if you start to mix and match. or ever worse, make the mistake of making the center channel smaller than the front L/R, watching a multichannel movie will suffer.
then let your A/V receiver handle the crossover between the subwoofer and the mains.
Infact, the tweeters are all the same in each speaker. the center and surrounds have the same drivers. the two towers have a different size drivers, but from the same series and made from same material.
So timbre matching is not an issue.
but me wanting to tweak them is
12-06-2009, 03:42 PM
#15
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Well, I rewired the center internally with 16ga OFC... and I redid the speaker wires from the AVR to the wall in 12ga OFC, Double sheilded (CL2 inwall stuff), and used banana plugs.
Everything else is the same, and TWICE today the AVR overheated and shut itself off. What the hell is that about?
I measured the impedence before and after and it's the SAME! Could changing the speaker wire change the impedence before the amp?
I've been waiting to get a mid range AVR, Onkyo HT-RC180. its almost twice the weight as my Onkyo SR-605, and am expecting much stronger amp.
I wasn't playing that loud or anything. Checked polarity, looks good there.
Everything else is the same, and TWICE today the AVR overheated and shut itself off. What the hell is that about?
I measured the impedence before and after and it's the SAME! Could changing the speaker wire change the impedence before the amp?
I've been waiting to get a mid range AVR, Onkyo HT-RC180. its almost twice the weight as my Onkyo SR-605, and am expecting much stronger amp.
I wasn't playing that loud or anything. Checked polarity, looks good there.