help with passive 2-way crossover design

eksine

Member
2014-10-17 5:34 am
I'm just learning how to make a crossover. I am sourcing parts from partsexpress.com and so far it seems like 2nd order linkwitz- riley is the most common type of crossover used. This is going into my 2002 honda Odyssey. it's taking me forever to select the woofer and tweeter for for the time being I am assuming 4 ohm tweeter, 8 ohm woofer and a 2800 hz crossover point (because morel tempo ultra 602 and polk momo crossovers are set to 2800 or 2750 hz). it will be a 2 way setup. I am confused as to why 2 ways don't have a protection built in to protect the woofer from playing too low, for example, below 150 hz if the woofer is rated to go down to 75 hertz. or why the tweeter has no protection from playing too high, for example above 20k hz if the tweeter is rated for 22k hz? parts express does have premade high pass and low pass crossovers (basically bass blockers and treble blockers), but I still do not understand how they would get added to the circuit. for the sake of me understanding the crossover so I can replace expired capacitors or other parts in the future I think building the crossover using the calculator would be best. instead of using the premade high and low pass crossovers from the website, can I just add a capacitor or an inductor to this circuit? please see my diagram, do I add this part to the end of the circuit nearest to where the amplified signal is coming out of the receiver or do I add it nearest the tweeter/ woofer?

as I'm still new I don't understand L-pad and speaker efficiency and how to match the woofer I choose to the tweeter I choose. must I match the tweeter and driver to the exact same efficiency, for example both must be exactly 91 db 1W/1m? if the ratig is in "dB 2.83V/1m" than I must find a way to convert that into "db 1W/1m" correct?

I did briefly see that the pioneer s6220bs receiver I have has something about "standard mode" to allow me to filter frequencies below 25 - 250 hz, or something to that effect. please help , and if a 2nd order linkwitz riley is not an ideal setup please let me know
 

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I'm just learning how to make a crossover. I am sourcing parts from partsexpress.com and so far it seems like 2nd order linkwitz- riley is the most common type of crossover used. This is going into my 2002 honda Odyssey. it's taking me forever to select the woofer and tweeter for for the time being I am assuming 4 ohm tweeter, 8 ohm woofer and a 2800 hz crossover point (because morel tempo ultra 602 and polk momo crossovers are set to 2800 or 2750 hz). it will be a 2 way setup. I am confused as to why 2 ways don't have a protection built in to protect the woofer from playing too low, for example, below 150 hz if the woofer is rated to go down to 75 hertz. or why the tweeter has no protection from playing too high, for example above 20k hz if the tweeter is rated for 22k hz? parts express does have premade high pass and low pass crossovers (basically bass blockers and treble blockers), but I still do not understand how they would get added to the circuit. for the sake of me understanding the crossover so I can replace expired capacitors or other parts in the future I think building the crossover using the calculator would be best. instead of using the premade high and low pass crossovers from the website, can I just add a capacitor or an inductor to this circuit? please see my diagram, do I add this part to the end of the circuit nearest to where the amplified signal is coming out of the receiver or do I add it nearest the tweeter/ woofer?
Wo there, slow down! That's a lot of questions in one paragraph!

If you have a subwoofer then you do crossover around the woofer's lower frequency, otherwise you probably want whatever you can get from it.


The audio band edges are easier to filter in the preamp, BTW, as there's no requirement to split energy to two destinations, just attenuate it. This is especially true for unwanted subbass which puts a big load on the amp just to have it discarded afterwards as heat in a voice coil. (ie as in that Pioneer you mention later).


There's little point protecting a tweeter from higher frequencies, they are most at danger from high power low/mid bursts of energy. The highest frequencies have much less energy in typical signals, and above 20kHz its usually been completely filtered out from the source anyway.


When designing a crossover from a calculator, don't try to combine it with other bits of circuit, the whole crossover works as a unit to steer energy to the right driver and to present a consistent load impedance to the amplifier (ideally). Well, it is possible to pick and mix if you know what you are doing (understand analog filter theory).
as I'm still new I don't understand L-pad and speaker efficiency and how to match the woofer I choose to the tweeter I choose. must I match the tweeter and driver to the exact same efficiency, for example both must be exactly 91 db 1W/1m? if the ratig is in "dB 2.83V/1m" than I must find a way to convert that into "db 1W/1m" correct?
Yup. The 2.8V figure is for 8 ohm speakers, as V^2/R = 1 watt for that combination. With speakers you are lucky if you can get to within 1dB accuracy, and the room response will alter things a bit too. But yes, you want the drivers to have the same power levels, hence the need for L-pads (a resistive attenuator network) especially for tweeters. You never want to attenuate the woofer, note, as that will affect its damping and waste a lot of power, so normally you ensure the mid driver matches the woofer and the tweeter either matches or is more efficient (and then you can use an L-pad to match it)
I did briefly see that the pioneer s6220bs receiver I have has something about "standard mode" to allow me to filter frequencies below 25 - 250 hz, or something to that effect. please help , and if a 2nd order linkwitz riley is not an ideal setup please let me know
There's a lot of opinions about the best crossover - they are all a compromize in fact. Higher order protects drivers from the wrong frequencies better, but creates more phasing/directivity artifacts when a tone and its harmonics are split across two drivers very discontinuously. And some schemes have constant power, some have constant volume and some have constant impedance, but you can't have all three.


There is no ideal setup, a 2nd order LR is a good starting point.
 
Just to add a little bit to Mark's excellent comments...

It is not enough to understand basic or even advanced configurations. It is also important that you understand how the parts --caps, coils, etc.-- work individually. To not understand this opens one to a large number of mistakes that, although easily avoided, are not apparent without an understanding of theory.

Give the link in my signature a look... That's where the real learning begins.
 
Just buy a set of component speakers that have cross overs. Then a sub woofer and an amp with electronic cross over built in to the amp. You can build your own box, (it's a good place to get your feet wet in DIY audio) or buy a pre built one.

You can design your own cross overs or you can go with a mini DSP but these are areas that require some experience and knowledge if you plan on doing it yourself. I would suggest that you lurk around this forum and read up on the subject and see if you have an interest in it. It takes a while to become proficient enough with the subject to start designing your own crossovers and there are way to many variables to tell you "Hey this is what you need to do.", beyond giving you the values for a text book generic crossover which you can just buy from parts express anyways.

Building your system is a fun and rewarding thing to do but trust me when I say that you will make plenty of mistakes along the way but having a good understanding of the basic principles will help you avoid making costly ones.
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
Playing too low won't hurt a woofer; TOO LOUD too low will, but also makes gross distortion. You have heard this in other cars.

Car sound is almost all 4 Ohms, because voltage is limited, low Z sucks more power.

Car-sound is 99% a cap on the tweeter and done. Do you really need 2nd-order filter? With today's economics you get more leverage by bi-amping. Don't even let the bass into the tweeter amp, a low-level crossover filters before the amps.

My Odyssey is 1996 and I've given up trying to get good sound in that large box of rattles. Even my 2001 Accord is getting clunky. (But as suggested, my last upgrade was pre-designed 2-way speakers--- I used to design crossovers for money but it's too much work to do right for one car.)
 

PRR

Member
Paid Member
2003-06-12 7:04 pm
Maine USA
www.diyaudio.com
Random dip: BOSS R2504 RIOT Amplifier is an honest 4 channels of 90 Watts in 4 Ohms each. This will cover your mids and highs well-enough for most (never enough for competition). It has various filter options to keep deep lows out. They have some strange connections which avoid use of a 5th channel for a subwoofer; looks simple and dubious to me.

Kicker DXA500.1 $230 is an honest 250W 4Ohm mono amp. Kicker Comp Series C15 looks like a serious woofer. (Yeah, it's big, as a woofer should be.)

250 Watts in a Fifteen in an Odyssey should curdle your milk. If you need more you have to shop bigger. (FWIW: I think some of my hearing loss is a mere 17W/ch in the Accord.)
 

eksine

Member
2014-10-17 5:34 am
Wo there, slow down! That's a lot of questions in one paragraph!

If you have a subwoofer then you do crossover around the woofer's lower frequency, otherwise you probably want whatever you can get from it.

I actually just want a 2 way setup, so a 6.5" "woofer", I probably should have said mid-range. for what I'm doing , for now, I want to only run the speakers off the pioneer receiver, so no subwoofer and no other amplifiers. What I ultimately am trying to do is restore this van and making it into a "stealth camper". to be brutally honest and short, was homeless once and I am building a van with a diesel heater, maybe some insulation, I want to add solar panels to the roof, etc. The speakers I am trying to hide them in the stock locations including using the original dashboard tweeter locations that are located in the front corners. I know that that is a bad location for them but my thinking is it will prevent casual theft. I am looking for a "basic" design but I want to make sure I didn't forget to protect the tweeters and mid-range from getting damaged on accident

The audio band edges are easier to filter in the preamp, BTW, as there's no requirement to split energy to two destinations, just attenuate it. This is especially true for unwanted subbass which puts a big load on the amp just to have it discarded afterwards as heat in a voice coil. (ie as in that Pioneer you mention later).

I don't think I was needing to split the energy into 2 locations. I basically thought that by adding a cutoff for the mid-range and tweeter that I was essentially trying to add "bass blockers" or "treble blockers" to each driver to protect them, but since I don't understand how this works, I didn't know if it was important enough to do. yeah setting the lower frequency limit in the receiver seems ok.

There's little point protecting a tweeter from higher frequencies, they are most at danger from high power low/mid bursts of energy. The highest frequencies have much less energy in typical signals, and above 20kHz its usually been completely filtered out from the source anyway.

Ok, I see, thank you


When designing a crossover from a calculator, don't try to combine it with other bits of circuit, the whole crossover works as a unit to steer energy to the right driver and to present a consistent load impedance to the amplifier (ideally). Well, it is possible to pick and mix if you know what you are doing (understand analog filter theory).

The only choices on partsexpress was either a premade crossover that has a 4/8 ohm for the woofer and a 8 ohm for the tweeter. many of the peerless/ vifa tweeters were 4 or 6 ohm so that wouldn't work. Than I saw they have "high pass" and "low pass" crossovers and in their descriptions it says you can combine them to create what you need, for example you buy the 8 or 4 ohm high pass crossover at 3,000hz and combine them with the low pass 8 ohm 3000 hz crossover. and I saw an article explaining that 3, 4-way + designs simply take the high frequency outputs and keep splitting them off to add more speakers to the design. so that's why I assumed you can simply treat each section like a module and mix and match them to change the crossover by adding in any features that you want

Yup. The 2.8V figure is for 8 ohm speakers, as V^2/R = 1 watt for that combination. With speakers you are lucky if you can get to within 1dB accuracy, and the room response will alter things a bit too. But yes, you want the drivers to have the same power levels, hence the need for L-pads (a resistive attenuator network) especially for tweeters. You never want to attenuate the woofer, note, as that will affect its damping and waste a lot of power, so normally you ensure the mid driver matches the woofer and the tweeter either matches or is more efficient (and then you can use an L-pad to match it)

Thank you, I think I understand, make sure the tweeter is equal or higher efficiency and add the L-pad to the tweeter. just quick question: isn't the L-pad simply a variable resistor? it looks like a ...I think they call it a rheostat?

There's a lot of opinions about the best crossover - they are all a compromize in fact. Higher order protects drivers from the wrong frequencies better, but creates more phasing/directivity artifacts when a tone and its harmonics are split across two drivers very discontinuously. And some schemes have constant power, some have constant volume and some have constant impedance, but you can't have all three.


There is no ideal setup, a 2nd order LR is a good starting point.
thank you, that sounds complicated, yes I think I'll keep trying to use the 2nd order LR
 

eksine

Member
2014-10-17 5:34 am
Just buy a set of component speakers that have cross overs. Then a sub woofer and an amp with electronic cross over built in to the amp. You can build your own box, (it's a good place to get your feet wet in DIY audio) or buy a pre built one.

I seriously thought about it. my choice would be morel tempo ultra 602, but this van has two 6.5" woofers in the back too. I figured I would try to match the sound all the way around. I know the back woofers don't contribute much however I am planning on making a "stealth camper" so I might not be sitting in the drivers seat while listening to sound. I likely might be laying on a mattress in the back using a long range antenna using the free wifi from a teriyaki restaurant near walmart's parking lot, or something like that. I want to not draw attention that I have nice speakers in the van, and I am going to add a second battery bank somehow so I rather not have a subwoofer and extra amps other than the receiver draining the battery and taking up space, for now anyways.

You can design your own cross overs or you can go with a mini DSP but these are areas that require some experience and knowledge if you plan on doing it yourself. I would suggest that you lurk around this forum and read up on the subject and see if you have an interest in it. It takes a while to become proficient enough with the subject to start designing your own crossovers and there are way to many variables to tell you "Hey this is what you need to do.", beyond giving you the values for a text book generic crossover which you can just buy from parts express anyways.

it's not quite that I couldn't sit here for a year learning it all but to be truthful, the audio isn't the most important thing right now. I actually DO want a "generic"-ish crossover, something I can maintain for years because I'll know exactly which capacitor and what not to replace when they expire. I also don't want to buy the speakers at best buy for $80, I'm not that crazy

Building your system is a fun and rewarding thing to do but trust me when I say that you will make plenty of mistakes along the way but having a good understanding of the basic principles will help you avoid making costly ones.

I've completely rebuilt the transmission on this and also found out the design flaw on a huge range of hondas from 1998-2006+, I figured out why the transmissions were failing, spent probably $5k+ doing that, than I wasted probably $1500+ learning how to paint, that one wasn't my fault, I listened to horrible advice, I actually was doing nothing wrong at all other than using clearcoat that had abnormal chemical reactions to the basecoat. it acted exactly how paint stripper does. I am looking for a generic-ish crossover design, I'm just making sure I didn't forget to cut off the really high or really low frequencies so the speaker won't be damaged
 

eksine

Member
2014-10-17 5:34 am
Playing too low won't hurt a woofer; TOO LOUD too low will, but also makes gross distortion. You have heard this in other cars.

Car sound is almost all 4 Ohms, because voltage is limited, low Z sucks more power.

The woofers and tweeter on partsexpress aren't really made for car's that's why it's not going to be 4 ohms all the way around, which is why I have to either use their high pass and low pass pre-built crossovers in the right impedance and combine them. the other premade complete crossovers do allow 4 or 8 ohm for the woofer, BUT the tweeter must be 8 ohms which is why I have this crossover problem. the tweeter could be 4 or 6 ohms. thanks for the explanation about playing too loud.

Car-sound is 99% a cap on the tweeter and done. Do you really need 2nd-order filter? With today's economics you get more leverage by bi-amping. Don't even let the bass into the tweeter amp, a low-level crossover filters before the amps.

well, I'm worried the woofer will try to play the high notes and make the overall sound really weird. I am trying to stay away from using amps and subwoofers

My Odyssey is 1996 and I've given up trying to get good sound in that large box of rattles. Even my 2001 Accord is getting clunky. (But as suggested, my last upgrade was pre-designed 2-way speakers--- I used to design crossovers for money but it's too much work to do right for one car.)
I actually have a 2001 accord v6, 235k miles on it, but while learning about cars I've rebuilt a lot of stuff on both vehichles. power steering pump, calipers, fuel pump, wheel bearings are completely rebuilt. new timing belts including all tensioners and bearings. the odyssey has a fully rebuilt transmission that's actually better now than the original design including a shift kit, it even has a rebuilt power steering rack and I rebuilt the subframe bushings
 

eksine

Member
2014-10-17 5:34 am
well the thing is I did read that conductors filter out the high frequencies and capacitors filter out the low frequencies. my basic question was what happens when I add them into the crossover design that the calculator gave me? I do not know how they affect each other when combined. to summarize all I am asking is how do I add a cutoff filter for the highest notes and lowest notes so the speakers do not accidentally get damaged. I am attempting to jump before I can walk. for me the sound is important but it doesn't seem right for me to spend a year learning about electronic theory to get a decent crossover as the end result. I don't understand what this crossover is doing, I'm not denying that at all. my end goal is that I don't think a simple bass block and treble blocker at 5000hz and 150 hertz is going to make me happy, maybe I'm wrong , it just seems like that would sound fairly bad.
I would just buy a generic premade crossover but as I've said, I can't find one that allows both a 4 or 6 ohm tweeter with an 8 ohm midrange and the ones I did find, it seemed like it would work but maybe I should just make one so it's simpler. I am cheating, I'm trying to get a decent crossover made without any knowledge of how it works, I'm hoping experienced guys can tell me what's going on so I can get it on the first try. the reason I'm doing it is so I can prioritize painting the van, fixing the interior, adding a battery bank, a diesel heater, and some kind of sliding solar panel bank on the roof. the audio is for all intents and purposes, important, but focusing months of study in order to build the crossover would be wrong for me

Just to add a little bit to Mark's excellent comments...

It is not enough to understand basic or even advanced configurations. It is also important that you understand how the parts --caps, coils, etc.-- work individually. To not understand this opens one to a large number of mistakes that, although easily avoided, are not apparent without an understanding of theory.

Give the link in my signature a look... That's where the real learning begins.
 
Partsexpress has individual 2nd order crossovers that you can get for the impedance of the speakers you have.

Inductors pass lows and block highs. Capacitors pass highs block lows. Generally speaking.

For a high-pass crossover, the capacitor is in series with the tweeter to block lows. The inductor is connected across the tweeter to bypass any lows that get through. The cap and inductor are chosen to work together to give the crossover point you need.

The same applies to the low-pass crossover but the component locations are reversed.

One more note, you cannot use a 2nd order (12dB/octave) crossover with an open output. You have to have a load on every output. If you leave an output unloaded, it will create very nearly a dead short at the crossover frequency for your amplifier.
 

eksine

Member
2014-10-17 5:34 am
yeah I did see those 2nd order crossover on partsexpress. That was a choice I thought of, but it requires you combine 2 crossovers together so I thought for the sake of simplification so I can replace less parts and it be less complicated to just build something from a calculator.
that open output you're talking about was the first thing that I thought of. what I'm asking is to have a bandpass for the tweeter and woofer using different sets of frequencies. since there's only a midrange and a tweeter I knew right away it wouldn't work because I also assumed you can't just have speakers that are missing and not connected. so basically my questions were about cascading or layering crossovers on top of each other to get the filters I want. I can always try it later, for now I'm going to pick my midrange and tweeter and build exactly what the calculator gives me. I'll check into some of the crossover building softwares online and see what they have too.

Partsexpress has individual 2nd order crossovers that you can get for the impedance of the speakers you have.

Inductors pass lows and block highs. Capacitors pass highs block lows. Generally speaking.

For a high-pass crossover, the capacitor is in series with the tweeter to block lows. The inductor is connected across the tweeter to bypass any lows that get through. The cap and inductor are chosen to work together to give the crossover point you need.

The same applies to the low-pass crossover but the component locations are reversed.

One more note, you cannot use a 2nd order (12dB/octave) crossover with an open output. You have to have a load on every output. If you leave an output unloaded, it will create very nearly a dead short at the crossover frequency for your amplifier.
 
If the woofer and tweeter aren't going to be mounted pretty close together and on the same plane (they rarely are in a car), it's pointless to nitpick over which 2nd order crossover type to use. It ain't going to end up like the graphs predict when it's all put together, so don't sweat those details to no avail.

A couple of things to consider-

Use a passive 1st order Low Pass on the woofer. They're going to be quite a bit off axis in the doors and the response will already be drooping a bit anyway. Hence, the electrical rolloff can be less steep, or even left off altogether.

If you want to filter the low bass from the woofers, do it with an active filter. Most head units and amps can do this, it won't interact with the Low Pass, it will be more accurate (predictable), cheaper and perhaps even adjustable.

Don't waste any more time considering a bandpass on the tweeter for protection, it's less than unnecessary- just use a 2nd order high pass.

I *would* suggest looking over at least the first page of this thread on designing crossovers. It won't take much time, and may be enlightening.

My 2¢.
 

eksine

Member
2014-10-17 5:34 am
If the woofer and tweeter aren't going to be mounted pretty close together and on the same plane (they rarely are in a car), it's pointless to nitpick over which 2nd order crossover type to use. It ain't going to end up like the graphs predict when it's all put together, so don't sweat those details to no avail.

Ok, right on, thanks

A couple of things to consider-

Use a passive 1st order Low Pass on the woofer. They're going to be quite a bit off axis in the doors and the response will already be drooping a bit anyway. Hence, the electrical rolloff can be less steep, or even left off altogether.

yes, this was what I was thinking. whether I do it with the design from the calculator or even with the prebuilt low and high pass crossovers by dayton audio both tweeter and midrange will be filtered at the same frequency 2800 hz. so either way the woofer will be covered, thanks

If you want to filter the low bass from the woofers, do it with an active filter. Most head units and amps can do this, it won't interact with the Low Pass, it will be more accurate (predictable), cheaper and perhaps even adjustable.

yeah, exactly that's what I'll do is adjust it in the pioneer receiver. it is adjustable from 25 hz to 250 hz. the only reason I asked was because I assumed you guys did it within the crossovers, but guess not

Don't waste any more time considering a bandpass on the tweeter for protection, it's less than unnecessary- just use a 2nd order high pass.

understood, thank you

I *would* suggest looking over at least the first page of this thread on designing crossovers. It won't take much time, and may be enlightening.

My 2¢.

alright, thanks. thanks for your help man
 

Gioba

Member
2012-07-24 9:36 pm
I agree tsmith.
To create a passive is difficult, i think not difficult your case, because your system not is complicated: HU + speakers.

I suggest a first order filter: a cap in series tweeter and an inductor in series midwoofer.
Like here for example only: https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&cad=rja&uact=8&ved=2ahUKEwjPiYDf4KfnAhVT6qYKHWsjBj8QFjAMegQIAxAB&url=https%3A%2F%2Fwww.diyaudioandvideo.com%2FTables%2FButterworthCrossover%2F1stOrder%2F&usg=AOvVaw2m0eOYfMJHxYv1JyvvUqbm
For to know what values you can put in series speaker we must to know which speaker are before.
You can post here your idea about the speakers and see together.

For a good sound is important to choose the right midwoofer for the mounting position (freee air, closed box, reflex) reading the parameters, the passive crossover comes after.
Maybe you can to fix the set up with a cap for tweeter only, and nothing for midwoofer.
 
The behaviour of an LC circuit depends on all the components in the network, each can affect the others - there's no real substitute for doing the network analysis (ie using a simulator or crossover design calculator).

LC circuits can only route power, as they (to a first approximation) don't absorb power. The amplifier output won't like power being pushed back at it (this could exceed the current or voltage limits well before full power for instance).

Thus passive crossovers aim to steer power to the correct driver for the frequency, without reflecting too much back at the amplifier.


Simple crossovers act as two separate circuits driven from the amp output, and are isolated from each other by the fact that the amp output is low impedance. This makes things simpler, but not that simple to do well as loudspeakers themselves have varying impedance with frequency - but its a very handy way to simplify the design for a 2nd order crossover.
 
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eksine

Member
2014-10-17 5:34 am
Thanks, I see that 2nd order is more common, why do you recommend 1st order? Do you know what the formula is used for that 1st order and also their 2nd order chart? I am leaning towards 2800 hz for the crossover point so that isn't on any of their charts

I agree tsmith.
To create a passive is difficult, i think not difficult your case, because your system not is complicated: HU + speakers.

I suggest a first order filter: a cap in series tweeter and an inductor in series midwoofer.
Like here for example only: https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&cad=rja&uact=8&ved=2ahUKEwjPiYDf4KfnAhVT6qYKHWsjBj8QFjAMegQIAxAB&url=https%3A%2F%2Fwww.diyaudioandvideo.com%2FTables%2FButterworthCrossover%2F1stOrder%2F&usg=AOvVaw2m0eOYfMJHxYv1JyvvUqbm
For to know what values you can put in series speaker we must to know which speaker are before.
You can post here your idea about the speakers and see together.

For a good sound is important to choose the right midwoofer for the mounting position (freee air, closed box, reflex) reading the parameters, the passive crossover comes after.
Maybe you can to fix the set up with a cap for tweeter only, and nothing for midwoofer.