Big_Bill
There are some handy tools here.
http://www.pvconsultants.com/audio/frdgroup.htm
What can help you is PCD (passive crossover designer that runs in Excel) and you can use SPL Tools to create FRD & ZMA from frequency response and impedance plots. These allow you to see what is happening to the driver behaviour which you can't do with calculators. It only goes up to a 3-way but it's not too hard to get a 0.5 woofer in to blend.
Zobels are handy to flatten the impedance rise on drivers and generally not required for 0.5 woofers crossed over low or tweeters. Most cases the actual values differ from calculated value as they are very useful for shaping the roll off on the drivers as well as pushing down nasties. Calculated values generally provide impedance correction almost all the way to Fs but this is not usually required and much smaller cap values can be used as well as different resistor values. I use them as a tailoring tool to achieve a final target.
Roman has some FRD and ZMA files that you can play with to become familiar with PCD. That way you can play with filters, zobels and all sorts of goodies and actually see how they effect the overall filter, phase, roll off, impedance etc.
http://www.rjbaudio.com/Audiofiles/Driver FRD files.html
You can look at some of his crossovers and then play looking at what it does to driver behaviour.
A good book like the Loudspeaker Design Cookbook can help to explain things (but can add more questions and slight confusion????).
There are some handy tools here.
http://www.pvconsultants.com/audio/frdgroup.htm
What can help you is PCD (passive crossover designer that runs in Excel) and you can use SPL Tools to create FRD & ZMA from frequency response and impedance plots. These allow you to see what is happening to the driver behaviour which you can't do with calculators. It only goes up to a 3-way but it's not too hard to get a 0.5 woofer in to blend.
Zobels are handy to flatten the impedance rise on drivers and generally not required for 0.5 woofers crossed over low or tweeters. Most cases the actual values differ from calculated value as they are very useful for shaping the roll off on the drivers as well as pushing down nasties. Calculated values generally provide impedance correction almost all the way to Fs but this is not usually required and much smaller cap values can be used as well as different resistor values. I use them as a tailoring tool to achieve a final target.
Roman has some FRD and ZMA files that you can play with to become familiar with PCD. That way you can play with filters, zobels and all sorts of goodies and actually see how they effect the overall filter, phase, roll off, impedance etc.
http://www.rjbaudio.com/Audiofiles/Driver FRD files.html
You can look at some of his crossovers and then play looking at what it does to driver behaviour.
A good book like the Loudspeaker Design Cookbook can help to explain things (but can add more questions and slight confusion????).
Thank you Moondog55 and Rabbitz!
I am using the xo design software from Jeff Bagby and am impressed. I have one quick question for you guys, does the "spread" Jeff Bagby uses in the software refer to the ten percent rule Ted has mentioned before? IE: For 300-3000, one would use 330-2700. Or does it refer to something different all together?
Bill.
I am using the xo design software from Jeff Bagby and am impressed. I have one quick question for you guys, does the "spread" Jeff Bagby uses in the software refer to the ten percent rule Ted has mentioned before? IE: For 300-3000, one would use 330-2700. Or does it refer to something different all together?
Bill.
I can't answer that one, maybe the answer is in the help files for the program.
The program should allow you to set the XO frequencies for each driver anyway, so you can see the results graphed, not sure that they will be accurate with-out using driver FRD and ZMP files tho
Bill FRD and ZMP files are the Frequency Response and Impedance data, have downloaded that set of programs but don't use it as much as ; perhaps; I should.
Play with it.
The wider the midrange spread the less the woofer and tweeter interaction though.
If you used XO points of 120 and 3840, which is 5 octaves, I think the "Spread" is 32, the inverse of 32 is 1/32 which is 3.2% you would not bother ( as I understand it )
It is usual to use 3 octaves at a minimum for the midrange .
Cross-overs are / used to be called dividing networks; I do think that term is a better description of what they do
The program should allow you to set the XO frequencies for each driver anyway, so you can see the results graphed, not sure that they will be accurate with-out using driver FRD and ZMP files tho
Bill FRD and ZMP files are the Frequency Response and Impedance data, have downloaded that set of programs but don't use it as much as ; perhaps; I should.
Play with it.
The wider the midrange spread the less the woofer and tweeter interaction though.
If you used XO points of 120 and 3840, which is 5 octaves, I think the "Spread" is 32, the inverse of 32 is 1/32 which is 3.2% you would not bother ( as I understand it )
It is usual to use 3 octaves at a minimum for the midrange .
Cross-overs are / used to be called dividing networks; I do think that term is a better description of what they do
Dividing Networks. I like that!
I accept that you’re no “expert”, but to me you are a close second. I really appreciate all your help!
Jeff’s software explains this “Spread” in what are to me vague terms at best. I’ll figure the values with the single purpose calculators as opposed to three way calculator and run them by you before proceeding.
First I will only “Zobel” the AV8 and Peerless.
I’ll disregard the Pyle at this point as you’ve recommended.
I’m in agreement about a first order Butterworth for the AV8.
I’m in agreement about a first order Butterworth for the top of the peerless.
I’m in agreement about the second order for the Peerless at the bottom.
I’m in agreement about a second order Linkwitz-Riley for the Vifa.
Now just so I’m clear, we are going to shift the first order Butterworth crossover point by ten percent in either direction, but do we use the same ten percent with the second order Linkwitz-Riley?
Post Script: ; As for the peerless, just for clarification do you mean second order Butterworth or Linkwitz-Riley?
Bill.
Moondog55 said:
I accept that you’re no “expert”, but to me you are a close second. I really appreciate all your help!
Jeff’s software explains this “Spread” in what are to me vague terms at best. I’ll figure the values with the single purpose calculators as opposed to three way calculator and run them by you before proceeding.
First I will only “Zobel” the AV8 and Peerless.
I’ll disregard the Pyle at this point as you’ve recommended.
I’m in agreement about a first order Butterworth for the AV8.
I’m in agreement about a first order Butterworth for the top of the peerless.
I’m in agreement about the second order for the Peerless at the bottom.
I’m in agreement about a second order Linkwitz-Riley for the Vifa.
Now just so I’m clear, we are going to shift the first order Butterworth crossover point by ten percent in either direction, but do we use the same ten percent with the second order Linkwitz-Riley?
Post Script: ; As for the peerless, just for clarification do you mean second order Butterworth or Linkwitz-Riley?
Bill.
I usually use and calculate L/R second orders electrical,
that 10% allowance for the spread query is difficult to explain quickly but I'll try as best I can.
As I understand things; unless the drivers are perfectly time aligned a first order XO has interactions that induce a ripple in the overall response of the speaker, and these ripples can extend for many octaves on either side of the XO frequency.
The steeper the electrical XO the less these ripples effect the overall sound, and the ripple effect is less.
All electrical components react with one another.
A 3-way XO isn't the same as two 2-way crossovers combined.
The "allowance" of 10% in the XO frequency is simply to stop a little of that interaction between the filter components, as you have decided on the width of the midrange it then makes sense to drop the XO frequency of the woofer by 10%, and at the same time increase the XO frequency of the tweeter by the same amount.
It isn't "accurate" as such; it is however a guideline that some expert designers recommend for beginners like me as a starting place for designing cross-overs
that 10% allowance for the spread query is difficult to explain quickly but I'll try as best I can.
As I understand things; unless the drivers are perfectly time aligned a first order XO has interactions that induce a ripple in the overall response of the speaker, and these ripples can extend for many octaves on either side of the XO frequency.
The steeper the electrical XO the less these ripples effect the overall sound, and the ripple effect is less.
All electrical components react with one another.
A 3-way XO isn't the same as two 2-way crossovers combined.
The "allowance" of 10% in the XO frequency is simply to stop a little of that interaction between the filter components, as you have decided on the width of the midrange it then makes sense to drop the XO frequency of the woofer by 10%, and at the same time increase the XO frequency of the tweeter by the same amount.
It isn't "accurate" as such; it is however a guideline that some expert designers recommend for beginners like me as a starting place for designing cross-overs
Good question, I don't know the answer.
Help with that one ??-- anybody???
I would like to know the answer as much as Bill
Bill it starts to get very complicated after this; you then have to decide if you are going to make changes in the XO to allow for driver horizontal offset, different filter "Q"s have different shapes, so "EVERYTHING" is interacting with everything else.
Are you a member of a local library? or have any mates who own the Vance Dickason " Loud Speaker Design Cookbook" that you could borrow?? you need to start learning lots of stuff.
I've been building speakers for a few years now and have only just started to scratch the surface of the subject.
Please see my sig at the bottom of the page
Help with that one ??-- anybody???
I would like to know the answer as much as Bill
Bill it starts to get very complicated after this; you then have to decide if you are going to make changes in the XO to allow for driver horizontal offset, different filter "Q"s have different shapes, so "EVERYTHING" is interacting with everything else.
Are you a member of a local library? or have any mates who own the Vance Dickason " Loud Speaker Design Cookbook" that you could borrow?? you need to start learning lots of stuff.
I've been building speakers for a few years now and have only just started to scratch the surface of the subject.
Please see my sig at the bottom of the page
What if.....
If the idea of ten percent is to have the drivers “Meet” where the frequencies intersect at minus three decibels in a first order x/o (6db per octave) then logic would suggest five percent would have the frequencies meet at minus three decibels in a second order x/o (12 db per octave) correct?
If the idea of ten percent is to have the drivers “Meet” where the frequencies intersect at minus three decibels in a first order x/o (6db per octave) then logic would suggest five percent would have the frequencies meet at minus three decibels in a second order x/o (12 db per octave) correct?
I think thats wrong, the cross-over frequency is where both drivers are down 3 or 6dB.
For 1st order BW that is 3dB down and for a 2-way, IF both drivers are radiating from the same plane ( i:e they have the voice coil centers aligned ) they should sum flat.
Speed of sound isn't fixed either is it? It varies depending on atmospheric pressure and temperature I think.
Don't get hung up too much on that 10% figure Bil, it was a recommendation from David Weems book and definitely aimed at beginners like me.
think it is used by him to stop the possibility of the tweeter acting in concert with the woofer in an additive or subtractive manner, I think thats why the advice to use the inverse ratio of the spread as a fudge factor.
Makes sense, as the midrange bandwidth shrinks ( becomes narrower ) the possibility of interaction between the woofer and the tweeter becomes more likely
For 1st order BW that is 3dB down and for a 2-way, IF both drivers are radiating from the same plane ( i:e they have the voice coil centers aligned ) they should sum flat.
Speed of sound isn't fixed either is it? It varies depending on atmospheric pressure and temperature I think.
Don't get hung up too much on that 10% figure Bil, it was a recommendation from David Weems book and definitely aimed at beginners like me.
think it is used by him to stop the possibility of the tweeter acting in concert with the woofer in an additive or subtractive manner, I think thats why the advice to use the inverse ratio of the spread as a fudge factor.
Makes sense, as the midrange bandwidth shrinks ( becomes narrower ) the possibility of interaction between the woofer and the tweeter becomes more likely
I have just been doing some reading, a lot of this interaction is due to the different distances from the ears of the drivers, even us old deaf peoples can here different arrival times apparently.
So if the woofer is a big one with a deep basket the voice coil could be 5 inches behind the front of the baffle, midrange drivers are smaller and usually shallower, so the voice coil will only be about 1inch behind the baffle.
At 250Hz an offset of 4 inches will be a delay of 147milliseconds, that is one reason why we need to use that separation of the XO frequencies.
Regards
Ted
So if the woofer is a big one with a deep basket the voice coil could be 5 inches behind the front of the baffle, midrange drivers are smaller and usually shallower, so the voice coil will only be about 1inch behind the baffle.
At 250Hz an offset of 4 inches will be a delay of 147milliseconds, that is one reason why we need to use that separation of the XO frequencies.
Regards
Ted
Check this out!
It’s from Jeff Bagby’s 3 way crossover calculator. I think it’s a fine place to start and then tweak. What do you think?
Second Order Linkwitz-Riley
Tweeter- High Pass Section
C1= 6.28 uF
L1= 0.45 mH
Woofer - Low Pass Section
L2= 5.87 mH
C2= 47.92 uF
Midrange - Band Pass Section
C3= 58.80 uF
L3= 6.29 mH
C4= 4.13 uF
L4= 0.52 mH
Bandpass Gain= 2.08 dB
R eq= 1.57 ohm
Midrange Polarity= Reversed
It doesnt look to expensive to build.
Bill.
It’s from Jeff Bagby’s 3 way crossover calculator. I think it’s a fine place to start and then tweak. What do you think?
Second Order Linkwitz-Riley
Tweeter- High Pass Section
C1= 6.28 uF
L1= 0.45 mH
Woofer - Low Pass Section
L2= 5.87 mH
C2= 47.92 uF
Midrange - Band Pass Section
C3= 58.80 uF
L3= 6.29 mH
C4= 4.13 uF
L4= 0.52 mH
Bandpass Gain= 2.08 dB
R eq= 1.57 ohm
Midrange Polarity= Reversed
It doesnt look to expensive to build.
Bill.
I agree to using what you already have in stock Bill.
Using a second order function for the low pass at 3000 on the midrange may actually make the acoustic slope too steep, the Peerless already has a nice clean second order roll-off, I'd stick with a first order there and change it later if needed, values are smaller and therefore the associated costs are lower if you do need to buy components.
Has any-one out there used Bills combination of the Peerless 832873 HDS 5-1/4" with his Vifa D26TG-05-06 ??
If so where did you cross and what XO did you use?
Using a second order function for the low pass at 3000 on the midrange may actually make the acoustic slope too steep, the Peerless already has a nice clean second order roll-off, I'd stick with a first order there and change it later if needed, values are smaller and therefore the associated costs are lower if you do need to buy components.
Has any-one out there used Bills combination of the Peerless 832873 HDS 5-1/4" with his Vifa D26TG-05-06 ??
If so where did you cross and what XO did you use?
I haven't used that driver but have done several using the older 850488 and that could be crossed over successfully between 3k-3.5k using 1st order networks.
The FR roll off only gives a small part of the story as even though the roll off can look good with the filter in place, the sonics can suffer. The P13 is a good example and sounds better when crossed over lower than it's perceived capabilities. I've just done a 5" SEAS where the response looked good enough to crossover around 3.5k but had to cut it off at the nuts below 2.5k as it became edgy.
Bill
Don't get hung up on the 10% thing. There used to be rules on 3-ways where you have a 3 octave or 3.4 octave spread between the crossover points but I think that was a lot to do with design formulae. Keeping the spread above 3 octaves (Fh/Fl=8) is a good idea and you find a lot of 3-ways presented here and on sites are way above that as builders are tending to cross over the woofer to mid much lower as there is a trend away from dedicated mids to mid woofers which can be pushed lower.
The summed FR is one thing but you really have to check how the drivers are summing at each crossover point (phase etc) and the easiest is checking the reverse null to see if it's nice and deep. If that's the case, then the phase at the crossover point is good.
That said, I've never had complete success with 3-way filters that I was completely happy with.... sounded good but not great.... so I'm not the best guide.
The FR roll off only gives a small part of the story as even though the roll off can look good with the filter in place, the sonics can suffer. The P13 is a good example and sounds better when crossed over lower than it's perceived capabilities. I've just done a 5" SEAS where the response looked good enough to crossover around 3.5k but had to cut it off at the nuts below 2.5k as it became edgy.
Bill
Don't get hung up on the 10% thing. There used to be rules on 3-ways where you have a 3 octave or 3.4 octave spread between the crossover points but I think that was a lot to do with design formulae. Keeping the spread above 3 octaves (Fh/Fl=8) is a good idea and you find a lot of 3-ways presented here and on sites are way above that as builders are tending to cross over the woofer to mid much lower as there is a trend away from dedicated mids to mid woofers which can be pushed lower.
The summed FR is one thing but you really have to check how the drivers are summing at each crossover point (phase etc) and the easiest is checking the reverse null to see if it's nice and deep. If that's the case, then the phase at the crossover point is good.
That said, I've never had complete success with 3-way filters that I was completely happy with.... sounded good but not great.... so I'm not the best guide.
That is not murder, it is justifiable homicide.
Seriously; stop worrying and build it!
What can go wrong? if it sounds awful we can help fix it, if it sounds better we can help you tweak it and if it sounds good NO PROBLEM !!
The world won't end if we have made a mistake.
Given what you had to start with that you said sounded awful, what you have now will sound reasonable.
It is a little bit like having a baby i suppose, but with speakers you CAN go back and do it again to fix possible problems.
Seriously; stop worrying and build it!
What can go wrong? if it sounds awful we can help fix it, if it sounds better we can help you tweak it and if it sounds good NO PROBLEM !!
The world won't end if we have made a mistake.
Given what you had to start with that you said sounded awful, what you have now will sound reasonable.
It is a little bit like having a baby i suppose, but with speakers you CAN go back and do it again to fix possible problems.
Hey you guy's!!!!!!!!
Here is what I've decided so far:
I've ordered a inexpensive (yet fairly accurate) LCR Meter. See: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=170329485828
The thinking behind this is that for roughly $28.00 US (shipped) I can "unwind" (to the needed values) the inductors I already have. This will save me $60.00 US versus having to purchase (and ship) "new" coil's. I basically get the meter for free! Well I am telling myself that anyway. Not to mention the added benefit of being able to test summed capacitance, voice coil impedance ect.. for myself!
As for "go ahead and jump" I'm ready! This is where I will start:
Second Order Linkwitz-Riley
Tweeter- High Pass Section
C1= 6.28 uF
L1= 0.45 mH
Woofer - Low Pass Section
L2= 5.87 mH
C2= 47.92 uF
Midrange - Band Pass Section
C3= 58.80 uF
L3= 6.29 mH
C4= 4.13 uF
L4= 0.52 mH
Now for the next catastrophe in waiting, "Actual acoustic measurements"!
I have borrowed a "Mate's" Radio Shack digital sound level meter. Will this meter "do" in a pinch? Where can I/should I purchase a proper test tone CD? How many different tones are needed to get a accurate representation of the speakers performance? Ect.........
Very gratefully, Bill.
Here is what I've decided so far:
I've ordered a inexpensive (yet fairly accurate) LCR Meter. See: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=170329485828
The thinking behind this is that for roughly $28.00 US (shipped) I can "unwind" (to the needed values) the inductors I already have. This will save me $60.00 US versus having to purchase (and ship) "new" coil's. I basically get the meter for free! Well I am telling myself that anyway. Not to mention the added benefit of being able to test summed capacitance, voice coil impedance ect.. for myself!
As for "go ahead and jump" I'm ready! This is where I will start:
Second Order Linkwitz-Riley
Tweeter- High Pass Section
C1= 6.28 uF
L1= 0.45 mH
Woofer - Low Pass Section
L2= 5.87 mH
C2= 47.92 uF
Midrange - Band Pass Section
C3= 58.80 uF
L3= 6.29 mH
C4= 4.13 uF
L4= 0.52 mH
Now for the next catastrophe in waiting, "Actual acoustic measurements"!
I have borrowed a "Mate's" Radio Shack digital sound level meter. Will this meter "do" in a pinch? Where can I/should I purchase a proper test tone CD? How many different tones are needed to get a accurate representation of the speakers performance? Ect.........
Very gratefully, Bill.
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