Hi , I'm looking for some assistance with a crossover I built a while ago . Here's the details :
3-way speaker with SS 8565-01 Bass , Vifa P13-WH Mid and Vifa XT-25 Tweeter in bass reflex enclosure , 1" MDF construction , lots of bracing and dampening etc added. Volume = 120L and tuned to 23hz.
I'm looking to improve the sound - At the moment the bass is excellent but the mid and treble are *average* , something is wrong with the crossover but I'm not sure what. It is a 6dB / Series design taken from basic textbook plan with a few minor adjustments to the tweeter padding.
I don't have any measuring equipment or software but am hoping someone can have a look at my crossover and tell me if there's something obviously wrong or what can be improved / fixed.
see attached drawing.
Andrew
3-way speaker with SS 8565-01 Bass , Vifa P13-WH Mid and Vifa XT-25 Tweeter in bass reflex enclosure , 1" MDF construction , lots of bracing and dampening etc added. Volume = 120L and tuned to 23hz.
I'm looking to improve the sound - At the moment the bass is excellent but the mid and treble are *average* , something is wrong with the crossover but I'm not sure what. It is a 6dB / Series design taken from basic textbook plan with a few minor adjustments to the tweeter padding.
I don't have any measuring equipment or software but am hoping someone can have a look at my crossover and tell me if there's something obviously wrong or what can be improved / fixed.
see attached drawing.
Andrew
Attachments
a bit more info :
xover points are ~ 300 & 3000
I want obviously to keep the drivers & cabinet and just tweak the crossover.
The sound is overall quite *OK* but something is missing when I listen in comparison to some "highend" commercial speakers I have.
The drivers are recessed not surface mounted and in traditional 3-way positioning....T M W
Inductors are aircored low DCR and quality Caps & resisters.
Any thoughts ?
xover points are ~ 300 & 3000
I want obviously to keep the drivers & cabinet and just tweak the crossover.
The sound is overall quite *OK* but something is missing when I listen in comparison to some "highend" commercial speakers I have.
The drivers are recessed not surface mounted and in traditional 3-way positioning....T M W
Inductors are aircored low DCR and quality Caps & resisters.
Any thoughts ?
Hi,
What is wrong with your c/o ? pretty much everything.
See :
http://www.rjbaudio.com/Audiofiles/FRDtools.html
and
http://www.geocities.com/woove99/Spkrbldg/DesigningXO.htm
(for elucidation try wading through :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=88567 )
/sreten.
What is wrong with your c/o ? pretty much everything.
See :
http://www.rjbaudio.com/Audiofiles/FRDtools.html
and
http://www.geocities.com/woove99/Spkrbldg/DesigningXO.htm
(for elucidation try wading through :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=88567 )
/sreten.Have look at Andy's site:
http://members.optusnet.com.au/~gradds55/SeriesXO/series_cross-overs8b.htm
He has a downloadable spreadsheet which should help you tweek your xover values.
Note that you need to use the ACTUAL impedance of your drivers at the xover frequencies.
If you don't have actual measurements, you can get in the ballpark by using the published impedance graphs (although that's not close enough for some here....)
Is there much difference in the sensitivities of the woofer & mid drivers?
http://members.optusnet.com.au/~gradds55/SeriesXO/series_cross-overs8b.htm
He has a downloadable spreadsheet which should help you tweek your xover values.
Note that you need to use the ACTUAL impedance of your drivers at the xover frequencies.
If you don't have actual measurements, you can get in the ballpark by using the published impedance graphs (although that's not close enough for some here....)
Is there much difference in the sensitivities of the woofer & mid drivers?
andrew01 said:
Gee thanks , I've played with them before & got similar results to what I built.
What in particular of "pretty much everything" is wrong ?
example ??
Everything ......
The crossovers assume 8R drivers - very wrong.
The crossover is 1st order electrical - wrong because its not right.
(you have no idea of the resulting acoustic crossover alignment)
The target acoustic slopes should be acoustic, not electrical - wrong.
Baffle step and diffraction effects are ignored - very wrong.
Driver responses are ignored - wrong.
Phase integration of drivers and offsets is ignored - wrong.
etc....
2nd order high pass L/R acoustic slopes on the XT25
(~ 3khz) is possible but it is not simple see :
http://www.zaphaudio.com/ZD5.html
Complementary (but assymetric due to driver offset) ~ 2nd
order low pass L/R acoustic slopes on the P13 is possible.
Mid highpass / bass lowpass is complicated by baffle effects.
Mid driver positioning and baffle size need to be included.
No simple answer without simulation.
Take a look a RJB's 3-way :
http://www.rjbaudio.com/AlpheusMkII/alpheusmkii.html
/sreten.Andrew, I see you’ve asked these questions before; series xovers can be difficult to understand eh? For that reason, I’d go with a parallel xover, easier to tweek.
Here’s how I would proceed using the published graphs & off the shelf components:
Mid unit, a good rep for sound but known to vary from published specs, so use real measurements if poss. I’d go 1st order on this, .82mH and 74uf (47+27 in parallel) in series with the driver.
Tweeter: an excellent 4 ohm unit but a rep for complaining when driven too low, I’d go 2nd order here, 7.4uf (4.7+2.7) in series, .33mH in parallel, tweeter connected out of phase.
L pad, 1 ohm in series & 8.2 ohms in parallel.
Woofer. 1st order needs 3 mh in series, but this needs to be adjusted for baffle step correction; how wide is your cabinet?
(later you may prefer to go 2nd order to let the mid unit do it’s own thing, and this will help with the peak as well)
Notch filter: using this calc: http://www.lalena.com/Audio/Calculator/SeriesNotch/
I get 12uF + .3mh +12ohms in series across the driver (I’ve never needed a notch filter so someone else may be more help here)
Check these numbers with this calculator:
http://ccs.exl.info/calc_cr.html#second
(this will also give you a feel for how component changes affect the result)
Here’s how I would proceed using the published graphs & off the shelf components:
Mid unit, a good rep for sound but known to vary from published specs, so use real measurements if poss. I’d go 1st order on this, .82mH and 74uf (47+27 in parallel) in series with the driver.
Tweeter: an excellent 4 ohm unit but a rep for complaining when driven too low, I’d go 2nd order here, 7.4uf (4.7+2.7) in series, .33mH in parallel, tweeter connected out of phase.
L pad, 1 ohm in series & 8.2 ohms in parallel.
Woofer. 1st order needs 3 mh in series, but this needs to be adjusted for baffle step correction; how wide is your cabinet?
(later you may prefer to go 2nd order to let the mid unit do it’s own thing, and this will help with the peak as well)
Notch filter: using this calc: http://www.lalena.com/Audio/Calculator/SeriesNotch/
I get 12uF + .3mh +12ohms in series across the driver (I’ve never needed a notch filter so someone else may be more help here)
Check these numbers with this calculator:
http://ccs.exl.info/calc_cr.html#second
(this will also give you a feel for how component changes affect the result)
Actually he has most of the components to do an ordinary and "experimental" simple paralel xo
4mH in series with woofer
0.42mH and 68uF in series with mid
6.8uF in series with tweeter
"easy" to ad paralel inductor on tweeter and various RC if needed
And yes, woofer may need a notch, but maybe a bit too advanced at this moment
Components are surely not the perfect values, but should give you some "feel" of the drivers and some idea of what should be done
4mH in series with woofer
0.42mH and 68uF in series with mid
6.8uF in series with tweeter
"easy" to ad paralel inductor on tweeter and various RC if needed
And yes, woofer may need a notch, but maybe a bit too advanced at this moment
Components are surely not the perfect values, but should give you some "feel" of the drivers and some idea of what should be done
Thanks Pete.
Some ideas to mull over.
I was going to do a notch filter but the different online calculators i tried all gave different values - so I left it out
I also tried a parallel xover as per tinitus' suggestion and I think I proved to myself there is no difference between series & parallel.
Will the cabinet naturally roll-off some of that spike at 2500hz ?
Some ideas to mull over.
I was going to do a notch filter but the different online calculators i tried all gave different values - so I left it out
I also tried a parallel xover as per tinitus' suggestion and I think I proved to myself there is no difference between series & parallel.
Will the cabinet naturally roll-off some of that spike at 2500hz ?
A simple 2way series xo may work ok ... I have never tried it ... but a simple 3way wont ever work just like that
You need paralel filter ... but it dont stop by just converting to paralel
Xo needs adjustment
Woofer really needs to be 2.order ... ad a paralel cap
Tweeter needs a paralel inductor ... attenuation may need adjustment
Midrange needs an RC ... and inverted polarity
With this you will achieve a 2.order acoustic rolloff ... with some luck ... but at least you may learn something
A hybrid may be possible ... but I dont know how
You need paralel filter ... but it dont stop by just converting to paralel
Xo needs adjustment
Woofer really needs to be 2.order ... ad a paralel cap
Tweeter needs a paralel inductor ... attenuation may need adjustment
Midrange needs an RC ... and inverted polarity
With this you will achieve a 2.order acoustic rolloff ... with some luck ... but at least you may learn something
A hybrid may be possible ... but I dont know how
sorry, but there is no way the 3-way linked will work effectively with the P13WH and XT25 tweeter.
Can you swap out the tweeter for a Seas or something, and lower the x-o points to say 250 and 2500, you may just have a chance then, although your woofer also seems to be of margina usefullness.
This type of crossover can work, but ONLY with the right driver choices, and a woofer with big breakup is always going to be problematic with a low order crossover.
Can you swap out the tweeter for a Seas or something, and lower the x-o points to say 250 and 2500, you may just have a chance then, although your woofer also seems to be of margina usefullness.
This type of crossover can work, but ONLY with the right driver choices, and a woofer with big breakup is always going to be problematic with a low order crossover.
Without measurement and simulation, you are really shooting in the dark.
If there is no measurement, at least simulation can help. I would use a number of FRD tools. First to create the FRD and ZMA files from manufacturer's datasheets. Then use BSD to simulate the baffle. Then plot them with SpeakerWorkshop. Then design your XO... You can get very good result.
If there is no measurement, at least simulation can help. I would use a number of FRD tools. First to create the FRD and ZMA files from manufacturer's datasheets. Then use BSD to simulate the baffle. Then plot them with SpeakerWorkshop. Then design your XO... You can get very good result.
I'm not trying to stir this can of worms, but series and parallel crossovers can indeed both be satisfactory. The big however, and it is big, is that series is much much more difficult to design, not least because the values are inter-dependent.
So definitely you should start with parallel; that way a value change experimentally will affect only one driver.
It would help a lot if you had minimal test equipment, a meter and an oscillator.
I would suggest paying close attention to some of the other replies, including Pete McK. Some real nuggets there.
I'd add to that advice; use a zobel on the woofer, a conjugate and a zobel on the mid, and a conjugate on the tweeter. These will provide for a much more constant driver impedance, so that the effects of the crossover components will be more predictable.
I'd also say that you should go for the trap on the woofer. One way to tell if it is effective is to just listen to the woofer with full range music, preferably classical with massed violins with the other drivers disconnected. (Another advantage of parallel design.) You should hear harshness without the trap, and an effective trap would kill the harshness.
So definitely you should start with parallel; that way a value change experimentally will affect only one driver.
It would help a lot if you had minimal test equipment, a meter and an oscillator.
I would suggest paying close attention to some of the other replies, including Pete McK. Some real nuggets there.
I'd add to that advice; use a zobel on the woofer, a conjugate and a zobel on the mid, and a conjugate on the tweeter. These will provide for a much more constant driver impedance, so that the effects of the crossover components will be more predictable.
I'd also say that you should go for the trap on the woofer. One way to tell if it is effective is to just listen to the woofer with full range music, preferably classical with massed violins with the other drivers disconnected. (Another advantage of parallel design.) You should hear harshness without the trap, and an effective trap would kill the harshness.
Andy,
I am happy to take your offer. Given your enormous contributions to the DIY community and posted such vast information about speaker building especially about series crossovers in your website, my hat is off to you. I read all the information you have on your website a couple of years ago and actually tried a series XO before. I am very curious about your results. I went to Newcastle twice in the past two months for my new speaker cabinets and missed the chance. But when I get less busy (doing house renovation at the moment) I will be happy to drive up there to visit you. I will have my NaO speakers in new cabinets very soon and will have my new MTMWWSubSub OB speakers (cabinets received this Monday) designed and built in the next a few months and you will be more than welcome to be my guest in Sydney. I live in a northwestern suburb and is only 1.5 hour away from Newcastle.
Regards,
Bill
I am happy to take your offer. Given your enormous contributions to the DIY community and posted such vast information about speaker building especially about series crossovers in your website, my hat is off to you. I read all the information you have on your website a couple of years ago and actually tried a series XO before. I am very curious about your results. I went to Newcastle twice in the past two months for my new speaker cabinets and missed the chance. But when I get less busy (doing house renovation at the moment) I will be happy to drive up there to visit you. I will have my NaO speakers in new cabinets very soon and will have my new MTMWWSubSub OB speakers (cabinets received this Monday) designed and built in the next a few months and you will be more than welcome to be my guest in Sydney. I live in a northwestern suburb and is only 1.5 hour away from Newcastle.
Regards,
Bill
Curmudgeon said:
or work with 2-way series for several speaker designs first., before attempting a 3-way linked
And for the 3-way linked you have to be VERY finicky about driver choice.
mid and tweeter about the same spl rating, woofer extra 3-4dB to allow for bsc, or you will be padding the ... out of the mid and tweeter !
ALL drivers need to be very well behaved for some distance either side of the operation band. etc etc etc
You are combining, NOT controlling the drivers.
Just my thoughts, be they wrong or right, only the ears can be the final judgement
Ok just for starters & fun I'll try Pete's suggestion.
PARALLEL Xover
*************
Tweeter 12dB 7.4uF with 0.33mH , with 1ohm/8ohm pad.
Mid 0.4mH and 68uF (re-use components)
Bass 12dB 4mH and somevalue C on ???.
(May need to add notch later)
( I'm not sure how to re-calculate the C value so that I can re-use the 4mH inductor ???? )
and my other question is :
Do I need to reverse the polarity on the tweeter only or both tweeter and mid ?
PARALLEL Xover
*************
Tweeter 12dB 7.4uF with 0.33mH , with 1ohm/8ohm pad.
Mid 0.4mH and 68uF (re-use components)
Bass 12dB 4mH and somevalue C on ???.
(May need to add notch later)
( I'm not sure how to re-calculate the C value so that I can re-use the 4mH inductor ???? )
and my other question is :
Do I need to reverse the polarity on the tweeter only or both tweeter and mid ?
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