Hello,
I am trying to build a passive crossover for the first time and here is the rough drawing of crossover that I sketched earlier today.
The drivers that I am trying to make use with the crossover are;
Eminence APT50 super tweeter
https://thespeakerfactory.com.au/products/eminence-apt50-horn-driver-1-50-watt
=> Recommended Crossover 3.5 kHz / 12 dB kHz
Eminence Beta 12a Woofer
https://thespeakerfactory.com.au/products/eminence-beta-12a-2-12-speaker-250-watts
Cap & inductor value got from online crossover calculator.
What I do not fully understand is if I put Zobel Circuit corectly in place. I put them in front of woofer and no zobel for tweeter. Am I on the right track?
And, not sure how I can make inductor with 0.73 mH value. Is there a way to measure the inductor value with multimeter by any chance?
Any guidance would be hugely appreciated.
Thank you.
I am trying to build a passive crossover for the first time and here is the rough drawing of crossover that I sketched earlier today.
The drivers that I am trying to make use with the crossover are;
Eminence APT50 super tweeter
https://thespeakerfactory.com.au/products/eminence-apt50-horn-driver-1-50-watt
=> Recommended Crossover 3.5 kHz / 12 dB kHz
Eminence Beta 12a Woofer
https://thespeakerfactory.com.au/products/eminence-beta-12a-2-12-speaker-250-watts
Cap & inductor value got from online crossover calculator.
What I do not fully understand is if I put Zobel Circuit corectly in place. I put them in front of woofer and no zobel for tweeter. Am I on the right track?
And, not sure how I can make inductor with 0.73 mH value. Is there a way to measure the inductor value with multimeter by any chance?
Any guidance would be hugely appreciated.
Thank you.
Attachments
Hi Decommo,
Online Xovers typically work with you inputting a frequency and resistance value. This gives a an electrical Xover set of values for a certain type of response 2nd order Butterworth or 2nd order Linkwitz Riley, there are others as well.
The actual impedance of the bass driver typically rises past a few 100Hz and can double in value which you need to factor into the equation, In your case you have a zobel which aims to counteract this impedance rise. You have chosen somewhere around 6 ohms or so.
Additionally depending on what size baffle the cabinet has will affect the frequency response. It will not be the same as the manufacturers nice flattish graph. This effect is known as diffraction loss or baffle step. to compensate people often use a larger inductor and tune the other components to get somewhere between 4 - 6 dBs attenuation to make the mids match the bass and achieve a flatter response. The cabinet edges will also add some ripples in the frequency response, which could also be considered and measured.
The tweeter is designed to go with a horn, so you will need to factor in which one you are going to buy. You have a choice of horns for that frequency range and 1inch throat diameter, At the same time horns offer sound dispersion or directivity characteristics you may want to match that with your bass unit directivity. Although that may need a lower frequency driver and bigger horn?? I have never done a large driver and horn tweeter but many others here have so they will add further information I am sure.
You may or may not need a resistive Lpad to make the tweeter output match the bass once corrected for diffraction loss. Tweeters can have Zobel's but quite often if the Xover frequency is 2 or 3 times higher than the natural resonance this gets ignored. Measurements can help with the decision.
Winding inductors is doable, but most loudspeaker component suppliers sell them, and the values you may end up with for a 2.5Khz Xover should not be too expensive.
You can search for information for Baffle step, edge diffraction, winding inductors, if you have older relatives who are ham radio or valve types they probably have a text book or two on winding and making your own inductors.
Your Xover is the beginning of something, and depending on where, you were planning on using the speakers and what sized enclosure you were going to mount them in could work wonderfully. At the same time it may benefit from some further tweaking.
As the two drivers would seem to be a useable together, although I havent checked the measurement graphs, it may be worth looking at the Eminence web pages for suitable kits or Xover and horn information for a 12" and 1 Inch tweeter.
Keep asking questions and have a look here as well:
https://www.diyaudio.com/community/...n-your-own-speaker-from-scratch.332688/unread
Online Xovers typically work with you inputting a frequency and resistance value. This gives a an electrical Xover set of values for a certain type of response 2nd order Butterworth or 2nd order Linkwitz Riley, there are others as well.
The actual impedance of the bass driver typically rises past a few 100Hz and can double in value which you need to factor into the equation, In your case you have a zobel which aims to counteract this impedance rise. You have chosen somewhere around 6 ohms or so.
Additionally depending on what size baffle the cabinet has will affect the frequency response. It will not be the same as the manufacturers nice flattish graph. This effect is known as diffraction loss or baffle step. to compensate people often use a larger inductor and tune the other components to get somewhere between 4 - 6 dBs attenuation to make the mids match the bass and achieve a flatter response. The cabinet edges will also add some ripples in the frequency response, which could also be considered and measured.
The tweeter is designed to go with a horn, so you will need to factor in which one you are going to buy. You have a choice of horns for that frequency range and 1inch throat diameter, At the same time horns offer sound dispersion or directivity characteristics you may want to match that with your bass unit directivity. Although that may need a lower frequency driver and bigger horn?? I have never done a large driver and horn tweeter but many others here have so they will add further information I am sure.
You may or may not need a resistive Lpad to make the tweeter output match the bass once corrected for diffraction loss. Tweeters can have Zobel's but quite often if the Xover frequency is 2 or 3 times higher than the natural resonance this gets ignored. Measurements can help with the decision.
Winding inductors is doable, but most loudspeaker component suppliers sell them, and the values you may end up with for a 2.5Khz Xover should not be too expensive.
You can search for information for Baffle step, edge diffraction, winding inductors, if you have older relatives who are ham radio or valve types they probably have a text book or two on winding and making your own inductors.
Your Xover is the beginning of something, and depending on where, you were planning on using the speakers and what sized enclosure you were going to mount them in could work wonderfully. At the same time it may benefit from some further tweaking.
As the two drivers would seem to be a useable together, although I havent checked the measurement graphs, it may be worth looking at the Eminence web pages for suitable kits or Xover and horn information for a 12" and 1 Inch tweeter.
Keep asking questions and have a look here as well:
https://www.diyaudio.com/community/...n-your-own-speaker-from-scratch.332688/unread
First of all, thank you so much for your thorough explanation. Yes, I chose 2nd order Linkwitz Riley from the calculator.
Yes, I put 6ohm which I got from bass driver spec.
Thank you. My initial idea is to try to build the simplest workable crossover to make it as simple as possible since I am total novice who never built crossover or measurement before. After trying one or two crossover building project, would love to consider these factors for further improvement & learning.
Yep. I think that there is a gap between 12" woofer and super tweeter and may need mid range driver between. I chose not to because this super tweeter can be screwed at the back of the bass driver and become coaxial driver which I thought cool and no need to make another mounting hole in the front baffle.
Thank you. I will just source suitable air core inductor at matching value. I have existing crossover that I sourced from another speakers but it has different value so I thought that I could salvage them. If measuring inductor is not easy, might just get new ones to save hassle.
Thank you for referring the link. It has so much information so it would take quite awhile to read and digest info on the thread.
For coaxial Eminence beta 12cx with apt50 driver there is Finnish DIY project whose crossover network is available here:
https://audiovideo.fi/wp-content/up...aiset-veljekset-beta-12cx-jakosuodin-uusi.jpg
Here is the project https://audiovideo.fi/opas/kaiutinr...eta-10cx-ja-beta-12cx-koaksiaalielementeista/
https://audiovideo.fi/wp-content/up...aiset-veljekset-beta-12cx-jakosuodin-uusi.jpg
Here is the project https://audiovideo.fi/opas/kaiutinr...eta-10cx-ja-beta-12cx-koaksiaalielementeista/
The online calculators don't account for the actual impedance as it varies with frequency for both drivers, and they supply an electrical slope. The don't and cannot account for the response errors of the drivers to allow you to arrive at a final acoustic slope, nor do they account for directivity and a host of other variables that factor into design. They're pretty much worthless.
The APT50 is not the correct driver for this application as it needs to be crossed at 3.5kHz min according to the spec sheet. It's a pretty average driver at best.
The APT50 is not the correct driver for this application as it needs to be crossed at 3.5kHz min according to the spec sheet. It's a pretty average driver at best.
Check threads from members Fabricadetobbaco and Celef they played a bit with Eminence's coax.
Link given by Tmuikku is a good source of info too for this drivers.
My experience with them is they are ok as wedge on stage for musician's monitor and can be pleasing as typical loudspeakers but they are definetly not the last word on accuracy. I'm with Brett on this.
That should not stop you to experiment with it anyway, there is knowledge to be gained... and satisfaction to have something done by yourself as outcome.
The infos you give are confusing to me: are yo trying to make a xover for a coaxial or 2 different drivers configuration ( beta+ apt on horn)?
There is some specific needs to take into account if you make a coax.
Link given by Tmuikku is a good source of info too for this drivers.
My experience with them is they are ok as wedge on stage for musician's monitor and can be pleasing as typical loudspeakers but they are definetly not the last word on accuracy. I'm with Brett on this.
That should not stop you to experiment with it anyway, there is knowledge to be gained... and satisfaction to have something done by yourself as outcome.
The infos you give are confusing to me: are yo trying to make a xover for a coaxial or 2 different drivers configuration ( beta+ apt on horn)?
There is some specific needs to take into account if you make a coax.
Thanks for the info. I guess that I have to mount drivers to actual cabinet and measure the impedance somehow. I will try to google how to measure the impedance of drivers after mounting into cabinet. I hope it is not too hard fo a novice.
Great to know. Is JBL Selenium D220Ti compression driver is better matching with 12" Eminence woofer? I believe that Selenium can also be mounted back of the woofer same as APT50.
Thank you. I will definitely search for two members' threads mentioned to check them out.
Good point and I am actually trying to build coaxial design so mounting compression driver into the bass woofer. APT or Selemium are screw on type so can be screwed at the back of the Eminence woofer to be coaxial design.
You are a legend! Thank you very much. I might try the crossover first and if it does not sound good then try to tweak the crossover or try different tweeter.
The cabinet that I am trying to utilise is quite large which used to have Tannoy 12" dual concentric Driver in there.
Cabinet actual dimension is 49(W) x 31(D) x79(H) cm = 19.3" x 12.2" x 31.1"
Ok great.
I think the Finnish design is a 'good' one and could be a back up answer if your own experiments doesn't please you.
You have a Tannoy donor box. Which model it initially was? Are you ok to mod it?
Closed box with around 80l you should have something along qtc 0.8 anf fc -3db around 60hz, -6db around 50hz.
Vented ask for double the volume at least...
I think the Finnish design is a 'good' one and could be a back up answer if your own experiments doesn't please you.
You have a Tannoy donor box. Which model it initially was? Are you ok to mod it?
Closed box with around 80l you should have something along qtc 0.8 anf fc -3db around 60hz, -6db around 50hz.
Vented ask for double the volume at least...
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The cabinet is DIY. The previous owner made this to mount HPD 315A drivers. He did not like the original cabinet so built wider & deeper & heavier but slightly shorter in height. Dimension is 49(W) x 31(D) x79(H) cm = 19.3" x 12.2" x 31.1" with two front ports like original.
Yeah its a design that works so quickest path forward from here
I had them some years back, although they weren't top notch soundwise they were lots of fun nevertheless, enjoyable! There is also version 2 for the audiovideo.fi project with D220ti tweeter but that is not publicly available, you would have to buy the plans. The dude who made the project has others projects published as well, some free some with fee, browse the audiovideo.fi site. I have no idea if other crossovers would be better or worse, probably many variations exists on various forums. Better tweeter is the first upgrade to do. Measurement gear and custom design would be most fun!
Yes, unfortunately this is the case like with most projects and commercial units out there...
The designer has some kind of status here in Finland and lots of people have build these and other projects of his. Of course this is not guarantee for anything else than its not his first or last speaker project In general I have impression people have been happy with the outcome, expectations met. We gotta remember, commercial projects are often made primarily to sell the products and for example many would see this is not project for them and build something else instead.
Edited previous post just recently but say it again the tweeter seemed weakest point but still the sound was enjoyable especially when I was accustomed to small "hifi" speakers. These brought smile on the face and now 12" is about smallest I'd go Lots of fun. Gotta mention my speakers were built by someone else and in undersized boxes. I used them with subwoofers, never heard them full range in properly sized box.
The designer has some kind of status here in Finland and lots of people have build these and other projects of his. Of course this is not guarantee for anything else than its not his first or last speaker project
In general I have impression people have been happy with the outcome, expectations met. We gotta remember, commercial projects are often made primarily to sell the products and for example many would see this is not project for them and build something else instead.Edited previous post just recently but say it again the tweeter seemed weakest point but still the sound was enjoyable especially when I was accustomed to small "hifi" speakers. These brought smile on the face and now 12" is about smallest I'd go
Lots of fun. Gotta mention my speakers were built by someone else and in undersized boxes. I used them with subwoofers, never heard them full range in properly sized box.
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That doesn't mean anything to me. Looks like the wrong CD for a number of reasons. If I cared particularly what people I don't know personally think things sound like, I'd be posting at 6Loons.
I am looking at the crossover and have I understood correctly that tweeter connection is inverted so negative wire is connected to positve side of tweeter and positive wire is connected to negative side of tweeter?
Is inverted connection common in speaker design?
https://audiovideo.fi/wp-content/up...aiset-veljekset-beta-12cx-jakosuodin-uusi.jpg
Is inverted connection common in speaker design?
https://audiovideo.fi/wp-content/up...aiset-veljekset-beta-12cx-jakosuodin-uusi.jpg
It depends the kind of filter topology used, some requires to have a driver with polarity inverted to garantee more linear behavior in their pass band ( around xover fc).
I bet there is some 3pole filter involved ( 18db/octave)... or there was some 'specifical issues' relative to coax trying to be taken care of.
I bet there is some 3pole filter involved ( 18db/octave)... or there was some 'specifical issues' relative to coax trying to be taken care of.