Hi, yeah I completely understand this and already expressed it. The project is made to sell products, and later on upgraded tweeter design came out to sell more. People in various stages of hobby might buy it and others would pass it.
Op already has the drivers so might as well copy the crossover to whip up a system and move on.
Decommo,
Some reading about coaxial passive filter approach:
https://greatplainsaudio.com/gpa-vintage-altec-ezine/jeff-markwart-corner/phase-shift-drivers/
https://greatplainsaudio.com/gpa-vintage-altec-ezine/altec-lansing-duplex-speakers/ check the 604 duplex exploded view (second picture) and identify the two voice coils, it helps understanding previous link
Variant for differents models;
https://greatplainsaudio.com/gpa-vintage-altec-ezine/altec-lansing-604-8h-crossover-revelations/
https://greatplainsaudio.com/gpa-vintage-altec-ezine/phase-correction-altec-ferrite-duplexes/
https://greatplainsaudio.com/gpa-vintage-altec-ezine/altec-lansing-604-8k-duplex-studio-monitor/
These are examples and can be adapted to your 12cx/compression driver.
About the compression driver i agree with both Brett ( there should be better) and Tmuikku: you already have the drivers, use them at worst it'll be educative.
Some reading about coaxial passive filter approach:
https://greatplainsaudio.com/gpa-vintage-altec-ezine/jeff-markwart-corner/phase-shift-drivers/
https://greatplainsaudio.com/gpa-vintage-altec-ezine/altec-lansing-duplex-speakers/ check the 604 duplex exploded view (second picture) and identify the two voice coils, it helps understanding previous link
Variant for differents models;
https://greatplainsaudio.com/gpa-vintage-altec-ezine/altec-lansing-604-8h-crossover-revelations/
https://greatplainsaudio.com/gpa-vintage-altec-ezine/phase-correction-altec-ferrite-duplexes/
https://greatplainsaudio.com/gpa-vintage-altec-ezine/altec-lansing-604-8k-duplex-studio-monitor/
These are examples and can be adapted to your 12cx/compression driver.
About the compression driver i agree with both Brett ( there should be better) and Tmuikku: you already have the drivers, use them at worst it'll be educative.
You might also check out this link. Michael doesn't show his crossover, but has always provided it after receiving an email.
https://ampslab.com/blog/2021/08/23/osprey12/
https://ampslab.com/blog/2021/08/23/osprey12/
I didn’t read the whole thread but saw my name mentioned. First I’d like to state that me playing around with various CD in Eminence coax combinations is perhaps not very useful to read as it contains no measurements and I have very little competence on crossover design. I can say a few things though but before doing that this thread has a few confusing infos. Anyway I’m not super experienced so take my advice with a pinch of salt
First some basics:
Did OP buy the drivers already? Did you buy Beta 12A or the CX version? What’s the application? Home use? HiFi or surround? Cabinet size? Sub, no sub? What amps? Any DSP/EQ available in the amp setup? Room size? What’s your experience level DIY?
Secondly:
Beta 12A and the CX version are somewhat different. The A does not have the possibility to screw a CD into the back. It has a thicker dust cap for one. The A version also have much more ugly peaks from 1kHz while the CX mostly break up from 2,5kHz. A is a bass. CX is more a mid bass/midrange. I think the A is best in 3-way with a midrange or in two way with a way larger horn, I don’t think APT50 will not work well with the Beta 12A.
My third point is the APT50 is a super tweeter working best way above the intended crossover for any 12”. Consider other CDs like ASD1001 or even better PSD2002/2013 which can be cut lower or use a midrange driver between 500-5000Hz. I have best experience with PSD2002 with the Beta 12CX. I also want to mention that I have used Eminence stock crossovers 1k6 and 2k5cx where the latter gave best results (probably because it’s acoustically adjusted to avoid 12” peaks.
I want to mention one more thing. The Eminence Beta range drivers have soft metal frame. It bends easily and not very robust. I will only buy die cast alu chassis from here on. If you want coax with screw-in CD I think your best bet is the new Kappalites. These do not have the ugly peaks around 2kHz and they seems to have much better performance. I’ll try those next year or so. Price is much higher though.
Another last point. If you can avoid coax I can really recommend Fane Pro 12-500 with Eminence ASD1001 with a APT150S flare and the Eminence 2k5cx crossover. Play great right out of the box. Choose only coax if you’re really into it and know how to deal with issues in the 2k range. In most cases a “normal” design is cheaper.
First some basics:
Did OP buy the drivers already? Did you buy Beta 12A or the CX version? What’s the application? Home use? HiFi or surround? Cabinet size? Sub, no sub? What amps? Any DSP/EQ available in the amp setup? Room size? What’s your experience level DIY?
Secondly:
Beta 12A and the CX version are somewhat different. The A does not have the possibility to screw a CD into the back. It has a thicker dust cap for one. The A version also have much more ugly peaks from 1kHz while the CX mostly break up from 2,5kHz. A is a bass. CX is more a mid bass/midrange. I think the A is best in 3-way with a midrange or in two way with a way larger horn, I don’t think APT50 will not work well with the Beta 12A.
My third point is the APT50 is a super tweeter working best way above the intended crossover for any 12”. Consider other CDs like ASD1001 or even better PSD2002/2013 which can be cut lower or use a midrange driver between 500-5000Hz. I have best experience with PSD2002 with the Beta 12CX. I also want to mention that I have used Eminence stock crossovers 1k6 and 2k5cx where the latter gave best results (probably because it’s acoustically adjusted to avoid 12” peaks.
I want to mention one more thing. The Eminence Beta range drivers have soft metal frame. It bends easily and not very robust. I will only buy die cast alu chassis from here on. If you want coax with screw-in CD I think your best bet is the new Kappalites. These do not have the ugly peaks around 2kHz and they seems to have much better performance. I’ll try those next year or so. Price is much higher though.
Another last point. If you can avoid coax I can really recommend Fane Pro 12-500 with Eminence ASD1001 with a APT150S flare and the Eminence 2k5cx crossover. Play great right out of the box. Choose only coax if you’re really into it and know how to deal with issues in the 2k range. In most cases a “normal” design is cheaper.
Thank you all for your suggestions. Hugely appreciate them. I actually out of internet for last few days and just be able to use internet.
Re: speakers, I almost completed and used the crossover design suggested with slight change.
https://audiovideo.fi/wp-content/up...aiset-veljekset-beta-12cx-jakosuodin-uusi.jpg
The inductor value that I used 2.45mH instead of 2.7mH suggested, and I have used 2.5uf instead of 2.7uf suggested for tweeter.
How does it sound? It actually sounds pretty good. I was afraid that it may be shouty and lacks mid-range and bass but it sounds quite smooth from mid-bass to treble and provides a balanced sound. One area I feel lacking is the lower bass. I think that it falls sharply below 60~70Hz.
I have not completed them yet so will complete them in next a few weeks and if I feel better component is needed, will try Selenium JBL D250X for tweeter.
Re: speakers, I almost completed and used the crossover design suggested with slight change.
https://audiovideo.fi/wp-content/up...aiset-veljekset-beta-12cx-jakosuodin-uusi.jpg
The inductor value that I used 2.45mH instead of 2.7mH suggested, and I have used 2.5uf instead of 2.7uf suggested for tweeter.
How does it sound? It actually sounds pretty good. I was afraid that it may be shouty and lacks mid-range and bass but it sounds quite smooth from mid-bass to treble and provides a balanced sound. One area I feel lacking is the lower bass. I think that it falls sharply below 60~70Hz.
I have not completed them yet so will complete them in next a few weeks and if I feel better component is needed, will try Selenium JBL D250X for tweeter.
I have run into a nasty bump at 8.5Khz on the PSD2002 which either people love a lot. Or nobody wants to discuss.
Just a heads up for anybody considering the PSD2002. If anybody runs across a solution for this pls let me know.
To the OP I read your post but its not clear what s/w your using to design your cross over.
That is strange. I cannot notice much of that but have not measured anything. What horn are you using? Is in a coax or a bigger flare. In my comparison by ear in coax only I found that:
- the selenium 220 have an ugly ringing which I believe is a resonance of the heavy duty grill it comes with
- the ASD1001 is really bright yet pleasing and forgiving but lacks some detail
- the PSD2002 is a bit dark showing most effective in the lower end of the HF range and are very honest almost harsh if the record isn’t the best.
- the APT50 is really uneven, with holes/dips in the range and lack of dynamic range yet could work as a supertweeter in a 3-way system
In every way I think the Celestion coax sound better than the eminence combos but to a much higher price. The eminence are still great fun I plan to use it for my home cinema.
- the selenium 220 have an ugly ringing which I believe is a resonance of the heavy duty grill it comes with
- the ASD1001 is really bright yet pleasing and forgiving but lacks some detail
- the PSD2002 is a bit dark showing most effective in the lower end of the HF range and are very honest almost harsh if the record isn’t the best.
- the APT50 is really uneven, with holes/dips in the range and lack of dynamic range yet could work as a supertweeter in a 3-way system
In every way I think the Celestion coax sound better than the eminence combos but to a much higher price. The eminence are still great fun I plan to use it for my home cinema.