After more than 25 year of inactivity and building my first speaker more than 50 years ago, I'm planning to try it again and build an open baffle 3-way system... but I can not decide on the coaxial. Would love to use the B&C 12CXN88 but unfortunately it is way over budget. I have an alternative list but can not decide:
B&C 12CLX64: https://www.bcspeakers.com/en/products/coaxial/12/8/12CLX64
Oberton 12CX: https://www.oberton.com/en/products/ferrite-coaxials/348-12cx.html
Lavoce CSF122.50K: https://lavocespeakers.com/single-product/?id=217
Celestion: FTX1225: https://celestion.com/product/ftx1225/
BMS 12C262: https://bmsspeakers.com/index.php-130.html?id=bms_12c262
For bass I will use two SB Bianco 12OB150's (U-frame).
Coaxial will be on pure open baffle, 18 inch wide.
No DSP or anything complicated just passive XO (I have limited knowledge 😉 ).
Input and comments welcome. Thanks.
B&C 12CLX64: https://www.bcspeakers.com/en/products/coaxial/12/8/12CLX64
Oberton 12CX: https://www.oberton.com/en/products/ferrite-coaxials/348-12cx.html
Lavoce CSF122.50K: https://lavocespeakers.com/single-product/?id=217
Celestion: FTX1225: https://celestion.com/product/ftx1225/
BMS 12C262: https://bmsspeakers.com/index.php-130.html?id=bms_12c262
For bass I will use two SB Bianco 12OB150's (U-frame).
Coaxial will be on pure open baffle, 18 inch wide.
No DSP or anything complicated just passive XO (I have limited knowledge 😉 ).
Input and comments welcome. Thanks.
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Bms offering should be considered too imho but passive xover will severely limit the outcome.
The general idea could sound awesome. Member Perry Marshall have an impressive loudspeaker project on same principle detailed in here. Worth a look for inspiration. I think it's called 'beech brew'.
Edit: found it:
The general idea could sound awesome. Member Perry Marshall have an impressive loudspeaker project on same principle detailed in here. Worth a look for inspiration. I think it's called 'beech brew'.
Edit: found it:
The Bitches Brew Open Baffle Live Edge Speakers
The Bitches Brew Open Baffle Live Edge Speakers
Stunning Imaging + 120dB Dynamic Range + Natural Wood Finish. Named after Miles Davis’ classic 1970 album.
I’ve been designing speakers for almost 40 years as a hobbyist, including a 3 year stint at Jensen’s OEM automotive division, where I designed speakers professionally for Honda, Mazda, Chrysler and Acura. I’ve built just...
The Bitches Brew Open Baffle Live Edge Speakers
Stunning Imaging + 120dB Dynamic Range + Natural Wood Finish. Named after Miles Davis’ classic 1970 album.
I’ve been designing speakers for almost 40 years as a hobbyist, including a 3 year stint at Jensen’s OEM automotive division, where I designed speakers professionally for Honda, Mazda, Chrysler and Acura. I’ve built just...
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Stunning, I was aware of his creation. Very inspiring indeed.
Thanks also for reminding me of BMS, forgot about them, I will look at their coaxials.
I'm not excluding the use of DSP but for now a passive XO is all I can manage.
Thanks.
Thanks also for reminding me of BMS, forgot about them, I will look at their coaxials.
I'm not excluding the use of DSP but for now a passive XO is all I can manage.
Thanks.
Stunning work from Perry i agree.
If used with DSP i really liked the BMS i heard. If you can listen to them it would not be wasted time imho.
Most coax offers the same challenge which come from drivers offset in z axis and DSP solve this issue easily, eq can help too massaging the driver response.
Can be done using asymetric slopes and playing with phase behavior with passive. GreatPlainAudio hosted a blog where this approach was explained for their Altec coax recreation used in Urei 'linear phase' monitor style.
I think it vanished when they redid their site, it should be availlable through 'wayback machine'.
If used with DSP i really liked the BMS i heard. If you can listen to them it would not be wasted time imho.
Most coax offers the same challenge which come from drivers offset in z axis and DSP solve this issue easily, eq can help too massaging the driver response.
Can be done using asymetric slopes and playing with phase behavior with passive. GreatPlainAudio hosted a blog where this approach was explained for their Altec coax recreation used in Urei 'linear phase' monitor style.
I think it vanished when they redid their site, it should be availlable through 'wayback machine'.
I have built and also heard a number of OB speakers with coaxial as the main driver. Alas, none on your list! 
The few I looked at on your list look like medium Qts woofers, which is good for OB. OB crossovers are not easy if you are a stranger to them. The woofer will not be efficient in the low end, so your woofer low pass filter has to take that into account. You will lose sensitivity and have to pad way down the compression driver, but that's the OB trade off.
Since you are doing dual 12" woofers for the low end, the loss of LF from the coax will not matter as much to you. But you still have to match the coax sensitivity to the dual woofers, and also control the top end of the dual woofer response. It's not a quick and easy crossover. I have had good luck with a subwoofer plate amp driving the lows, with a passive crossover for the coax.
I will help with what I can.
The few I looked at on your list look like medium Qts woofers, which is good for OB. OB crossovers are not easy if you are a stranger to them. The woofer will not be efficient in the low end, so your woofer low pass filter has to take that into account. You will lose sensitivity and have to pad way down the compression driver, but that's the OB trade off.
Since you are doing dual 12" woofers for the low end, the loss of LF from the coax will not matter as much to you. But you still have to match the coax sensitivity to the dual woofers, and also control the top end of the dual woofer response. It's not a quick and easy crossover. I have had good luck with a subwoofer plate amp driving the lows, with a passive crossover for the coax.
I will help with what I can.
The crossover is going to be the hardest nut to crack for me. If the end result look and sound halve as good as the Bitches Brew, I will be happy. First I need to decide on the coaxial. Unfortunately I can not hear the coaxial speakers drivers, but every time a hear a coaxial I'm surprised how good they sound, they used to sound "bad" 40 or 50 years ago. I'm used (long time ago) to build speakers from an existing plan, this time from scratch and that is a completely different ballgame. But then, creating a new speaker is the best hobby is the world, combining technical knowledge, design and crafts to recreate the highest form of art i know: music. I have a lot of reading to do. 🙂
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I truncated off your post there... where you make a mistake.
I am not a big fan of coaxial drivers for OB/dipole speakers. They are basically a cop-out when it comes to open baffle speakers that ignores what is happening to the rear. You need the acoustic output to be the same to front and rear up to about 5kHz. There is no way a coaxial driver can do this.
Also, the SB Bianco 12OB150 is not a good choice for a woofer in an OB unless your baffle is HUGE. The driver only has Fs=44Hz and Xmax is 6.8mm. That is not going to cut it for OB bass.
The only way this sort of speaker will be successful is when the baffle is really large. But that sort of design loses the advantages that an OB/dipole speaker offers and instead is more like a traditional IB speaker.
I'm not 100 percent sure I'll use an open baffle for the bass, I'll test it first. If I do not like the level/sound of the bass I will use a closed or ported box for that. I had in mind to use a cf of 1,4khz for the coaxial, 5khz is indeed high. A bipolar design is out of the question, too expensive. Maybe I need to use a tweeter, I look in to that. Thank you for your feedback, appreciated.
Yes it is. OB crossover takes some work.
I would not worry about it being a coax - sure you are supposed to have rear radiation thru the whole bandwidth, but I was surprised to learn that it didn't matter than much. My first successful OB was a 2-way with an Altec horn up top so it was less OB than your coax idea. Still sounded very clean and open. I did experiment with rear firing tweeters, but they didn't do much for me. The woofers were a 15" Selenium each side with a Qts of about 0.66 and I loved them. Two 12s with decent X-max and a mid Qts will sound nice. H-baffle will help with dynamics.
18" wide baffle? Sure you could go wider, but you don't have to. I've done many with a 16-17 wide baffle and short rear wings. See here:
Sorry I can't be of help for the coax choice. I have used BMS drivers, specifically their coaxial compression drivers and have found them excellent. That's all I know in your lineup.
After I decided what coaxial to use I will first build a dummy baffle with wings to get an idea of the bass and sound in general, I got some older wood here to experiment. I have added the BMS 12c262 to my list, this driver looks very well build but is also about 40 percent more expensive than the other drivers in the list. I could go for super cheap like this Master Audio https://www.hs-sound.de/Master-Audio-CSX12 but I do not think that is a good idea. 😉
It used to be normal to publish the distortion of a driver but that seems not important now? 😕
Thanks all for your feedback and help!
It used to be normal to publish the distortion of a driver but that seems not important now? 😕
Thanks all for your feedback and help!
I'm sure it's a very fine driver, but that low Q woofer won't give you much bass on OB. You can get it, but it takes more crossover tricks. It's more suited for horn loading.
The speaker is called (I believe) the bitches brew. Perry certainly knows what he is doing, but I have I head the speaker in person. It makes an impact but I wasn't a fan of the coaxial for the highs with the additional rear tweeter. OTOH woodwork was amazing! One must be careful about the low end - 35Hz is doable at decent SPL with a 15" driver with healthy Xmax but it is very easy to underestimate how much displacement will be needed once you have a lot of dipole loss going on down there.
What I stated in general about 5kHz is what has been generally reported by others like John Kreskovsky regarding the sound coming "out the back" and the listener. You can certainly design an "open baffle" speaker in my different ways, but many of them are not the best approach and will have built in problems with the power response and tonal balance that cannot be fixed. In my opinion this includes system with a coax. But I feel the same way about other types of speakers, like full-rangers in horns or whatever, so YMMV.
Hey Friends,
I find myself in a similar dilemma. I allways liked the airyness of my Magnepans but they don't kick ***.
And I like the Tannoy sound (old 15" dualconcentric).
Then I read about Papa's Slobs and tried that with some Lii Fast 8's. Nice for three piece Jazz but made me puke with complex/rock music.
So no whizzer-cones
Perry's Life Edges take a different aproach and the critics seem to like them.
But I don't want minidsp -
Anyway, I bought some pairs of 8" coaxes (Redcatt/LaVoce/Oberton) hence my appearance here.
- still fumbling with the XOs - measuring - listening - change - measuring - listening ...
I don't come anywhere near to what I want. Maybe I should just take a Beta 8 and put a tweeter on top and leave the lab.
comments welcome.
cheers
Attila
I find myself in a similar dilemma. I allways liked the airyness of my Magnepans but they don't kick ***.
And I like the Tannoy sound (old 15" dualconcentric).
Then I read about Papa's Slobs and tried that with some Lii Fast 8's. Nice for three piece Jazz but made me puke with complex/rock music.
So no whizzer-cones
Perry's Life Edges take a different aproach and the critics seem to like them.
But I don't want minidsp -
Anyway, I bought some pairs of 8" coaxes (Redcatt/LaVoce/Oberton) hence my appearance here.
- still fumbling with the XOs - measuring - listening - change - measuring - listening ...
I don't come anywhere near to what I want. Maybe I should just take a Beta 8 and put a tweeter on top and leave the lab.
comments welcome.
cheers
Attila
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Did finally go with Celestion coaxial FTX1025 (10") and 2 x GRS10PT-8 (10") for the bass.
Build a dummy bass u-frame first of 47" wide x 30" high.
Coax baffle will be build later.
Findings: bass is very lean but tight and absolutely not boxy. Good bass... but too little.
Tomorrow I will use a lid on the u-frame (hmm, is that not a box almost? 😉 ).
Findings are in line with what I read here on the forum: open baffle bass is good but lean.
EQ will be necessary.
I will report later. Thanks.
Build a dummy bass u-frame first of 47" wide x 30" high.
Coax baffle will be build later.
Findings: bass is very lean but tight and absolutely not boxy. Good bass... but too little.
Tomorrow I will use a lid on the u-frame (hmm, is that not a box almost? 😉 ).
Findings are in line with what I read here on the forum: open baffle bass is good but lean.
EQ will be necessary.
I will report later. Thanks.
Has anyone ever opened the back of the compression drivers in coaxial systems in open baffles?
I mean, not just for inspection, but to make it dipole.
I did so and I'm amazed how everything seems to fall in place.
I exchanged the backchamber behind the diaphragm with a wooden ring to keep the coil and membrane in place.
It's still a work in progress but much better than everything before
I mean, not just for inspection, but to make it dipole.
I did so and I'm amazed how everything seems to fall in place.
I exchanged the backchamber behind the diaphragm with a wooden ring to keep the coil and membrane in place.
It's still a work in progress but much better than everything before
