several years ago I built an OB with two 7" Scanspeak illuminator and a Raal 140-15D dipole ribbon, with a separate 18" dipole sub. The crossover is a 3 way DEQX and the amp a very nice 6 X 125 watt Vecteur AV6. The WAF was low, as they were never properly finished, and after we re did the living room I decided to make something that actually looks nice or at least finished.
So after some research, I purchased 4 AE dipole 15 woofers, intending to add them to the 7" midwoofers and ribbon. I was never fully satisfied with the mid to upper mid range of the 7" illuminators though. The little wiggle at 1khz may be a clue as to why. So then I went down a rabbit hole and decided to get four 4.5" Scanspeak illuminator mids.
With only a three way x-over, the plan at this point is to have the 15s crossed over to the 4.5"s at about 300hz, then to the tweeters at maybe 3500.
My doubt is weather there will be too much of a directivity mismatch between the woofers and mids. I had read that the AE woofers can be crossed over quite high, but I assume that the off axis directivity will not be ideal. Is this just a plain bad idea?
The other option is to keep the 7" midwoofers and add a passive crossover, probably between the mids and tweeter, with the active treating the mids and tweeter as one driver. I have no experience with building complex passive x-overs though and I don't have tons of time to study up on them...
Thanks for any constructive advice!🙂
So after some research, I purchased 4 AE dipole 15 woofers, intending to add them to the 7" midwoofers and ribbon. I was never fully satisfied with the mid to upper mid range of the 7" illuminators though. The little wiggle at 1khz may be a clue as to why. So then I went down a rabbit hole and decided to get four 4.5" Scanspeak illuminator mids.
With only a three way x-over, the plan at this point is to have the 15s crossed over to the 4.5"s at about 300hz, then to the tweeters at maybe 3500.
My doubt is weather there will be too much of a directivity mismatch between the woofers and mids. I had read that the AE woofers can be crossed over quite high, but I assume that the off axis directivity will not be ideal. Is this just a plain bad idea?
The other option is to keep the 7" midwoofers and add a passive crossover, probably between the mids and tweeter, with the active treating the mids and tweeter as one driver. I have no experience with building complex passive x-overs though and I don't have tons of time to study up on them...
Thanks for any constructive advice!🙂
To get smooth response and directivity with low distortion, dipole speaker must be 4-way.
You have excellent drivers now and you can use your 3-way DEQX and make passive xo for upper mid and tweeter Hybrid Design
The reason for complexity is narrow bandwidth of real dipole radiation and need for lots of equalization (relative boost in low range of each radiator)
Best sources for additional information behind my advice are:
Original Offerings - study the story of NaO Note versions and read Tech studies
Dipolplus - Alles über offene Schallwände
Linkwitz Lab - Loudspeaker Design
You have excellent drivers now and you can use your 3-way DEQX and make passive xo for upper mid and tweeter Hybrid Design
The reason for complexity is narrow bandwidth of real dipole radiation and need for lots of equalization (relative boost in low range of each radiator)
Best sources for additional information behind my advice are:
Original Offerings - study the story of NaO Note versions and read Tech studies
Dipolplus - Alles über offene Schallwände
Linkwitz Lab - Loudspeaker Design
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Having heard and also built a fair number of very good 2-way and 3-way OB speakers, I will dispute that claim. 😉
@audioartspeaker: If you are using a wide band midrange, then your crossover becomes easier to get right than if using a dedicated midrange. I've heard and built OB with wide band speakers supported by large woofers using wide band from 3.5" to 12". 6.5 to 8 inch mid is the sweet spot for me.
Remember that if you are doing OB woofers, they will have a pronounced rising response because of the OB bass losses. You need to tame and level that rise somehow, either with the low pass filter, or with active EQ. The bass losses will depend on the woofer and on baffle size - losses can be 10dB or more. Meaning that an OB crossover is not going to look like a box speaker crossover. You will often find that you must electrically cross the woofers much lower than the acoustic point you are trying to achieve. To get a 300Hz acoustical slope, you might use a low pass of 80-100 Hz. Again, that is woofer and baffle (and some room) dependent.
Maybe you already know this, but I thought it worth mentioning since it took me so long to understand, and I've heard too many OB designs that obviously didn't understand this. Good luck on your project, you seem to be well on your way. Get the crossover right and you'll have a speaker to love.
My intuition says that it will be a better system with the 7" midwoofers included, so that's the way I am leaning right now.
For the passive crossover I have Harris labs Xover pro, and I do have a measurement system to tweak it. What do people usually do, buy the quality crossover parts from the calculated parts list, or cobble something with cheap parts first then tweak before getting the good parts?
For the passive crossover I have Harris labs Xover pro, and I do have a measurement system to tweak it. What do people usually do, buy the quality crossover parts from the calculated parts list, or cobble something with cheap parts first then tweak before getting the good parts?
The best designers I know cobble together from quality parts and tweak from there. 🙂
Not having those deep pockets I either use cheap parts to prototype and then buy better parts, or do most of the work with active and DSP keeping in mind that it has to be built passive.
I agree that your all important midrange will benefit from your 7" midwoofer.
Not having those deep pockets I either use cheap parts to prototype and then buy better parts, or do most of the work with active and DSP keeping in mind that it has to be built passive.
I agree that your all important midrange will benefit from your 7" midwoofer.