This is my third hybrid omnidirectional project, intended to push the limits of that concept. The hybrid concept is one in which the low and mid frequency drivers are omnidirectional to a point where they cross to the tweeter, where the tweeter is front and the radiation pattern transitions from 4pi into 2pi space. I believe this gives the best of both worlds, with an expansive soundstage, a very open midrange, yet good spatial imaging because of the front firing element. In this case I wanted to push the omnidirectional output to cover as much of the frequency range as possible before making the transition. The 3way, all passive crossover, is not yet final, but the crossover points are going to be about 365hz and 3500hz, which I believe is about as high as a dual cone midrange driver (up and down firing) design can be taken in this kind of design, due to driver baffle interactions compromising frequency response.. The other goal was to be able to get this design into the “budget” category at the IowaDIY, which has been under $300 for drivers and crossover parts. This barely makes it and it will take some electrolytics on the woofer shunt to get there.
The drivers include one Dayton RS225-8, two of the HiVi B3A-B buyouts (the ill fated RS90, I believe), and one Aura NT1 neo tweeter. I originally was using the Dayton ND20-FA, but was having some distortion issues at this crossover point and decided to try the Aura, which I like considerably better. This necessitated the need for a small baffle for the tweeter, where there was none with the ND20-FA, which you may have seen in a previous photo I posted.
The Crossover is 2nd order electrical on the woofer low pass and mid high pass, approximating a 3rd order Bessel acoustic slope. The -f3 points are spread so the drivers sum flat at the crossover point. The woofer is wired in reverse polarity. The mid low pass and tweeter high pass are 3rd order electrical, approximating a 4th order or steeper LR acoustic slope. I’ve done some different things in the midrange net to raise the impedance, which dips to as low as 3.5ohms, but is about 6ohms nominal overall. I have two versions of the crossover I will be deciding between. One has a typical Lpad before the tweeter and the other, posted here, has a series resistor for the tweeter net, on the amp side. The drivers are time aligned vertically for a listening position of 38” ear height at 3 meters. The phase match is optimized for that location.
I have just one prototype speaker built, but I’m very happy, really kinda shocked, with how very much I like it. The midrange is incredibly open and natural sounding and the overall balance is right on the money, IMO. We’ll see if that is still the case when the pair is completed.
Parts Express really needs to go ahead with offering the RS90 driver, IMO. It is a really nice, clean midrange, with a pretty wide band capability and small form factor.
Included is a photo of the prototype, a mock-up of the finished look, followed by the Xover and simulated FR and Z and Phase responses.
Thanks for looking! Comments are welcome.
The drivers include one Dayton RS225-8, two of the HiVi B3A-B buyouts (the ill fated RS90, I believe), and one Aura NT1 neo tweeter. I originally was using the Dayton ND20-FA, but was having some distortion issues at this crossover point and decided to try the Aura, which I like considerably better. This necessitated the need for a small baffle for the tweeter, where there was none with the ND20-FA, which you may have seen in a previous photo I posted.
The Crossover is 2nd order electrical on the woofer low pass and mid high pass, approximating a 3rd order Bessel acoustic slope. The -f3 points are spread so the drivers sum flat at the crossover point. The woofer is wired in reverse polarity. The mid low pass and tweeter high pass are 3rd order electrical, approximating a 4th order or steeper LR acoustic slope. I’ve done some different things in the midrange net to raise the impedance, which dips to as low as 3.5ohms, but is about 6ohms nominal overall. I have two versions of the crossover I will be deciding between. One has a typical Lpad before the tweeter and the other, posted here, has a series resistor for the tweeter net, on the amp side. The drivers are time aligned vertically for a listening position of 38” ear height at 3 meters. The phase match is optimized for that location.
I have just one prototype speaker built, but I’m very happy, really kinda shocked, with how very much I like it. The midrange is incredibly open and natural sounding and the overall balance is right on the money, IMO. We’ll see if that is still the case when the pair is completed.
Parts Express really needs to go ahead with offering the RS90 driver, IMO. It is a really nice, clean midrange, with a pretty wide band capability and small form factor.
Included is a photo of the prototype, a mock-up of the finished look, followed by the Xover and simulated FR and Z and Phase responses.
Thanks for looking! Comments are welcome.
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