After messing around for a month, my Aurasound drivers came. I made a cardboard test cab for them, and I proved that the rear radiating wave can be effectively cancelled by a separate driver placed perpendicularly by listening to the space between the two drivers.
There was buzzing from the poorly made cab, but I still found excellent spacing and imaging with this set of speakers. BTW, they are meant for close field listening and not blasting, so don't feed them with extremely loud music. Anything with heavy bass with a sound pressure level of above 96dB is not recommended as this may bottom out the drivers.
There was buzzing from the poorly made cab, but I still found excellent spacing and imaging with this set of speakers. BTW, they are meant for close field listening and not blasting, so don't feed them with extremely loud music. Anything with heavy bass with a sound pressure level of above 96dB is not recommended as this may bottom out the drivers.
Attachments
I believe tekton has already resurrected the patent for this design and as usual, claims it's the ultimate loudspeaker. But I'd like to hear more anyway.
I have the tekton ob4.5s they definitely sound better and offer a more full range sound than the regular single drivers, I'm selling them though because bass is still not enough for watching movies and I'm getting into DIY now.
Good to know it's working.
I assume you'll be building a "proper" box for them, so (for the purpose of experiment), would you consider trying ported vs sealed on the rear driver?
I assume you'll be building a "proper" box for them, so (for the purpose of experiment), would you consider trying ported vs sealed on the rear driver?
@yyhtbs, they are the 3" variant, so they should be good up to 12kHz, while Aurasound claims 15kHz. I think I want a super tweeter and cross at 10kHz.
Chris, I think I'll make a proper box with 1/2" ply wood with bitumen pads inside. Porting the driver would create a nasty steep roll off around 40Hz and I'm aware the power handling problem. There's bass, but you'll need a 6dB bass boost to make them sound like 6" woofers.
BTW, with this design, off axis is not very pleasant, so they are more suitable as close field (maybe studio monitors?)
You will need a subwoofer if you listen to Mariah Carey or Madonna unless you feel safe having a 6dB boost.
Chris, I think I'll make a proper box with 1/2" ply wood with bitumen pads inside. Porting the driver would create a nasty steep roll off around 40Hz and I'm aware the power handling problem. There's bass, but you'll need a 6dB bass boost to make them sound like 6" woofers.
BTW, with this design, off axis is not very pleasant, so they are more suitable as close field (maybe studio monitors?)
You will need a subwoofer if you listen to Mariah Carey or Madonna unless you feel safe having a 6dB boost.
@Inclined Plane
Yup, Tekton tried to get a patent, but it's still patent pending, so feel safe to use it for personal use. BTW, I believe this is a bit different from Tekton's patent, and to twist the design a bit, I want to try use a transmission line for the cancellation driver.
Anyway, they sound very spacious and vocals are excellent. It reveled that Madonna's albums are DSPed with some phasing tricks and as these speakers are highly directional (real monopole bass), it sometimes sound like "out of the head".
Yup, Tekton tried to get a patent, but it's still patent pending, so feel safe to use it for personal use. BTW, I believe this is a bit different from Tekton's patent, and to twist the design a bit, I want to try use a transmission line for the cancellation driver.
Anyway, they sound very spacious and vocals are excellent. It reveled that Madonna's albums are DSPed with some phasing tricks and as these speakers are highly directional (real monopole bass), it sometimes sound like "out of the head".
Boris, the transmission line idea is fantastic, provided it's long enough to give a near-infinite baffle loading to the driver (correct stuffing should help this).
Have you crossed the rear driver over? I found 2nd order LP around 400Hz good on my design a while ago.
Have you crossed the rear driver over? I found 2nd order LP around 400Hz good on my design a while ago.
I did not use a single filter. I just inverted the cancellation driver to limit the treble from the cancellation driver. For those who hate reactive elements, this is a good thing. 😉 But I still think I can try adding a filter.
... But you don't listen to the space between the drivers. What do you hear when you set them up in a "standard" listening configuration, then switch the rear drivers on and off? Then switch the front drivers on and off while leaving the rear drivers on?
My point is, at the frequencies for which the rear driver is supposed to be effective at back wave cancelling, I suspect you will find that the majority of the bass you hear actually comes from the rear driver.
I don't honestly think this design idea makes much sense. WIth such a small baffle, unless you sit within inches of the front speaker cone, the low end is going to be totally dominated by the box woofer. You may as well make a true two-way, or 1.1, you might call it. Besides, what you really have here is mainly a passive radiator tuned to a few hundred Hertz, lol.
It might help with midband performance for close-to-wall installations.
It might help with midband performance for close-to-wall installations.
Last edited:
@Don Hills: I have small ears so I did actually listen to the space between the drivers. There's absolutely no bass from the rear, and bass is really monopole in this design. The mids and treble is dipole as it's not as effectively cancelled out.
@Andrew, I didn't think it would work, but it did work. No passive or active components, no crossover. There's no bass from the rear. Close-to-wall didn't help a single thing in this design, it messes up the mids.
@Andrew, I didn't think it would work, but it did work. No passive or active components, no crossover. There's no bass from the rear. Close-to-wall didn't help a single thing in this design, it messes up the mids.
You have to listen to this thing, it's just awfully surprising. But you need either a 6dB bass boost or a subwoofer to make it sound like a bigger speaker.
I trust your statement about the mids. That scene is probably pretty complicated. However, you're still certainly dealing with an overall monopole woofer, created by the driver in the box. The monopole will seem to appear at the front cone, but it will be dominated by the box woofer response.
@Andrew, but there's absolutely no bass from the rear... I can't figure it out... Maybe you can treat the OB as a system and the box as another system, then you'll end up with the conclusion that bass is from the boxed driver, but if you treat the front as a system and the rear as a system, you'll end up with my conclusion. I think we need some one with a PhD in Physics or acoustic engineering to solve this problem as we cannot "label" waves like we do in chemistry.
But anyway, the truth is there's monopole bass, unlike what some suggested. It's a funny experiment, and you've got to listen to that. Who said bass must be omni-directional!
Noo, no PhD, the bass is not that hard to figure out. Thinking ideally you just have two cones moving exactly as much but opposite in the back. No sound. So the monopole appears at the front cone.
Unfortunately the cones aren't moving exactly the same. And since the dipole cancels at very low frequencies in exactly the same way, except for slightly different compression levels of air because of the box sound pressure, you are left to listen to the box woofer at more than a few inches from the front cone. No big deal.
Unfortunately the cones aren't moving exactly the same. And since the dipole cancels at very low frequencies in exactly the same way, except for slightly different compression levels of air because of the box sound pressure, you are left to listen to the box woofer at more than a few inches from the front cone. No big deal.
@ Andrew, that sounds pretty reasonable. And maybe that's why people mount isobaric subwoofers that way instead of mounting one perpendicularly to the next one. 😉
- Status
- Not open for further replies.