I put a pair of these together to see how combining this "BMR" driver with the so-called "Time-domain" (see illustration Below) might sound like. I picked the BMR driver for its supposed ultra-wide dispersion characteristic, which I thought would suit the design.
Not realizing the driver had a massive 20db comb at ~2kHz until after making solder connections to the terminals... I like what I'm hearing with these placed generously out into the room; the sound seems to float well behind the speakers and the imaging location and sound remains pretty stable as you move about the room.
Right now the 4X36" sealed tubes are stuffed with 1/2 lb of polyfil. There's really no bass to speak of. Aside from the remarkable disappearing act they do, regarding where the sound apparently comes from, they're just not that good a sounding speaker. I'm sure that huge FR response anomaly has something to do with it.
How might I improve the sound of these and this design? I'm tempted to purchase better drivers, but no ordinary cone driver is going to have the off-axis response that these do - which is making the part of their sound that I like. Short of just trashing the whole idea and building a set of LX-Minis...
One feature of the original design is the so-called "grounding rod", which connects the driver mechanically to the base. I've not implemented this in mine, as I figure I have bigger fish to fry with it, in terms of stages of improvement. For example, if someone suggested making the tubes aperiodic, the screened over end at the bottom would effect how this rod would hit the floor.
Thanks,
Not realizing the driver had a massive 20db comb at ~2kHz until after making solder connections to the terminals... I like what I'm hearing with these placed generously out into the room; the sound seems to float well behind the speakers and the imaging location and sound remains pretty stable as you move about the room.
Right now the 4X36" sealed tubes are stuffed with 1/2 lb of polyfil. There's really no bass to speak of. Aside from the remarkable disappearing act they do, regarding where the sound apparently comes from, they're just not that good a sounding speaker. I'm sure that huge FR response anomaly has something to do with it.
How might I improve the sound of these and this design? I'm tempted to purchase better drivers, but no ordinary cone driver is going to have the off-axis response that these do - which is making the part of their sound that I like. Short of just trashing the whole idea and building a set of LX-Minis...
One feature of the original design is the so-called "grounding rod", which connects the driver mechanically to the base. I've not implemented this in mine, as I figure I have bigger fish to fry with it, in terms of stages of improvement. For example, if someone suggested making the tubes aperiodic, the screened over end at the bottom would effect how this rod would hit the floor.
Thanks,
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Dear jjasniew,
Diffuser is effective for improving high range.
And, there is a way to spiral the inside to improve the low range.
It is also good to attach a duct to the bottom.
Both are methods for omnidirectional systems of PVC pipes.
Diffuser is effective for improving high range.
And, there is a way to spiral the inside to improve the low range.
It is also good to attach a duct to the bottom.
Both are methods for omnidirectional systems of PVC pipes.
Any idea of the size of the duct/port? Also, for the diffusers is there an angle that's optimum? A diffuser looks relatively simple if a guy has a lathe.
Thanks,
Mike
Thanks,
Mike
@nandappe - those are some real works of art. The spiraling staircase steps about a center threaded rod is quite the artwork also!
@mikejennens - I'd say the duct dimensions depend on the type of enclosure - I went with a sealed style for simplicity. The diffusers I've seen are non-linear curves, which I s'pose is the secret sauce of various designs, that match the driver underneath.
Dont know how you'd make one w/o a lathe...
@mikejennens - I'd say the duct dimensions depend on the type of enclosure - I went with a sealed style for simplicity. The diffusers I've seen are non-linear curves, which I s'pose is the secret sauce of various designs, that match the driver underneath.
Dont know how you'd make one w/o a lathe...
Hi Joe, Ive got some of those tectonic drivers and am planning to use them in some tricolumn enclosures.
A very simple Quarter wave pipe the MidiTrike
But first I am trying to tame the driver response problem around 1.7K, which so far has been promising by using cone/surround edge treatment, when i finalise the results I will post some measurements.
cheers
Arthur
A very simple Quarter wave pipe the MidiTrike
But first I am trying to tame the driver response problem around 1.7K, which so far has been promising by using cone/surround edge treatment, when i finalise the results I will post some measurements.
cheers
Arthur
I think that the duct size should be calculated as a bass reflex box.
There are various methods for the diffuser, so I think it's best to try it.
Another way to increase the bass, it is making the inside horn-shaped and damp the exit.
There are various methods for the diffuser, so I think it's best to try it.
Another way to increase the bass, it is making the inside horn-shaped and damp the exit.
Free field measurement
Today was very nice out for a change, so I took my Tectonic based "Timedomain" into a nearby field for some measurement. I can see the response I posted earlier reflected in what I'm getting -
Curious about the combing outlined in red. Do I need to stuff the tube more densely? I've got 0.5 lb Polyfil in each one. Thanks!
Today was very nice out for a change, so I took my Tectonic based "Timedomain" into a nearby field for some measurement. I can see the response I posted earlier reflected in what I'm getting -
Curious about the combing outlined in red. Do I need to stuff the tube more densely? I've got 0.5 lb Polyfil in each one. Thanks!
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@afa - I'd like to see your measurement results - and learn how you did it! Good luck with your effort.
@nandappe - I tried a diffuser one time with a small KEF uni-Q driver. I couldnt get it to measure every well, no matter how I adjusted the z-offset above the driver. Not that the Tectonic driver measures all that well...
The various methods of internal to the pipe duct structures you're sharing are very interesting! I'd sure like to hear what the volcano sounds like. My efforts lately have been for a set of bedroom speakers, leaning more towards airy and ambient than hard rock performance. I think I got close, we'll need to work on improvements; yes better bass than the sealed would be an achievement!
@nandappe - I tried a diffuser one time with a small KEF uni-Q driver. I couldnt get it to measure every well, no matter how I adjusted the z-offset above the driver. Not that the Tectonic driver measures all that well...
The various methods of internal to the pipe duct structures you're sharing are very interesting! I'd sure like to hear what the volcano sounds like. My efforts lately have been for a set of bedroom speakers, leaning more towards airy and ambient than hard rock performance. I think I got close, we'll need to work on improvements; yes better bass than the sealed would be an achievement!