Thanks AllenB, I saw and read most of that thread, but it seemed a too cheap to be good product; I wouldn't mind spending 1K USD per pair for better drivers, if the result is significantly better. Hence I thought embarking on the full DIY journey...
I am trying my first DIY experiment build with Tang Band 1808 fulrange driver and 2 nos Beyma 12BR70 12" woofers per side. I have miniDSP 2x4HD and Hypex ncore 2 amps 100 watts each I am learning how to use miniDSP and REW with umik find it very technical at age 52 from finance background to learn is not easy this REW. I also have SB20FRPC30 8" FULLRNAGE DRIVER will see how both perform next 2 onths will be exciting and challanging for me. I want active cause i dont know how to solder and dont understand caacitor resistance etc
wish me luck.
... Olsond3 thanks, your posts are very clear and useful. In the meanwhile I've found out that SBA produces open-baffle-friendly drivers. My question, considering I do not listen at high volume neither I need a ton of bass, if I was to use an active subwoofer to take care of the very low range, say 20-50 Hz, and use two 12" SBA 12OB 150 (fs=44Hz , xmax ± 6.79mm) which would move each 732cm3 of air, would one decent tweeter (like the SS DISCOVERY D2608/91300) be enough to cover the audible frequency range? From the charts it seems ok to me but I don't know whether I'm not considering other variables.
Thank you in advance,
D
One of my speaker projects at the moment is a dipole. The idea I want to try out is to mount the magnet on its own separate stand, which will be a vertical slab of granite located behind the baffle.
This may not be unique, but certainly unusual: the metal outer rim of the speaker will not be directly connected to the baffle. Instead, there will be a slight gap for tolerances and a secondary rubber surround or 'gasket' to make it air-tight. Therefore, the anti-phase vibrations from the magnet will be prevented from shaking the baffle like an actuator.
Even though P-P amplitude of vibrations from the magnet should be minimal:
~0.015kg cone vs ~1kg magnet
=> 3mm cone Xmax * 15 / 1000 = 0.045mm
the entire surface area of the baffle would be set in motion with high efficiency. I could just use a much larger and heavier slab for the baffle itself, but cutting round holes in granite is a skill that I don't have.
(Edit: if anyone has tried playing sound through a raw driver while holding it in your hand, you'll have felt those vibrations, and experienced how playing it on a table will shake the table...)
2nd idea:
I'm also inspired by Karlson tubes to cut some approximately exponential slots into the baffle, resembling flower petals. Off-axis energy may be unevenly distributed, with nulls in a few directions, but I'm hoping to avoid diffraction modes by varying the length of the "short circuit" path between front and rear.
This may not be unique, but certainly unusual: the metal outer rim of the speaker will not be directly connected to the baffle. Instead, there will be a slight gap for tolerances and a secondary rubber surround or 'gasket' to make it air-tight. Therefore, the anti-phase vibrations from the magnet will be prevented from shaking the baffle like an actuator.
Even though P-P amplitude of vibrations from the magnet should be minimal:
~0.015kg cone vs ~1kg magnet
=> 3mm cone Xmax * 15 / 1000 = 0.045mm
the entire surface area of the baffle would be set in motion with high efficiency. I could just use a much larger and heavier slab for the baffle itself, but cutting round holes in granite is a skill that I don't have.
(Edit: if anyone has tried playing sound through a raw driver while holding it in your hand, you'll have felt those vibrations, and experienced how playing it on a table will shake the table...)
2nd idea:
I'm also inspired by Karlson tubes to cut some approximately exponential slots into the baffle, resembling flower petals. Off-axis energy may be unevenly distributed, with nulls in a few directions, but I'm hoping to avoid diffraction modes by varying the length of the "short circuit" path between front and rear.
Last edited:
That's not how it works, learn to choose the right parameters. Otherwise the cabinet is the big determinant of what you get. Find out what an open baffle does and how to make one work in your room.
A closed 1 inch dome tweeter and a 12 inch woofer won't have matching radiation patterns that is the biggest problem. The woofer will have a figure 8 pattern up to maybe 500-700hz or something and than the tweeter needs to be crossed over around 2.5khz (3 times fs minimal as a shorthand) which the woofer won't reproduce cleanly nor with a good radiation pattern at those frequencies, while the tweeter is omni directional at those frequencies at the same time the woofer only fires in the front direction due to the beaming of the big cone. This basically means that you will have way to much mid and high energy in your room compared to bass and lower-mid. To compensate this which btw isn't possible you would have to lower the overall amplitude in those frequency bands via a notch filter or shelf filter which will ruin the on axis (= bad idea) frequency response. So no this won't work. This will result in a horrible sounding speaker as you cannot build a speaker that has good tonal balance, as it is impossible to realize a good on axis response and off axis response at the same time with 2 drivers in an open baffle (especially those you mentioned). The charts are by the way for the speaker on an infinite baffle or iec baffle so are not representative for how it would look when used in a real speaker baffle especially not an open baffle one.
I would completely forget 12inch woofers and 2 ways. As said before it won't work. 2 way open baffle speakers can be made (probably somehow) but not by a beginner. The best way forward if it has to be 2way and an existing open baffle kit would be, as you said you're open to subwoofers, to make just the Linkwitz lx521 top baffle with the passive mid crossover which will be a 2 way 2 channel per side dsp speaker and than use subs for 150hz and below. The lx521 is probably the only diy kit that somewhat comes close to a good sounding open baffle design. Manzantia, PureAudioProject, Spatial audio etc. are all bad designs absolutely not worth it (to copy) if you value good sound and neutral frequency response (google around if you want to see measurements, frequency response deviations of +-5db or more aren't uncommon; you don't want that). I am not sure if the lx521 is a neutral (read good sounding) speaker, never heard it, but it comes closer to how a good dipole speaker should look like than any commercial and kit open baffle speaker I've seen. I absolutely don't recommend or endorse it by this comment (because I have not heard it myself and think the design has some serious compromises i.e. frequency response linearity, polar response and max spl) but if you want a good sounding open baffle than it should at least resemble the lx521 design; 3/4way, small baffles, dsp etc. Maybe the mentioned compromises are acceptable for you and it is something your willing to experiment with than it might be even a solution or a direction you could go in but I think it is important to understand that those compromises are likely to exist in all open baffle designs to varying degrees and depending on what you choose may be more pronounced than is acceptable to you.