"The way, to do it flat passively, is to lower down upper freqs, either low pass or - high shelf. Very low sensitivity/efficiency is side effect."
this is basically what Im doing. My mid/tweeter planar is about 86db sens., the woofer is a 96db sens .32 Qts , BUT the woofer is chopped hard at 300 hz so ya end up with a flat response down to about 50 hz in a 22 inch wide baffle.
This works with any crossover slope, 6, 12, 18..... ya just have to use a low enough mid/tweet sensitivity to come in about 5-7 db below thw woofers level spl and blend accordingly.
I end up with the system sensitivity of the mid at around 86db. Yes there is no huge rise below 100 hz as many want BUT imo the room gain offsets this and it sounds clean and fast with no overhang. I have also done this with a 28 inch wide baffle and the results are a useful increase down low. All this with a .32 Qts woofer so I suspect a .5 or so Qts would be another 3db-5db gain down low see pics. The second pic not labeled well. It shows the difference between a 22 inch wide and a 28 inch wide baffle. first pic shows the direct driven woofer response in 22 inch baffle VS the same with the 18db/oct cross at 300 hz
IF the desire is to have a big rise in response below 100 hz then yes you will need to cross lower than 300, maybe about 150 AND then the mid will have to be able to go lower to meet it AND you will have to pad the mid down so that you allow a larger difference in close mic outputs between woofer and mid thus ending up with quite low sensitivity maybe down around 82 db? depending on how much rise ya want in bass below 100hz. I have done this and it certainly works BUT imo often sounds deep but polite. I like the more dynamic sound of crossing at 300 18db better. . If ya want to get sensitivity back up to reasonable you will need two woofers per side if crossing way down at 150hz
this is basically what Im doing. My mid/tweeter planar is about 86db sens., the woofer is a 96db sens .32 Qts , BUT the woofer is chopped hard at 300 hz so ya end up with a flat response down to about 50 hz in a 22 inch wide baffle.
This works with any crossover slope, 6, 12, 18..... ya just have to use a low enough mid/tweet sensitivity to come in about 5-7 db below thw woofers level spl and blend accordingly.
I end up with the system sensitivity of the mid at around 86db. Yes there is no huge rise below 100 hz as many want BUT imo the room gain offsets this and it sounds clean and fast with no overhang. I have also done this with a 28 inch wide baffle and the results are a useful increase down low. All this with a .32 Qts woofer so I suspect a .5 or so Qts would be another 3db-5db gain down low see pics. The second pic not labeled well. It shows the difference between a 22 inch wide and a 28 inch wide baffle. first pic shows the direct driven woofer response in 22 inch baffle VS the same with the 18db/oct cross at 300 hz
IF the desire is to have a big rise in response below 100 hz then yes you will need to cross lower than 300, maybe about 150 AND then the mid will have to be able to go lower to meet it AND you will have to pad the mid down so that you allow a larger difference in close mic outputs between woofer and mid thus ending up with quite low sensitivity maybe down around 82 db? depending on how much rise ya want in bass below 100hz. I have done this and it certainly works BUT imo often sounds deep but polite. I like the more dynamic sound of crossing at 300 18db better. . If ya want to get sensitivity back up to reasonable you will need two woofers per side if crossing way down at 150hz
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Very nice build and I used the below Leonidas crossover published in the SBAF forum with changes as below for w1808
L1: 4.7mH, C: 82Mf, R1: 0.1ohm, there's no R2
I have been contemplating a very similar setup for a while now. Where are you located? Do you have a full write-up/measurements posted anywhere?
I’m in Portland OR. I don’t have a write-up of my build but there are a few threads on Audio Circle about this design. Search in the GR-Research “circle” for “Line Force”.
I am running a pair of the Celestion 15ftr3070c woofers in a k402 MEH horn without a cabinet and I was able to get pretty good bass, but when I added a 2nd MEH without a compression driver (just 2 Celestion 15ftr3070c woofers), the bass got considerably better.
In my config... I am running 2 k402 MEH horns per channel (stacked), and each ftr15-3070c pair has its own fosi v3 monoblock amp. With one MEH I did not have to do much tuning to get pretty flat all the way down to 20hz, but it was driving them harder than I wanted, so I added a pair of LilMikes f20 sub horns crossed over at 80hz., and it got better, but the big difference was when I added the 2nd MEH horn (no compression driver...just 2 ftr15-3070c woofers). Now I not only get to 20hz, but wit a good 6db more spl..
I originally had the ftr15-3070c in the MEH, but everyone said the Emminence Alpha 15As were the way to go...so I bought 2 pair. I found several differences.
The Alphas were warmer sounding, but when compared to the ftr15-3070c woofers the Alpha were muddy and the ftr15-3070c woofers dug deeper with much more clarity.
The Celestions were also a good bit more efficient...more than 6db which meant they were also a better match for the Celestion axi 2050 comp drivers and also with the f20 sub horns. The setup is tuned as a 3 way...with the ftr15-3070c being used for 80hz to 300hz, and the f20s from 20hz to 80hz.
I am very happy with the 15ftr3070c woofers compared to the Alpha 15As. The Alpha 15As will be moved to my surrounds, and I will be ordering more ftr15-3070c woofers for a 4 woofer sealed center channel with a xyz horn and EV DH1A comp driver. I figure since the center is usually a bit bass shy...that 4 woofers in a sealed cabinet should be close to the stacked k402 MEHs.
Discussion of these speakers popped up on ASR recently: Fourier Transform Speakers (website "coming soon"). I don't want to post Youtube videos here, but this is what they look like:
And this appears to be the prototype:
I suppose they qualify as "open baffle speakers". I tried to do a search to see if they have been discussed to no avail. I can see some advantages (e.g. omnidirectional dispersion) but I would have many concerns about the design.
And this appears to be the prototype:
I suppose they qualify as "open baffle speakers". I tried to do a search to see if they have been discussed to no avail. I can see some advantages (e.g. omnidirectional dispersion) but I would have many concerns about the design.
This picture/concept would neatly qualify for the thread Post a Picture that Makes You Laugh.
https://audiosciencereview.com/foru...st-speaker-to-reproduce-a-60hz-sq-wave.50863/
Far fetched Fourier... the guy left the thread!
Far fetched Fourier... the guy left the thread!
Why you posted ported bass box and sealed box mid/treble in 'ultimate open baffle gallery' thread?
Would you be able to provide a more detailed explanation as to why you think the idea is absurd?
Yeah the responses on ASR were really brutal.
Form follows function. For standard acoustical results, studio monitors or line arrays have to look boringly similar. What a pain to live in such a normalized world.
Form follows function. Function claimed in this case is named Fourier. You may now read some basics about Fourier theory if you like, and then e.g. relate the theoretically needed number of channels in order to reach the claimed goal to the ones set up physically. Then you may e.g. read some basics about radiation patterns of different sound sources, and then mentally examine the whole system for it's 3d radiation pattern. You may think about the gear battle needed to miss a theoretical goal. You may then ... You may then ... You may then finally come to the conclusion, that the system may contain some absurdities, let's name it, at least in terms of acoustics and in terms of the application of the basic fourier theory claimed behind this setup.
Form follows fantasm. Fourier becomes fou rire ... I do not contest that this system has a charming quality of uniqueness. It certainly in some (multi-)way lines up to the most original setups ever seen, kind of most hilarious builds since Mordillo. And this is a quality for it's own.
Form follows fun. We live in such a serious world, so any contribution which makes us smile or laugh is most welcomed.
Form follows function. So let's seriously and functionally laugh about this one, then. Thank you.
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Dipole bass and sort of cardioid midrange, passive speaker
https://audio.com.pl/testy/stereo/kolumny-glosnikowe/4101-silent-pound-challenger-ii#laboratory
Normalized horizontals
https://audio.com.pl/testy/stereo/kolumny-glosnikowe/4101-silent-pound-challenger-ii#laboratory
Normalized horizontals
Very interesting. I recall DNA Sequence speaker, with massive aura woofer, open baffle, with quad of midrange units and tweeter in the middle. Exept no cancelation holes for mids. So not exactly the same concept, but close.