Much of the music on a stage is oriented toward the audience. The PA, guitar and bass cabinets, most horns, woodwinds, guitar sound hole are a few examples. In a symphony orchestra, the players bodies must block/absorb backward radiating sound, especially HF.
It seems like a di-pole with cone drivers would do something vaguely similar.
It seems to me that two plate amplifiers may be best addition to the system.
That way there would be no changes to the amplification, no active crossover, no ad convertor, no dsp.
You could use parallel or series crossover, which would be much simpler, since crossover would be only two way for mid and tweeter. No big inductors would be needed.
Plate amps would piggiback on the signal from amp, directly or through some resistors, some plate amps have already two inputs, line level ans speaker level, which just containes one higher wattage resistor inside.
Plate amps have separate volume, cut off and often phase to adjust. Infinitely more flexible than passive crossover.
Shallow natural rolloff for mid combined with steep active for woofer is way to go. By crossing woofer lower plus rasing its level one can compensate for cancelation thus increasing around 30Hz for flatter bass without nasty midbass.
Just a suggestion.
I find that my sealed NHT 1259 12" sub in 3.3 Cuft cabinet with a plate amp works well to extend response below 50hz, which is the frequency where my open baffles start to drop off big time. Not that there is not response lower down, but the curve gets pretty steep.
I could see using my second 1259 in a aligned stereo set-up, but I have not done so, because they are big----so they are tucked away other places in the room.
I could see using my second 1259 in a aligned stereo set-up, but I have not done so, because they are big----so they are tucked away other places in the room.
Curious... What is the OB bass driver(s)?
I recently measured my LX521-inspired clones in a friend's huge space. The drivers are two SBA 10″ SB29SWNRX-S75-6 in a W-frame per side. With just one speaker @ 1m, the bass was just about flat to 30 Hz; maybe 5-6 dB down at 25 Hz. It sounds that way too.
(Don't have access to the REW data from my laptop -- will post if I remember to save it to my server.)
I built two OB pairs that work well alone, or with the sealed NHT 1259 sub for music that has very low bass, or was recorded in a large hall.
One pair has 8ohm, 18" Tymphany subs, that are only about 91dB sensitive, and about 31hz Fs. They also use 12" vintage Bozak woofers with Fs of about 45hz. The 18's would make 30Hz, if they had requisite boost applied; but they are simply rolled off passively, very low, 1st order, with 20mH coils.
The other build is similar, with the same 12" Bozak woofers. A 2nd set of woofers have low Fs, but are less capable of low end output than the 18's, with smaller cones and limited mechanical excursion---vintage 12" JBL 123A. These speakers can still play pretty loud---but the 123A woofers would likely self destruct with low freq. boost. I wanted to have a sleeker, narrower baffle shape for these, so no 15's or 18's. A similar build with more robust, low Fs, woofers plus EQ/Boost, would likely play nice-'n'-low.
Relevant to my last post above, the 18" woofers and the JBL123a woofers are each mounted in 7" deep U-frames on the back, that closely surround the drivers. H-frames might give more bass, but as these drivers, passively filtered, have significant output well into the midrange, I wanted to avoid added effects of the short pipe that would face forward in an H-frame.
I have heard similar 18" drivers in 24" square H frames, passively crossed, and found the low midrange to have more added coloration than I would like. I felt/feel that one of the great things about open baffles, the clear midbass/low midrange, to be compromised. Also, they take more room space, and look clunkier.
I currently feel that less space around the woofer in a U-frame, the better. I have a project in mind that would use concrete form tubes, matching the diameter of the woofer frames, about 7" long, as U-frames. They might be painted black, or maybe veneered.
I have heard similar 18" drivers in 24" square H frames, passively crossed, and found the low midrange to have more added coloration than I would like. I felt/feel that one of the great things about open baffles, the clear midbass/low midrange, to be compromised. Also, they take more room space, and look clunkier.
I currently feel that less space around the woofer in a U-frame, the better. I have a project in mind that would use concrete form tubes, matching the diameter of the woofer frames, about 7" long, as U-frames. They might be painted black, or maybe veneered.
Thanks for the info @howardg -- some pics would be useful. U-frames for 18" woofers just 7" deep -- that's interesting.
How are the subs positioned?
I'm considering exactly how to employ 2 SB Audience NERO-18SW1900D subs that are meant to support the deep bass for a pair of OB speakers. DSP & steep crossover slopes are available so I don't need to worry much about pipe resonances. They will likely operate only below 50-60 Hz.
The main speakers are dual-opposed W-frame 12" SB34SWPL76-4 bass + SBA WO24TX + upper mid (still being considered) + Aurum Cantus AST2560 AMT. Crossovers at 125-150Hz, 1-1.5 kHz, 3-4 kHz. miniDSP Flex 8 for the main speakers. Slopes to be determined experimentally & finalized in situ. The subs will run off the sub output of a Wiim Ultra, which currently applies LR4 40~140 Hz filters on both main & sub
I know all that could be overkill for the bass but it's going into a voluminous room about 52' x 30' with a ceiling that's 15-20' high, and open extensions to other rooms. There's a desire for the bass never to be strained at any volume to >100 dB.
My friend, for whom I'm building this system, is a recent gung-ho convert to OB speakers.
How are the subs positioned?
I'm considering exactly how to employ 2 SB Audience NERO-18SW1900D subs that are meant to support the deep bass for a pair of OB speakers. DSP & steep crossover slopes are available so I don't need to worry much about pipe resonances. They will likely operate only below 50-60 Hz.
The main speakers are dual-opposed W-frame 12" SB34SWPL76-4 bass + SBA WO24TX + upper mid (still being considered) + Aurum Cantus AST2560 AMT. Crossovers at 125-150Hz, 1-1.5 kHz, 3-4 kHz. miniDSP Flex 8 for the main speakers. Slopes to be determined experimentally & finalized in situ. The subs will run off the sub output of a Wiim Ultra, which currently applies LR4 40~140 Hz filters on both main & sub
I know all that could be overkill for the bass but it's going into a voluminous room about 52' x 30' with a ceiling that's 15-20' high, and open extensions to other rooms. There's a desire for the bass never to be strained at any volume to >100 dB.
My friend, for whom I'm building this system, is a recent gung-ho convert to OB speakers.
Correction: 30~250Hz. The Wiim also has a "Sync Subwoofer and Speakers" to bring them into time alignment.
The subs are mounted at the bottom of the open baffle stereo pairs.
PICS: I have had trouble with my android phone and windows 10, getting the Microsoft software to allow me to transfer just the files I want to. These things should be so simple at this point, without having to give up other types of privacy and choice.
Both Google and Microsoft seem to want me to install/use a whole suite of things. Google has been involved in updating my phone, so now I have to navigate away from their prompting screen, just to do simple things. I have to take extra steps to avoid signing up through Google---similar story on the computer.
Tech is engineered to remove our agency and privacy from us. Like the proverbial frog, boiling in the slowly heating pot.
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Yeah - if you dont pay in one way, you'll "pay" in another.
My wife remarked "what are we going to do!" when W10 - which we use on all our computers - hits the skids; I just laughed. I said "we'll be like that guy on DIYAudio, where it seems if you even think of something, it somehow auto-magically shows up on your M$ OS home screen to buy!"
I share your apparent disgust with all of it.
Hi folks,
sorry for not being here for a while, had some pneumonia issues... but I had time for listening sessions - and for plans...
So the journey continues.
Today I received two W8-1808 full range drivers and on Wednesday I will get two SB 15OB350 woofers 👍
Both are completely different animals in comparison with my current drivers so I'm really curious how they sing together.
I'm already working on the xo in the sim... and it is far easier to use the SB woofer. My current EA15A has a nasty break up which is hard to deal with, there is a need for a big cap.
The new xo will contain a maximum of 4 parts (one of them is optional) - and I will try parallel and series versions. Because of the parts there will be no phase shift, the simulated graph is within a 5° range.
Further, I plan to use a two-part 4 cm wood baffle instead of the current 18 mm MDF.
Fun, fun, fun 😀
sorry for not being here for a while, had some pneumonia issues... but I had time for listening sessions - and for plans...
So the journey continues.
Today I received two W8-1808 full range drivers and on Wednesday I will get two SB 15OB350 woofers 👍
Both are completely different animals in comparison with my current drivers so I'm really curious how they sing together.
I'm already working on the xo in the sim... and it is far easier to use the SB woofer. My current EA15A has a nasty break up which is hard to deal with, there is a need for a big cap.
The new xo will contain a maximum of 4 parts (one of them is optional) - and I will try parallel and series versions. Because of the parts there will be no phase shift, the simulated graph is within a 5° range.
Further, I plan to use a two-part 4 cm wood baffle instead of the current 18 mm MDF.
Fun, fun, fun 😀
Did you have a particular/recognized approach to keeping phase in good shape, or did you experiment with virtual parts until a nice result was obtained, or---?
Waiting eagerly for the results as I am using EA15A 2 per side with 120uf cap
I just played with the sim and "know" that first order gives an ideal phase approach (but I know there are many duscussions). Further, the math tells the "truth", which means, 45 degrees of phase shift per driver will sum up zero degrees of phase shift.
In my current design there is no such layer, so I may stick to this way, but it's not a must. I will report.
Same here, I use 107 nF but even so, the bump is there, only at a lower volume.
So it will be completely different with the SB.
Hi again,
being sick again... I had time to build the series crossovers and change the drivers - it's a drop in story, so very easy.
Now, everything is new, no break-in/burn-in, but I very much like what I hear.
Everything is "more": resolution, clarity, crispness, stage, dynamics, emotions...
Ok... not everything: less distortion and less sharpness (in fact it's gone).
I still have to tune the relation between woofer and FR, but even so it is just great.
Much better than the EA15A-TB2145 combo. Period.
I'm delighted
being sick again... I had time to build the series crossovers and change the drivers - it's a drop in story, so very easy.
Now, everything is new, no break-in/burn-in, but I very much like what I hear.
Everything is "more": resolution, clarity, crispness, stage, dynamics, emotions...
Ok... not everything: less distortion and less sharpness (in fact it's gone).
I still have to tune the relation between woofer and FR, but even so it is just great.
Much better than the EA15A-TB2145 combo. Period.
I'm delighted
Beautiful.
I followed your OB journey, amd it was interesting to watch how you made step-ups : you had started with SB Acoustics fullrange, then TB W8 2145, now TB W8-1808. Well each has its place and merits, but the price increase is not trivial (roughly SB is 3 or 4 times cheaper than TB 2145, which is almost twice cheaper than TB W8-1808).
But hey, we don't buy speakers every month, so I believe it's worth it 😉
Also the Eminence Alphas: They should have been changed first. While they are good for a begginer OB, they lack the "oomph" for something more serious. So, good 🙂
And a question: How would you compare the sound of only TB 2145 vs 1808? Is it worth more than twice the cost?
P.s. I believed that you will upgrade to some of the Sonido fullrange driver, but on the other hand, I heard just praise about TB W8-1808...
I followed your OB journey, amd it was interesting to watch how you made step-ups : you had started with SB Acoustics fullrange, then TB W8 2145, now TB W8-1808. Well each has its place and merits, but the price increase is not trivial (roughly SB is 3 or 4 times cheaper than TB 2145, which is almost twice cheaper than TB W8-1808).
But hey, we don't buy speakers every month, so I believe it's worth it 😉
Also the Eminence Alphas: They should have been changed first. While they are good for a begginer OB, they lack the "oomph" for something more serious. So, good 🙂
And a question: How would you compare the sound of only TB 2145 vs 1808? Is it worth more than twice the cost?
P.s. I believed that you will upgrade to some of the Sonido fullrange driver, but on the other hand, I heard just praise about TB W8-1808...
Hi Viktor, many thanks!
It was a tough decision because it's not available here in Europe... so after a very long consideration I ordered them in the US. Transport prices are extremely high and I also have to pay taxes...so... well... it's expensive.
But - yes, the 1808 is that good, no question for me, even if I only had a short listening (just one CD).
You are right, the EA15A is... okay. But the SB 15OB350 is just wow! It's built like a tank, it's much-much heavier than the EA.
Soundwise - again, I still have to tune the system - it has much more details, it's much more differentiated, not just "deep, but every sound is the same". I didn't tried it at volumes where "oomph" is working, because it's new, but soon.
When I change the FR again (never say never), then I would go for a field coil Sonido.
It was a tough decision because it's not available here in Europe... so after a very long consideration I ordered them in the US. Transport prices are extremely high and I also have to pay taxes...so... well... it's expensive.
But - yes, the 1808 is that good, no question for me, even if I only had a short listening (just one CD).
You are right, the EA15A is... okay. But the SB 15OB350 is just wow! It's built like a tank, it's much-much heavier than the EA.
Soundwise - again, I still have to tune the system - it has much more details, it's much more differentiated, not just "deep, but every sound is the same". I didn't tried it at volumes where "oomph" is working, because it's new, but soon.
When I change the FR again (never say never), then I would go for a field coil Sonido.