I never really got that far. I looked at the size of the waveguide to match the 18" and they just got to be so big. Remember that halving the Xover frequency means doubling the waveguide radius - quadrupling it in area. Things get problematic fast. I think that I would likely have gone up on the aperture to 1.5", but then again, the driver choice isn't really very important. It's the total system design that counts.
Does the waveguide match the woofer at the crossover? Too small and the waveguide narrows at the lower end making CD impossible. Move the crossover higher to avoid this and the woofer gets too narrow. Could narrow the waveguide coverage to match, but then it has to get longer. As much as I looked at the problem it just seemed that a 15" woofer was the max that is feasible and that 12" and 15" really represent the sweet spot.
I also found that most 18" woofers could not handle the upper range very well. A good 15" does this surprisingly well. 15" is a highly refined design that is hard to best.
At least this is what I found.
Does the waveguide match the woofer at the crossover? Too small and the waveguide narrows at the lower end making CD impossible. Move the crossover higher to avoid this and the woofer gets too narrow. Could narrow the waveguide coverage to match, but then it has to get longer. As much as I looked at the problem it just seemed that a 15" woofer was the max that is feasible and that 12" and 15" really represent the sweet spot.
I also found that most 18" woofers could not handle the upper range very well. A good 15" does this surprisingly well. 15" is a highly refined design that is hard to best.
At least this is what I found.
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Me too, but with an 18" I can't think of many options.
> 600Hz with an 18" is pushing it imo and most 1" don't like < 1000Hz.
Besides, I heard a few 3" diaphragm drivers that beat my DE250s, even in the top octave.
This is one (that can also be crossed at 600Hz):
An externally hosted image should be here but it was not working when we last tested it.
Earl
That's what I thought (not that you didn't get that far but that you would use a bigger driver). From many of your posts I got the understanding that using a typical 1" crossed over at ~800 Hz to 15" is already about at its limits. But then you also stated many times that bigger drivers suffer too much at high frequencies (from your point). So the natural question that comes to mind is - would there be really a point in doing that? (i.e. to use 18" + 1.5") What is to gain? A little bit of constant directivity extension to the lower midrange?
That's what I thought (not that you didn't get that far but that you would use a bigger driver). From many of your posts I got the understanding that using a typical 1" crossed over at ~800 Hz to 15" is already about at its limits. But then you also stated many times that bigger drivers suffer too much at high frequencies (from your point). So the natural question that comes to mind is - would there be really a point in doing that? (i.e. to use 18" + 1.5") What is to gain? A little bit of constant directivity extension to the lower midrange?
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Mabat - you get the picture. I had no reason to believe that any of this would improve things enough to make the design viable.
As to HF content, you need to look at the polars. If the waveguide narrows, as poor ones do, then the axial response will be basically flat, but the power response will be falling. This, to me, is a bad trade-off.
I have yet to hear a system that matches my 15" designs, so I don't feel that there is much room to go larger. I've had basically the same 15" system for almost twenty years with no regrets. I'm just not motivated to do much more.
Active does offer some advantages that I never fully flushed out. But the problem gets to be implementation. For a home theater there simply are not inexpensive solutions to the multi-channel problem (the receiver), again making this solution less than attractive.
I am using active now, but I don't like what I had to do to achieve it. I basically have to take a signal off of the receiver outputs (8 ohm) and convert them to high level signals via a resistor pad to driver a MiniDSP - a solution that will appal many. Then there are all the separate amps and yada yada, yada ... Many might like this kind of complexity, but I don't. If I ever do anything more to my system, it will be to go back to passive.
As to HF content, you need to look at the polars. If the waveguide narrows, as poor ones do, then the axial response will be basically flat, but the power response will be falling. This, to me, is a bad trade-off.
I have yet to hear a system that matches my 15" designs, so I don't feel that there is much room to go larger. I've had basically the same 15" system for almost twenty years with no regrets. I'm just not motivated to do much more.
Active does offer some advantages that I never fully flushed out. But the problem gets to be implementation. For a home theater there simply are not inexpensive solutions to the multi-channel problem (the receiver), again making this solution less than attractive.
I am using active now, but I don't like what I had to do to achieve it. I basically have to take a signal off of the receiver outputs (8 ohm) and convert them to high level signals via a resistor pad to driver a MiniDSP - a solution that will appal many. Then there are all the separate amps and yada yada, yada ... Many might like this kind of complexity, but I don't. If I ever do anything more to my system, it will be to go back to passive.
Is this some Faital? Which one? Beware of the scale - it's 100 dB, everything will look good at that scale
I've only a limited experience with Faitals. I quite like Celestion overall - never disappointed me. But as Earl says, it's a comodity... Oh, and did I say I like Eighteensound?
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And that is exactly the same reasoning that drives me away from multiple subs. I believe I would be happy with the results but I just hate this idea of the implementation. Not to mention so many boxes and cables (oh how I hate cables) around the room...
You just made me listen to that song. It is not my kind of music though. But it is indeed one that can be used to massage the diaphragm whikle it is also easy on the ear. There are no ear-splitting mids but the mids that are there sound clear and transparent. The latter is not always the case with bass-heavy tracks.
Thanks for the tip.
Regards
Charles
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Hi David,
I hear you on the solution not depending on software and do know what you mean. If I could, I would go that route as well, but all of the H/W firmware devices I looked at are very limited in the number of FIR filter taps available per channel. Like an order of magnitude less than a software solution (i.e. 6000 taps versus 65,536 taps and beyond). Then arguably, one has the same issues as mentioned about software, now applied to firmware of the device.
However, I must say I am running several DSP software packages on my main computer that I purchased in 2011. The only upgrade since has been a SSD that made a major speed difference for startup and launching applications. I have not had any real issues and I use this computer to experiment on a lot. I do listen to vinyl from time to time using a phono preamp, Lynx Hilo ADC and JRiver digital input.
There are folks that run multi-way, multi channel HT and music systems, using Audiolense or Acourate quite successfully. Both softwares are well supported and have been around for +10 years.
Wrt to the software. A linear phase crossover is used to convolve the individual drivers responses into the linear phase XO slope so that they sum together perfectly in the frequency and time domains, as per the article I linked to in the previous post. The acoustic centers of each driver are also time aligned down to the resolution of one sample at 48 kHz. When one tailors the magnitude response of the system, using a minimum phase target, the phase response is also being corrected. The software does extract the excess phase separately and corrected separately for room modes and any other timing issues. Works pretty good. And contrary to popular belief, it is not just at one mic location either. The sweet spot is easily across a 3 seat couch area, including time alignment of drivers.
Anyway, I get what you are saying. Perhaps something in between like a dedicated Linux box with BruteFIR maybe the best compromise.
For the purposes of this discussion on a large two way, a software DSP XO solution would be a snap
With DSP software like Audiolense, the above could be achieved in 30 minutes.All the best.
Mitch
I'm using an arrangement similar to SLs. Drivers are 13" SS Revelators, four drivers in two boxes almost touching the back of the couch. These are crossed at 80Hz to dipole L&R mains. Very little eq is needed to flatten response to 20Hz. One most interesting feature is the complete lack of bass bleeding into adjacent spaces. This will be used to great advantage when I downsize into an apartment in a few years.
It was a prototype for a commercial offering that never went ahead due to packaging/perception issues.
Attachments
Geddes
Sorry so late, to join the conversation. You commented that angling devices did not work well in your experience? I wonder if I didn't make myself clear? I just meant, to tilt the enclosure/front baffle to point at the ear. Certainly that is no different than turning the speaker to the left or right, in order to once again, point the drivers at the listener.
Please clarify that thought, if you'd be so kind. I do see difference, concerning, the ears performance on different axis and whatever variations of reflective energy.
GM
I did say from the get go that sweet spot was the only listening position that mattered =) Especially around the time of discussing horns and I kept defending Tractrix horns over the many suggested CD horns. MTM you say? You like it I love it. ~17" tall per woofer....23" horn.....57" tall MTM...leaving 23" from the top to the ceiling if sitting on the floor.....so floor reflections aren't and issue but ceiling reflections are...is this because of how our hearing works? This would put my horn center at ~29" off the ground....my ears are at 48" off the ground....so now I tilt the whole thing towards my ears right? Or if I move the horn to ear level, The top enclosure is only a few inches from the ceiling....isn't this bad?
I like the idea of the coupling performance of dual woofers when positioned right next to each other....still in the 10.5ft3 enclosure I'm still presenting the idea of tilting the baffle towards my ears
This thread is getting deeeep, you guys are generating great conversation, and I really appreciate you all....as well do other onlookers as well, so much learning and passing of wisdom.
The argument about sealed vs ported, for this projects sake, is null and void. If focusing on a 2 way woofer, there is no sealed woofer that as going to allow sufficient SPL without realizing ridiculous excursion, that would be detrimental to the mid range that it is responsible for. End of story
Also, there are arguments for ported still, is their not? The increased sensitivity....there is a connection between sound quality and efficiency is there not? The trouble with ports exist below the tuning freq or no? (I didn't thoroughly read the whitepaper) with a tuning freq of mid 30's or lower....for music....pretty much everything is going to be above that. Also, aren't there sonic benefits to lowered excursion? I haven't seen too many sealed woofers make to 30hz 0db (linear) without crazy excursion requirements. Maybe I didn't find the right driver. Still, I recognize the advantages of a sealed woofer....its the whole excursion vs mid range performance thing and this is a 2 way project.
Also! Xover...I am copying the xover from the 4722 (630hz)? Seems like a good idea....the polar isn't, unless dead on axis, which is the goal....there was just the concern of the timbre caused by reverberation vs the lobing. Jbl seemed to think it was find for the 4722 =?
Sorry so late, to join the conversation. You commented that angling devices did not work well in your experience? I wonder if I didn't make myself clear? I just meant, to tilt the enclosure/front baffle to point at the ear. Certainly that is no different than turning the speaker to the left or right, in order to once again, point the drivers at the listener.
Please clarify that thought, if you'd be so kind. I do see difference, concerning, the ears performance on different axis and whatever variations of reflective energy.
GM
I did say from the get go that sweet spot was the only listening position that mattered =) Especially around the time of discussing horns and I kept defending Tractrix horns over the many suggested CD horns. MTM you say? You like it I love it. ~17" tall per woofer....23" horn.....57" tall MTM...leaving 23" from the top to the ceiling if sitting on the floor.....so floor reflections aren't and issue but ceiling reflections are...is this because of how our hearing works? This would put my horn center at ~29" off the ground....my ears are at 48" off the ground....so now I tilt the whole thing towards my ears right? Or if I move the horn to ear level, The top enclosure is only a few inches from the ceiling....isn't this bad?
I like the idea of the coupling performance of dual woofers when positioned right next to each other....still in the 10.5ft3 enclosure I'm still presenting the idea of tilting the baffle towards my ears
This thread is getting deeeep, you guys are generating great conversation, and I really appreciate you all....as well do other onlookers as well, so much learning and passing of wisdom.
The argument about sealed vs ported, for this projects sake, is null and void. If focusing on a 2 way woofer, there is no sealed woofer that as going to allow sufficient SPL without realizing ridiculous excursion, that would be detrimental to the mid range that it is responsible for. End of story
Also, there are arguments for ported still, is their not? The increased sensitivity....there is a connection between sound quality and efficiency is there not? The trouble with ports exist below the tuning freq or no? (I didn't thoroughly read the whitepaper) with a tuning freq of mid 30's or lower....for music....pretty much everything is going to be above that. Also, aren't there sonic benefits to lowered excursion? I haven't seen too many sealed woofers make to 30hz 0db (linear) without crazy excursion requirements. Maybe I didn't find the right driver. Still, I recognize the advantages of a sealed woofer....its the whole excursion vs mid range performance thing and this is a 2 way project.
Also! Xover...I am copying the xover from the 4722 (630hz)? Seems like a good idea....the polar isn't, unless dead on axis, which is the goal....there was just the concern of the timbre caused by reverberation vs the lobing. Jbl seemed to think it was find for the 4722 =?
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Whats the formula for this type of enclosure? Since The waves of sub bass are so large a di-pole/open baffle sub is comparable to sealed/ported correct?
How can I predict potential spl levels for this type of appliocation?
Lots of great info on the late SL's site. Nearfield the low frequency loss is much less than at a distance.
This will make the wavefronts cross each other. Of course it will also project them into the same (similar) space. Further, it affects how they fit together physically. There is always something to consider when the acoustic centres aren't in the same space.
DIY Sound Group Waveguide
Getting back to waveguides for a 15" 2 way solution.
It seems no one ever mentions the possibility of using the DIY Sound Group Waveguides (or complete kits for that matter). Their Fusion 15 (maybe no longer available as a kit) seems to mostly fit the bill for covering the complete range with controlled directivity. At least some of their designs use the DE-250.
Some of the graphs of their waveguides posted elsewhere look nice, but I don't know how much "normalization" or "smoothing" is going on. They're supposedly based on an OS profile.
Anyone here using their products or have measured their products?
Getting back to waveguides for a 15" 2 way solution.
It seems no one ever mentions the possibility of using the DIY Sound Group Waveguides (or complete kits for that matter). Their Fusion 15 (maybe no longer available as a kit) seems to mostly fit the bill for covering the complete range with controlled directivity. At least some of their designs use the DE-250.
Some of the graphs of their waveguides posted elsewhere look nice, but I don't know how much "normalization" or "smoothing" is going on. They're supposedly based on an OS profile.
Anyone here using their products or have measured their products?
Not really, camplo. Aren't we talking about the possibility of a 2 way covering the entire spectrum?
There are pages and pages discussing various waveguides in the thread, but the DIYSG is never mentioned. I'm wary of the hype posted on other sites and simply wondering if anyone here is familiar with their "SEOS" products.
There are pages and pages discussing various waveguides in the thread, but the DIYSG is never mentioned. I'm wary of the hype posted on other sites and simply wondering if anyone here is familiar with their "SEOS" products.
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