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If you had a choice of three lowpass crossover points for a three way system; 140hz, 175hz, or 250hz.Which would you choose, and why?
Edit: Sad that I have to say this; Industry Professionals and Manufacturers should feel free to give their opinion.
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Big speakers and little amps blew my mind!
Edits: 07/05/15Follow Ups:
then other factors at play as well. Do you have the drivers?
E
T
No sir I don't.
This was just an inquiry for any known virtue held by any of the three crossover points. It's very general and hypothetical.
I apologize for wasting your time.
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Big speakers and little amps blew my mind!
Assuming both drivers have acceptable response over the region in question, I'd first want to figure out whether the midbass driver will be overstressed in this application with the lower crossover points.
Assuming that's not an issue, I'd next want to look at the response curves of both drivers (including off-axis if they are directional at these frequencies) and see if their response curves are "telling us" where they want to be crossed over.
If there is no clear indication from the curves, then I'd look at what is the most practical to implement. The phrase "most practical to implement" covers a lot of territory, and I'd want to take as much into account as possible before choosing the crossover point.
If this were my project, I'd want to start out by asking the question, "what's the best way to meet goals xyz?", and from there let the logical design choices dictate where my crossover(s) should be as the design process unfolds. And I would want to take everything into account; overlooking one little thing (like the phase angle of the impedance curve) can screw up an otherwise promising design. It might turn out that a second-order lowpass at 120 Hz on the woofer combined with an underdamped third-order highpass at 180 Hz on the midbass is what works best, but we won't know that far enough in advance to choose the crossover points beforehand.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
I agree with everything you just said.
> "It might turn out that a second-order lowpass at 120 Hz on the woofer combined with an underdamped third-order highpass at 180 Hz on the midbass is what works best, but we won't know that far enough in advance to choose the crossover points beforehand."
That's finesse. There is an art and a science in what you suggest. I certainly respect the people who have that kind of knowledge base.
However choosing basic crossover points doesn't seem that difficult. Using all the considerations you listed below to be sure. I just ham-fist it with a 24db Butterworth slope at the point I want. That's the good thing about active crossovers. A fourth order BW sounds as good as most anything else. Maybe you could do better. Even though this is all just conjecture, I bet Tom's simulations will be pretty close to the actual result. It's just will it sound good?
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Big speakers and little amps blew my mind!
I never approach a design with a crossover point in mind, but I always approach a design with the off-axis response and system dynamic capabilities and overall synergy very much in mind. The specific high-pass and low-pass transfer functions (what the filters do to the signal) are simply means to an end, in my opinion.You asked: "I bet Tom's simulations will be pretty close to the actual result. It's just will it sound good?"
No, it will not sound good, it will sound SUPERB, because Tom is a superb designer.
Designing crossovers is pretty easy. Designing really good ones is what's hard.
Duke
Me being a dealer makes you leery?? It gets worse... I'm a manufacturer too.
Edits: 07/05/15
Since we are on the subject of simulations.
I would be very surprised if even Tom Danley has a mathematical model that could simulate the internal reflections generated within a given acoustic horn.
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Big speakers and little amps blew my mind!
> You asked: "I bet Tom's simulations will be pretty close to the actual result. It's just will it sound good?"
No, it will not sound good, it will sound SUPERB, because Tom is a superb designer." <
I really meant to say, very close to the actual results. Possibly even spot-on.
To my knowledge no one has ever made a wide range acoustic horn sound good. Audiophile good. PA good is different. It would be quite a trick. I think if anybody could do it Tom Danley could. We'll see.
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Big speakers and little amps blew my mind!
The usual choice of the low pass frequency is based on where off-axis response falls off, typically by no more than 6dB at 30 degrees off-axis, while axial response is still flat. By that criteria a direct radiating fifteen inch woofer may be perfectly fine to at least 800Hz.
"The usual choice of the low pass frequency is based on where off-axis response falls off, typically by no more than 6dB at 30 degrees off-axis, while axial response is still flat."
Okay I get it. Can I ask you one question I've had for a while? What do you recommend as the upper cutoff for your horns, like the HT Tuba. The curves you post show 200hz and beyond, but I want to know it they go all the way up to 250hz?
Thanks,
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Big speakers and little amps blew my mind!
They go to 200Hz and beyond, but I wouldn't use them that high. As a general rule discreet subs should not be run high enough so that they're directionally locatable.
I would say in the context of this thread that they would be used as bass bins, not as discrete subs.
That brings us back to the choices of 140hz, 175hz, and 250hz. Which would you choose for the HT Tuba? Don't be coy.
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Big speakers and little amps blew my mind!
> That brings us back to the choices of 140hz, 175hz, and 250hz. Which would you choose for the HT Tuba?
No higher than 140Hz, as it was not designed with that intent. Horn loaded subs, or any horns for that matter, with parallel walls start to sound boxy if run too high. That's why my DR series of wide bandwidth horns have no parallel walls.
I like the sound of my HT Tubas crossed over at 160 Hz, but that is with a 96dB/octave crossover slope accomplished with a DEQX.
Thanks, that's an answer I can understand.
Your comments about parallel walls are interesting. I remember Bruce Edgar writing that folded horns should not have 90 degree angles. I look at my La Scalas and see lots of parallel walls.
For the benefit of the forum readers I will piece together a little horn system;
Use a BF DR-300 cab. It's 30" wide and that matches the width of the Danley Fig. 7 horn. You could probably cover 80hz to 15khz at -3db, and maybe 60hz to 20khz at -10db. That ain't bad for what is essentially a two-way speaker. Overall system efficiency would be around 108db.
Not too shabby if you ask me.
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Big speakers and little amps blew my mind!
Even 180 degree bends work fine, if properly configured. I wouldn't use the DR300 other than in its intended use, pro-touring PA. Even DR280 is overkill in a home, but there are those who like overkill.
Well the way I look at it; If you have a 30" wide mid horn, you might as well have a 30" wide bass bin. The space has already been set aside.
Let's see. The DR300 is about the size of the Klipsch Belle. The DR280 is the same size as my La Scalas.
Really I see your point. Might as well use the smallest DR250 and fill in the bottom with a sub. That's what most people would do with all three.
Myself, I could get by with two 80hz mid/bass horns and no sub. I could live with that. Not putting it forward as best.
Since I've got you on the line. Can I ask how high you would use your DR series? 350/400/500hz?
And that's the rub. These three low pass options are very low in my experience. There would be too much bandwidth overlap with a folded W horn. Wasted bandwidth really.
The solution for these crossover points I'm looking for are more like an HT Tuba at 140hz. That is; you are getting very close to the max top end of the bass driver. That should translate to good bass extension on the other end. Little or no wasted overlap. Why use a folded W horn to cover just 120hz to 250hz? Just one octave.
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Big speakers and little amps blew my mind!
> Can I ask how high you would use your DR series? 350/400/500hzThe DR200-280 woofer horns are good up to 2kHz, the DR300 up to 1.2kHz, but 31 band EQ is an absolute necessity. They are, after all, PA speakers, and in pro-sound 31 band EQ is SOP.
> To my knowledge no one has ever made a wide range acoustic horn sound good. Audiophile good.
Read this:
http://www.avsforum.com/avs-vb/showthread.php?t=1353217
Edits: 07/06/15
Yes I use a Yamaha 31 band eq for my Synergy-style horn. Have to. I prefer to go easy on the eq and cut but not boost. I'll just go with 500hz is okay.
Mr. Danley has proposed an acoustic horn that would cover something like 140hz to 15khz. That's more than two decades. That's what I meant by a wide-range acoustic horn.
Your DR280 would certainly be considered a wide-range acoustic horn at 100hz to 2,000hz. But that's only one decade and one octave. More than one decade is excellent by anyone's standards. But your horn would have to go from 100hz to 10khz to be comparable to Danley's proposed horn, which is theoretical.
Putting it in those terms I know you realize the enormity of the problem.
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Big speakers and little amps blew my mind!
> Your DR280 would certainly be considered a wide-range acoustic horn at 100hz to 2,000hz. But that's only one decade and one octave.
That's also just the woofer.
I realize that.
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Big speakers and little amps blew my mind!
Thanks for the post Bill.
So are you saying that your major consideration would be to match the collapsing off-axis response of the bass driver to a similar off-axis response of the mid-horn?
Direct radiating fifteen inch woofers be damned. You know what I'm trying to get at.
BTW, as a guy who's crossed over a lot of speakers. Do you think there is anything intrinsically better about a source that covers 140hz to 15khz, as opposed to one that goes 300hz to 15khz?
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Big speakers and little amps blew my mind!
You said it was a three way speaker, which usually implies a direct radiating woofer. If what you meant was three separate sources that's something else entirely.
As for a source that goes from 140Hz to 15kHz, that would usually require at least two drivers to accomplish well. The same applies to 300Hz to 15kHz. Any single driver speaker, even if horn loaded, with adequate displacement limited output below 500Hz or so will usually have a very narrow dispersion pattern much above 8kHz.
Sorry this thread is a spill-over from the "How large is too large for HE" thread. It's all hypothetical.Tom Danley will begin work on a front loaded acoustic horn driven by 5" or so coax driver. It could have a -3db down point at 140, 175, or 250hz depending on the size of the horn at 108 to 110db efficiency. Let's just say it goes to 15khz.
I guess this thread was a way to explore the best bass bins for the given cutoff points.
When I think bass. I think front loaded bass horns. :)
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Big speakers and little amps blew my mind!
Edits: 07/05/15
My Quarter Pie would be a good match and get you down to 50 Hz, since it's about 5.5 feet.
https://community.klipsch.com/index.php?/topic/148054-quarter-pie-bass-horn-measured-fr-how2build-and-hornresp/
Claude I love it, but 48" by 48"?! Lordy that's big. You win!I would just as soon cover 100hz to 35hz with a PPSL. They are compact. For all my big talk, real bass horns are too big for me to fool with. I'm willing to cheat on the low end. :)
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Big speakers and little amps blew my mind!
Edits: 07/09/15
We should have been talking about PPSLs by now.
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Big speakers and little amps blew my mind!
"We should have been talking about PPSLs by now."
I agree.
I think a PPSL with a Danley Synergy mid-HF horn on top would be a good choice for high efficiency and reasonable size.
A LaScala sized cabinet would be able to do -3dB at 27hz, and over 100dB/2.83V/1M.
The plan and cut-sheet for the 35hz PPSL is online, about 104dB/2.83V/1M and useable to 250hz (using a Q=1 12dB low-pass it will have a LR24 low-pass function).
The 48 x 48 horn from claudej1 is fine, if you have the space, and you are planning on adding subs.
Well the Bat-signal does work.
Of the three low pass points, do you have a preference, and why?
The PPSL would mate well with the smaller proposed Fig.7 horn. If he builds a 4' long horn, maybe not so much. Of course it's the time alignment that is a key advantage. I bet all this talk of folded horns has been making TD squirm in his seat. :)
Djk, I have a question about PPSLs that has been nagging me. I'm sorry if it's a touchy subject, but if I'm confused about it, then probably somebody out there is also.
You've written that the PPSL goes up to 400hz or so, but then I read on another forum that the square shaped slot creates a 1/4 wave resonance. The slot looks to be a cube with one end open. Sort of like a cubed horn. I would imagine that a cubed shaped horn would do funky things, like produce a 1/4 wave resonance. These posters seem to say that this resonance relegates the PPSL to sub duties. What do you say about this?
With these rather low crossover points I guess it won't matter too much. Maybe the 12" driver PPSL would be a better fit for 250hz? Your newest iteration of the PPSL with the flared slot looks like it would solve this resonance problem. Really it looks like the drivers should be mounted in something like a waveguide as opposed to a cube.
Thanks,
Jamie
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Big speakers and little amps blew my mind!
"Maybe the 12" driver PPSL would be a better fit for 250hz? "
Yes.
EV made a dual 15 PPSL that was crossed at 800hz, but it got a little rough.
Art Welter made some extensive measurements on a double 15 PPSL that he built, it showed a small 3dB peak around 175hz, and was useable to 250hz.
The shallower the plenum, the higher the PPSL can go.
Thanks.
A 3db peak doesn't seem so bad. Nothing that can't be fixed with EQ. When I read the word resonance, it made me think of a sound quality anomaly like a hum or buzz, or a reverb quality to the effected point.
And the depth of the plenum is determined by the size of the driver?
You haven't given us any update on your new PPSL. The on that looks like a Belle, and has a flared plenum. Anything you would like to tell us about it SQ wise? FR wise?
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Big speakers and little amps blew my mind!
The 48 x 48 horn from claudej1 is fine, if you have the space, and you are planning on adding subs.> > DJK
That horn has great bass definition. In it's defense, it's low profile,a 48" RADIUS fits perfectly into a corner, and takes up less cubic feet than a LaScala when you think about how much "dead air" space is wasted with those 100 Hz. "short horns."
The PPSL sounds like a good way to go (very interesting optimization of DR's and ports), though, but it's NOT a horn, and there are no free lunches, eh?
"The bigger the horn, the better the horn"........Claude Jodoin
I like your horn Claude. I would probably stand it on it's side, so it's tall and long, but skinny. My problem is that I don't have even one good corner, much less two.
Like big horns? Check out the spiral bass horn from Inlow sound, 20hz to 140hz. I might actually lay this horn on it's side like yours. I wonder if you can go mono at 140hz, or is that too high?
No free lunch? Ain't it the truth.
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Big speakers and little amps blew my mind!
There is no corner required, it just fits in there quite nicely.
"but it's NOT a horn, and there are no free lunches, eh?"
It can be time-aligned without DSP, goes deeper, is simpler to make.
Oh, it will also have less distortion.
In a side-by-side test, the PPSL ate the Klipschorn's lunch, going deeper, and sounding cleaner.
Well, then I should built one just to see what you are talking about at last. link?
PPSL is a concept.I have plans and a cut-list on line for the 35hz PPSL with the Kappa Pro 15LF2.
I have one friend that bult one and used the Yung SD500-6 500W Class D Subwoofer Plate Amplifier Module with 6dB boost at 25 Hz in his home stereo.
He is using a pair of Klipsch HIP for the tops.
Edits: 07/12/15
Hello Djk,
On diyaudio you have wrote that port is 2,5'' high but from drawing it seems its 4''. 32(B) - 9.125(E) - 9,125(E) - 7.5(F) - (3*0,75).
So I'm wondering which one is incorrect?
I'm tempted to built this one with 2xKappaPro15LF2. I'll have to rearrange it because my limiting boundaries are slightly different (W.30/D.18/H.36).
Without considering the behavior of the upper and lower systems your mating together, it would be hard to go past picking ones favorite number.
What are the upper and lower systems, and how do they behave / measure?
Tom,
This may be a silly question to ask given what I've read of yours, but here goes.
Does a 3 to 5ms delay between the bass and mid drivers in the 140hz to 175hz region negatively effect the sound quality very much?
Thanks,
Jamie
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Big speakers and little amps blew my mind!
Let me give you one psycho-acoustic consideration.
I have noticed when listening to Neil Young sing, and watching a spectrum analyzer at the same time, being struck by how much of his vocal energy was in the 200hz to 400hz range, and he is considered to have a high pitched voice.
Now it would seem to me that a transducer that could handle everything from 250hz up might very helpful with sound quality, because it would capture the majority of the male voice.
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Big speakers and little amps blew my mind!
I ask the question from the perspective of available high efficiency, or any, bass bins. Lets take as a given an Exemplar mid/tweeter horn that would match the three criteria. Not necessarily one horn for all three.
It comes down to the given physics the bass bins that are available to use; a folded W bass horn may only go to 350hz. A PA style folded horn may only go to 250hz. A powered sub woofer may only go up to 150hz. Straight mid/bass horns could have any number of upper ranges. John Inlow has a gigantic 20hz horn that goes up to 140hz. I am not sure of a PPSL's upper limit, nor a Karlson's for that matter.
Also I guess we could examine the psycho-acoustics of it. A crossover point of 300hz was deemed significant to the Bell Labs researchers. In music isn't there something called the Golden Octave. I just tried to Google it with no luck. Somewhere between 100hz and 300hz.
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Big speakers and little amps blew my mind!
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