Thank you fluid, very kind words.Don't discount it too heavily, I don't
Earl having read all of Mark's thread's on his builds I am certain he means within his own speakers he cannot find a measurement that explains his preference.
And Earl, yes I mean on my own speaker builds, which have all been MEHS's for nearly three years now.
(Before i was building more classic designs, similar to this thread and some of your i've seen.)
I can make the same sized conical MEH have very close to the same polar transfers, no matter the driver compliment that is mounted on the horn.
With completely indistinguishable mag and phase traces (both zero flat) for the reference axis.
@camplo, the smallest horn I've built is 31"x21". It's also the widest pattern @ 90x60. Even it holds horizontal pattern control down to 360Hz, using Keele's classic formula. Most of my builds have been about 48" wide, which of course holds pattern substantially lower.
Directivity differences are not what i'm hearing when adding small mids.
I truly suspect we give up some SQ pushing CDs too low, even when transfers or RTA's say they can do it......whether we are talking MEH's, or designs like you are considering.
If not for that suspicion, i think my MEH talk would be OT.
But i don't think it is, i think the question of how low can we really use CD's optimally, for any design, is on topic.
Why can't it be as simple as limiting excursion to half of xmax, or where ever the BL curve falls off.
Your horns, I remember having a discussion about cutoff, and the lowest cutoff horn we talked about was somewhere around 300hz....which is your B&C horn believe? WE talked about how the horns cutoff would need to be as much as 1 octave below desired XO or lower to achieve proper low end for desired xo... So unless you are referring to a horn that loads to at least ~200hz or lower, how could you ever achieve good SQ crossing over at ~400hz with a compression driver?
Your horns, I remember having a discussion about cutoff, and the lowest cutoff horn we talked about was somewhere around 300hz....which is your B&C horn believe? WE talked about how the horns cutoff would need to be as much as 1 octave below desired XO or lower to achieve proper low end for desired xo... So unless you are referring to a horn that loads to at least ~200hz or lower, how could you ever achieve good SQ crossing over at ~400hz with a compression driver?
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I can believe that. As I have said before, the system design dominates the SQ not the drivers.
While it's certainly easier to design a crossover if you have flat response well past the xo point, it's not an absolute requirement. The other consideration of course is matching the directivity of the woofer. It may be though, that the directivity of the woofer is disappearing across the same range that the horn begins losing directivity. Then Xo point can be played with somewhat.
Would be nice if things happened that way. Unfortunately they don't. The woofers DI will rise with F and the waveguide is either flat or mostly erratic. I've never seen the situation that you describe in reality, although it is not physically impossible, just very difficult to do.
Not to derail the thread, but to maybe make camplo feel better about his high dollar cd. I completely agree that the design dominates, but in some situations, drivers matter. As another example, I recently went through a process to select a small full range driver for line array. I bought about a dozen different candidates. I mounted them in a way that I could immediately a/b 2 drivers at a time. I even had them eq'd individually. The difference in sonic character was extraordinary. There are sonic differences that tonal balance and polars can't explain. Maybe Mark's preference for mids in his meh is due to some such difference, that can't be measured. I know that's heretical. If anyone knows what those differences might be, I'd like to know in a new thread perhaps.
So basically, you are saying that all these different drivers measured identically in tonal and polar response? Otherwise, there are measurable differences.
There is nothing that we can hear that cannot be measured. We don't necessarily know how to decipher those measurements, but that's very different than saying that they "can't be explained."
Small drivers can differ in a myriad of ways, especially wider range ones. which will influence their perception. But it's all there in the data. You just have to look.
Mabe mine collapses pretty evenly because its a tractrix while caplo is set on a constant directivity horn.. My mistake, Thank you for the correction
They are happening that way with my big horn.....essentially anything crossed under a ka=2 of the lower woofer and an Xo lower than the width of the horn/waveguide...is there right?
Its the harmonic decay
I have a tractrix horn too and I concur in that the profile seems easy to work with given complimenting dimensions are used. My judgment based on my time simulating and estimating the polars of my woofers in cab vs horn
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That's an excellent point, I only measured and eq'd on axis, I guess I assumed polars would be similar because the drivers were of similar size. I did not examine spectral decay either. I guess my point remains a bit though that drivers do matter some. Allenb I'm not sure what you are asking.
Technically it is dead on...I changed it to harmonic decay which is yet a little more specific
Spectral
: of, relating to, or made by a spectrum
Decay
: to decrease usually gradually in size, quantity, activity, or force
I believe each drivers unique decay characteristics cause changes in perception, pretty sure thats already a known thing.
Spectral
: of, relating to, or made by a spectrum
Decay
: to decrease usually gradually in size, quantity, activity, or force
I believe each drivers unique decay characteristics cause changes in perception, pretty sure thats already a known thing.
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It might be that simple. It might be that IMD goes up so fast with increased excursion, that just looking at how low a horn loads at small signal testing, fails to provide the info needed to know how SQ degrades with large signal. Especially since excursion for a fixed sized driver has to increase 4X per octave decrease.
This was the point of my mentioning what I've perceived by adding mids in my MEH's, and raising the CD xover frequency.
I have no idea how to judge excursion in a CD, but i can listen to various xover frequencies....
Since you don't have a horn yet (i think), you have a clean sheet of paper to choose horn size/ crossover freq/ and cone driver mating size.
Personally, I'd be careful trying to use the AXI too low. You've no doubt seen Josh Ricci's forum posts on the AXI, but in case not https://data-bass.ipbhost.com/topic/1324-celestion-axi2050-2-compression-driver/
As well as a thread on big horns with the AXI. (i'm gonna have to spring for that big CD someday !)
I think the idea that a horn's cutoff need to be an octave below xover is yours. A decent idea imo, especially if wanting to prevent excessive excursion as discussed above, and using conventional relatively shallow sloped xovers.
If SPL and excursion are kept low however, i think xover at horn cutoff can work fine, as long as horn keeps the desired acoustic order rolloff below xover.
In my case, with steep linear phase xovers, i only need 1/6th to 1/3rd octave good performance below xover for smooth integration. So it just comes down to what sounds best, from horn loading freq up to wherever sounds best mated with what's underneath (again, in a MEH with no directivity changes.)
Oh, and yes, the B&C ME464/DCX464 combo has been the lowest loading conventional horn I've used. I was trying what Earl said a few posts ago that he was doing on paper, mating a larger (22") horn to a same sized sealed 18". Funny that, because I didn't like the sound of the 18" running from 30Hz up to 300-500Hz. Muddy. Decided to just use the 18" sealed as a mid-low woofer from 100 to 300-500Hz, and add a real sub to that combo...a 18" bass-reflex working up to 100Hz. LOL Much nicer, cleaned up. Same ole IMD issue maybe. Art has pointed me towards making IMD tests several times....i think it's about time i listen, and do it when weather warms up.
Very telling, good information, thank you for sharing.
I have not researched the Axi because I came to my own conclusions before I spent the money however long ago that was... Since then I just read more of the same.
https://data-bass.ipbhost.com/topic...pression-driver/?do=findComment&comment=24941This has been a on going impression of the Axi2050. Great if not "the best" midrange with good enough treble, in my on words The lf extension
I'm starting to think that people who think there is no signal below 30hz, in music, don't have ears...or systems to play it.....or RTA's...
At 7:30 you will, if possible, have a 20hz note on beat with the bass drum as the bass guitarist rocks us slowly in his arms of bass love lol. For a mastering monitor, this stuff must be covered accurately....or at least an attempt. I vote to move the LF standard for music mastering to be extended to 20hz. Tell those certain mastering engineers to stop cheating and high passing everything at 35hz and calling it good lol.
In regards to IMD, I remember Earl saying that we'd likely run into strong forms of some other distortion before IMD
@fluid - I think the aspect I am trying to describe is likely an issue of summing and polar radiation size and location. Side firing woofers aren't going to sum as well as having a single or single like source on the front baffle unless the width is much shorter than my 32" cabinets. The closer you get the sources together the better. Having the highs/mids/bass appearing from a single point is the goal.
I have not researched the Axi because I came to my own conclusions before I spent the money however long ago that was... Since then I just read more of the same.
https://data-bass.ipbhost.com/topic...pression-driver/?do=findComment&comment=24941This has been a on going impression of the Axi2050. Great if not "the best" midrange with good enough treble, in my on words The lf extension
I'm starting to think that people who think there is no signal below 30hz, in music, don't have ears...or systems to play it.....or RTA's...
At 7:30 you will, if possible, have a 20hz note on beat with the bass drum as the bass guitarist rocks us slowly in his arms of bass love lol. For a mastering monitor, this stuff must be covered accurately....or at least an attempt. I vote to move the LF standard for music mastering to be extended to 20hz. Tell those certain mastering engineers to stop cheating and high passing everything at 35hz and calling it good lol.
In regards to IMD, I remember Earl saying that we'd likely run into strong forms of some other distortion before IMD
@fluid - I think the aspect I am trying to describe is likely an issue of summing and polar radiation size and location. Side firing woofers aren't going to sum as well as having a single or single like source on the front baffle unless the width is much shorter than my 32" cabinets. The closer you get the sources together the better. Having the highs/mids/bass appearing from a single point is the goal.
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