Hi mark,
Can you measure the polar response on this multiple entry horn? Or the size is just too big to be possible?
Before I saw the polar response you shared on DCX464 discussion thread with XT1464 and it's really great.
Does the MEH kind of horn also possess such good directivity control?
Thanks!
Can you measure the polar response on this multiple entry horn? Or the size is just too big to be possible?
Before I saw the polar response you shared on DCX464 discussion thread with XT1464 and it's really great.
Does the MEH kind of horn also possess such good directivity control?
Thanks!
Hi, I really should make a full set of polars.
The big rig is easier to move around than anything I've ever built, with its 6" castor wheels.
There is a turntable built in, in between the sub cart and main horn.
And I have a permanently setup mast with 4 vertical mics off the back deck......
But i can't find the motivation to grab some polars....
The rig sounds so dang good, I'm like "why bother".
And I've learned what I would change about syn11, if baltic-birch or a true affordable equivalent, every comes available again.
I'd make the main horn 90x60 (like syn10), vs the 75x60 it now is.
Use 15"s as the sub drivers in the main horn, instead of the 18"s in it...to help make it a little smaller, and reduce port sizes.
Use one center round port for the two 12" lows, instead of two ports more in the corners.
Anf the biggest change, I'd make the sub cart a PPSL with a vertical slot up its center. Top of the slot would be two 18" in vertical clamshell alignment.
Bottom or the slot, would be the bass reflex port. No more downward firing ports.
Anyway, to try to partially give some info you asked.....
I don't think a conical unity/synergy can ever produce as nice a set of polars for a CD, as horn made just for CD's.
Unless maybe something like the hexagonal horn Mabat has been showing can be fitted with external drivers.
I think ports alone are gonna dick up polars some. And then there's the need to wrap some kind of box around the horn to seal up the cones, and the mouth termination issues that brings.
All that said, I've found the tradeoff of living with compromised CD polars, in order to gain driver integration lower in frequency (all the way to sub level now)....
to be well worth it. 🙂
Looking at the last set of polar work I did on syn11, I see it was all about working on individual sections, and the effects ports were having on each section.
Didn't bother with entire speaker polars ...don't remember why not.
Here's the dcx464 CD...0 to 30 degrees, steps of 10. It's pretty typical of where i stop fussing with polars further.
I'm currently using the CD from 900Hz up.
The big rig is easier to move around than anything I've ever built, with its 6" castor wheels.
There is a turntable built in, in between the sub cart and main horn.
And I have a permanently setup mast with 4 vertical mics off the back deck......
But i can't find the motivation to grab some polars....
The rig sounds so dang good, I'm like "why bother".
And I've learned what I would change about syn11, if baltic-birch or a true affordable equivalent, every comes available again.
I'd make the main horn 90x60 (like syn10), vs the 75x60 it now is.
Use 15"s as the sub drivers in the main horn, instead of the 18"s in it...to help make it a little smaller, and reduce port sizes.
Use one center round port for the two 12" lows, instead of two ports more in the corners.
Anf the biggest change, I'd make the sub cart a PPSL with a vertical slot up its center. Top of the slot would be two 18" in vertical clamshell alignment.
Bottom or the slot, would be the bass reflex port. No more downward firing ports.
Anyway, to try to partially give some info you asked.....
I don't think a conical unity/synergy can ever produce as nice a set of polars for a CD, as horn made just for CD's.
Unless maybe something like the hexagonal horn Mabat has been showing can be fitted with external drivers.
I think ports alone are gonna dick up polars some. And then there's the need to wrap some kind of box around the horn to seal up the cones, and the mouth termination issues that brings.
All that said, I've found the tradeoff of living with compromised CD polars, in order to gain driver integration lower in frequency (all the way to sub level now)....
to be well worth it. 🙂
Looking at the last set of polar work I did on syn11, I see it was all about working on individual sections, and the effects ports were having on each section.
Didn't bother with entire speaker polars ...don't remember why not.
Here's the dcx464 CD...0 to 30 degrees, steps of 10. It's pretty typical of where i stop fussing with polars further.
I'm currently using the CD from 900Hz up.
Thanks for sharing!
Looks like within 30 degree the dispersion is even better than DCX464+XT1464...
Looks like within 30 degree the dispersion is even better than DCX464+XT1464...
Hi Mark
Wouldn´t it be pretty straight forward to convert your three SYN 10´s to SYN 12´s with two 15" woofers attached on the sides? Or four shallow 12" woofers on each side!?
You could even make room for the 15" woofers with some permanently attached secondary flares! I know you hate secondary flares, but here is a chance where they make sense twice, better polars and room for the woofers! The whole build will get too heavy to carry around anyway.
Just a crazy idea. 🤔 Oh, I almost forgot. You will need another Subcart!!!!!!! 😵
But I guess there is still that Kitchen.........
Steffen
Wouldn´t it be pretty straight forward to convert your three SYN 10´s to SYN 12´s with two 15" woofers attached on the sides? Or four shallow 12" woofers on each side!?
You could even make room for the 15" woofers with some permanently attached secondary flares! I know you hate secondary flares, but here is a chance where they make sense twice, better polars and room for the woofers! The whole build will get too heavy to carry around anyway.
Just a crazy idea. 🤔 Oh, I almost forgot. You will need another Subcart!!!!!!! 😵
But I guess there is still that Kitchen.........
Steffen
Welcome 🙂
Well, I was kinda dissing homemade flat walled conicals (like my builds) for their inability to avoid ripple (especially after ports are added haha)
But give the devil it's dues... constant directivity is NICE !!!
Makes for a sweet zone, and screw a stinkin sweet spot 😛
Very cool Steffen, i've studied if i can do that.
Room on the wall is there for 15"s....I just hate to alter something that is so damn good.
And still not sure how box wrap around would work.
I really want ports that fire staight at the listening position..
The downward firing ports on the current sub-carts have convinced me more than ever that subs have a directional vector as part of their sound.
They are muddy compared to direct.
Muddy like multi-sub muddy, averaged over omni-sound. I know a lot of folks like that even smooth sub sound. Enveloping, etc.
I don't. I like raw hitting subs, and the utterly awesome sound they impact.
Oh made me laugh..yep I have no WAF to contend with, when it comes to audio....
But there is the WAF when it comes to life !!!
Hi Mark,
How did you measure the bass and lower mids section of the MEH?
I'm going to fabricate the MEH designed by Scott Hinson but I'm going to use the passive crossover for DCX464 part (FB464 from B&C).
I guess I'll need to measure the response myself and do the crossover again.
On typical speaker I know I can measure the woofer cone near field and sum with the port response to get the woofer response.
And with basta! to calculate the baffle step gain for the mid/high to correct the response.
Mids/Highs can be measured using gating method to get ~200-300 Hz information and merge this with the woofer response.
However in the MEH system can I measure from the tap port to get the woofer response and sum it with the bass reflex port? Would I need to consider the horn effect on the bass region?
What's your way to get the proper measurement for FR in your MEH system?
Thanks!
Hi, it's a bit tough to know exactly how to measure. For me, I rely on two approaches and compare them.
First is outdoors pointing off a deck to mic(s) about 3m away.
Second is indoors about a meter from the mouth.
I've never gotten data right at the ports that i thought was any good, maybe because there are always more than one port in play for mids and lows.
Outdoors is pretty reliable.
The close up indoors suffers from two things beyond normal room reflection issues.
When the mic is close, the relative distances between acoustic centers is greater than mic further away. Tis true for all speakers I guess, but give a unity/syn typically has more z-plane offsets, so it makes it a bigger issue up close.
The same z-plane differences makes relative SPL levels tougher too. For a simple example, on a big syn, a mic at horn mouth maybe be only 1ft to the low ports, but maybe 2 -2.5ft to CD
Doubling the mic distance to 2 ft from low ports loses -6dB, but only attenuates the CD -3 to -3.5dB.
Stuff like this is why i stick to outdoors without any stitching as much as possible.
@mark100 when making tap holes, you're usually at 1/8 of driver Sd right? Is there a resource out there to determine when a smaller tap hole turns into an acoustic low pass? I'm working on a project with some 6.5" mids that I want to cross over to 10" lows. The 1/8 Sd for the driver is 1 & 3/8". But I'm worried that that small of a hole won't let enough 400Hz through as that's my targeted crossover to the 10's. What resource would one use to know what wavelengths are truly making it through?
I also saw your comment about bumping up to 1/5 driver Sd, but I wasn't sure if you meant porting the lows or widening a tap. Thanks.
I also saw your comment about bumping up to 1/5 driver Sd, but I wasn't sure if you meant porting the lows or widening a tap. Thanks.
Hi swiegert2011,
I do not know of any resource like that...if you find one, please pass it on.
I've used 1/8th of Sd for low-mids, 12" through 8" drivers designed to get down to 100Hz.
With 4" mids, I'm using about 1/12th Sd, and they reach down to 200Hz fine....some folks might use them even lower, if building a low SPL design.
The 1/5th Sd i mentioned somewhere, had to be for the 18"s I've put into syn-11. Not sure that works any better than 1/8th.
But the 18" sensitivity is lower than I hoped, so i tried larger ports (by just making their fat cigar shape bigger).
(I guess in retrospect, I'm just not used to how relatively inefficient sealed 18"s are to vented.)
Given the time, effort, and expense of trial by error with port sizes in actual horns, I built a small surrogate test box.
I drop a driver in, then put a plate on top the driver with whatever size port, and measure. And move the port hole over various locations on the driver, like center vs edge, etc. Nothing even needs to be fastened down really. And different baffles for drivers' sizes can be used in the test box.
Here's pict of the test box, and then like said, just make a plate with port size hole in it to set on the driver....oh, and make the plate big enough to cover the whole driver with the port out near the surround...like my stupid butt forgets to do lol...
Hope this helps..
I do not know of any resource like that...if you find one, please pass it on.
I've used 1/8th of Sd for low-mids, 12" through 8" drivers designed to get down to 100Hz.
With 4" mids, I'm using about 1/12th Sd, and they reach down to 200Hz fine....some folks might use them even lower, if building a low SPL design.
The 1/5th Sd i mentioned somewhere, had to be for the 18"s I've put into syn-11. Not sure that works any better than 1/8th.
But the 18" sensitivity is lower than I hoped, so i tried larger ports (by just making their fat cigar shape bigger).
(I guess in retrospect, I'm just not used to how relatively inefficient sealed 18"s are to vented.)
Given the time, effort, and expense of trial by error with port sizes in actual horns, I built a small surrogate test box.
I drop a driver in, then put a plate on top the driver with whatever size port, and measure. And move the port hole over various locations on the driver, like center vs edge, etc. Nothing even needs to be fastened down really. And different baffles for drivers' sizes can be used in the test box.
Here's pict of the test box, and then like said, just make a plate with port size hole in it to set on the driver....oh, and make the plate big enough to cover the whole driver with the port out near the surround...like my stupid butt forgets to do lol...
Hope this helps..
The resource you are looking for is HornResp. In HR, you can model a full MEH and tune the size and localation of the ports, or at least the axisymmetric equivalents of them. Its the combination of the amount of air trapped between the driver cone working against the area and length of the port through the wall into the horn that creates the acoustic LPF
Thanks Jack,
does Hornresp model the location of the port relative to the driver, like centered under the cone vs the periphery?
And can it model one port vs two, per driver?
Oh, and can it model port in horn center vs port in corner?
Thx!
does Hornresp model the location of the port relative to the driver, like centered under the cone vs the periphery?
And can it model one port vs two, per driver?
Oh, and can it model port in horn center vs port in corner?
Thx!
nope. its blind to those kinds of things. for that you would need ABEC, which I have spent the last month beating my head against for an open baffle/Uframe design.
HR will help in shaping, characterizing low pass filter effect and making total port area sufficient to avoid turbulence/port noise and seeing the reflection null
HR will help in shaping, characterizing low pass filter effect and making total port area sufficient to avoid turbulence/port noise and seeing the reflection null
Some more thoughts....and where HR would be particularly useful.
I get the sense most unity/synergy builders are aware of how the acoustic LPF works..it's been discussed fairly often.
What isn't discussed much is what determines the acoustic hpf filter....port sizes and locations in horn....
TD had a page up for a while on the DSL website, that talked about location vs flare rate...I bet HR is great for that sort of analysis.
t
that is right. Danley made a big point about locating the drivers at points on the horn optimum for their frequency range but that is least investigated part by DIYers. We focus on getting drivers close enough to apex to avoid null in passband and usually don't go any further. Probably give up some efficiency points which really doesn't matter at home levels
Yep, that seems most common.
For me, once the transition mechanics between CD and mid drivers became well understood, my quest has always been looking down the frequency curve not up. IOW, how low can I get each subsequent driver section to reach. It's been a hell of a lot harder task, than how high, in complete candor.
Ironically, syn-11 is the first version that the low-mid driver reached below 100Hz easily....has a f3 at 80Hz.
I say ironically, because it's the one I added 18"s to.....
Anyway, point of all this is that i think if folks ignore low port locations thinking it doesn't matter because the don't care about efficiency due to home levels,...that's all well and good, but they may be missing the boat in terms of low frequency extension.
My guess is that wherever efficiency is greatest, may also be the point of lowest extension. Would love to have that guess confirmed or denied.....
The point can be demonstrated relatively easily in simulation.
I had a model for a small horn (by your standards) on the computer. I modded the port location. Then prepared the attached diagram
comparing acoustic impedance (the load Z seen by the driver) and power conversion efficiency for a port 10 cm from the throat vs 20 cm. Doubling the port distance resulted in a marginal increase in efficiency below 200 Hz. Likely would be a larger effect on a larger horn...
It would be fairly easy to throw together a simple model of your horn if you wanted to look deeper. Just post or send me the dimensions and driver T/S params
(The big peak circa 90 Hz is the driver resonance.)
I had a model for a small horn (by your standards) on the computer. I modded the port location. Then prepared the attached diagram
comparing acoustic impedance (the load Z seen by the driver) and power conversion efficiency for a port 10 cm from the throat vs 20 cm. Doubling the port distance resulted in a marginal increase in efficiency below 200 Hz. Likely would be a larger effect on a larger horn...
It would be fairly easy to throw together a simple model of your horn if you wanted to look deeper. Just post or send me the dimensions and driver T/S params
(The big peak circa 90 Hz is the driver resonance.)
Attachments
Thanks guys. If I can get it all to play smoothly, I'm hoping to have my mids cover 400-4000Hz for the vocal range. Looks like it'll be a little bit of trial and error will be needed, but that's to be expected. Any tips on crossover vs Fs? The driver for my mids does have an Fs at 406Hz, so would 400Hz not be the ideal crossover?
Nice, and thx!
I figure others would like to see what you're doing too, so I'll post my data here...
syn-11 is a 75x60 horn, 33"x 25"; with an axial length of 21" from CD mount to mouth exit
The 2 low drivers are Faital 12pr320's. They each have two 2.44" round ports centered 7.5" axially from CD, for a total area of 9.4 in2.
Here's TS and a little chart putting the above into metric. ( inkow HR let's direct english entry, like said...just trying to help others follow.)
The port area is total area for one driver.
Hope this helps make it a little quicker....lemme know what's missing if be the case...