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GJALLARHORN Re-Fold ?!?! - Page 2

post #31 of 153
Quote:
Originally Posted by LTD02 View Post

"If L45 is 25 cm and the throat is another 25 cm, that eats up 20", so there is not a lot of room left in that 32" for the panel widths (about 4.5") and the needed horn area (about 14" or so, depends on internal panel widths)."

i'm not sure what you are saying.

Well, my thought got lost in the translation there.... About three or four parallel thoughts jumbled up in that post, coupled with a few interruptions. Sorry for the confusion.

With 32 inches of cabinet width, minus 20" for the baffle (L45 plus 1/2 the driver diameter), you're at 12 inches remaining. Subtract one panel width (for the back), you're at 11 1/4". The Ultra is 12 1/4" deep when it is face mounted. Yeah, it's around the corner, and yeah, the horn expands some between the corner and S4, but there is not a lot of room left to work with. Also remember that the Ultra has a vented pole, which doesn't like to be placed right up against a panel.

What I was trying to get at is that I'd personally like to see a bit more room at the driver, I've choked horns with too big of a driver in too small of a horn, the results don't match the sims (in a BAD way) when you do that.
post #32 of 153
great catch lilmike.

while the drawing is to scale and the driver "width" is to scale, i did not check the actual depth of the lms ultra. i'll have to check on that.
post #33 of 153
Thread Starter 
What about the UXL 18?
I can't check at the moment but perhaps it requires less depth.

Edit. It looks like the UXL only requires 9.5 inches. So, it would work nicely provided the response is not adversely affected.
Edited by jpmst3 - 9/26/13 at 6:36am
post #34 of 153
looks like there are about 3 inches of clearance behind the driver. might have to make the panel that it attaches to a hair wider as the driver is 18.5" wide, not the 18" nominal that i used before.



source for driver spec:

http://www.parts-express.com/pdf/293-666m.pdf
post #35 of 153
here is the uxl vs the lms.

uxl is dark line. lms is light.

i'd say the uxl looks...better!

post #36 of 153
Thread Starter 
Nice!
Gotta love that curve!
Plus it's almost half the price for 90%+ the performance.
post #37 of 153
on paper, but that doesn't mean that it will sound the same. :-)
post #38 of 153
Thread Starter 
True, but it sure does look good thus far.
post #39 of 153
Agreed!
post #40 of 153
Quote:
Originally Posted by LTD02 View Post

on paper, but that doesn't mean that it will sound the same. :-)

With ~21% less motor force, and ~11% less excursion, something has to give...especially in a horn...
post #41 of 153
With less motor and excursion, is the ultimate output in the nether regions effected where more xmax comes into play? Or, would there be a change in the characteristic of the sound?
post #42 of 153
Thread Starter 
Quote:
Originally Posted by lukeamdman View Post

With ~21% less motor force, and ~11% less excursion, something has to give...especially in a horn...

Possibly, but it seems that there are limits imposed by the design of the horn where more power and more excursion do not always equate to more output.
If I understand correctly it might be function of the system rather than the driver alone, at least to some extent.
Edited by jpmst3 - 9/26/13 at 4:13pm
post #43 of 153
"With ~21% less motor force..."

horns are weird. sometimes a little less motor can give a little better frequency response.
post #44 of 153
"With less motor and excursion, is the ultimate output in the nether regions effected where more xmax comes into play? Or, would there be a change in the characteristic of the sound?"

excursion obviously limits spl where spl is excursion limited. :-) which in this case is in the 23hz ballpark, so the lms will have a max spl advantage there.

as for the change in characteristic of the sound, that is tough to say from the frequency response and the fact that the motors on these drivers are quite close in power. how audibly different they might sound is tough to say without an a-b. the lms does have that linear motor technology going for it, so maybe a little stronger up near the limits.
post #45 of 153
Thread Starter 
Ok, now what do we call this monster?!?!
post #46 of 153
unfinished?

:-)
post #47 of 153
Thread Starter 
Not the catchy name I was hoping for! tongue.gif

Anyway, so what is left to do?
I guess we need a scaled up diagram with dimensions so that something can actually be built...
post #48 of 153
"Not the catchy name I was hoping for!"

:-)~ not sure ricci would want to be associated with this cludge of a horn with the big dead space right in the middle of it. i can't even think of a single build that 'wastes' space like that. so, i don't know...Kludgehorn! sounds germanic enough to be on the same field as the gjallarhorn* ??? or i suppose you could pee in everybody's wheaties and call a gjallarwrecker. :-)

as for what is left, we need to make sure the driver fits on the panel that it is mounted to. might require a minor adjustment, nothing big. also if the baffle is doubled up, another little adjustment might be required. so, just some minor things....







* A kludge is a workaround; a quick-and-dirty solution; a clumsy, inelegant, yet effective and quick solution to a problem
Edited by LTD02 - 9/27/13 at 9:19am
post #49 of 153
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

"Not the catchy name I was hoping for!"

Kludgehorn! sounds germanic enough to be on the same field as the gjallarhorn* ??? or i suppose you could pee in everybody's wheaties and call a gjallarwrecker. :-)

as for what is left, we need to make sure the driver fits on the panel that it is mounted to. might require a minor adjustment, nothing big. also if the baffle is doubled up, another little adjustment might be required. so, just some minor things....


* A kludge is a workaround; a quick-and-dirty solution; a clumsy, inelegant, yet effective and quick solution to a problem

biggrin.gif I like it! Very clever.

Ok, I am looking forward to seeing the progression. If we could somehow eliminate the free space it would make the build easier.
post #50 of 153
Fill the dead space with concrete.
post #51 of 153
"Ok, I am looking forward to seeing the progression. If we could somehow eliminate the free space it would make the build easier."

so if you are familiar with the gjallarhorn, the guts look like guts, twisted and scrambled all over the place. it may be possible to eliminate the dead space in the horn while keeping within the form factor, but i'm not sure that it would make it build easier.

post #52 of 153
some flavor of this *might* work, but i'm not sure that is "easier".



than

post #53 of 153
Thread Starter 
Agreed, that might not be easier. In fact, perhaps to the contrary.

Is there any advantage to having more folds rather than the dead space?
It would seem the horn path is longer not leaving the dead space...what do the extra folds due to the response curve?
post #54 of 153
What's the big deal about the dead space? If its a permanent install and the space is available, it doesn't matter.

Fill it with molten lead.
post #55 of 153
from the first fold up, we learned that the section from the driver to the mouth of the horn doesn't need to be long at all, which opens the door to another option.

something like this *might* work, but it would be tricky and to model it properly would require using akabak, which i don't know how to use. any model would be a guess in hornresp, but it might not be all that far off.

post #56 of 153
Couple of things...Dead space= an unoptomized design and performance left on the table. IMO

John try to eliminate the dead space by increasing the SD or volume of the horn sections in that area. You have 3 sections there should be no deadspace left. This will increase low bass sensitivity if done right. In order to do this you may need to play around with the expansion angles of those 3 sections. Sometimes you can keep all the same and other times not. You want the least amount of 180 degree turns and actually the least amount of turns period as you can get. The Gjallarhorn design is a product of fitting a horn with a specified low corner into a specified cabinet shape and size, which results in a lot of compromises. In fact I have learned so much since then that the fold of that makes me facepalm myself. Needless to say, among a bunch of other horn designs I have tucked away I have a redesigned version that is greatly improved in a lot of areas. (I am not giving it out so please don't email or pm me for it. Thanks.)

As far as your fold here a couple of areas cause concern to me. The driver baffle seems like a potential weak spot. the panel at the end by the driver and mouth will flap all over the place with any real input power in the low bass. That has got to be braced substantially which will be difficult with the driver right there.
post #57 of 153
Thread Starter 
Quote:
Originally Posted by Stumbo View Post

What's the big deal about the dead space? If its a permanent install and the space is available, it doesn't matter.

Fill it with molten lead.

Then you will have to get the EPA involved and all sorts of permits, etc. biggrin.gif

Not a big deal at all, but it is dead space. If it can be used more effectively/efficiently then we should try to do it.
post #58 of 153
i haven't modeled it in hornresp, but i bet this one will work. the essense of the idea is like the gjallarhorn to have a long slow expansion for the first 80% or so of the horn, then a more rapid expansion toward the remaining 20% or so. hhmmm.... we'll see.



thanks for weighing in josh!
post #59 of 153
i just back of the enveloped it in hornresp and it is going to work! the plan will be a little tricky, but i'm sure it can be done. once the precise measurements are calculated, it should actually be a pretty easy build.
post #60 of 153
Quote:
Originally Posted by jpmst3 View Post

Agreed, that might not be easier. In fact, perhaps to the contrary.

Is there any advantage to having more folds rather than the dead space?
It would seem the horn path is longer not leaving the dead space...what do the extra folds due to the response curve?

From Danley's Labhorn notes:
Quote:
Still more complication, at the point where the wall area is a significant acoustic
size, the sound pressure couples to the width mode resonance (caused by the parallel
walls) which puts the first in a series of notches in the response coming out of the
mouth. In this situation, there is a 1/2 wavelength standing wave with the pressure
maxima at the walls and velocity max in the center. Coupling to this mode saps off
energy at frequencies related to the N 1/2 wavelengths. Here, your horn mouth width
(where it has parallel walls) also kind of sets your upper frequency limit. For a 21
inch wide horn like the LAB sub, the first width mode notch should be in the mid 300's
which is a non issue.

He's talking about the horn width there but the same thing applies to the segment lengths when there are parallel walls on each end. The longest a physical segment with parallel walls at each end can be before risking notches in response is about 3 feet. Any longer than that and you could get notches in response down into a typical subwoofer's passband.

For the record, I agree with Ricci. There's nothing I hate more than dead space. It means you could have either better performance or a smaller box. But horn folding is not a trivial pursuit and if you have a choice between a simple fold with dead space or nothing, perhaps it's best to not look a gift horse in the mouth.

Quote:
Originally Posted by LTD02 View Post

... to model it properly would require using akabak, which i don't know how to use.

This program will work as well. http://www.diyaudio.com/forums/software-tools/220421-transmission-line-modelling-software.html
And it's much, much easier to use than Akabak. It's even easier to use than Hornresp. A few simple instructions should have you up and running like a pro in about 5 minutes. The only problem is the results are not exactly the same as Hornresp. Very close but not exactly alike. Here's a comparison of a somewhat complex four segment horn done in this program and Hornresp.



The results between Hornresp and Akabak should be identical (as long as the Hornresp sim uses CON segments, which itself could introduce as much difference as the sim pictured above from a Hornresp sim with PAR segments, especially if the segments are long).

Either way, if you (or anyone) needs help with a multi segment sim that Hornresp can't handle I can sim it with either TL.app or Akabak, or at least provide instruction to get you started using TL.app on your own. (If you want me to do a sim though, I require all cross sectional areas at each segment marker and the lengths between them - figuring out this info is the hardest part of the sim.)

EDIT - looks like you figured out an alternative while I was typing. That does eliminate the dead space but I'd still be a bit concerned about potential 1/2 wave notches in those very long segments. But good luck, this looks like a lot of fun.
Edited by diy speaker guy - 9/27/13 at 1:17pm
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