Re: Re: Re: Port diameter for JX125 MLTL
u got me interested too. how big is your SAF cabinet? I am considering a cabinet that loonks like carolina audio's JTM about 36" tall, 3" (int) in depth and 12" wide. in fact I was looking to taper the depth from 3" (int) at the top to 7" (int) at the bottom.
on top of the JX125 cabinet I was thinking of putting the JX53 in an box with no rear panel (top, front and sides only) however some posters discoruged me from using the JX53 in OB esp since I was looking at a XO freq of less than 500Hz. what about using a MLTL for the JX53 too?
looks nice. I might copy it. ok with you?
cheesehead said:
u got me interested too. how big is your SAF cabinet? I am considering a cabinet that loonks like carolina audio's JTM about 36" tall, 3" (int) in depth and 12" wide. in fact I was looking to taper the depth from 3" (int) at the top to 7" (int) at the bottom.
on top of the JX125 cabinet I was thinking of putting the JX53 in an box with no rear panel (top, front and sides only) however some posters discoruged me from using the JX53 in OB esp since I was looking at a XO freq of less than 500Hz. what about using a MLTL for the JX53 too?
cheesehead said:
looks nice. I might copy it. ok with you?
GM said:
which calculator do you use? I use the one online at
http://www.lalena.com/audio/calculator/box/ i get this....
Dimensions
for the JX125 having foll specs
Vas = 54 lts
fs = 30 Hz
Qts = 0.45
D = 14.6 cm
Fb = 42 Hz
---------------
Vas = 62.88 liters = L x W x H
f3 = 26.99 Hz
fb = 42 Hz
Dv = 5.08 cm
Lv = -3.52 cm
I assume 62.88 liters Vp. How does one handle a -ve number for Lv? Does one just Mod the number and treat it as 3.52cm?
Hi all,
I am jumping on this thread rather late...
I've also been playing with the Jordan JX 53 unit, although my plan is to use an oldstyle Audax HM 170Z as bass driver in a TL cabinet (models surprisingly well in AJ Horn!).
The JX53 will sit in a separate cabinet on top of the bass unit, and since I just got the upper cabinets finished I might as well show you a pic or two!
They have a wedge shape like Colin mentioned and are finished in multiplex and pear veneer. For my taste they are looking dead gorgeous!
Still on the waiting list are the TL cabinets and the XO, but maybe I am going to get them finished by the end of the year....
Xo will be simple using 6dB filters with impedance equalization, the crossover point will be 500 Hz-ish like recommended.
Attachments
>which calculator do you use?
====
I have a bunch of different ones and they vary a bit depending on how simplified they are, though none are anywhere near as small as this one predicts, but BoxPlot 3.0 is what I use for quick calcs as it's easy and 'close enough'. Using published specs, it predicts a max flat of 78.2L/26.7Hz Fb. The one you used is too low IMO and choosing such a high Fb means it will be a highly underdamped (boomy) alignment.
====
>I assume 62.88 liters Vp. How does one handle a -ve number for Lv?
====
Correct, at least for a starting point depending on your performance goals. You have to increase the vent's CSA to make it longer. Best to ditch this program and use Unibox, Winisd pro, subsim, or other more accurate/flexible program.
====
>what is SO/SL? Area of the terminus or area of the begining of the TL?
====
These define the pipe's CSA in MJK's Mathcad worksheets, with SO = the closed end and SL = the open end of a TL or the terminus of the main pipe before the vent.
====
>And a raytracing how it's supposed to look...
====
Cool!
GM
====
I have a bunch of different ones and they vary a bit depending on how simplified they are, though none are anywhere near as small as this one predicts, but BoxPlot 3.0 is what I use for quick calcs as it's easy and 'close enough'. Using published specs, it predicts a max flat of 78.2L/26.7Hz Fb. The one you used is too low IMO and choosing such a high Fb means it will be a highly underdamped (boomy) alignment.
====
>I assume 62.88 liters Vp. How does one handle a -ve number for Lv?
====
Correct, at least for a starting point depending on your performance goals. You have to increase the vent's CSA to make it longer. Best to ditch this program and use Unibox, Winisd pro, subsim, or other more accurate/flexible program.
====
>what is SO/SL? Area of the terminus or area of the begining of the TL?
====
These define the pipe's CSA in MJK's Mathcad worksheets, with SO = the closed end and SL = the open end of a TL or the terminus of the main pipe before the vent.
====
>And a raytracing how it's supposed to look...
====
Cool!
GM
Re: Re: Re: Re: Port diameter for JX125 MLTL
I'd feel inclined to stick with the closed box for a single JX53, especially if running below 500Hz. It could do with the extra loading. Stixx's go-faster JX53 enclosure looks a good way to go. You could try a straightforward TL, in the manner of the B&W Nautilus. Leave it open ended, then plug to compare and see what it does to driver excursion.
BTW, keep the JX125 calculations coming - I have another 4 here awaiting enclosures (and, being on a Mac, no access to the ML mathcad.)
Colin
navin said:
I'd feel inclined to stick with the closed box for a single JX53, especially if running below 500Hz. It could do with the extra loading. Stixx's go-faster JX53 enclosure looks a good way to go. You could try a straightforward TL, in the manner of the B&W Nautilus. Leave it open ended, then plug to compare and see what it does to driver excursion.
BTW, keep the JX125 calculations coming - I have another 4 here awaiting enclosures (and, being on a Mac, no access to the ML mathcad.)
Colin
Re: Re: Re: Re: Re: Re: Port diameter for JX125 MLTL
I doubt Excel has some of the exotic math functions Martin is using, for this to be straightforward.
I use MathCad 7 in VirtualPC to run Martin's sheets... an attempt to open them in MathCAD 6 (last Mac version) failed. Hopefully with more & more of the science community migrating to OS X (ie UNIX + MS Office (bad as Office is) all on one stable, fast box) we will see pressure mount to have an OS X version.
dave
macmeech said:
I doubt Excel has some of the exotic math functions Martin is using, for this to be straightforward.
I use MathCad 7 in VirtualPC to run Martin's sheets... an attempt to open them in MathCAD 6 (last Mac version) failed. Hopefully with more & more of the science community migrating to OS X (ie UNIX + MS Office (bad as Office is) all on one stable, fast box) we will see pressure mount to have an OS X version.
dave
Enclosure & crossover
Let's see if I'm getting the idea about this speaker stuff...
I like GM's box (57" tall, thin, with the woofer abt 20" down) but then I wonder where we should put the JX53. If it's in the main box (say, 3" above the 125 and with planet10's PVC pipe sealed behind) then there will be a perturbation of the TL response due to the JX53's sealed volume. I think I could model that on Martin King's sections worksheet. I think this design would have a way cool SAF. Tall, thin...
But wouldn't the time alignment of the JX53 and JX125 be a problem, esp. with a first-order crossover like the one recommended on the Jordan web site? (FWIW, I'm limited to a passive XO.) So I'm kind of leaning towards Stixx's design (also the design on dave's site) where the JX53 is in a separate enclosure. Put the JX125 (or 150?) in a folded TL, about 30" high, with the driver just short of the midpoint (therefore near the top of the cab).
Time alignment? It looks like Stixx's JX53 enclosure moves pretty well!
(Hmm, maybe a ML-TQWT, with the slope of the baffle taking care of the time alignment...)
At least, that's the plan for today! Still need to consider BSC & the XO
mike
Let's see if I'm getting the idea about this speaker stuff...
I like GM's box (57" tall, thin, with the woofer abt 20" down) but then I wonder where we should put the JX53. If it's in the main box (say, 3" above the 125 and with planet10's PVC pipe sealed behind) then there will be a perturbation of the TL response due to the JX53's sealed volume. I think I could model that on Martin King's sections worksheet. I think this design would have a way cool SAF. Tall, thin...
But wouldn't the time alignment of the JX53 and JX125 be a problem, esp. with a first-order crossover like the one recommended on the Jordan web site? (FWIW, I'm limited to a passive XO.) So I'm kind of leaning towards Stixx's design (also the design on dave's site) where the JX53 is in a separate enclosure. Put the JX125 (or 150?) in a folded TL, about 30" high, with the driver just short of the midpoint (therefore near the top of the cab).
Time alignment? It looks like Stixx's JX53 enclosure moves pretty well!
(Hmm, maybe a ML-TQWT, with the slope of the baffle taking care of the time alignment...)
At least, that's the plan for today!
Still need to consider BSC & the XO mike
>1. the reason i chose a higher Fb was to reduce Vb. WAF dictates as low a Vb as possible. Perferably 25 liter or so.
====
At 25L, sealed is the only reasonable alignment, with it being excursion limited below ~90Hz.
====
>2. SO/SL was quoted as 83.258"^2 so i figred it was an area and not a ratio. SO/SL should be 3 right?
====
SO and SL defines the cross sectional area (CSA), so in^2 is correct and defines a straight taper, ergo gross Vb = (83.258*57.28)/1728 = ~2.76ft^3 or 78.154L.
====
>I like GM's box (57" tall, thin, with the woofer abt 20" down) but then I wonder where we should put the JX53. If it's in the main box (say, 3" above the 125 and with planet10's PVC pipe sealed behind) then there will be a perturbation of the TL response due to the JX53's sealed volume.
====
Not a good plan IMO. Fold it at the top of the driver with the 'top' of the cab at the bottom front and the vent in the lower rear or side. Figure how high up off the floor you want the JX125, which I imagine will leave some cavities below both ends of the pipe. Fill them with kitty litter/whatever to mass load/keep them from resonating. Allow for a sufficiently large base to make it stable.
Put the JX53 in a separate sealed cab of the same width and perched on top using short, inverted cone spikes once the setback has been determined. Apply some Deflex or equal to any exposed cab top to damp reflections.
GM
====
At 25L, sealed is the only reasonable alignment, with it being excursion limited below ~90Hz.
====
>2. SO/SL was quoted as 83.258"^2 so i figred it was an area and not a ratio. SO/SL should be 3 right?
====
SO and SL defines the cross sectional area (CSA), so in^2 is correct and defines a straight taper, ergo gross Vb = (83.258*57.28)/1728 = ~2.76ft^3 or 78.154L.
====
>I like GM's box (57" tall, thin, with the woofer abt 20" down) but then I wonder where we should put the JX53. If it's in the main box (say, 3" above the 125 and with planet10's PVC pipe sealed behind) then there will be a perturbation of the TL response due to the JX53's sealed volume.
====
Not a good plan IMO. Fold it at the top of the driver with the 'top' of the cab at the bottom front and the vent in the lower rear or side. Figure how high up off the floor you want the JX125, which I imagine will leave some cavities below both ends of the pipe. Fill them with kitty litter/whatever to mass load/keep them from resonating. Allow for a sufficiently large base to make it stable.
Put the JX53 in a separate sealed cab of the same width and perched on top using short, inverted cone spikes once the setback has been determined. Apply some Deflex or equal to any exposed cab top to damp reflections.
GM
Other software?
Mostly in response to comments a few replies up...Is there any interest in seeing the code ported to other programming environments? I was thinking either Matlab or Mathematica. Both are relatively expensive and may not be that common... but I thought I pose the suggestion. If there was enough interest, I might give it a try...
Mostly in response to comments a few replies up...Is there any interest in seeing the code ported to other programming environments? I was thinking either Matlab or Mathematica. Both are relatively expensive and may not be that common... but I thought I pose the suggestion. If there was enough interest, I might give it a try...
>what do you consider excursion limited?
====
Xmax since Xsus and Xmech isn't published. Then there's the rapid rise in distortion to consider.
====
>I was hoping for a F3 of 45Hz or so in 25 liters. My expected MAX SPL at 2m (i dont listen much closer than that to the speaker) would be 95db @ 50Hz.
====
At a glance it would be ~92dB in half space to keep it within Xmax, so assuming you're talking peak SPL and there's only a 3dB loss over distance in the LF, then it would have to hit up to 98dB/m if out away from the walls, requiring excursion to almost double, so you would have to check with Jordan to see if it can handle it.
GM
====
Xmax since Xsus and Xmech isn't published. Then there's the rapid rise in distortion to consider.
====
>I was hoping for a F3 of 45Hz or so in 25 liters. My expected MAX SPL at 2m (i dont listen much closer than that to the speaker) would be 95db @ 50Hz.
====
At a glance it would be ~92dB in half space to keep it within Xmax, so assuming you're talking peak SPL and there's only a 3dB loss over distance in the LF, then it would have to hit up to 98dB/m if out away from the walls, requiring excursion to almost double, so you would have to check with Jordan to see if it can handle it.
GM
Re: Enclosure & crossover
Another advantage of keeping the JX53 in a separate enclosure is flexibility if you decide to experiment with other JX125 enclosures.
btw, MathCad into Excel is somewhat a moot point as my Mac is practically a Microsoft-free zone, so no Office either. I'll have to blag a go on someone's PC sometime.
Colin
Another advantage of keeping the JX53 in a separate enclosure is flexibility if you decide to experiment with other JX125 enclosures.
btw, MathCad into Excel is somewhat a moot point as my Mac is practically a Microsoft-free zone, so no Office either. I'll have to blag a go on someone's PC sometime.
Colin
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.