I erroneously posted my plea for help in the wrong forum section, which has thus far yielded zero responses. So, I'm hoping for better luck here, in the multi-way loudspeaker forum.
Simply, I'd like some idea of how well, or poorly, my driver might perform in a particular enclosure. Freeware enclosure design software I've found online weren't useful for MLTL modeling. I hope I'm not asking too much, but it would be immense if someone with software could help. I'd even be grateful for an educated guess.
The enclosure is the MLTL design from Morel's Moretrix kits. http://www.madisoundspeakerstore.com/pdf/Morel 2way MoreTrix.pdf
The T/S parameters of my driver:
Thanks in advance!
Simply, I'd like some idea of how well, or poorly, my driver might perform in a particular enclosure. Freeware enclosure design software I've found online weren't useful for MLTL modeling. I hope I'm not asking too much, but it would be immense if someone with software could help. I'd even be grateful for an educated guess.
The enclosure is the MLTL design from Morel's Moretrix kits. http://www.madisoundspeakerstore.com/pdf/Morel 2way MoreTrix.pdf
The T/S parameters of my driver:
Thanks in advance!
I just realized, the T/S info I provided was for a different driver. The correct info is:
Morel provides T/S specifications for "small signal" and another set of T/S specs for 1V. Not sure which to compare with my own driver, and also not sure how much variance, in which of the variables, would still provide acceptable results.
Morel (small signal) vs Morel (1V) vs My Driver
Fs 45Hz vs 33Hz vs 60Hz
Qts 0.42 vs 0.29 vs 0.62
Qms 4.68 vs 2.47 vs 2.85
Qes 0.47 vs 0.32 vs 0.80
Mms 16.8g vs 16.8g vs 14.2g
Vas 14L vs 29L vs 10-30L
I'm not expecting my driver to magically be a drop-in replacement for the Morel; however, I am hoping it's similar enough. The difference in Qts between the my driver (0.62) and 1V Morel (0.29) makes me think this could be a bad idea. Again, any assistance or guidance about the consequences of the swap would be fabulous.
Otherwise, it seems it may not be possible to get over this hurdle on my own without modeling software. Is there is a good no cost, or low cost option? Thanks again for the help.
Morel provides T/S specifications for "small signal" and another set of T/S specs for 1V. Not sure which to compare with my own driver, and also not sure how much variance, in which of the variables, would still provide acceptable results.
Morel (small signal) vs Morel (1V) vs My Driver
Fs 45Hz vs 33Hz vs 60Hz
Qts 0.42 vs 0.29 vs 0.62
Qms 4.68 vs 2.47 vs 2.85
Qes 0.47 vs 0.32 vs 0.80
Mms 16.8g vs 16.8g vs 14.2g
Vas 14L vs 29L vs 10-30L
I'm not expecting my driver to magically be a drop-in replacement for the Morel; however, I am hoping it's similar enough. The difference in Qts between the my driver (0.62) and 1V Morel (0.29) makes me think this could be a bad idea. Again, any assistance or guidance about the consequences of the swap would be fabulous.
Otherwise, it seems it may not be possible to get over this hurdle on my own without modeling software. Is there is a good no cost, or low cost option? Thanks again for the help.
For my records, what is the new driver's brand/model # ?
You compare 'apples to apples'
.
Qts' dominates until Vas gets extremely large, ergo not really, the new driver's ~F6 = 40 Hz Vs ~25 Hz with spec'd. optimal tuning, damping according to Hornresp
, so basically a bit more mid-bass, then 'dropping like a stone' to a ~identical ~20 Hz F10 in comparison, though if located near/at a corner to boost it could be the better overall choice.
Vb = 20*Vas*Qts^3.3 [note this power can be as low as 2.87 depending on the program]
Qts' = Qts + any added series resistance: mh-audio.nl - Home
HR: Hornresp
GM
You compare 'apples to apples'
.Qts' dominates until Vas gets extremely large, ergo not really, the new driver's ~F6 = 40 Hz Vs ~25 Hz with spec'd. optimal tuning, damping according to Hornresp
, so basically a bit more mid-bass, then 'dropping like a stone' to a ~identical ~20 Hz F10 in comparison, though if located near/at a corner to boost it could be the better overall choice.
Vb = 20*Vas*Qts^3.3 [note this power can be as low as 2.87 depending on the program]
Qts' = Qts + any added series resistance: mh-audio.nl - Home
HR: Hornresp
GM
Hmm, need to reset the frequency response plot for all but true sub system design.........
Input Parameters/Tools/Frequency Range: check box '10-20000 Hz'
Anyway, it's far worse than your sim, which is for a simple reflex plus the MLTL is closer to 37 L.........
Attached is my two Offset Driver [OD] sims to download/import into HR for you to save, make new copies to modify. Note that due to HR not taking any losses into account, the raw sim of any type TL in the Acoustical Power window will typically look hideous, so always view, modify, add stuffing, etc., in the Loudspeaker Wizard, then Save on exit if desired.
GM
Input Parameters/Tools/Frequency Range: check box '10-20000 Hz'
Anyway, it's far worse than your sim, which is for a simple reflex plus the MLTL is closer to 37 L.........
Attached is my two Offset Driver [OD] sims to download/import into HR for you to save, make new copies to modify. Note that due to HR not taking any losses into account, the raw sim of any type TL in the Acoustical Power window will typically look hideous, so always view, modify, add stuffing, etc., in the Loudspeaker Wizard, then Save on exit if desired.
GM
GM, thanks for sending the files. Apparently I hadn't figured out how to use HR correctly at all.
I played around a bit with the MW160GT sim and ended up with the following by removing some fill and changing the port length. At least that's what I think I did. I hope I'm on the right track.
I played around a bit with the MW160GT sim and ended up with the following by removing some fill and changing the port length. At least that's what I think I did. I hope I'm on the right track.
Attachments
You're welcome!
Historically, the goal is to minimize stuffing density to maximize acoustic efficiency, so moving in the right direction in that the total density is a bit less, but now it's concentrated down where we normally don't want it since the closed end has the highest pressure, so at the very least it needs to be extended to above the driver to ensure no reflections back through the driver off the top, sides, back walls that HR can't sim and ideally begin at the top and extend to at least a bit below the driver.
Curious why the vent change, i.e. the larger the vent area [Av], the longer it must be, so while there's more acoustic gain it's at the expense of increased vent pipe harmonics comb filtering with the driver's output, ergo needs more damping, pretty much negating the gain, hence the smallest vent that meets the < 5% mach [~17.2 m/sec = ~56.4 ft/sec] at max usable power [not necessarily amp or driver rating] is the goal. See 'Particle Velocity' pg 57/82 in HELP File.
Note too that by making the cab taller reduces vent length for a given tuning and why I typically spec a ~56-60" internal height [i.d.] to get the driver at the most commonly used ~38" tweeter seated height when a massive 1.5" thick base is used.
With vintage spec drivers that have a high Vas spec, it's not uncommon to not only reduce vent length [Lv] to baffle thickness for a low tuning, but require enlarging the vent area also, to the point of making it larger than the driver's effective piston area [Sd], which is considered to be a no-no for reflex alignments, but then except for RCA's 40" tall HIFI speaker [really a MLTL, so lost a marketing perk], reflex cabs were historically 'lowboy' end table, etc., furniture, so no 1/4 WL TL action to damp the vent.
GM
Historically, the goal is to minimize stuffing density to maximize acoustic efficiency, so moving in the right direction in that the total density is a bit less, but now it's concentrated down where we normally don't want it since the closed end has the highest pressure, so at the very least it needs to be extended to above the driver to ensure no reflections back through the driver off the top, sides, back walls that HR can't sim and ideally begin at the top and extend to at least a bit below the driver.
Curious why the vent change, i.e. the larger the vent area [Av], the longer it must be, so while there's more acoustic gain it's at the expense of increased vent pipe harmonics comb filtering with the driver's output, ergo needs more damping, pretty much negating the gain, hence the smallest vent that meets the < 5% mach [~17.2 m/sec = ~56.4 ft/sec] at max usable power [not necessarily amp or driver rating] is the goal. See 'Particle Velocity' pg 57/82 in HELP File.
Note too that by making the cab taller reduces vent length for a given tuning and why I typically spec a ~56-60" internal height [i.d.] to get the driver at the most commonly used ~38" tweeter seated height when a massive 1.5" thick base is used.
With vintage spec drivers that have a high Vas spec, it's not uncommon to not only reduce vent length [Lv] to baffle thickness for a low tuning, but require enlarging the vent area also, to the point of making it larger than the driver's effective piston area [Sd], which is considered to be a no-no for reflex alignments, but then except for RCA's 40" tall HIFI speaker [really a MLTL, so lost a marketing perk], reflex cabs were historically 'lowboy' end table, etc., furniture, so no 1/4 WL TL action to damp the vent.
GM
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