Xrk, It is definitely inspired by Greg B's design ....The Karlsonator is an incredibly clever bit of engineering! This style of fold worked out perfectly for the Lab15 (special) ML-Transflex cab, when the single fold scheme i was trying at the time wasn't panning out (path length wasn't adding up properly amongst other things)..
It might be possible to make a single fold style work with more offset , something like a scaled up version of the box featured in post #742 ....
Hmm, what worthwhile advantage does the MLTP have over this smaller, simple Vb = Vas, Fb = Fs reflex? All I see is a marginally better phase response in its usable passband.
GM
GM
??? Not sure how you arrived at this since I can't get WinISD Pro to run properly on this Win7 pro/64 laptop, but I don't recall there being a discrepancy between the two programs on the old XP Pro/S2 desktop.
Regardless, using HR for comparing both alignments shows no audible peak SPL advantage for the MLTP with the reflex having some if a > ~80 Hz XO is used due to its much lower group delay.
GM
Regardless, using HR for comparing both alignments shows no audible peak SPL advantage for the MLTP with the reflex having some if a > ~80 Hz XO is used due to its much lower group delay.
GM
Hi GM,
When using the Hornresp simulation by chips and palsa for his tapped, mass-loaded arrangement, and trying to match the minimum of the diaphragm displacement w/ a BR, I get a little lower SPL for the BR (@ the same Eg), and a much higher mouth particle velocity (47.1 v. 12.7 m/s). The slight differences in group delay and phase response will probably all go away when one adds HP/LP filters.
I don't know how real all this is w/o building, or at least going into AkAbak.
Regards,
When using the Hornresp simulation by chips and palsa for his tapped, mass-loaded arrangement, and trying to match the minimum of the diaphragm displacement w/ a BR, I get a little lower SPL for the BR (@ the same Eg), and a much higher mouth particle velocity (47.1 v. 12.7 m/s). The slight differences in group delay and phase response will probably all go away when one adds HP/LP filters.
I don't know how real all this is w/o building, or at least going into AkAbak.
Regards,
The Lab15 (special) design is remarkably close to a Karlsonator, and that one is known to be a good performer ....
The compromises made are all reasonable like the Mass loading , the offset , the tapped effect but are all used in moderation as to not take away from performance too much ...
I am confident that it will outperform a BR box but by how much is yet to be seen, someone has to build one and report back ...
In my past building experience (which i admit is not as much experience as some of the DIYaudio veterans) i have had low VAS high-ish QTS drivers disappoint me in bass reflex boxes but when i put those same drivers in an eigenmode based cabinet the results were satisfying to me .... Both designs simmed well enough in software but the eigenmode cabs (like TLs or Tapped Pipes) seemed to perform noticeably better, but i cannot honestly explain why that is *shrug*........... So after a few of those observations i try to stick with designing cabs that have at least some amount of quarter wave action ..... call it personal preference ...
Of course if a person plans on placing their cabinet's FB below the driver's FS (like in Pete's 4x12 ML-TL cab) the advantages seem to be even more pronounced...
I remember reading something a very popular designer (I think it was BFM?) said in some forum a while back about how quarter wave resonances always trump helmholtz resonances and i am beginning to think he was right about that ...
The compromises made are all reasonable like the Mass loading , the offset , the tapped effect but are all used in moderation as to not take away from performance too much ...
I am confident that it will outperform a BR box but by how much is yet to be seen, someone has to build one and report back ...
In my past building experience (which i admit is not as much experience as some of the DIYaudio veterans) i have had low VAS high-ish QTS drivers disappoint me in bass reflex boxes but when i put those same drivers in an eigenmode based cabinet the results were satisfying to me .... Both designs simmed well enough in software but the eigenmode cabs (like TLs or Tapped Pipes) seemed to perform noticeably better, but i cannot honestly explain why that is *shrug*........... So after a few of those observations i try to stick with designing cabs that have at least some amount of quarter wave action ..... call it personal preference ...
Of course if a person plans on placing their cabinet's FB below the driver's FS (like in Pete's 4x12 ML-TL cab) the advantages seem to be even more pronounced...
I remember reading something a very popular designer (I think it was BFM?) said in some forum a while back about how quarter wave resonances always trump helmholtz resonances and i am beginning to think he was right about that ...
Looking at this box, I'm starting to wonder if I can apply the same principal to my LAB12 reflex box; keep similar outer dimensions but implement the same mass loading, offset and quarter wave folding to get better performance from the driver...
The path length may be too short to get any benefit with a low corner of 35Hz however.
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The path length may be too short to get any benefit with a low corner of 35Hz however.
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Looking at this box, I'm starting to wonder if I can apply the same principal to my LAB12 reflex box; keep similar outer dimensions but implement the same mass loading, offset and quarter wave folding to get better performance from the driver...
The path length may be too short to get any benefit with a low corner of 35Hz however.
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The path length may be too short to get any benefit with a low corner of 35Hz however.
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Chips , That driver has such a low FS figure, A sharp high pass filter below FB would be required for a box tuned above FS .... Not sure what the optimal alignment would be, it is just a matter of tinkering with it in sim ..... Tapped effect and a little bit of offset are already being utilized in some other designs with the LAB12 so that apparently works ... Adding some mass loading to shorten the line a little might be a worthwhile experiment ..
I was looking at another thread for a LAB12 based mass loaded transmission line. The box was much larger than my current one (mine is 16x18x22) but the box ran flat nearly to 20Hz as a result hit Xmax at a peak SPL of 110dB. This made me think that the box could be made much smaller to gain SPL by losing 15-20Hz of extension.
However, to implement quarter wave folding, the entire box would turn Into a large port it seems, which may be a chuffing hazard depending on the CSA. I will have to play with the sim for the LAB15 box and see if anything can come of it, as I do not have the best understanding, but it seems CSA and taper rate (none here) are proportional to SPL.
All I would be looking for is output upwards of 115dB with a low corner of 35Hz with an external volume of ~100 liters. If anyone thinks this is possible with anything other than a reflex, let me know!! Fingers crossed [emoji51]
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However, to implement quarter wave folding, the entire box would turn Into a large port it seems, which may be a chuffing hazard depending on the CSA. I will have to play with the sim for the LAB15 box and see if anything can come of it, as I do not have the best understanding, but it seems CSA and taper rate (none here) are proportional to SPL.
All I would be looking for is output upwards of 115dB with a low corner of 35Hz with an external volume of ~100 liters. If anyone thinks this is possible with anything other than a reflex, let me know!! Fingers crossed [emoji51]
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Hi chips and palsa,
There are probably a number of possibilities, but the devil is always in the folding and fitting. Here is an OD-T-TL (offset driver tapered transmission line), its Vnet=72.8L, can be easily modified up or down, needs filling to smoothen the response:
Regards,
There are probably a number of possibilities, but the devil is always in the folding and fitting. Here is an OD-T-TL (offset driver tapered transmission line), its Vnet=72.8L, can be easily modified up or down, needs filling to smoothen the response:
Regards,
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Chips,
I loaded the Lab12 parameters into Hornresponse and it looks like this driver could easily beat 115db in halfspace at 100 liters net, or even 75 liters net for that matter if the box is tuned to 35hz ....
Initial impressions:
I am getting around 120db (at 40hz , 117@35hz) for a 100 liter tapped pipe (with minimal tapped effect) at 13mm xmax, and i get about 117db (average) at 75 liters net (in a slightly different alignment, sort of like what is seen in post #742 but with a longer port) ....117db Peak at 40hz & -3db at 35hz
The Lab15 special box made narrow would work but would end up being a bit over 100 liters if made 13.5 inches wide ... Would be best to fill the closed end section with stuffing, sim shows a saddle shaped response centered around 80hz, -3db down from 40hz ....... Real world results may show less saddle ... No guarantees though..
The suspension isn't particularly tight on this driver and it's FS is very low .... A sharp high pass filter below the cabinet's FB is highly recommended ...
There are some DIYaudio guys who made a 35hz tapped horn for this driver, you might want to check out those discussions ...
Of course this driver was intended to be a good candidate for a front loaded horn, so that might also be something worth looking into ..
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Thanks for the designs guys! I'm not too good at taking HR inputs and translating them to real life unfortunately, or the other way around for that matter. That kind of SPL with a 35Hz F3 sounds great for that size; id love to use that for my small party rig and dual LAB15 special boxes for my full rig [emoji5]️
MMJ and tb46, did you guys have rough dimensions of those designs?
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MMJ and tb46, did you guys have rough dimensions of those designs?
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MMJ - I just made arrangement to pick up another Lab 15, 4 ohm - so I will be building two boxes.
I'll be running each of these beneath my Eminence Delta-lite 2512 midbass.
I'll be running each of these beneath my Eminence Delta-lite 2512 midbass.
Can't wait to hear how these work out! I have a 2512 loaded OTop12 I'd be running on top of those boxes.
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Palsa,
I am tinkering around with a few things for your Lab12 in simulation right now, are you ok with a tower-like shape and small footprint?