i've copied the important information into this post so that it is all in one place. if i left anything out, please let me know and i will add it. thanks...
Originally Posted by Fattykidd
Is this still "recommended" for a pair of uxl's?
only if you need more than 130db output at 20hz in your home.
the compression ratio was made low (only 2:1; most horns are 3 or higher), so it is friendly to the driver.
here is max output with 2kw power, 30mm xmax, 2pi space, 1 horn. red is where the driver is running out excursion and black is where it is running out of power. rough estimates are that it would be equal to about 2 ported cabs (double drivers and double power) tuned to around 20hz and equal to about 3 cabs (triple drivers and power) at the upper end of the bass.
the model has the motor detuned significantly because of the inductance effects (and the cab was modified from the original for that reason). the driver may not need quite that much detuning, but it shows that the horn will have a great response even if the inductance effect significantly limit the effective motor strength. de-tuning the motor of high inductance drivers for horns was given an extensive treatment in a paper by diyspeakerguy. a search should pull up his post and the paper that several of us contributed to on the topic. bottom line, i think that we have a pretty close model here. my guess is that room effects are going to have a much greater impact than the margin of error in the model at this point.
also, be careful with this much output, as it can damage hard drives and other equipment that is sensitive to vibration damage.
the simulation uses 80 volts. the re of the driver is 3.2 ohms, so that would translate to 2000 "watts".
it was brought to my attention that the current version of hornresp has an option for modeling large voice coil drivers (such as the uxl).
this is the frequency response with the large voice coil simulation option selected. it is substantially similar to my 'manual adjustment' of the driver parameters.
other drivers may work. we would need to take a look at them one by one.
this is the UM18 with data-bass (ricci) measured t/s parameters and the hornresp default de-tuning adjustment. looks like the driver will work well. it seems that the drivers with relatively high moving mass end up with more 'chopiness' on upper end of the bass. in return, they provide more output with their greater excursion capability. this is the same 80v input, which with the um's re at 4.1 ohms is about 1560 "watts". excursion above the low corner (which is around 22hz) is only 22mm, so there is even more output in the tank if one wanted to hit it with more power. going up to 100v (max output from a channel of an inuke 6000 or a bridged 3000) still doesn't exceed xmax above the low corner and output is about 2db higher across the board. that would technically be about 2400 "watts" into the driver, so I'm not sure if that isn't a little high for the um for extended duration playback.
here is a comparo of the UXL (gray) and the UM18 (black) with 2000 "watts" power into each (80v and 90.55v respectively) using my back of the envelope method for detuning the drivers. the uxl appears to perform a little better, but it is also quite a bit more expensive.
driver displacement minimum is around 22hz in model. in practice, it will probably be a hair lower. a protective high pass around 20hz is necessary when running with high power, 3rd order at 20hz or so would be a good starting point.
25.5" wide x 36" deep x 80" tall
25.5" inches wide, so all center panels are ~24" width--cut sheet friendly.
height was increased until horn length and rear chamber fit model.
driver de-tune is guess, so there may be "better guesses".
compression ratio was kept very low, shouldn't be much risk of damaging driver (high pass required obviously)
man scaled to 6' tall.
80 volts into 3.2 ohms is exactly 2000 watts. driver at first maximum comes up to around 30mm.
"I'm intrigued, do continue. Is this something you've been on for a while or did we peak your interest enough to draw this up?"
with what we learned about de-tuning high inductance drivers for horn modeling (thanks primarily to diy speaker guy), i thought it was about time to go ahead and redo-Submaximus. this one has a similar fold pattern as the f20 but this one is MUCH larger. it is huge actually. not meant to go after the very lowest notes, i still think the ported are best when that is the goal (i wouldn't be surprised to see this one get strong response down to around 16-17hz in room, even with a protective high pass, but that will depend on the room).
i lack any more creativity, so this one shall be known as...SUBMAXIMUS V3 UXL.
UXL driver (detuned as well, and showing inductance effects) in a ~15 c.f. ported cab tune a little under 20hz driven with same 2kw power. looks like this horn is good for about 5-6db across most of the range. since it will be asked, dark red line is 5.5 cubic footer sealed. 2kw same motor detuning. hits just over xmax in this size cab with that power.
- the internal panels are 24" wide (slightly less from rip cutting won't matter)
- the "braces/brackets" showing the measurements are for the internal air space.
- good bracing is required.
- i'm not sure if the black diagonal deflector at 14/15 actually does anything other than serve as a brace.
- side panels are 36" x 80". best practice would be to draw the panel layout onto a side piece.
- the measurements will vary by a slight amount depending on the precise thickness of the wood panels ("three quarter inch plywood" in many cases is 23/32). that won't affect performance in any way, just be aware of it where you want the panels to line up just right (on the outside of the cab for example).
- try to get measurement 1 as close as possible to 3.23 inches. that measurement sets the "compression ratio", which for this horn is actually pretty low, so there is actually some wiggle room there. but still, if only one measurement on the entire horn is 'perfect', that should be it.
- a removable panel could be cut in the side for access to the driver if that is desired.
- this aspect of the design process actually required the most time/work. if somebody could double check these measurements, i'd appreciate it.
one bracing strategy--single row of 6" braces down the center of the cab. two rows might be even better, but more work. doubling up on the first brace in front of the driver might not be a bad idea.
cut sheet layout suggests 4 sheets may be possible.
measured results compared with model indicate that this one...hit the target.
pink line is measured result--asarose247
black line on bottom is target response rescaled to the same as the measurement.
blue line is the same as the black line, overlaid for comparison.