A rule i have when making a musical BR alignment is that the 1st derivative of the simulated curve does not cross zero more than once. Yours does so twice. The box is too big for the tuning. Raise the tunign or shrink the box.
dave
Honestly, I learned the fundamentals of acoustics ~ a decade before T/S began to become a 'thing', consequently only bothered with the fundamentals like I posted earlier and even then not following it for the most part till I was ~ forced to if I wanted to participate on DIY forums, so without researching it, no clue how to respond other than I know from experience that by the pioneer's standards it's under-damped without a more rolled off response.
WRT box damping, the pioneers taught me to line just the top [or whatever side was opposite the vent wall], one side and back with suitable sound absorbing material [historically a long list of materials with appropriate test results to choose from] and if it was still under-damped, then 'critically' damp the vent to remove any 'ringing' using the 'click' test and one's ears or nowadays by using an impulse response to get it technically exact.
Click test: Click Test | GM210 | Flickr
Honestly I've thought about it. But I have to draw the line somewhere. Also it will be a motivation to save up some money for the 604.If your place is that big you should’ve chosen FTX1530
You can send me the 12”s
Thanks. I appreciate your input.
Apparently you missed this post where I noted that the [Sd] spec is way wrong, so should at least use the factory specs: Big coaxial box
edit: Not that it matters though, as [Mmd], [Mms], [Cms], [BL] are now just as far off in another direction once the right [Sd] is used based on Fs, Qes, Qms.
Once these are corrected, Vas increases 10x to 120.8 L, so maybe a typo, but this sort of 'misdirection' was once pretty common and would have immediately assumed the super low [Vas] spec was suspect back before making ever smaller speakers apparently became the primary goal, so I'm more inclined to not be so forgiving.
In short, unless others' measured specs for Celestion drivers have been accurate 'enough' to published, best to measure your driver's specs and use the average to design with.
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Agreed, my theoretically ideal 8" would have a conical HF horn like the pioneer's except with the WG built into a permanently installed grill like used on some Babb speakers to create a wide BW co-ax WG that could be further WG loaded to a lower Fc even if just a flat baffle.
Depends on how far away the listening position [Lp] is and what peak SPL is desired and whether or not at least half of music's 10 octaves of acoustic power is augmented: < [16*16,000]^0.5 = < ~506 Hz.
Apparently you missed this post where I noted that the [Sd] spec is way wrong, so should at least use the factory specs: Big coaxial box
edit: Not that it matters though, as [Mmd], [Mms], [Cms], [BL] are now just as far off in another direction once the right [Sd] is used based on Fs, Qes, Qms.
Once these are corrected, Vas increases 10x to 120.8 L, so maybe a typo, but this sort of 'misdirection' was once pretty common and would have immediately assumed the super low [Vas] spec was suspect back before making ever smaller speakers apparently became the primary goal, so I'm more inclined to not be so forgiving.
In short, unless others' measured specs for Celestion drivers have been accurate 'enough' to published, best to measure your driver's specs and use the average to design with.
Celestion also recommend box/port for these drivers, why not try sim that?
60l for the 12” 48Hz
95l for the 15” 55Hz
If you go up a little maybe you get deeper bass but less sensitivity or punch.
https://celestion.com/wp-content/uploads/2019/09/FTX1225-crossover-design.pdf
https://celestion.com/wp-content/uploads/2019/09/FTX1530-Crossover-datasheet.pdf
IIRC, back when you explained this I did a bunch of the pioneer's Vb = Vas/1.44, Fb = Fs sims and all met this criteria, though of course only looked good in a sim when optimized BR specific specs was used.
Looked up the math just now, but couldn't figure out how to manipulate it for non optimal specs.
Thanks, didn't notice/look since factory cab recommendations typically are more about high power handling/driver protection than SQ, so based on the math I posted earlier including 0.5 ohms [Rs]:
'Classic' BR = 84 L/42.1 Hz Fb [QL = 7], 3.5" dia. x 6.26" vent, ~150 W [my preference]
T/S max flat = 155.18 L/39.3 Hz Fb [QL = 7], 5" dia. x 2.56" vent, ~60 W
I’ve been following and thinking (dangerous I know)...especially about whether a large coaxial would be right for me...or if its just that I want “what to he other kids have”.
Since the subject of room size was brought up...
I have a modest home with two spaces I can set up audio in.
My living room measures about 13.5 X 19.5 feet (attached to 12 X 14 dining area in an L shape) and a sunroom I’m refinishing which is about 12 X 14 feet.
I’ve struggled with 8” fullrange drivers in front horns in the living room for a while, beaming being the main problem. I often thought the problem wouldn’t be as bad if I had more room and could sit further away.
Switching to open baffle experiments with the same drivers reduced beaming greatly at the expense of perceived detail, clarity and soundstage depth in my opinion.
So I’m wondering if a large format coaxial will have its own set of problems in the same space?
Also...to Cal and others with experience...is the general opinion that buying vintage Altec duplex units is a risky endeavor and that the new Great Plains units are the smarter choice?
Since the subject of room size was brought up...
I have a modest home with two spaces I can set up audio in.
My living room measures about 13.5 X 19.5 feet (attached to 12 X 14 dining area in an L shape) and a sunroom I’m refinishing which is about 12 X 14 feet.
I’ve struggled with 8” fullrange drivers in front horns in the living room for a while, beaming being the main problem. I often thought the problem wouldn’t be as bad if I had more room and could sit further away.
Switching to open baffle experiments with the same drivers reduced beaming greatly at the expense of perceived detail, clarity and soundstage depth in my opinion.
So I’m wondering if a large format coaxial will have its own set of problems in the same space?
Also...to Cal and others with experience...is the general opinion that buying vintage Altec duplex units is a risky endeavor and that the new Great Plains units are the smarter choice?