... as shown in the attachments.
Attachments
Greets!
Those are two different designs with the first an inverse tapered TQWT best suited for lower Qt drivers and the other horn tapered vented [ML] TQWT such as Freddi's which are best suited to higher Qt drivers, while a constant [straight] taper [ML] TL is best suited for medium Qt drivers such as the Beta CX12.
Of course you can mix n' match, just this 'rule of thumb' [ROT] has its [minor] benefits, so planning a simple MLTL [no folds] like worked so well way back when, but need to know at what height off the floor you want the driver and what, if any, dimensional limitations.
GM
Those are two different designs with the first an inverse tapered TQWT best suited for lower Qt drivers and the other horn tapered vented [ML] TQWT such as Freddi's which are best suited to higher Qt drivers, while a constant [straight] taper [ML] TL is best suited for medium Qt drivers such as the Beta CX12.
Of course you can mix n' match, just this 'rule of thumb' [ROT] has its [minor] benefits, so planning a simple MLTL [no folds] like worked so well way back when, but need to know at what height off the floor you want the driver and what, if any, dimensional limitations.
GM
Hi GM
Thanks for the clarification. I am still trying to get a reference for what is considered high/low Qts and what kinds of configurations are favourable for each. My understanding is that it a speaker has high Qts it could be used in OB and can produce a larger FR in A smaller box (extension (?)) And control the voice coil/pole dampening in OB conditions (less controlled/no outside pressure from enclosure?). A speaker with smaller Qts does well in a sealed enclosure but could gain some extension with compromises in a vented box (?) And, a middle of the road Qts driver does well in a ported box... (?)
As far as speaker size, I think WAF would dictate smaller the better but if I do a good job finishing maybe I can get away with a bit more...
Because it is a coax I'm thinking 33-36" on centre give it take? If anyone has any suggestions, I'm open. Ideally, if the cabinets are not taller than 48" ( for height and plywood sizing... My tools are not so great). Footprint would keep the cabinets closer to the wall (not stick out too much).
That said, I'm open to ideas with SQ being the focus...
Thanks again and very much appreciated!
Thanks for the clarification. I am still trying to get a reference for what is considered high/low Qts and what kinds of configurations are favourable for each. My understanding is that it a speaker has high Qts it could be used in OB and can produce a larger FR in A smaller box (extension (?)) And control the voice coil/pole dampening in OB conditions (less controlled/no outside pressure from enclosure?). A speaker with smaller Qts does well in a sealed enclosure but could gain some extension with compromises in a vented box (?) And, a middle of the road Qts driver does well in a ported box... (?)
As far as speaker size, I think WAF would dictate smaller the better but if I do a good job finishing maybe I can get away with a bit more...
Because it is a coax I'm thinking 33-36" on centre give it take? If anyone has any suggestions, I'm open. Ideally, if the cabinets are not taller than 48" ( for height and plywood sizing... My tools are not so great). Footprint would keep the cabinets closer to the wall (not stick out too much).That said, I'm open to ideas with SQ being the focus...
Thanks again and very much appreciated!
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Hi GM
Thanks for the clarification. I am still trying to get a reference for what is considered high/low Qts and what kinds of configurations are favourable for each. My understanding is that it a speaker has high Qts it could be used in OB and can produce a larger FR in A smaller box (extension (?)) And control the voice coil/pole dampening in OB conditions (less controlled/no outside pressure from enclosure?). A speaker with smaller Qts does well in a sealed enclosure but could gain some extension with compromises in a vented box (?) And, a middle of the road Qts driver does well in a ported box... (?)
As far as speaker size, I think WAF would dictate smaller the better but if I do a good job finishing maybe I can get away with a bit more...
That said, I'm open to ideas with SQ being the focus...
Thanks again and very much appreciated!
Greets!
You're welcome!
Don't recall ever seeing an official one from the T/S pioneers, but mine is:
< ~ 0.312 = low
~ 0.312 ~ 0.62 = medium
> ~ 0.62 = high
Didn't quite follow all that, so will just say that when Qts' is:
~0.403, Vb = Vas, Fb = Fs
< ~0.403, Vb = < Vas, Fb = > Fs
> ~0.403, Vb = > Vas, Fb = < Fs
Qts' = Qts + any added series resistance [Rs]: HiFi Loudspeaker Design
EBP is for newbies, casual DIYers to choose what basic type of cab to use: Red Spade Audio: Efficiency Bandwidth Product (EBP)
Calculator: Efficiency Bandwidth Product Calculators - EBP, Speaker Resonance Frequency, Speaker Electrical
All other types are for meeting the needs of specialized apps and well documented on the forums, so recommend Google as I seem to have much better luck than searching the forums here and elsewhere.
Well, 38" for 'FR'/co-ax has proven popular for seated ear height on axis, so what's yours if this is acceptable?
FYI, we normally recommend 3/4" [~19 mm] BB ply, commonly 5 x 5 ft, so up to 58.5" i.d. is what we normally work with and full height is the norm for me and also prefer at least 24"- 28.5" i.d. to minimize/negate the need for any baffle step compensation [BSC], reduce depth.
If this isn't acceptable, then post the max o.d. dims and I'll do the best I can with it and 'it is what it is'.
GM
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Hi GM
Thank you so much for that info. The EPB link clarifies it nicely. I read from Eminence their take on Qts (Understanding Loudspeaker Data | Eminence Speaker) and they state <0.4, 0.4-0.7, & >0.7 for their low, mid, and high ranges. ... Then they talk about an exception to the rule... ;P
Anyhow, let's go with the BB ply dimensions (up to 58.5 I d.) And I can go from there.
Thanks again and much appreciated!
Thank you so much for that info. The EPB link clarifies it nicely. I read from Eminence their take on Qts (Understanding Loudspeaker Data | Eminence Speaker) and they state <0.4, 0.4-0.7, & >0.7 for their low, mid, and high ranges. ... Then they talk about an exception to the rule... ;P
Anyhow, let's go with the BB ply dimensions (up to 58.5 I d.) And I can go from there.
Thanks again and much appreciated!
and "Qts = 0.312" is "the" reference number for 6th order assisted bass reflex.
Commercial examples of 6th order bass reflex boxes included Electro-Voice's "Interface" series and Cerwin Vega's "S1" 3-way speaker.
For well over a decade I hoped Eminence would make a regular line 12CX with qts ~0.3 and a "Super 12LTA" with 56 oz magnet - but looks like those ain't gonna happen.
Using an underdamped active 2nd order highpass filter, this type conserves cabinet volume, with applied peaking boost at or near Fb where cone motion is minimal, plus the highpass action got rid of totally wasted cone excursion below system tuning.
Notes from the late and great DJK (Dennis Kleitsch)
August 2010 at 1:09am
The classic B6 assisted alignment is best with a Qts=0.312
This requires a high=pass filter of a Q=2 at Fb, and the Fb=Fs.
Because the moderate boost is at Fb, cone excursion doesn't go up a lot, and distortion is low.
Without the Q=2 filter the box is an SBB4, with the best transient response of all the standard vented alignments, with the filter it is a B6(maximally flat).
The quick calculator fudge (Qts=0.312) is Vas*0.4 = box size.
For different Qts values, use (Qts^2)*Vas*4.5 = box size. Fb should be (Fs/Qts)*0.312
Trick:
If the Qts is a bit low, just pretend it is a bit higher (no more than 20% or so). This works because you are pretending the motor is weaker than it actually is (obviously doesn't work the other way if the Qts is too high). Also, when driving hard the Bl goes down and the cabinet is now correctly tuned!
The quick B4 calculator fudge (Qts=0.4) is Vas*0.8 = box size, Fb=Fs.
Commercial examples of 6th order bass reflex boxes included Electro-Voice's "Interface" series and Cerwin Vega's "S1" 3-way speaker.
For well over a decade I hoped Eminence would make a regular line 12CX with qts ~0.3 and a "Super 12LTA" with 56 oz magnet - but looks like those ain't gonna happen.
Using an underdamped active 2nd order highpass filter, this type conserves cabinet volume, with applied peaking boost at or near Fb where cone motion is minimal, plus the highpass action got rid of totally wasted cone excursion below system tuning.
Notes from the late and great DJK (Dennis Kleitsch)
August 2010 at 1:09am
The classic B6 assisted alignment is best with a Qts=0.312
This requires a high=pass filter of a Q=2 at Fb, and the Fb=Fs.
Because the moderate boost is at Fb, cone excursion doesn't go up a lot, and distortion is low.
Without the Q=2 filter the box is an SBB4, with the best transient response of all the standard vented alignments, with the filter it is a B6(maximally flat).
The quick calculator fudge (Qts=0.312) is Vas*0.4 = box size.
For different Qts values, use (Qts^2)*Vas*4.5 = box size. Fb should be (Fs/Qts)*0.312
Trick:
If the Qts is a bit low, just pretend it is a bit higher (no more than 20% or so). This works because you are pretending the motor is weaker than it actually is (obviously doesn't work the other way if the Qts is too high). Also, when driving hard the Bl goes down and the cabinet is now correctly tuned!
The quick B4 calculator fudge (Qts=0.4) is Vas*0.8 = box size, Fb=Fs.
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Anyhow, let's go with the BB ply dimensions (up to 58.5 I d.) And I can go from there.
Thanks again and much appreciated!
Greets!
You're welcome!
OK, you didn't comment on the 38" height, so assume it's close enough.
Anyway, forgotten how big these need to be to go low[er], so rounded it all up so that [1] sheet makes [2] ~30" x 60" panels, [1] sheet makes [5] ~12" x 60" = [4] side panels, [2] top plates, so [3] sheets total.
The bottom can be MDF, ditto the two internal top plates that reduce the internal height to 57" i.d..
OK, so allowing 1/8" for saw cuts and 0.75" thick panels, overall width = ~31.375" x ~11.9" depth, ~281 L/9.923 ft^3 gross.
All dims outside [o.d.]:
L = 60"
Zd = 22"
Zp = 49"
vent = 8" i.d. dia. pipe 2" long, though best to make it longer and fiddle with tuning once in place in room as often need different tunings for each cab.
The MDF top plates stiffen it up sufficiently and adds a bit of downward mass loading, so a single crossbar/motor support brace is sufficient horizontally.
The ~ 30" panels need a couple of vertically oriented ~1" x 3" boards offset at some ratio and ideally the driver, vent is offset also, making them mirror image.
A couple of front/rear ~1" x 3" boards at some offset ratio finishes off the bracing.
GM
Hi GM
Thank you for the calculations and the measurements! You weren't kidding when you said big! Lol! So if I am to understand this clearly, the box is 30x60x12. The driver could be mounted on the 12" or the 30" side?
Also, could you please clarify Zd an a Zp? I am trying to find references for them for speaker boxes but keep finding products...
Again, much appreciated!
Thank you for the calculations and the measurements! You weren't kidding when you said big! Lol! So if I am to understand this clearly, the box is 30x60x12. The driver could be mounted on the 12" or the 30" side?
Also, could you please clarify Zd an a Zp? I am trying to find references for them for speaker boxes but keep finding products...
Again, much appreciated!
so that's about 13CF "net" - it probably would play some pipe organ notes - what's the hornresp record?
one thing to get good results will be the crossover - sometimes they don't sound fully coherent - I used a passive allpass network on a 12cx between a 2nd order electrical lowpass and the coax woofer - whether that was correct or not, it did seem much better in focus.
I wish Eminence would slap a 56oz (or more) magnet on 12LTA and 12CX, get that qts down towards 0.31 and offer them as "super" versions.
fwiw - a 40 liter sealed box plus 350uF series capacitor - this will not work with high output impedance amplifiers. Some stuffing and the 40 liter box might be closer to the 56 liter box response.
btw, some years back I bought a pair of Eminence custom cast frame 12cx with an improved (smoother response) woofer cone than Beta 12cx from a former president of Cetec-Gauss (who developed the Gauss 5181 Karlson 18" box). He used those 12cx in a stuffed 1 cubic foot box with crossover to bigger speakers. I'd assume that bi-amped could perform as well or better than the big box in less overall cabinet volume.
one thing to get good results will be the crossover - sometimes they don't sound fully coherent - I used a passive allpass network on a 12cx between a 2nd order electrical lowpass and the coax woofer - whether that was correct or not, it did seem much better in focus.
I wish Eminence would slap a 56oz (or more) magnet on 12LTA and 12CX, get that qts down towards 0.31 and offer them as "super" versions.
fwiw - a 40 liter sealed box plus 350uF series capacitor - this will not work with high output impedance amplifiers. Some stuffing and the 40 liter box might be closer to the 56 liter box response.
btw, some years back I bought a pair of Eminence custom cast frame 12cx with an improved (smoother response) woofer cone than Beta 12cx from a former president of Cetec-Gauss (who developed the Gauss 5181 Karlson 18" box). He used those 12cx in a stuffed 1 cubic foot box with crossover to bigger speakers. I'd assume that bi-amped could perform as well or better than the big box in less overall cabinet volume.
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You're welcome!
No, it's a full height 5x5 ft board or 60" high or whatever fraction thereof if not exact and: "OK, so allowing 1/8" for saw cuts and 0.75" thick panels, overall width = ~31.375" x ~11.9" depth, ~281 L/9.923 ft^3 gross." So only fits on the wide side just as I said I would if there were no objections.
What Dave said; 'z' specs is something MJK uses in his MathCad TL worksheets, though did abbreviate them.
GM
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