Is this driver suitable for MLTL?

[mondogenerator]

i have a pair of Audax drivers im thinking of trying to design an MLTL for, and i just wanted to pick the brains of anyone who can help.

ts parameters:

Fs 64
vas 4.7 litres
Qts 0.49
Qms 2.16
Qes 0.63
BL 4 NA
Sd 50.5 cm²

im considering 'trying' to make a bookshelf type, i.e. small as possible, and perhaps folded as well. I was just slightly unsure whether the Qts of 0.49 was too high for an MLTL; or conversely whether the fairly high Q would be ideal to squeeze some more LF out of this driver.

thanks for taking the time to read, and for any advice in advance.

[mondogenerator]

unless im mistaken there are no alignment table posted for the MLTL, as there are for the TQWP. UNfortunately, mathcad isnt exactly my forte...

[pkitt]

Give me the values for Re and Le and I'll see what I can model for you in an ML-TL. How "small" must this cabinet be? Do you already have in mind height and width?
Paul

Originally Posted by mondogenerator

i have a pair of Audax drivers im thinking of trying to design an MLTL for, and i just wanted to pick the brains of anyone who can help.

ts parameters:

Fs 64
vas 4.7 litres
Qts 0.49
Qms 2.16
Qes 0.63
BL 4 NA
Sd 50.5 cm²

im considering 'trying' to make a bookshelf type, i.e. small as possible, and perhaps folded as well. I was just slightly unsure whether the Qts of 0.49 was too high for an MLTL; or conversely whether the fairly high Q would be ideal to squeeze some more LF out of this driver.

thanks for taking the time to read, and for any advice in advance.

[bjorno]

Originally Posted by mondogenerator

UNfortunately, mathcad isnt exactly my forte...

Hi,

Why do you hide the driver Brand identification numbers? Are your T/S # measured or the manufacturers?

need some classic tl advice

See the consequence when using your data:first picture:

Wild guess: See the second picture.

b

[mondogenerator]

ah yes a slight oversight on my part i see. specs are manufacturers data, and ive seen some on both zaph and hennessys' sites, which maybe are more accurate.

quoted VC inductance is 0.45mH
DCR 6Ohm

LOL @ Bjorno: yes easy to guess really! Ive had them lying around for ages. they could be a rapid build easy sealed or vented design, but im toying with other ideas

I have seen some things with small fr drivers in 'bookshelf' MLTLs which looked ok, but havent been able to model one. Abandoned the idea of a TQWP a while ago, due to size.

I figured, (i think), in the most basic way; the way i designed my last QWP, i ended up using a 20:1 taper. i did model it further, with higher ratios, but i settled at 20:1 for the minimum port area i was prepared to accept. essentially youre doing the same as early reflex designs that used just a simple port hole and a large Vb. PKITT i think you helped me with that project! So thanks again for the help.

size wise....hmm.

depth im not bothered about really, so HxWxD id say:

12"- 15" x 6"- 8" x 12"- 15"

ballpark ideas really. it will either be going with an TM025F1 or tangband W2-800SL and xovers to suit whichever. when i figure out a tapped horn on Hornresp im going to see what i can model in a similar size crossed to the tangband around 300Hz. it may be a ridiculous idea though...

i envision maybe a folded MLTL, 2,3, or 4 folds, but with a taper. However, with a net taper of zero over the first 2 or 3 sections, depending on how many folds may suit. eg in 3 fold design, 3:1 in the 1st section, 1:3 in the 2nd, and 3:1 again in the last. perhaps even just a straight untapered last section, im unsure. just an idea, no idea if its a good one! lowest vent area with that driver? maybe 2 in²?

[mondogenerator]

Hennessy quotes some of the AP100ZO ts parameters after 30 hours run in. these have had loads of run in, but i havent gotten around to measuring anything myself yet. (cheap DMM, and with a desire for accuracy, the necessary calibration curve beforehand.........)


Fs = 60.9
Qms = 1.60
Qes = 0.63
Qts = 0.45
Vas = 4.36

[GM]

Well, a T/S max flat alignment is ~ 6.3 L/55 Hz Fb, so converting it to a MLTL nets us a slightly lower 51-52 Hz Fb due to 1/4 WL vent loading (all dims approximate):

L = 27.54"
WxD = 13.96"^2
zdriver = 9.256"
zport = 26"
dport = 0.75" dia
Lport = 1"

Fold into an inverted 'U', which puts the driver up near the top and the vent down near the bottom and since this is a max flat alignment you may want to try longer vents to roll it off if too 'boomy'. That or use more damping. Sim is minimally damped.

GM

[mondogenerator]

thanks GM, thats quite compact, i am, to be honest, surprised. theres only one thing that would concern me a little, the vent area. assuming i can up the vent area and length appropriately and in a similar way to reflex ports, then perhaps ill up the vent area a little.

cheers for the input, i think this project may definitely be worth persueing

[GM]

You're welcome!

With a 30 W rating and TL vent loading, the vent doesn't have to be as big as in a simple reflex or ducted port. Regardless, at a glance it looks like there's not enough room to increase vent length much, so tuning any lower won't be an option if you start with a bigger/longer one. All you can do then is add stuffing which at some point may start 'muffling' the driver's HF output.

GM

[mondogenerator]

true enough. ive had these drivers running fairly loud sealed and vented, and they really probably cant tolerate much more than 10 watts in either alignment, and the mids suffer a little nasal sound when driven hard, so in all likelihood, and when i think about how im going to be using the speakers, the port area probably isnt a huge concern. bonus is i can use 1" timber for the panel and just drill the port with a ¾" spade bit.