First floor-standing 3-way considerations

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
frugal-phile™
Joined 2001
Paid Member
Is there a popular MLTL sim I can try out and tinker with? Something like WinISD, or HornResp perhaps?

HornResp works, Leonard Software’s TL modeler is good (there is a thread here), but unfortunately a bit in limbo right now, Martin King’s sw is no longer readily available, Augpurger’s costs money and has not been updated for almost 2 decades so not up to date.

dave
 
frugal-phile™
Joined 2001
Paid Member
So, with my newfound knowledge of MLTL physics, I'm getting nervous that another build I've lazily been building won't sound like I modeled it up.

That looks to be dimensions such that it could well be in the transition zone… not quite either a BR or a TL. Actually measuring the bass response when built (not completely straight forward) and adjusting the vent size would be the way forward. Since it is a slot vent, and if it needs adjustment it is likely a lower tuning would be required, a vent spacer to decrease the vent area can be done (we have done that in a couple boxes when we repurposed a box for a different driver — the pictured box started out with 3 vents per side (original box is the 1st one in this thread miniOnken/Fonken gallery pictures only)). The quick bandaid would be to stuff the vent pushing it towards aperiodic.

Fir-Mar-Kel70wT.jpg


dave
 
Just wondering.... would it be easier to design my own 'regular' TL? I'd looked into them a while ago and ran across a video where a guy explains them very simply, and effectively here. That doesn't seem to be nearly as difficult as MLTL. Checking around a little bit, the only major difference I've been able to spot is that a TL may be just a little bit bigger than a MLTL. Thoughts?
 
MDF turns into a wet cracker when too much humidity, so for outdoor use I'd go with marine plywood (with great bracing) or solid 3/4 inch oak (I've had great luck with oak) (also well braced). Transmission lines are way too heavy. Ported boxes seem to be the way pro level speakers get max efficiency for low bass out doors. Without nearby walls, outdoors, low bass will be much weaker than the same speakers indoors, so go bigger on the woofers; I'd go with 12 inch.

Personally I'd bi-amp between the woofer(s) and midrange drivers, and use active EQ to pump up the bass under 100HZ, making it acoustically somewhat flat down to 30HZ, and use a sealed cabinet (better woofer cone damping). Tweeters really need to be at least 36 inches off the ground, no matter what else that means. I've done the research on that. Making a speaker more directional makes good sense for outdoor use for the sake of efficiency, depending on a bunch of variables, but not if people at your out door party will be wandering around somewhat randomly. Let me know if you need a good circuit for an active crossover or low bass active EQ.
 
The Econowave woofer can use tall MLTL to lower bass reflex -F3 about 10% , standard bass reflex, or sealed box in future 3-way.

Hoffman's Iron Law Example: Three 12" woofers with different efficiency, -F3, and ported box volume. WinISD plots attached.

-3db @32hz 90db/w 3cuft Dayton DS315-8 $75
-3db @34Hz 94db/w 4cuft Eminence Kappalite 3012LF-8 $ 185
-3db @40Hz 96db/w 5cuft Eminence DeltaLite II 2512 $125 (-3db @36Hz in a tall MLTL box)

==Positive reviews== $240 + $45 passive crossover + free shipping.
Eminence Deltalite II 2512 Neo 12" Speaker Driver
|Model: Deltalite II 2512 |Part # 290-593 |$125

PRV Audio WG35-25-B 1" 90 x 60 ABS Waveguide 2-Bolt
|Model: WG35-25-B |Part # 294-2892 $9.88

B&C DE250-8 1" Polyimide Horn Driver 8 Ohm 2/3-Bolt
|Model: DE250-8|Part # 294-605 |$103

=======SAVE $70 with lower cost CD====
Dayton Audio D250P-8 1" Polyimide Compression Horn Driver
|Model: D250P-8|Part # 270-402 |$35
 

Attachments

  • 3woofs.JPG
    3woofs.JPG
    276 KB · Views: 104
  • MLTL EconoWave.jpg
    MLTL EconoWave.jpg
    151.5 KB · Views: 103
Free MLTL design tools. A speaker with a Qts ~ 0.4 is usually suited for MLTL alignments

1) download Keith Webb spreadsheet. After you enter the driver T/S parameters, start with a MLTL which uses a SL/SO termination of about 0.1, such that the Area of the open end is a good port area. Now you can adjust SL/SO until you hit an acceptable port area, and an acceptable Actual length, and an acceptable Area of Closed end(the box internal width*depth area). A WinISD sim of a QBE (Quasi-butterforth) alignment will generate a minimum internal volume, and an EBS3 (Extended Bass Shelf -3db) alignment will produce a maximum box volume for most MLTL analysis work.

Transmission Line Theory

Alignment Tables Spreadsheet by Keith Webb (Excel 3/03/09)

2) Download Leonard Audio TL simulation tool. Leonard's website is dead, but a diy member has hosted a copy of the original software with Leonards approval. Start with the spreadsheet values, and adjust to get the best design. The Leondard Audio TL thread has excellent information, like starting with the speaker 20% down from the top often produces the maximum smooth-boost, and starting 32% down from the top can remove most resonances. This tool can be used with any box shape + stuffing + driver + port location to design-out undesired internal resonances.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.