Horn/TL combo

[Ed LaFontaine]

You may display more response detail in the Frequency graph. To do this reset the range of the graph. Clicking on it will allow you to enter different values where you have 110 & 60 now. I suggest 105 & 75 for 3 dB gradations or 104 & 84 for 2 dB gradations.

Varying Zdriver may have an effect upon the response ripple around 500 Hz.

You may consider a slot port as an alternate to an 8" diameter round port. Your locating the port close to the floor is favorable IMHO. I plan to investigate the use of an oversize slot port and stuff it lightly for tuning purposes. YMMV

[buzzforb]

Thanks for the comments. I am clearly new to the program. Is i tpossible to model a slot or do you just figure volume of the port. WinIsd lets you use double ports. With this, i was just playing with total vloume of the port. Next time i will post the impedance plot sas well to discuss what they mean an dhow they should look.

Your port idea is basically similar to aperiodic loading, correct. ZM posted a TQWT with large volume slot earlier.

[Ed LaFontaine]

I think it depends on your software. It appears you are using an older version of worksheet. Martin now provides worksheets which are based upon the volume components, Area & length.

[buzzforb]

I have his newest sheets. In the MLTL worksheet, it only has an option for port radius and length. Further down, you can fine tune the box parameters for in room response, but none of the changes made there affect the upper response graphs which I showed. I assumed that this was to mean that if you wanted other shapes, you would have to just figure volume.

[GM]

Originally Posted by Ed LaFontaine

Varying Zdriver may have an effect upon the response ripple around 500 Hz.

You may consider a slot port as an alternate to an 8" diameter round port. Your locating the port close to the floor is favorable IMHO. I plan to investigate the use of an oversize slot port and stuff it lightly for tuning purposes. YMMV

Right on. MJK's math dictates a L*0.349 location, which only considers length while mine factors in CSA, so varies depending on the aspect ratio and since this cab doesn't have a very high one, it calculates L*0.487, even lower down than a golden ratio's L*0.46233, so no significant 1/4 WL vent loading unless the driver, vent is at the extreme ends. Plus, there’s the room’s vertical modes to consider WRT driver location.

Hmm, I figured a slot vent was planned since a 4" radius vent was located 2" off the bottom.

Coming from a 'critically' damped reflex vent oriented time, all my large vent alignments have/had them, so still recommend them when appropriate, though most folks want to take the extra time/effort required to tune a duct when they can temporarily slide in different length tubes to find the best overall vent length.

For sure, if a maximally flat alignment such as this one is used in a wall or corner loaded app it will tend to sound a bit 'boomy' [AKA 'west coast sound'] typical of many old Altec, JBL consumer products once BSC is dialed in.

GM

[buzzforb]

I was just playing with the program. Next try will be 15ft^3, that 24x32x37, with driver 1/3 way down. I'll also play with mankinf port longer and see how the affects tuning. If there is a way to use square port, I would love to know.

[Zen Mod]

..... not bad at all

[buzzforb]

Couple of questions.

How important is consistency of wavelets(?) of the first two impedance graphs?

How do you determine port tuning? I have been using WinIsd. I dont know how to model aperiodic tuning.

Here is try using better box ratio. Cant figure out why acoustic impedances are so ugly and why there is nasty port phase issue

[Zen Mod]

let GM say last word here

I'm sort of short in time today , besides fact that I have no clue , comparing to him

observe difference in length of your TL and mine

your's is too short

[buzzforb]

The length is indeed major differennce, but if i have read right. The porit acts as a sort of inductive loading, lengthening what would be a shorter pipe, making it similar to tapered down pipe. I assume you would just fold you tl in half, correct.