AkAbak for Dummies ;) - Page 2

This has been a HUGE help, just wondering if you did and advanced modeling thread somewhere or if its still in the works. I'm trying to figure out how to model impedance equalizers and other things

If there were a way to get this into the sim I'd be very interested to see how it effects it

Awesome thanks for the help. its all about the nodes I guess. I follow the chain but I'm still a little fuzzy about the renaming of the driver nodes [Node=1=0=100=101] I know you wrote they flow from left to right so 1=(+) 0=(-) so which would 100 and 101 be? does it go [Node=(+)=(-)=(-)=(+)] or [Node=(+)=(-)=(+)=(-)]

I cut it back to the basics [Req, Ce] on the imp.eq the thing would cost to much to put together, guessing that's why they aren't used in most designs

the basic imp.eq brings the peak @ 52Hz from 64ohms down to 51ohms and it doesn't cost that much

How would I go about modeling bracing in a TH? My best guess would be to to something similar to your explanation of a dual port box. But how to make them end up in the same area when numbering them differently? Am I trying to over complicate things maybe hahaha. I've successfully made a few great sounding small TH enclosures but it's time to step it up and I know bracing is a must!

Thanks!

Thanks soho54, that makes sense. I came up with another question. Tom Danley made a comment in a post about the added mass of folding


Is there a way to model this effect in Akabak?

Also might be cool to add a section for lining/stuffing sections using the "visc=#" (#=1-50) from what I've read. I'm still playing with it and no where no a pro

Awesome! Thank You for the link. Looks like I've got more reading to do I love this stuff

Great work there soho! It's a good resource for the diy community and great to see diyers helping each other out. I haven't had a chance to read through it all and give it a go, but learning this thing is on the to do list!

I've been side-tracked the last several months with work but I've got a new question I hope you can help me with. Akabak has a helmholtz calculator but how do I get it to run in the script? I'm working on reducing unwanted peaks in my TH designs

Thanks

Wondering if there is a way to sim something similar to the way DSL used Helmholtz resonators in the DTS-20 to tame the unwanted peaks

I'm trying to get the graph of a vented box to match from HR to Akabak.

Here's what I'm seeing:

HR exported Script shows the enclosure being modeled as a Duct, whose area*length is equal to the enclosure volume. This produces a frequency response graph pretty much identical to the actual HR plot. But when creating a nearly identical script from scratch and specifying the enclosure from Net->Acoustic menu, even though it has the proper volume, and length, generates a different frequency response plot.

here is a pic of akabak "generic" script vs HR vs akabak w/ HR exported script




soho54, if you would be so kind as to tell me what in the world is going on, I can resume being sane, as this tiny little thing is driving me nuts.


oops, here are the scripts

Generic script where enclosure is modeled as an enclosure from the Net->Acoustic Menu:


HR-type script (edited the original to simplify it) where the enclosure is modeled as a duct:



Does this mean that HR simulates the enclosure as a duct? one predicts a huge null in the response and the other predicts a huge spike, right after 100 Hz. Which one will reflect reality?

I see now. I think. According to HR, zero path length difference implies the port output is radiated from the same "spot" as the speaker, which is not possible, but works because its a close enough representation of a front-facing port, correct?

This is the main part that I'm just not sure of: in HR, if path length is indeed specified as zero, then the distance from the driver radiator to the LP is the same as the distance from the duct radiator to the LP, correct? (if correct, then that means that the duct radiator is on the same baffle/plane as the driver, correct?

if so how can your diagram (which is essentially the same as the HR schematic) be correct, where the duct radiator is (length of rear chamber+duct length) cm away from the driver radiator?

Ah I see. MUCH clearer now.

One last question. Is it possible to make the script that specifies an Enclosure (not double duct) to mirror the double duct plot?

Hi

just wondering if you could explain how radiation cones work specifically with regard to conical horns. a few things are puzzling me:

with a conical horn the manual says that because the radiation cone will have a constant convexity the sides of the horn are the same as the radiation cone. if I make the radiation cone smaller but keeps the same wall angle so it still follows the horn walls but only covers part way down from the throat this significantly improves the HF response without affecting the LF response. But if I make the whole horn smaller it does not improve the HF response. what is going on here?

If I have a horn that is made of two conical sections so that the flare angle is greater nearer the mouth how should I specify the radiation cone? I'm thinking I should specify it as the same shape as the section nearer the throat but does Akabak know to locate it in the first waveguide near the throat or will it put a small radiation cone in the middle of the wider section near the mouth? Does this matter? Or I can make it the shape of a cone that fits the section near the mouth but extrapolate the walls back into the horn to where their apex would be to get the radius? In this case does it make a difference if I use a horn section or waveguide+radiator?

I know it is possible to get decent HF response from a 1" driver on a conical horn because I have seen measurements of it. the only way I can get a decent sim from a 60 degree 40cm long conical is to specify the radiation cone as about 5cm long and 5cm high. as it is playing wavelengths down to about 1.5kHz which is roughly 22cm this doesn't seem right. the longer frequencies must experience the whole of the horn as a radiation cone - so shouldn't the size of the radiation cone be frequency dependent???

I'm a bit frustrated the manual doesn't have more examples of such a complicated subject - can you shed any light on this?

cheers
Phil