checking horn measurments are correct

Hi kieran the throat chamber size is (vf=80cm3) 80cm3 so far i have not found how to sim a phase plug, But i think if i work out what the throat chamber size would be after phase plug is fitted this would give me a lower (vf) and model the horn on this..... did you take a look at the link bitzo posted on phase plugs its a very good read. There are 3 types of horn you can design in akabak a , radial, conicle, and exponential. you can sim a square or round throat and exit throat etc. The sim for changing the shape of the horn is (Rw=20.7cm Wc=19.8cm Rh=20.7cm Hc=20.1cm) see pic below.



So far i think akabak is a fantastic programe, and not as complicated as its made out to be ill have to write up a beginners guide to get you guys started.

regards

Ben

ok, it's starting to make sense now. Is dth the throat diameter? This would give a round throat of around 95cm2? Akabak is certainly looking more exotic than hornresp, though I'm not convinced I have the patience for this- I would have had the saw out by now, maybe that's where I'm going wrong. Please continue your designing though, you may well convince me yet!

I've been returning to Graeme's excellent website for years now. It's the only useful info on phase plugs that I've ever seen on the web. I also like his approach of looking at the theory, thinking about it and then experimenting with bits of wood, I think this is the only way to do it considering the lack of info available to us diyers. It seems the only people with the equipment and time to do serious research these days are the manufacturers, and they are not likely to give their knowledge away. This is in danger of turning into a rant, so I'll stop now smiley1

lol to you rant, well who knows we could spur on a hole new movement in phase plugs...... yes dth is the diameter of the throat in this case it is 11cm in diameter this would work out to be 34.5cm in circumference. In the advanced section of this site i have started writing a beginers guide to akabak were i am using the mt121 as a guide hopefully i can convince you to have a go......... trust me akabak is not hard at all to use, and very easy to adjust your designs with very quick results.

ok im happy with my design now so im going to start choping up some wood this week hopefully....... as for phase plugs im still looking into it, but i still need to do a bit more research...... then once the horn is made ill move on to it.

I have been reading this tread with interest, having made many different shape horns and a few "phase plugs", albeit, without the aid of a computer. You may not find these particular thoughts in the program, but the logic seemed to work for me.
I was always aware that the clearest sound from a cone will produced when the cone moves in a linear way. objects in front of a speaker will affect this movement. When I did the MX range of mid horns, my starting point was consideration for the loading of the cone. I took the piston diameter of the cone and worked out the area. The end result is that the phase plug area that the speaker sees is equal to the area on the other side of the gap, therefor rendering equal pressure on the cone. On the outside of the gap is a phase ring ( my own term ) made to follow the cone shape. I am sure that this method of speaker loading has helped in creating an efficient box. Unless you know something different.

If i understand right then tony see pic below



if a = phase plug and is 2inches in diameter
then b = 1inch in from edge of speaker.....

creating the same pressure in the center as the edge of the speaker

Bee, The idea is right, I have always taken the piston diameter as the diameter across the speaker ending at the start of the suspension.
I have forgotten why I chose the gap, which, I believe is 18mm, it could be the way the figures worked out when I calculated the 2 areas. I still can't think of a more logical way to load the cone. This is one of the things that stopped me trying to improve the MX600, apart from making everything larger, and risking losing some high end out of the 12's.
One more thing, just to make everything clear. It is not linear measurements, it is the area the of the phase plug equaling the area of the balance after the gap. Hope that's clear. T.

The Oracle speaks!
and we have to interpret his tips. Long is the path to the forces.... ok stop joking smiley1

To me Master Tony means that the plug area is equal to the "donut" area.
so taking the same bee variable
plug area= (a/2)^2*pi=donut area
phasing ring area=(6"/2)^2*pi-2*plug area
phasing ring internal radius= sqrt((2*plug area)/pi)

I love this forum smiley20

thank you tony for your imput, and yes i love it to bitzo

Here's my take on what Tony's suggesting.

This example is for an 8" driver.

Cone diameter 17.5cm
Sd 240cm2
Target throat area 100cm2

You need to cover up 240-100= 140cm2 of driver, therefore plug and baffle will cover 70cm2 each.

Plug radius is sqrt(70/pi)=4.7cm

baffle cut out radius is found by adding the plug area 70cm2, and doughnut or open ring bit 100cm2 then using sqrt(170/pi)=7.4cm

This gives a gap of 7.4-4.7=2.7cm

Does that make sense?


Kieran