JF Vented Horn

Prototype:







I gave it a quick raz lastnight and it seemed pretty good (only 200w into it) im gonna work out the tuning tommorrow and get a mate round with a better amp so i can really try it out.

The port might be too small but the only way to find out is to test it.

Should be flat from 45/50 - 120/130, then EQ'd up from 38ish. They're cheap drivers but should be able to handle 600/700w in this cab...

I'll do an impeadence plot tonight and post it up here, then fine tune the port size. Then laterif i can get a dB meter i can attempt a freq/resp graph.

Heres the full thread i made when designing it on SP if anyones interested... the design has changed a bit since then tho... JF Vented Horn (P-audio E18-600a)

Looks interesting, more plots yes please!

Predicted impedance:



This is the impedance plot i have just taken....

Theres a few weird bits that i dont understand:


That dip @ 46 seems wrong, but i measured it several times and my multimeter is definatly good, so i dont know what the problem is...?

Also the wave generator i used only goes down to 30Hz so i couldnt do lower. I'll do a better one when i have time.....

gotta go..Edited by: Jake_Fielder

It could be 2 peaks close to each other, but I agree it looks strange Could you up the resolution and take more readings from 40-55 Hz?

Can you post a simulated impedance plot from Hornrespo? Very useful to compare the two.

I just put the predicted one up. Basically they are very similiar, theres just two dodgy readings though @ 48Hz and 50Hz.
I hacked a small bit off the port after seeing the impedance plotto raise the tuning slightly, so i'll have totakeanotherplot anyway...

I dont know whats causing that dip though, the top and bottom of the cab havent been glued on yet and there is no bracing inside either, (i'll glue it all together once i know i have the tuning right!) would the resonance of a panel flapping effect the graph? bearing in mind i didnt notice that the panels were lose and ididnthave it up loud at all, i could only just hear it.

You do need to measure down to 10Hz really to get the full picture. I used the oscillator built into WinISD, that'll do 10Hz.

Jake, you want to measure your cabs with this free fancy bit of software:
www.fesb.hr/~mateljan/arta/

chaudio wrote: You do need to measure down to 10Hz really to get the full picture. I used the oscillator built into WinISD, that'll do 10Hz.

Ah, i wasnt aware that there was one! I intended to measure lower but didnt realise until last night that the program i was going to use went down to 30Hz.

Im going to do another one tonight, do you have any idea about the dip in the middle of the peak? im sure it isnt right. I think it was something to do with the kit i was using or something i was doing wrong...?

What version of winisd has it? i cant remember if i have alpha or beta? i remember uninstalling one versionso that I coulduse a different one which had more drivers already programmed into it.

Deadbeat wrote: Jake, you want to measure your cabs with this free fancy bit of software:
www.fesb.hr/~mateljan/arta/

Cheers, im going to check it out when i get home.
Unfortunatly i managed to squish my memory stick last night that has all my speaker programs and files on , so i cant download at work anymore.