tapped horn design

william cowan's research is very interesting, we are so very indebted to those who take their time to document this stuff for the good of fellow enthusiasts... what i don't get is why his 60 Hz horn gets worse as you move the driver up the horn? having read danley's white paper and looked at the other commercial tapped horns i thought that the driver in the mouth would not load the upper range of the horn's response, and was accordingly going to try a different position on the mkII giatt...

can anyone hint at what's going on here then? or do i need to make a series of boxes at the different "tappings" and try and measure them all?

james.

yeah i don't know why cowans results were bad for the driver being away from the mouth as this is apparently what the danley dts20/pb12 model is.

none of the diy attempts at a tapped horn other than mine have moved the tap away from the horn throat which i think is very important for good results. doing so moves the driver away from a velocity minimum and means you can keep the compression ratio and cabinet volume low at the same time. it will also reduce resonant modes as is done when offsetting drivers in a transmission line.

not too sure what varying the compression ratio from 1;1 will do but i think this must be the case in something like the TH215 or the horn wouldn't fit in the cabinet volume. i worked from the assumption that 1;1 compression would give the best bass response and least stress on the cone.

will post some measurements from my cabinet as soon as i have some. got some ideas about how the TH112 and outline boxes are folded so might be able to make something along those lines. not found a very suitable 12" driver yet though.

Phil

I may be completely off base, but I wonder if the classic scoop dip in response at ~100Hz has anything to do with the dip that can be seen inm William Cowan's results. I was thinking about it the other day and maybe a scoop could be considered as a tapped horn with driver located right at the start of the horn and the front of the driver firing into a very large last expansion (the room.) 

I may well be wrong because I haven't done much research on scoops (because the measurements and sound of most scoops I have seen/heard has been unpromising).

jethrocker wrote: odc04r, Moray James started discussion on this over in the scoop forum and we were wondering if the tap horn effect in a scoop might be enhanced by angling the baffle into horn mouth, this would also enlarge mouth area to the size of the front of the whole cab.

Haha! your ketching up with me

i have been working on a sub called "DUBSUB" (scoop) with a 12.75 ft around 3.65 metre horn and is the cats wisker's and scare's the life out of me

Edited by mykey - 02 February 2007 at 9:27am

ok ! but not an internal one

Edited by mykey - 02 February 2007 at 9:07am