EAW BH760

2625 (cm^2) = 28"*15"*2.5*2.5...ie half the enclosure. I was assuming a symmetry between the two and that although it would have an effect on the low end response it wouldn't be ridiculously drastic.

The numbers you put in ARE areas, cm^2 right, like it says in all the instructions?

Also, if one is building horns like this that are expanding linearly, rather than conically, what is the protocol?

I get the impression that it is meant to be 107dB right down to 29Hz (-3dB) from the EAW website. I was getting it down to about 85dB at 30Hz

mxlemming wrote: Hi, First post on the forum. My name's Dave, a third year mechanical engineering student at uni. I like speakers, a lot, and do a lot of techying and rigging for gigs at uni, but have never done any audio engineering stuff except what I have learnt perusing forums... It's kind of become an obsession. I'm playing about with Hornresp, learning how it works etc, with the aim of spending a few weeks this summer building myself a little PA, and perhaps, if I seem to get on with it, going into audio... It seems that modelling this cab in Hornresp doesn't work -  segment 2, the first section in front of the speaker which seems to basically be two paralell walls gets the Cir<1, invalid form. The output results are then clearly garbage. The idea was I'd try and model a few things that have been observed to work well, then when I seem to be able to create meaningful results fairly reliabley move onto designing my own stuff/playin about with AkAbak.... which currently seems inpenetrable. Basically: ciare 12sw params (seemed like a fairly likely choice and someone above said it would kill in this box... S1 = 360 s2 = 375 s3 = 400 s4 = 750 s5 = 2625 All set as con (but gave equally retarded results wen I set it as exp) Speaker set as offset. All of these are measured off the screen with a scaling ruler. for the EAW BH760. Where am I going wrong?

Ok, now i am at home so can explain a bit more.

S1 should be the cross section area of the baffle opening (how do you came up with a 360 figure?)
S2 should be the cross section area at the first 180 degrees bend That should be way more than 375)
S3 should be the cross sectional area at the second 180 degree bend
and
S4 should be the mouth area ( and that is around 4000cm2 mark IIRC)

That 29Hz figure is maybe achievable for BH760 but only in a big group of boxes (maybe 8) and again that will be at least 3-6 db lower than its sensitivity in the 40-90Hz region. But that is very usable amount anyway for any type of contemporary music material.

What we do not know here is:

Com4tee wrote: Hi There   The EAW box seems to be somewhat "generic". Presise measurements showed quite a lot of even or nearly even values like 1 meter, 20 sm, 15 cm... all to perfect for what's comming from phisycs modelling. Do they just experimented with a set of "shelves"?! Lets put 1,5 meter now and see if it works better approach?   PS.  TS parameters taken from http://www.madisound.com/catalog/product_info.php?products_id=8578

Yeah, you have basically redone what I did, more precisely - I didn't bother too much with correcting the angle, just measured it and made rough corrections based on experience of photoing stuff at wierd angles.

I also thought at the time hmmm.... not much effort has gone into this, all the dimensions seem to be 10, 20, round numbers, just a case of getting the longest posible horn into the smallest possible box, but hey, noone else seems to make them and by accounts they are fairly good?

I also got a similar plot for eigth space 0.5pi, but I was unimpressed with the half space - which I now realise is a kind of fundamental limitation of horns. Remember eigth space is similar to a large conical horn extension. This horn has a mouth far too small, redesign so the opening is on he largest face may help if your not going to stack loads of them.

I also used params for a Ciare SW12 following someone earlier in the thread, which apparently is invincible, and pretty cheap.

Frankly, you'll be more proud of yourself if you don't copy it and invent something of your own. I now have a sketchbook of ideas, and would be building if I could decide on which one I want.

BTW could anyone measure T/S of the 760 orginal driver? Just out of curiosity I would like to model it in hornresp and see what happens.

TDA-Audio - the box is 30" x 30" x 45" so the depth is 30". The rest you can see on the pictures. I have no other drawings, but this info is just enough to modell it  / redesign for avaliable drivers.