Ive been going on about an idea of mine for ages in a load of threads, and im going to give it a shot to pull it all together and see if i can get some help from u good folks.

basicly want to build a 3 way cab that runs loud down to 100hz, or a little lower if need be, built round the TMS mid horn, but hopefuly leaving the originals for dead. (yea i know, im not half optemistic am i). as i have said before, this will be in the public domain and id love it if this could become a sucess of the forum, much in the was the lab horn has been. designing these succesfully by myself i believe is beyond me unfortunatly.

heres the deal. im thinking to remold the back of the tms phaseplug and slot an 18sound driver in there, which looks like it should be the bollox, and pump out a LOT of sound. so i need some kicks to keep up which is the missing link in many diy plans i think, but i want em to be straight horn loaded (straightish), and play down low enough for peeps to be able to use their sub of choice. the driver i have chosen is the PD 12SB30. i know it sounds like a strange choice given it should be a sub driver, but the xmas and mass corners are perfect, not to mention a nice bl. it sims well, better than many other 12 inchers i ran.

ok ill stick some pics below, and hopefuly they will be clear.

the ATC will be octagonal, as will be the S1. the S2 however wiil be rectangular, so as you can imagine i have some serous work to do calculating all the angles of the things given that the octagonal S1 and the rectangular S2 will be at arround a 45 degree angle.

the phase plug in the front chamber will be a simple cone, although i need some serous advice on how to do this. im thinking ill never ger a BPH to sound good in the upper ranges unless i have some kind of pathlength correction, especialy given the small S1, in comparison to the ATC. that advice would you give about this, i imadine i should make the expansion between the wlls of the front chamber and the phase plug constant. it will be conical, exponencial will be just to hard to make....

im also realy worried about the reflex ellement. its needed to make this thing work to spec without becoming a monster. ive herd bad things though, and no one else has done this realy since altec, and they wernt using a bandpass chamber on their horn

anyway thats more or less it to get the ball rolling. tell me what you think?


Edit: spelling (i wont try and cover that up ), but more so i think the pics havnt loaded what should i do? is there a limit to attatchments? there are 4 or 5 of them. some hornresp data and a badly out of scale microsoft paint sketchup... ill tyu upload agian in this edid, hist with the sketcup and the hornresp input. Ok actualy i just realised i need to hit the insert button (from here to the world)

ok help with pictures please... good start yea...

i would start with the kick section first, desiging it around the footprint size of the finished cab.....

Sounds a bit like Cubo Kick (been working on it (well, them) for more then a year now). Octagonal throat, octagonal/ square horn mouth, straight horn, reflex assisted, usable from 80Hz up to 250 - 300 Hz.

Cubo K15 (5th prototype now, including octagonal phase plug), Cubo K12 (4th prototype), Cubo Double K (started yesterday).

One piece of advise, expect a few dB deviation or easily 20 Hz shift in response if soley relying on Hornresp.

If you need any help, let me know.

Best regards

Cubo

Excelent. theres the pics o wanted to add in the OP. the sims are not the best ones, i can tweek em much better, in particular with the phase, although i always run into a small xmas problem just above the port frequency.
its not a big deal though and a bit of dynamic eq would eliminate it completly (+ i have been told that hornresp goes over the top a bit with the predictions for excursion so i think it should run at rated power even with no eq and not have any fatal problems, coil would be slightly out of gap without processing thouh, for sure)

it reason ive not realy gotten into tweaking the design to perfection yet is i still dont know if these different elements can work together and sound ok. i know that theres a lot that a hornresp sim cant tell me. i know someone is going to say it looks like a martin philishave with ports, but that realy wasnt my intention, i just cant keep it short enough if i make the horns totaly straight, and also i think i will be able to use the space arround the horn as a chamber better this way. having the drivers straight would make the thing taller, deeper, and generaly make the volume of air in there huge, creating the neeed for a partition (ie; wasted space)

@bee. thats what im doing. i agree its the most logical way to do it. when i said i was designing arround a tms mid horn i meant in terms of the output and bandpass. the depth limit for the cab is roughly the same as a cubo 18, perhaps a little deeper, but for sure to be able to have the center of gravity well over the sub. i also want to limit the width to about 600mm. the picture above makes it look like i want to build it like one horn fed from 2 chambers/drivers. i think this would complicate things a little in an unnecissary way and the partition down the center between the 2 chambers would be much longer in reality. perhaps a little like the USB.

@ Walt. wow thats great to hear ur doing something similar. it makes me much more confident im not just working on something stupid which would never work. when i started thinking about this a few months ago i thought of PMing u as i remembered you had told me u were building a top for the cubo, and was intrested to hear how u would do it, interesting to hear we have come to similar conclusions. for me its the only way to go unless its folded or just huge. what do you mean with hornresp. should i expect more/less SPL, a les flat responce, different frequency responce? im also particularily worried now about the phase responce, cos its already on the edge of unacceptable. what can i do to help flatten it out?

thanks for the intrest guys

cheers
dave

its interesting to see both you and cubo are working on this type of design, as i allso have been working on a production cab very like the one you are trying to design. Currently the cab is in advanced testing, and the plotts taken by an independent company look very good.... ill try and get a few sneak peak photos up in the next few weeks, for a bit of inspiration.....

Ill try and help were i can, but cant give specifics out about the current design at the mo.....

This cab will be apart of the new Ligwa dance stack.......

i just posted a longish reply and id didnt load, so ill just give a quick summery.

its great to see we have all come to the same plan, to overcome the same obstacle i imagine. this gives little old amature me a lot of confidence.

i understand there is only so much that u guys can share with this, especialy you be with the ligwa thing, but its good to hear that there is already a prototype working. i was realy doubting my idea with this, but now im full of self confidence.

what i would like to know is if u guys recomend i sim in akabak as well, and where do i get it?

also where can i get a free 3d design program cos it will me hard work doing the plan with good old pen and paper.

id love to see some picks bee, if u can.

there was a little more ranting in the original post i lost but ive got to get to bed, so thats all i can write now

cheers guys
dave

google sketch is a free app to use for 3d drawings..... as for an akabak scripts, there is no data base of designs to work from, its a case of starting from scratch...... to get you going you could all ways do the basic design in hornsresp, then export it into akabak, then start adding things to it, like driver angle, etc.....

ok thanks ill have a look over the weekend.

oh by th way mr cubo, ive just realised i think ive got ur name mixed up there. sorry bout that. im shite at names realy

cheers
dave