Megaton EM 15 Bass

I'm still new so dont hash me to bad but i was looking at the "usb /hd15/stipe es18bph" tryn to find a way to build a 15" version of the usb...i dont like any because of the following reasons:
1. dont like the bends on the hd15 and doesnt play well after 180hz.. from what i've read
2. usb is loaded with 18's
3. stipe also loaded with 18's

so after doing some reading on bandpass designs "such as those above" some say... i did some calculations and it apprears to me as the bandpass port doubles as the horn throat for the horn... "well makes since to me" so looked at the only 15" version i could find:

Megaton EM 15 Bass


since i have some evx-155 drivers laying around i plan to use those..
i figured the volume of the sealed chamber - estimated driver space,
i figured the volume of the front chamber + adding cone area,
then modeld as a 4th order bandpass --- turns out the horn throat area is exactly what is expected as the port

here are the results of winisd :


and the listed spl chart:


i am new at this so i tried to make pictures as good as possible for review

then i proceeded to model the horn of the box in hornsrep:


conclusion:
looks like the horn is only good for about 180 to 250hz
and the bandpass is tuned to 150hz in my winisd
i feel that this helps to smooth out the responce of the box overall

my goal is a dual 15" from 100hz up to about 250hz -although all the plans i've seen get funky at about 200.

i hope some find this post entertaining at least, any suggestions welcomed.Edited by: b52productions

try to sim a reverse mount of the driver.
sealed chamber volume + cone volume
front chamber - estimated driver space

Designs such as this have been around for years, popularised mostly by Turbo.
They are known as BPH as they are, you're right, a bit more bandpass than horn. That said all horns are bandpass devices to an extent.

A few clues:
1) Model with Hornresp or Akabak, normal lumped parameter modelling softs won't do.
2) These benefit a lot from large stacks due to end correction making the 'horn' seem longer
3) They have been done to death by many many manufacturers...that doesn't mean that they're effective.

You can see a popular example of a diy version here:
www.speakerplans.com/index.php?id=hd15horn

And Rog's thoughts on the old BPH (read this):
speakerplans.com/index.php?id=faq15

i assume that the hd15 doesnt play well over 180hz because its speaker is directly angled toward the back of the enclosure compared to the "usb or the em15" in which the driver arrangement is more in line to the horn throat.

the stipe18 has a reversed driver mounting which probably blocks reflections from the rear chamber and provide better bass.

has anyone heard this enclosure? em15bass

my last alternative would be the selenium 15" {hb1505d1} but thats alot of material
so incorporating that horn with fullrange speakers would be quiet large.

since we are comparing let me post the quater space from hornsrep.. that is what is posted of the hd15:
now that doesn't look so bad to me.Edited by: b52productions

b52productions wrote: i assume that the hd15 doesnt play well over 180hz because its speaker is directly angled toward the back of the enclosure compared to the "usb or the em15" in which the driver arrangement is more in line to the horn throat.
<div> </div>
<div>the stipe18 has a reversed driver mounting which probably blocks reflections from the rear chamber and provide better bass.</div>
<div> </div>
<div>has anyone heard this enclosure? em15bass </div>
<div> </div>
<div>my last alternative would be the selenium 15" {hb1505d1} but thats alot of material </div>
<div>so incorporating that horn with fullrange speakers would be quiet large.<FONT face=Arial size=6></div></font>

Hi,

Actually, which way round and where the driver is pointed is pretty irrelevant at these frequencies. The direction the driver faces will really only have an effect on volume in the front and rear chambers. A quick read of the diyaudio guide on hornresp will inform you on what the sizings of such chambers do. 'Reflections' really really won't occur.

An added bonus of the reverse driver mount is that you get air rushing round the magnet, cooling the driver more effectively.

Merry Xmas

Omar

good one..
thanks, you to.

just about done with new plans...one more question if you would lol.

when calculating volumes with the driver in reverse position .. that wouldnt change the volumes in WINISD would it? i mean inside the sealed box is still the rear chamber for this programs right? well i hope anyways. could make a big difrence in my design lol.

lookn alittle better :



thanks in advance.

Edited by: b52productions

Just wanted to say thanks for everones input.. i have finished my design and tested blasted the crap out of it to much apeal.. smiley20

just as a followup i wanted one more pic. and i am still very happy with the outcome smiley20



thanks again !!

So you have now the plan for Megaton EM15 bass???