Horn loaded double 15\" with a port

Felt like a bit of a play... i was thinking of something like this perhaps to cover 35 to 110hz. Posssible?

<A id=the ="return fitsIn;"> </A>

Interesting, and possible, like an Xtro kick section with a long port. Fitting in the right port length might pose to be a bit more difficult, but you can extend the back end so it is no longer flush with the 15"s.

I thought of a similar idea a while ago, it was like a Martin 215 with a big ramjet-style port poking through the middle.

have you dont any modeling, the cabinet will have to be quite deep over 800mm i would have thought

Heathy my friend, I used to doodle when I had an idea, but because I had no grounds for the design, I used to make the cab. Some were O.K. some got thrown away. What I'm saying is, the only way to find out whether these things work or not is to build them. The BS1200 started life with me doodling and then putting some sort of outside dimension on it. I had the build it though to find out whether it was a good one, or one for the skip.

HBL what sort of efficiency are you aiming for - I keep getting shocked by the plots of the BFM Omni 15 bottom end. Its basically a reflex box for a 15" where the driver fires through a letterbox slot into the horn and the rear chamber also ports into the horn.

Heres a build thread where someone has built just the bottom end to use as an enhanced reflex sub

billfitzmaurice.com/phpBB2/viewtopic.php?f=3&t=5931

Heres a plot of the bottom end



100dB at 40Hz up to about 104dB by 70Hz

Seeing that made me think about the Martin 215 - what about taking a design similar to that and porting it? Been done?

Stu

Stu, I never had much luck with later tryout designsregarding horns with ports. I don't think they work well with small compression chambers. The one that did work for me was the bass in the Q system, but the chamber was quite large. The old court/JBL cab seemed to work but again it has a large chamber. Just an observation.

Tony here you can see how BFM approaches the situation of putting reflex on steroids, driver slot loaded into a short flare which no doubt doesnt add much under 100Hz, but the flared port in the design is quite large as is the box from the looks of it.

Seem straightforward enough to you?

StuEdited by: Strapping Young Stu

Stu, I can understand that. My last efforts involved trying to get more out of the R2U system I did. That cab has a very small chamber and I was trying (as we do) to get a bit more, however I put the port in the front and the response took a dive because the port went totally out of phase with the horn. As I closed the port the bass response came back, so it stayed sealed. This is how most of my practical knowledge, such as it is, has been gained.

I wonder what sort of technologies are being employed here. Have you any idea what slot loading the woofer does when its into a short horn like that?

Does the loading DO anything do you think, would a driver with a round cutout do something different.... if so,,,, what?

Any thoughts, it looks like a nice idea to add a bit more gain to the bottom and probably roll off the higher frequencies at the top, but is the bass coming from the fact that the box is just quite large or the loading do you think?

Stu

I think it's a bit of a doodle myself. I've done it plenty of times, and a lot of times it works. If you have the facility to do quick mods, it's surprising what can be done. Don't forget, all the designs from the old days that we speak about and like were mainly done like this. It would be wrong for people on this or any other forum to think Martin Audio, Turbosound F1 and indeed ASS were ever conceived through a technical calculation on a PC program. This is why old school geezers like me have a problem with people useing printed responce charts to choose a speaker.