View Full Version : Front horn build log, 3 DD1508

02-14-2007, 07:20 AM
I've wanted to make a bass horn for some time and now I'll finally get around to doing it.

This will be a modular build since my car has a tiny boot opening and the completed horn has no chance of fitting in one peice, the modular construction also allows me to expriment with the throat geometry to achieve the best performance.

This is the opening in the front of the boot where the mouth of the horn will be situated with the intial peices of mdf temporally held in place;


The yellow crap everywhere is contact adhesive from the soundproofing and carpet of a previous install.

This is the view from the boot opening;


Once I get the angle right I take it inside and add some more peices;




The basic shape is coming together, now we use some lycra (stretches in both directions) to form the rest of the mouth shape;



I used some flat cotton cord to pull the lycra into a more suitable shape.




More pics to follow over the weekend as I resin and apply glass to the mouth.

02-14-2007, 07:25 AM
lookin good man, will definately check back

02-14-2007, 08:08 AM
very intrested>>>>>>>>.

02-14-2007, 08:13 AM

02-14-2007, 08:17 AM
looks pretty good.
i was planing to do a similar build. with the port in fiberglass as well as other parts of the enclosure but the lack of trunk space made me change the idea.
got a design drawing of how its going to look at the end?
keep up the good work. and the pics coming.

02-14-2007, 08:25 AM
sick build man

02-14-2007, 08:51 AM
looks pretty good.
i was planing to do a similar build. with the port in fiberglass as well as other parts of the enclosure but the lack of trunk space made me change the idea.
got a design drawing of how its going to look at the end?
keep up the good work. and the pics coming.

The design is pretty much in my head at this stage and isn't even finalized yet (That will happen when I get the DD8''s in about a week or so, run tests on them and run the final horn sims) the mouth is pretty safe to build beforehand since it's mostly size limited (ie the biggest mouth I can fit in) and the exponential flare won't change, it's the throat length and cross sectional area that will determine the end response.

The horn will end up taking up most of the space in the boot though, I'd have to remove the throat section to access the spare (though I've never needed to in 12+ years so far...)

Here's some crappy ms paints of the provisional design concept;


The different colours repesent the different modular sections, the throat may also need to be folded back on to it's self if the extra length is needed.

This is how I intend to mount the drivers on the throat;


The subs will most likley not need rear chambers (though they will get them if that is required), the boot will be well sealed off from the cabin space so the back wave of the drivers can't interfere with the horn output.

02-14-2007, 09:12 AM

02-14-2007, 10:49 AM
Looks pretty good so far. Hopefully you won't have any issues with firing the mouth straight into the cabin. With the horn I built, firing it forward gave me no output at all. It sounded the exact same with the RCAs disconnected when firing forward. This was in a hatch so it was completely different though.

Good luck with the build!

02-14-2007, 10:52 AM
subscribed. pics of the subs!

02-14-2007, 11:04 AM
I laid in bed this morning with ideas of a horn in my head and then see this post. Spooky...

02-17-2007, 03:47 AM
Well poor weather and my slightly stale resin have conspired to slow my progress somewhat, the resin has finally (mostly) cured on the stretched material, and here it is having a test fitting in the car to make sure the frame hasn't warped (it hasn't), now to start some glassin.



02-17-2007, 04:24 AM
that is looking good.
i cant wait to see how this turns out.


02-17-2007, 05:11 AM
1st couple of layers down on the large section, air bubbles rolled out.




02-17-2007, 05:34 AM
i wish i could build one of those, for one solo 8" .......

02-17-2007, 06:12 AM
i wish i could build one of those, for one solo 8" .......

Have patience young padawan...;)

02-17-2007, 07:03 AM
yes master

02-17-2007, 08:47 PM
Thats freaking sweet.

02-17-2007, 11:04 PM
more glassing;



02-18-2007, 04:59 AM
none of your damm pics work

02-18-2007, 06:19 AM
none of your damm pics work

My image host is working fine, there must be a truck stuck in a tube somewhere on the intarwebs...

02-18-2007, 11:46 AM
They're working now.

02-18-2007, 11:51 AM
crazy looking box, but i like it

02-19-2007, 08:45 AM
More glass on the backside;


This cavity;


which extends around the mouth like so;


I'll fill with something, haven't quite decided yet what that will be.

This is starting to become quite strong now, I'm not sure how many layers of glass I've put down. I tend to mix up a batch of resin and continue to roll glass on untill the resin runs out:D

02-19-2007, 10:11 AM
will that car have a back seat? nice work

02-19-2007, 10:32 AM
so someone school me on the pros/cons of a horn versus a traditional ported enclosure?

02-19-2007, 10:53 AM
fill the cavity with expanding foam. strangest / trickyest box build ive ever seen in a car, x 2 on horns work best backwards.

pwnt by pat
02-19-2007, 10:54 AM
This is going to be very cool, but I'm just curious as to why you didn't build a "window" for the back of the mouth and pull the fabric from the boot straight to the window. It would have aleviated you of the empty space you have now and make a smoother transition from throat to mouth.

02-20-2007, 09:50 PM
any updates?

02-20-2007, 09:56 PM

02-20-2007, 11:37 PM
so someone school me on the pros/cons of a horn versus a traditional ported enclosure?

Well they are more efficient than ported boxes, can have a larger passband, usually better transient response, but require much more space, they're usually a more complicated design/build, need something to load off of, and can be very very picky about vehicle choice and placement. If you don't have everything right, they can sound terrible in a car.

02-20-2007, 11:41 PM
sounds pretty tricky

02-21-2007, 03:57 AM
Here's some graphs to demonstrate horns v vented;

Three 8'' subs (old school JL 8'' in this case, since I don't have the DD's yet) in a 1.6cuft SQ enclosure tuned to 35hz, these graphs are generated by the same software I use for the horn design;(edit, the dotted blue line is a reference response, the drivers in infinite baffle)


The same drivers in a 2.5cuft 55hz tune SPL fart box;


The same drivers in a 160'' long exponential flare horn with a 1780 square inch mouth (cross sectional area of the car it's self, since it becomes the final mouth of the horn);


note, the graphs use an input voltage of 2.83v which in this case works out to just over 7w of power. Also these are raw plots with no cabin gain ect added.

Death By Bass
02-21-2007, 04:13 AM
forward firing horns never work.

especially not in a sedan.

unfortunatly, I guess you're going to find this out yourself, after all this work.

Immacomputer made a folded horn for a 6.5inch woofer that I designed.

forward firing in a hatch/coupe kinda vehicle, it did ZERO output:


02-21-2007, 06:31 AM

02-26-2007, 09:19 PM
Update time,I've made up the flanges that will join the mouth to the first throat section. These will be bolted together and due to the shape of the mouth some of the bolts need to be permanently attached (captive bolts) to avhieve this I've braized peices of backstrap to the heads of the bolts, like so;


I can then screw the bolts onto the flange before it is resined into place;


Here is the flange secured to the mouth and the matching flange for the first throat section;


just a shot test fitting the two flanges;


Top and bottom of the throat section cut out;


stay tuned...

02-26-2007, 09:43 PM
you cant stop i know cos your addicted and want dat bass like the rest of us, but its not gonna work.go ahead and finish it,life is about the journy enjoy the build, the glass itch, the sealing, the adjusting gains and x over points, checking the wires, looking for leaks laying in bed searchin searching searching for the reason the reason........................... its built perfect but there is NO ****ING BASS.

we all support your mission but some of us already know the result.

how are we so ****ing sure?

thats right,

we did it all before you.............................just like your doing it, hours and hours of work and all that money wasted.

$30 sais a small sealed box will actually have more output and beter sq than that horn in that particular application :(

02-27-2007, 03:08 AM
:( **** that *****.

but keep up the good work:)

02-27-2007, 08:22 AM
:( **** that *****.

but keep up the good work:)

Thanks for the support, I see a lot of "OMG a front firing horn will never work!" but I've seen precious little "I don't think you will get good results with your setup because of X,Y,Z reasons". I didn't just wash in with the latest forum boner, the design and implementation of this horn takes full advantage of the loading available in the car (despite the "forward firing"), I think the naysayers need to just sit down and enjoy the ride.

More pics;

The S-bend in all it's glory, if it doesn't work as a horn I can always use it as a dunny:naughty:


There's a good reason for the extended peices of wood, that will become apparent later.






02-27-2007, 09:55 AM
**** that actually looks really good good job

02-27-2007, 10:28 AM
wow you are a enclosure master. that box will work for sure, its perfect. keep up the good work.

i predict the end result to be a underdawg victory.

02-27-2007, 11:14 AM
I love the way that hardwood looks with resin on it. The build looks pretty good so far; I hope it sounds just as nice!

Oh, and for us ignorant americans, what's a dunny? Toilet?

02-27-2007, 01:11 PM
Oh, and for us ignorant americans, what's a dunny? Toilet?


02-27-2007, 02:56 PM


Death By Bass
02-27-2007, 03:05 PM
for interests sake, this weekend, I might chuck my 8inch horn in my parents car, fire it through the ski hole thingo, and seal around the opening...

see how that goes, but, I'm not expecting much from it at all, especially not in that config, but we shall see...

02-27-2007, 06:01 PM
Looks good. :thumbsup:
I hope it puts out good results for ya!

Keep them updates coming!

02-27-2007, 06:51 PM
i like how is coming out.
keep up the hard work. and i hope it works as expected if not better. keep us updated.