Car horn question

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I decided to put some of my holiday spare time to good usage.
I've been playing with Hornresp for a bit trying to simulate a decent horn for a hatchback car but don't seem to be have a huge amount of luck.

The attached pics are what I've come up with sofare. I had a look at other threads and kinda guessed the driver side of the specs (besides the cone area). To be honest I don't have the thiell-small specs for this 15 inch driver which makes it a little harder.

Firstly.... will it sound alright? (by usual car doof doof standards :xeye: )

second... can anyone see a way to improve the design?
 

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It's not a bad curve, as cabin gain will fill it in below 40 Hz. Howver, using a fifteen is absolutely unnecessary. Large drivers and small horn cabinets don't mix. Use no more than a ten. And where is your rear chamber? A rear chamber volume of zero is only seen with high frequency compression drivers, and even they have some rear chamber volume, if only a cc or two.
 
Horns with small mouths compared to the wavelengths they are going to reproduce will always have a rollercoaster frequency response or else they have way to much damping.
Yours is not the worst one, approximatly pluss minus 5dB from 40-100 Hz. Not unusual for subs at all, and like Bill said, you'll get some gain below 40.

But the good news is that I have tried a similar horn in cars, and if you have enough free air inside your car it will have an unbelievable impact. If you have <2 cubic meters of free air, you should concider building a rear chamber or a regular box instead.

Horns with no rear chamber (like yours at this stage) work best with a lot of free air around them:
If you have >3 cubic meters of non occupied air, this would be a nice project. You just have to be careful with your ears....doof doof....:D
 
fr0st said:
I had a look at other threads and kinda guessed the driver side of the specs (besides the cone area). To be honest I don't have the thiell-small specs for this 15 inch driver which makes it a little harder.

Doesn't all this guessing make the design or any comments on it a waste of time? Surely better to have all the required TS parameters before attempting to design a horn? Or am I just being a killjoy?
 
And where is your rear chamber? A rear chamber volume of zero is only seen with high frequency compression drivers, and even they have some rear chamber volume, if only a cc or two.

I read in another thread that having it at zero means your only rear loading the driver which I did to save space and the response curve was better.

Horns with no rear chamber (like yours at this stage) work best with a lot of free air around them:
If you have >3 cubic meters of non occupied air, this would be a nice project. You just have to be careful with your ears....doof doof....

By 'free air' are you refering to the the boot (which is only seperated from the cabin through a carpet/cardboard parcel shelf) or the entire car?

Doesn't all this guessing make the design or any comments on it a waste of time? Surely better to have all the required TS parameters before attempting to design a horn? Or am I just being a killjoy?

Your half right. Although I am missing a large chunk of driver specs, I tested with different dirver specs and the varience was not overly huge. At worst the dips in the response curve went down to 100db but the peaks stayed as is. I assume alot of the charactoristics of a horn speaker are from the horn and not the driver.... but I could be very wrong.

If it sounds terrible I'll just tear out the middle and make the box *gasp* normal :D
 
By free air I'm referring to non occupied air in the space where the side of the driver which is not loaded by the horn is facing.

If this side is in the boot, you can calculate the volume and subtract everything you put in there including the box;)

There is a lot of guessing when you do not know S&T parameters, but the ones you choosed are pretty typical for a car driver (not the real good ones) so I guess your sound will be quite similar to what you have calculated.

Good luck with your project, and please tell us how it sounded when you're finished...
 
Zero rear chamber volume is correct for a rear-loaded horn. And you're correct, with a horn 90% of the result is from the horn, 10% from the driver. But you're still not taking advantage of a horns potential with that big driver. This is what you can do with a 14x14x32 inch horn using an eight.
An externally hosted image should be here but it was not working when we last tested it.
 
Sorry, was there surpose to be a pic/link with your post bill?

I'm using the 15 purely because I have it sitting on my bedroom floor. How does the cone area actually influence the horns response?

My physics knowledge behind this kind of thing is not very good :cannotbe:
 
A bit of both, but most of what I've picked up over the last ten years has been self-acquired through building a lot of horns, on average six a year. Most of the major research on horns ended rather abruptly in the mid 1970s, when ported boxes designed with T/S theory and driven by high power solid state amps took over the market. Those of us who've wanted to go beyond 1970's horn technology have pretty much had to find our own way.
 
Bill's designs are available on the internet, for a small price, but people report very good results. His first bass horn plan that he offered commercially has been gaining lots of attention, by fans and skeptics alike. But having heard one myself, I would say it does what it is designed to do, quite well. Part of the animosity towards the Tuba 24 horn is because the pro sound elite (with $1,000,000 rigs) feel affronted that people would try and seriously discuss the Tuba 24 as a professional subwoofer, even though it handily outpaces a single-18" subwoofer without being appreciably bigger. People don't want to take it seriously because Bill focuses on designs for the smaller market, but the designs are very serious in what they are capable of.
 
Well, it's not as agressive as some of the names that have been coming out, like "Punisher" (uses Ciare 12.00SW, huge output to 50 Hz but not much deep bass), "Crusher" (my own design, HL-10A driver horn loaded to 40 Hz when used 4 per side), etc., but Tuba really does reflect the curved nature of the horn folding in the Tuba 24, 30, 36, Autotuba, etc. and when you get right down to it, just because I call my design "Crusher" doesn't mean it will "crush" you any more than if I had just called it something boring, like BH-10, or something like that.
 
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