Tapped Horn For Car

[MikeHunt79]

After reading "The Smallest Tapped Horn" thread, and also the thread on DIYMA, it does look like an impressive box, a lot of output for such a small box. I'm lucky enough to have 3x MCM 8" woofers, so I'm hoping this box will prove to be a better size for my car.

My problem is that my car's boot/trunk is very small, only 3 and a bit foot wide, and just over 1.5 foot deep. Here's a pic of my dual driver autotuba, the external dimensions being 32x14x17 inches, in my car, it's a tight squeeze....

The mouth is on the left, but I think that the sound is being restricted due to the mouth being too close to the side of the car...

I was hoping a smaller box would allow more room around the mouth of the horn, and allow a higher output. I still need to measure out a 2x2ft square in my boot/trunk however, in order to check it does not hit the rear window, as my car has a sloped rear window like this:


I was wondering if you tried different mouth directions with your Triple8 when in the car? I'm guessing it would be best with the mouth pointing towards the front of the car but would it also work firing to the side of the car like the Autotuba is in my car? Do you know if having the mouth pointed at the rear window would cause any problems? I guess this could use the glass as part of the mouth but I wouldn't want to break my window!

Finally, after looking at your impedance plots of the Triple8, I'm guessing the horn starts to take effect from 35Hz upwards, do you use a HPF at all or are you not running enough power into the MCM 8's in order to exceed x-max?

I was hoping to run around 18v into each driver, and I was going to use a separate amp channel for each driver as opposed to wiring them in parallel, as my amp is not 2 ohm stable, and I have a 4-channel amp, so I'm guessing a HPF at 30Hz may be good idea?

Originally Posted by Patrick Bateman

What would you like to know?

The AutoTuba is a very impressive design - Bill F knows his stuff. It is the flattest box that I've ever measured in a car. Unfortunately, that's actually A Bad Thing in a car. I've found that boxes that measure flat in a car sound too lean. Nonetheless, it's musical, dynamic, inexpensive and relatively easy to build.

The TH-Mini clone *might* be my favorite of all the tapped horns I've built. The last octave is completely AWOL, but above that, it's ridiculously efficient and the bass is very 'tight.' Distortion is a non-issue with this box - there's a big fat null between 100 and 200hz that just zeroes out distortion. The downside to the TH-Mini is that there isn't much output from 20-40hz, the woofer is relatively expensive ($150), and it's fairly large (close to 5 cf.)

The Triple8 is probably the best compromise. It plays lower than the TH-Mini clone, absorbs three times as much power as the AutoTuba clone, has more displacement thanks to a higher SD, and is the smallest box of the three. The TH-Mini clone is audibly "cleaner" from 100 to 200hz, but it should be - it uses a woofer with lower distortion and lower inductance.

My solution to get "the best of both worlds" was to simply put the Triple8 in my trunk. The rear seat filters out high frequencies, and distortion along with it. (I was running the TH-Mini clone on my back seat. It was designed to take up one seat. It's light enough not to scuff up the upholstery.)

I would upload plans if I had them. But the Triple8 is the exact same box as the Th-Mini clone, but with an extra piece of plywood that extends the path. You can see it in the pics. As long as you get the mouth right you'll be fine. Just take a look at the pics, and draw it out on your plywood. The outer dimensions are 24" x 24" x 9". The plans for the Th-Mini clone are in "The Smallest Tapped Horn" thread.

[Fuzzymuff]

Hey mwmkravchenko, Hi, could you explain how this is done

I drive the tuba sub with my pioneer head unit with the rear channels bridged and get 22 real watts. Those 22 real watts give peaks of 122db.

, is this doable in all head units? Please

Thankyou Fuzzymuff

[mwmkravchenko]

Your in a tough spot with this one!

I purchased this head unit because it is one of the few avaliable with discrete amplifiers that can have them bridged. It's done with some settings on the unit and a slight rewire of the rear channel outputs. But I'm quite sur that few other head units can pull this off.

Mark

[MikeHunt79]

I've measured my car, and it seems the 24x24x9 triple8 will be too big for my car, unless I drive everywhere with the boot/trunk open the whole time!

I think I'm going to be better off either going for a re-fold of that design or designing a new TH from scratch.

[Eva]

But your cabin is also smaller than average, so there is more gain and not that much SPL is required...

[mwmkravchenko]

Hi Mike

What is the optimal size that you can put up with? Is a bit bigger than the auto tuba OK?

A second thought Why not do a vented enclosure and go with a bigger amplifier? Two Tang Band or similar 8 inch drivers will knock your socks off in a small enclosure. Heck I know that you can get the TRIO8's in Holland from Henkjan. They blow the Tang Band out of the water in terms of build quality and performance. I have both right now i my shop. A client just played with both of them and readily stated that the TRIO8 product was better made.

Mark

[MikeHunt79]

Originally Posted by Eva

But your cabin is also smaller than average, so there is more gain and not that much SPL is required...

Yep I guess trying for higher SPL levels isn't really needed here. I was just after something a little smaller than what I have right now, but still high efficiency. I do quite like the horn sound, personal preference I guess.

Originally Posted by mwmkravchenko

Hi Mike

What is the optimal size that you can put up with? Is a bit bigger than the auto tuba OK?

I guess I could have a box that was little longer than the autotuba, but it would have to have the mouth in a different place so it does not point towards the side of my car. Maybe 40"x14"x16" max....

I've made some adjustments to the placement of my autotuba, and I think I may stick with it for now, I think I can improve things a little once I get a DSP/EQ installed, as I need to delay the fronts and reduce a big peak at around 80Hz. It gives mindblowing output, but it needs to be tamed a little in my cabin...

I guess I'm going a little offtopic now, but I really like the idea of a TH for the car, and I'll be keeping an eye on this thread and I may end up making another box at some point if we ever get some decent weather.

Originally Posted by mwmkravchenko

A second thought Why not do a vented enclosure and go with a bigger amplifier? Two Tang Band or similar 8 inch drivers will knock your socks off in a small enclosure. Heck I know that you can get the TRIO8's in Holland from Henkjan. They blow the Tang Band out of the water in terms of build quality and performance. I have both right now i my shop. A client just played with both of them and readily stated that the TRIO8 product was better made.

Mark

I'll have to check out the TRIO8, if it beats then tangband then it must be a very nice driver, I think it would be nice to have a vented box anyway, for those times when I need to use my boot/trunk, but don't want to do away with bass.

[mwmkravchenko]

I'm done with this thread. The design for the dual TRIO8 is now owned by someone else and I will post the details when appropriate. Hard to beat the Autotuba for SPL!

Mark

[Patrick Bateman]

Originally Posted by MikeHunt79

Yep I guess trying for higher SPL levels isn't really needed here. I was just after something a little smaller than what I have right now, but still high efficiency. I do quite like the horn sound, personal preference I guess.

I like the horn sound too, but I could never really tell why that was. Over the past year I've been a freaken' LUNATIC with my measurements, I've literally done over a thousand measurements this year.

It's really helped me get a grasp on WHY i like horns.

Over on diymobileaudio I'm digging into the subject in a thread titled "natural bass."

I am 100% honest about my designs, if they suck, I'll be the first to admit it. That's one nice thing about doing this as a hobby, I have no incentive to "sell" my designs.

The Triple8 has excellent frequency response, but I *personally* prefer the sound of the TH-Mini clone.

After a lot of measuring and listening, I believe that drivers with low distortion make an audible improvement at ALL frequencies. (Some have argued that distortion isn't a big factor at low frequencies.)

Maybe I am just particularly sensitive to distortion, but I really believe that lowering it makes an audible improvement.

I think this is one of the reasons that I personally like "the horn sound", and it may be why you like it too. Horns reduce distortion by reducing excursion. In my measurements, distortion just goes BANANAS as the drivers excursion rises.

If my hypothesis is correct, then I should be able to make an even better tapped horn with a driver which is more sophisticated. At the moment I am focusing on drivers that have all kinds of distortion killing mechanisms. (underhung motors, shorting rings, push-pull alignments, etc...)

The results so far are VERY promising. For instance, I have a tapped horn and a front loaded horn that use the AuraSound NS4 woofers, and it's audibly "cleaner" than the MCM.

The TH-Mini is still a champ though - the P-Audio SN-12MB is a woefully under-used driver.

[mwmkravchenko]

Just thought it may be interesting to you dudes to see the redo of the first UNHORN. The larger UNHORN has been running for quite a few months. A couple of gents have built it and are quite happy with it. One gent even built two of them!

But it was the small one that interested the greater majority. The cost of the drivers was a bit of a problem. So along comes a review of Exodus's Audio ANARCHY driver in Voice Coil and I get to thinking. What if? So short story is a smidge bigger and the response below.

We are still talking about a box that is really only good for acoustical and soft rock. But hey It's just over a cubic foot right?



The second set of plots is the response you could get from 50 watts. Notice there is no over excursion at this power input. If you put this box in a car you can get a bit better SPL numbers.


Mark