Tapped Horn For Car

[DarpMalone]

Neither rap, nor any other bass driven music rely on high distortion components to sound good (unless distortion sounds good to you). Nor does that explain why Mark's horn performed the way it did with rap music... I would imagine that @ moderate levels, the horn sounded great (better than a one note, distorted boom box would have sounded at the same SPL, playing the same material) You need to move more air and quickly dissipate heat in order to faithfully reproduce the music @ higher SPL.

I use a 12" peerless xxls sub in my car (not the loudest sub, but it can go louder than necessary), but more importantly, they are very low distortion subs. I power it with an extremely clean autotek BTS amp that can provide double the sub's RMS at 0.015% THD, so any distortion is being generated by the car itself. I'm not sure how low it goes in the car because I've never measured it, but it sounds fantastic with any music it's presented with, even rap

Mark, your design sounds very interesting... If you decide to design one for 8" drivers, I look forward to building one of my own.

[brsanko]

Oh I'm sorry we must be morons. Do you have a school we could attend? Distortion doesn't sound good to me but niether does rap. Rap is not music, it is computer generated noise and distortion. The window rattling rib cage jaring "bass" noise in rap recordings is a very simple product of computer induced DISTORTION. Low quality enclosers (i.e. anything besides a horn) exgerates this effect. A truely low distortion clean sounding sub (i.e. a horn) will have an entirely different sound that will not have the desired effect, but despite this will be a more acurate rendering of what is actually in the recording. Any actual music (acoustic recording) will sound the way it did originally. If you don't have a horn sub you have no idea how clean, dynamic and distortion free a subwoofer can actually be!

[mwmkravchenko]

Hi DrpMalone

I don't put to much effort into saying how great things are with this design. A couple of gents tried it out. The one on the left promises to post his thoughts on the matter.

As for some of your comments they are well taken but I would add this little blurb.

You no doubt understand that to our ears a heavily distorted 2 and 3rd harmonic of the original note being played sounds like louder bass. In simpler terms if we have a low b flat from a 6 string bass we are looking at a fundamental of about 32hz. The vast majority of subs cannot really give you that note with out compression or loss of amplitude better described as sound pressure level. So what we hear is the 2nd harmonic 64hz and the third harmonic 128hz. It sounds impressive. But it's not the real low bass you'd hope for. This distortion is unfortunately there in most of the subs that I have worked with and requested by most of the people I do custom work for. You DarpMalone are a man after my own ideal of clean undistorted bass. Just that I have 22watts and not a heck of a lot of space to do it in.

Your system is interesting. I modeled it below and found with cabin gain in most midsized cars your maximum acoustical output is 112db. This is dictated by the diameter of the cone and the throw of the suspension. Not the available power. Once you hit these mechanical limits there is nothing that can be done to make it louder. Except add more drivers. Double the drivers and you get 3db more. You also need double the box.



I will humbly point you in the direction of post number 83

We were hitting sustained SPL of 112 and peaks of 114 with less than 15 watts. None of us wanted to go louder we had no hearing protection. The sub could go louder as shown in post # 6

http://www.diyaudio.com/forums/showt...43#post1850643

That is the difference between a normal box and even this little poor excuse for a horn. Efficiency. Just think about it two 6.5" drivers match your 10 in a box that is just over 22 liters. A cubic foot is 27 liters! A lot of thinking went into this design.

What this little box cannot do has all ready been presented. Below about 40hz it is out of it's happy space. It's passband is from 38hz to 125 hz. Your lovely box is good down to much lower. And keep up the 112db. With any horn you trade reproducable bandwidth for efficiency.

Mark

P.S. The 8" driver has been chosen. Creative Sound Solutions Trio 8. It was chosen because it has the highest output at the best base SPL of any affordable 8" driver. Actually that was the same reasoning to use the SDX7. Nothing else even came close. The 4pc SDX7 in a proper horn is coming down the pipes. (Yes Pun intended ) It depends on how many rain days I get this week!

[Taterworks]

Mwm,

I'm interested to know what the cone excursion behavior in this enclosure is like. The inner driver seems to be on a panel with no acoustic structure separating it from the volume of the large internal 'chamber'. I'd imagine that overexcursion would be a problem with this driver (which has a physically separate motor and moving structure from the driver that is in the expanding part of the 'non-horn'. Overexcursion issues may be why this sub objected to having rap music played through it.

[mwmkravchenko]

The best way to explain it is that I have carefully designed this enclosure to get the maximum available sound level output from two small drivers over a very narrow bandwidth. Outside of that bandwidth like any vented enclosure you get massive cone flap. A horn behaves just like a vented enclosure when driven by a frequency below what the horn was designed for. We have all seen cones flapping madly on vented boxes to. Within it's sweet spot the cones actually are very well behaved. If you had a high pass limiter for the low frequencies you could really drive this sub to crazy levels.

Referencing post Number 6

http://www.diyaudio.com/forums/showt...43#post1850643
this is the simulated output that came from Hornresponse

Post # 55

http://www.diyaudio.com/forums/showt...19#post1862219

Actual measured response. The bump was a measurement artifact in the car. Tests at a different position gave us minus 1db plus 2 over the same range.

Both drivers are wired so that they pressurize the interior of the horn compression chamber. It produces a more coherent pulse coming out of the horn. This is both simulated and tested in real life. So that means using the driver mounted in the mouth as a start the interior driver is wired with opposite polarity. If it is wired in like polarity there is a null in the output of almost 3db measured at the mouth as it should be in theory. Wired as explained the drivers sum in output and play nice.

The rap music that we were trying had loud fundamentals in the area of 25hz. Adam was the gent who isolated this using a spectrum analyzer on his computer. This horn is not designed to play anything that low. What you get is a very clean sounding small box that will play most popular music to levels that will give you hearing damage in about 15 minutes. I don't know what else you would want other than a competition grade setup. I have designed these. Requests have come in excess of 140db. It can be done but the box requires a trunk donation.

Mark

[brsanko]

I apologize if I offended anyone with my last comment I am an artist and get very emotional at times.

[DarpMalone]

Actually I'm an artist as well (If your interested I can direct you to a place where you can sample my music )... I'm not emotional or sensitive, but I just read your last post and had to reply. Hopefully no one else reading this thread felt that I was assuming you were a moron. Far be it for me to say anything in a public thread that could potentially offend other members of the community or prejudge someone's intelligence, based their musical preferences.

The majority of popular rap music (the stuff that you hear in repetition on the radio and TV all day) is not for me either, but believe me, rap music is an extremely diverse MUSIC and broadly accepted by many of the world's greatest and most highly respected musicians. Like most genres of music, it can be extremely enlightening or it can be plain ignorant. You may not dig them, but perhaps you should check out The Roots, a hip hop band, widely considered to be one of greatest live bands in the world today. They actually play instruments too! It seems that you've only been exposed to pop rap, the same way that the majority of this generation unfortunately will have little or no exposure to classical music because it's not played commercially.

As much as I respect and try to enjoy all music, I also know that apart from acoustic instruments, analog and digitally stynthesized instruments make great music as well and are every bit as valid

I won't attempt to further hi-jack this great thread with a discussion about musical tastes. Anything further from me will be of a constructive nature and relevant to this threads topic.

d

[mwmkravchenko]

You guys are in it for the right reasons.

The music so if you have strong feelings then go for it. All these boxes and widgets are made because I, we all enjoy music enough to devote time to manufacturing it and listening to it.

Mark

[Piek]

Hi,

I've read this thread with interest, since I've build a small Tapped Horn as well (for home use, with parametric eq at 40Hz and lowcut), that is maybe suited for car use at moderate SPL, didnt test it in car yet.
The rolloff is dependant on what driver you will use, a wide range of 130mm drivers are possible.
Squirrel-TH

Do you think the rolloff is complimenting the car pressure chamber effect?

-Micha

[mwmkravchenko]

It never hurts to try.

You seem to have the means to measure the effects of what you have accomplished so. Put it in the car and check what happens. You will definitely get a boost in the bass response. But you will not get anything more than the horn was designed for. It will just couple more effectively with the smaller air mass in the car and the close boundaries of the car interior.

Mark