Tapped Horn For Car

[mwmkravchenko]

Don Posted:
"I'm currently working on using two drives to complement each other. Often, the most afficient (highest SPL) )configuration results in a peak at the LF limit, then a dip, then another peak an octave higher. I'm trying to make the second driver "fill in" the dip. Troels Gravesen does something similar with his "doppel horns", where two tapped horns are tuned a fifth apart. It's harder to do it in a single horn."

Hi Don.

You and I are after the same animal. Evil little thing to nail down that magic point where the drivers actually complement each other. You are successfully taking my design apart. All the more power to you. The next lower playing version is to be built some time this week. And I may make the box in such a manner that I can play with the positions of the drivers. I think that this way I can finally get empirical data that matches the theoretical.

I think Bjorno made the comment about highest SPL does not always get you the best response. He is completely correct as are you. The sneaky trade-off is the correct combination. An example would be a broad 3db dip would not be to noticeable but a peak will irritate an acute listener.

"One thing I missed before, your original Hornresp input parameters in post #43 show a large chamber defined between the driver(s) and the "S2" point of the horn. Is that intentional? This may explain the response difference you see. The attached picture shows a Hornresp graph with the chamber (grey line) and without (black line). There is a significant difference. The black line version exactly matches my Akabak model, which does not have the chamber."

All my secrets are getting revealed. Nice work Don.

"I agree, the hourglass or bowtie shape is what you get when you combine chamber (Helmholtz) resonators with 1/4 wave resonators. The aim is to get the best of both in the same box - a true reflex. This is an old use of the term "reflex", from the early days of "steam" radio when tubes / valves were expensive. It was quite common to use one tube to amplify the RF signal, then after conversion to AF the signal would be fed back through the same tube again to amplify the AF (audio) signal. In this case, we're using the same box both as a Helmholtz resonator and as a pipe resonator."

Yes this is basically what an Unhorn is. But the design of the little monster is not that easy. This you know to be sure. The second generation will be put together with more rigor than the first. The first was a try and see. The second is going to be done with some insight and a little less chance and good happenstance.

Mark

[Don Hills]

Originally Posted by mwmkravchenko

All my secrets are getting revealed. Nice work Don.

It does help the low end response, as the graph showed. I just wondered because I did not see the chamber in the actual box. I have seen tapped horn designs with a chamber, sometimes for its own sake, sometimes as a result of trying to fit two drivers in the same space.

On the subject of multiple drivers, it doesn't seem to be essential to make complicated box structures to try and get the drivers to be "coincident". Arranging the drivers along the length of the horn seems to work just as well.
Akabak allows modelling the different driver arrangements and comparing them.

Originally Posted by mwmkravchenko

Yes this is basically what an Unhorn is. But the design of the little monster is not that easy. This you know to be sure. The second generation will be put together with more rigor than the first. The first was a try and see. The second is going to be done with some insight and a little less chance and good happenstance.

I wait with bated breath... (Why does everyone spell that "baited"? Don't they teach English at school any more? )

[mwmkravchenko]

Have a fancy vanity cabinet to assemble then there is watching paint dry. I cut it all out today and did some of the rough assembly. The life of a cabinet maker. That gives me time to work. Four small easy boxes to make then the two horns tapped and Unhorn. The weird thing is the latest work I'm doing on a circa 20hz car horn for 2 SDX7 is functioning more and more like a tapped horn. My current best is 44 liters and 22hz. If this pans out I may be happy to have a very small box go down low.

Mark

[mwmkravchenko]

The UNHORN 2 Dual 8 inch version is almost ready. It is an almost exact replica of the simulation so you guys will find out how it operates just after I do.

Mark

[mwmkravchenko]

This iteration is a real pain to fold correctly. I have worked it through twice yesterday and today it dawned on me that the useless leftover area that I could do nothing with in the folds would allow me to take it down a little lower if I repositioned the folding method. In plain englrish I'm making one part longer to make the whole thing fold better into a rectangle.

But it is not easy! AHHHH


98% of the way. Whoever said perseverance and invention go together should pay me a visit. I folded unhorn 1 in 20 minutes. This son of a motherless dog will end up taking the better part of a day. Here is a tidbit to tease you.



This is with 2 pcs MCM 8 inch. It is much flatter with dual Trio8. That is the driver the enclosure is optimised for. But in the real world the 3db dip is not going to mean a hill of beans amidst all the standing waves and enigmodes we get in real rooms or automobiles. The driver compliment will get you where you want to go.

How big is the box? At this point 28" x 10" x 19 1/2" Not small but pretty much unbeatable for the size and output. With the TRIO8's and 300 watts you will peak out around 125db. Try modeling the drivers in a reflex cabinet and see what you get!



Again this can only be done using the TRIO8's you will get a paltry 114 with the MCM drivers. Not bad either way. When I have a box tomorrow I will post some pics.

Mark

[mwmkravchenko]

Still a bit left over. Had a son to pickup and entertain this weekend unexpectedly. Life in the fast lane. All fooling around stops to be a good father. But tomorrow I still have the day off. There are some benefits to being self employed.

Mark

[mwmkravchenko]

In the ever present desire to better an already better design....

I have all the pieces for a great many boxes but none assembled. Work rears it's ugly head once again. The good thing is the weekend is coming fast and assembly generally is quite quick. I really did design the horn one more time. I really want it to fit into a more or less rectangular shape. So tossing and turning the fold and I get a more or less useful rectangular shape. The greatest struggle is keeping the drivers at the location simulated and the compression chamber created in an area that will still let the horn function. Nasty but accomplished.

Here is some more info:



Not the largest box at under 2 cubic feet ( 28 liters /cubic ft ) We'll see how it performs. I'm thinking that this one in a car will be lethal. In a house it should be a room pounder that is if the simulations hold true again.





For all you guys thinking about the box in a car here it is at 1oo watts. 1/8th space. If you look closely at the SPL chart there is the ghost of a 1 watt input. The excursion plot is X-max + 25% or 10 mm.

Any comments?

Mark

[Fuzzymuff]

Hello.
Would love a Tutorial from keying in the driver parameters to finished design. Would like to try various drivers and designs myself. But, I'm really enjoying what I'm reading, so thank you, just for the read, but a tutorial would be nice.
Regards
Fuzzymuff

[sixgen]

yeah a tutorial starting from hornresp to drawing of the enclosure would be nice for not so technical person as myself. =)

[bjorno]

Originally Posted by Fuzzymuff

.. but a tutorial would be nice..

Hi,FYI, Not a tutorial but: See my pictures comparing the last presented 'Unhorn' with simple ported and closed boxes.

b