# ID horn modifications



## Mike Hall (Jun 30, 2006)

I have a couple sets of Imagine dynamics horns which one pair I have had for over 20 years now. Those original full body horns have been in so many cars but lately I am finding it impossible to fit them in many of my last vehicles. I had the idea that if I could change the mounting position of the drive on the horn body I may could utilize them in some of my future projects. What I had in mind was some kind of multi position mounting or swivel mounting into the throat of the horn. I have a plastic set of USD horns that have somewhat of the same kind of concept but those horns are so flimsy I have never even used them before. I guess my question is does it really matter at what angle the driver is firing into the horns throat? 

I also have a set of Mini horn bodies that could benefit from being able to adjust the driver position. Sometimes mounting the driver flat like the old full body horns would be perfect for some places I have wanted to mount these horns. Again, i guess it all depends on if there are major issues with how the driver may fire into the actual horn throat. Any advice would be fantastic. I want to use some horns in my current ride but I as or yet they are not going to fit without hamper the ability to drive the car with out some interference.

Thanks
Mike


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## thehatedguy (May 4, 2007)

Yes, it matters a great deal.

You need a 45 degree reflector across the whole entry to allow the wave front to realign properly. This reflector needs to be as close to the driver exit to keep nulls in the HF from occurring. 

Now if you could find a square section of the throat after the reflector, you could rotate the driver and reflector like a reubic's cube to move the driver to 4 different places. I think you could do this with the minis easier than the full bodies, but I haven't pulled a mold of the big bodies to see if this wold actually work or not.


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## Mike Hall (Jun 30, 2006)

Yep, what you are saying it exactly how the USD horns are build. the driver mounting has a 45 deg reflector and it is able to rotate. Here is a picture I found of the USD horn driver mounting setup. I can not find my USD horns as they are packed away somewhere. :laugh:

I think you are right on which ID horn bodies may be modified easiest. The minis do have a nice square areas that may could be used to rotate to the 4 different points. I will have to take some measurements to see if that is possible.


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## Elgrosso (Jun 15, 2013)

Nice project, I've been wanting to try something like that for a while too.
My FB don't fit anymore with my 10s in footwell, and the minis don't fit perfectly right now. I would need a side driver on the full, or up/down on the mini to put them deeper.
Waiting for a pair of usd to see if it would help for my mount and to see how this system is built (+ test the sound but I don't have big expectations).
Then asked Eric if he had some spare/bad horns so I could cut and test before going on the good ones.
I might try other things, like adapting them for over dash mount. I think my dash shape could be leveraged here, smooth, symmetric and curved (roughly the idea is to cut part of the bottom side of the horn, and re-complete the horn with the top dash).
Few ideas but not enough time...

I don't remember the throat cross section of the minis, and they're in the car right now.
But the full in hand, it might be impossible without heavy mods.
The only square section I can see would cut the deflector right in its middle.
And including the whole deflector in the cut part would create a rectangular section, so not rotatable.

But let's see what Eric says!


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## Mike Hall (Jun 30, 2006)

I have a mini horn body in my hand and it sure looks like there is good square area just in front of the 45 deg reflector. It may not be exactly square though. I was thinking of putting something inside to make a mold of the throat then seeing if that had any good square cross sections or at least something very close to being square. I would rather do that than cut the horn to find its just not even close.


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## thehatedguy (May 4, 2007)

I have already pulled a mold of the minihorn


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## Mike Hall (Jun 30, 2006)

YOU may be able to confirm that there is a square area or not then.


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## Mike Hall (Jun 30, 2006)

If I had the ability to rotate the driver on the Mini body horns I think I could make them work. The only way to get them totally out of the way would be to have them pushed as far to the outside as possible which will be limited with the driver in the location it is now. 

You know, I had once thought about making a mold out of my full body horns being they been broken and repaired a number of times. I figured if I went though such trouble I would cast them out of aluminum which is something else I plan to dabble in someday. (casting aluminum that is) I assume the horn bodies are made so thick and out of a special material to keep the Resonance down and that is why i considered the USD horns that I have unworthy to even be used. haha


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## thehatedguy (May 4, 2007)

Aluminum due to the shape will ring pretty bad...I've owned and still own a set of Veritas aluminum bodies that take some mods to tame down.


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## Mike Hall (Jun 30, 2006)

See there, I knew someone would know why I shouldn't do that. haha It almost looks like these horns bodies are made of bondo. Maybe a mixture of bondo and resin poured into the mold. I bet something like a polyurethane be good for casting a set of horns. You can get some pretty dang hard polyurethane but maybe not as rigid as this stuff these are made from. Anyhow, I am not so sure I want to fab up a new set of horns although the thought of molding a set into existing dash panels has crossed my mind. I may explore modifying these mini bodies and see what I cant come up with. I have actually never used these before as I have always been able to fit the full body horns in or either neither would fit.


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## thehatedguy (May 4, 2007)

They are made out of urethane.


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## Elgrosso (Jun 15, 2013)

And what if you only mod them for straight through, much easier, would they fit?


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## Patrick Bateman (Sep 11, 2006)

If you want a waveguide that's shallow, why not use something like the JBL progressive transition waveguides or the QSC oblate spheroidal waveguides?

Each is about 3" deep.

The polars on the JBL are spectacular; here's a measurement I made:










Like any constant directivity waveguide, the JBL requires eq to play flat, but that's just the nature of CD waveguides. (Same amount of acoustic energy spread over a wider beamwidth means EQ is required to play flat.)

Due to the insanely good performance of the JBL, you basically sit anywhere inside of their beamwidth and the sound doesn't change. I wish my own waveguides performed this well! JBL clearly did some BEM modeling on these and I wouldn't be surprised if they perform better than what's in their flagship, the M2. (IMHO, they overdid it with the weird 'beaks' in the M2.)









Here's a measurement of the same waveguide made by Dr Earl Geddes, but this measurement is with a Selenium compression driver. _Note the high frequency performance isn't as good._ I believe this is because the JBL ring radiators perform better in the top octave due to a superior phase plug. The Geddes measurement includes the aforementioned constant directivity EQ. Note the Geddes measurement is at a tighter scale than my measurement also. Original post from seven yrs ago here: Great Waveguide List - Page 2 - diyAudio


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## Elgrosso (Jun 15, 2013)

PB are you talking about in car use really?
I ask because I tried last we a bunch of home horns in different places in the car, and nothing was really convincing.
Sure they can measure better, smoother or well loaded, but on listening I just prefered the ES (mini actually, full would have been even better).
Like in your example, also here it better be good with only 22 degrees off! 

I just think the dispersion pattern of a regular horn cannot work well in a car, unless it's completely integrated in the dash/cabin shape etc, and then it's no more a regular horn.

About the m2, did you see the scl2 (or something like that, the new synthesis).
Same design but a bit smaller I think, and in wall. It works insanely great, I moved around 180 degree and it was super smooth, clean, while real loud!
And it's super shallow, like on the 705, the models I heard had the d2 + 3x8" and 2409h + dual 4 or 5", I really think there's something for us here. 
jbl/hk is still an engineer driven company (for now), "beaks" for me are here for good reasons, the solution to the square circle (remember the old thread about that?).
I tried to get more details directly from the engineers but failed... 

I think we could gain something here, but using circle to triangle instead, to match our car needs.


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## Patrick Bateman (Sep 11, 2006)

Elgrosso said:


> PB are you talking about in car use really?
> I ask because I tried last we a bunch of home horns in different places in the car, and nothing was really convincing.
> Sure they can measure better, smoother or well loaded, but on listening I just prefered the ES (mini actually, full would have been even better).
> Like in your example, also here it better be good with only 22 degrees off!


Sure! Waveguides generally have less "gain" than horns, but this is 2017. The cost of amplification has never been lower, so waveguides start to look attractive.

Basically the home audio and prosound community has embraced waveguides, but the car audio community has largely ignored them. I guess this is mostly because the proponents of waveguide technology aren't very active in car audio?

IE, companies like JBL, Genelec, Danley and B&O are doing great things with waveguides in home and pro audio, but only one of those companies does car audio.










It looks like even JBL has given up. Their top of the line speaker set (660gti) used to use a waveguide, but it looks like they abandoned it in the new model. (670gti)


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## Elgrosso (Jun 15, 2013)

The 660s were great, had them, shouldn't have sold them...
The woofer was a big part of the value, for the waveguides, I never did an extensive with/without comparison in the same spot. But when I could install them like in doors and central dash, the whole thing sounded really good.

I understand why they discontinued them, how many threads here where new owners wanted to ditch them?
But we can still find some tweeters with waveguide or embryo of.

Recently I tried my Cds hornless on top of the dash, and was surprised by the result.
I really think that just a shallow waveguide adapted to its placement would give great results.


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## Patrick Bateman (Sep 11, 2006)

Elgrosso said:


> The 660s were great, had them, shouldn't have sold them...
> The woofer was a big part of the value, for the waveguides, I never did an extensive with/without comparison in the same spot. But when I could install them like in doors and central dash, the whole thing sounded really good.
> 
> I understand why they discontinued them, how many threads here where new owners wanted to ditch them?
> ...












Keep in mind that the phase plug will load the driver down to about 2000Hz or so. A lot of the loading occurs inside of the compression driver itself.










Horns like the XT1086 use a diffraction slot to create a wavefront shape that's like a ribbon, not a dome. 

Basically it goes like this :

diaphragm -> phase plug -> diffraction slot -> waveguide/horn

The best description of all this is here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.536.5361&rep=rep1&type=pdf


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## Elgrosso (Jun 15, 2013)

Patrick Bateman said:


> Keep in mind that the phase plug will load the driver down to about 2000Hz or so. A lot of the loading occurs inside of the compression driver itself.


2Khz! I still had the adapter on the horn so about 1 more inch to load.
But since it was straight I’m not sure it loaded anything 
But it sounded good, not perfect there were some artefacts.
I’m waiting for some super short waveguide to test again.



Patrick Bateman said:


> Horns like the XT1086 use a diffraction slot to create a wavefront shape that's like a ribbon, not a dome.


I don't see any diffraction slot here, or do you mean in the CD?
Btw, the beaks in the M2 must act like diffraction slots too.




Patrick Bateman said:


> The best description of all this is here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.536.5361&rep=rep1&type=pdf


Yes already read this one, really nice article.


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