# Horns for midrange only



## Navy Chief

So I have been debating between running a set of horns or a set of widebanders, just looking to change things up. I am also trying to get smoother midrange for vocals. So while reading up on widebanders I noticed that everyone seems to run them down closer to 500hz whereas horns closer to 1000hz. The other thing I noticed is that many people are running a tweeter with both their widebanders or horns to add that extra "sparkle". So I started thinking since I am going to run a tweeter anyways why not find a horn driver that will play as low as a widebander and essentially go 3 way with a horn on mid duty only. Here is what I am looking at.

Selenium D250-X 1" Phenolic Horn Driver 1-3/8"-18 TPI Pro Audio Compression Driver 264-204

Has anyone ever tried this idea or driver here. I will be using USD waveguides, will this driver even play down to 500hz on a horn that small. I am running 4 eclipse 8061 6 1/2" midbass made by Vifa and have a pair of eclipse 8001 silk dome tweeter on the dash almost on axis. Curious to hear thoughts on whether this is worth trying and any predictions on the output.


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## Mic10is

Frequency limitation is more a function of the horn, not the compression driver. ID mini horns are only usable down to around 1000 which is why that a common XO point

full size horns can typically play down to 5-800.


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## Eric Stevens

The USD horn doesnt work to 500 Hz, my V.2 full size work noticeably better but are still stretching it for 500 Hz.

If you were using the V.2 full size I would suggest 600 but encourage trying it a 500 and If it was edgy and forward sounding to raise the crossover up to 600-800 hz depending on how much volume you are after. USD I think would be a couple hundred hertz higher due to the lack of loading from the horn below 1000 Hz.

Eric


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## Navy Chief

Thanks Mic. So waveguides should be able to get down around 800hz. If my full size horns don't sell I may just try them. So saying we can get down to between 500 and 800hz how would it sound with horns playing up to around 8000hz and then the tweets above that.


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## nubz69

It's all in the horn body. The bigger the better.


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## subwoofery

Navy Chief said:


> Thanks Mic. So waveguides should be able to get down around 800hz. If my full size horns don't sell I may just try them. So saying we can get down to between 500 and 800hz how would it sound with horns playing up to around 8000hz and then the tweets above that.


You'll need to find a tweeter that has at least 104dB 1w/1m sensitivity in order to match up with a your Selenium suggestion... 
Part express has some that are much higher in sensitivity but I really don't know how those sound... 

Kelvin


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## Navy Chief

Eric Stevens said:


> The USD horn doesnt work to 500 Hz, my V.2 full size work noticeably better but are still stretching it for 500 Hz.
> 
> If you were using the V.2 full size I would suggest 600 but encourage trying it a 500 and If it was edgy and forward sounding to raise the crossover up to 600-800 hz depending on how much volume you are after. USD I think would be a couple hundred hertz higher due to the lack of loading from the horn below 1000 Hz.
> 
> Eric


Eric thanks for responding, your input is one I was hoping to get. I have the V2 full size horn, they are just a tight fit so I was trying to sell them. If this concept will work I may just have to try again. Have any of your customers or even yourself tried this idea. I will cover all but the last three octaves with the above mentioned driver. What kind of phasing problems can I expect picking up about 9k and up on conventional tweeters. Also does being able to get low (potentially 500hz) outweigh the negatives of having to use tweeters to capture the top octaves. My tweeters are 6ohm and I could get a pair that are 4ohm, how much less sensitivity can i get away with if I essentially double the power to the tweeters. I will be driving the tweets and horns using the same amp a PPI A200, 50x2 at 4ohm. Thanks again for all the great input from everyone.

Mark


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## thehatedguy

You would really want a large format compression driver too. You can get a 1.5" driver on the full sized horns with a little work. But you WILL spend a lot of money on some good ones that can play that low and they WILL be large drivers. My old Beyma CP755Nds were about as small as they come for a large format that can play that low, and you would have a hard time getting them under your dash easily.


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## thehatedguy

You would not want to run "regular" tweeters on top of some midrange horns. You would either burn them up trying to get them to play loud enough or you would severly pad the horns down to get them to mate well.

You would want the tweeters to be at least 105 dB sensitive...and 108-110 would be even better.


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## thehatedguy

This a road I was trying to travel down a couple of years a go before I got a new car...Eric and I had a LOT of conversations about doing this.


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## Navy Chief

Great input, thank you. I was only considering doing this if I can make it work using the drivers from Parts Express. This is kinda budget oriented, so large format drivers are probably not an option. The best I can seem to find for regular tweeters is 100db. I did intend to use a passive equalizer to avoid having to use a 30 band EQ, I was also going to load the horn with open cell foam. So this should bring me down in output a bit but not sure if it will bring it in range of the tweeters. The plan you were working on how high did you intend to run the large format drivers and why did you not go through with it.


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## Eric Stevens

If on a budget you could do a selenium super tweeter too. Wont be the best you could do but it will still perform well but need more tweaking. but you need something with some sensitivity similar to the hlcd. I have done this in a couple of systems and it worked great, although both werent budget minded, one was all TAD ,TD2001 and Et703, and the other was CD2 Neo with Fostex T90 horn super tweeters i believe


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## thehatedguy

I was going to run those Beymas all the way to 20k.

The new car was a lot smaller than my previous car and I had a daughter at the same time...so no major surgery to the new car like I did to the old Accord.

I did the open cell foam too...and you won't loose that much sensitivity.

I wouldn't even think about trying to do this with passive EQ.

A project like this and budget really don't go together.


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## Patrick Bateman

Navy Chief said:


> So I have been debating between running a set of horns or a set of widebanders, just looking to change things up. I am also trying to get smoother midrange for vocals. So while reading up on widebanders I noticed that everyone seems to run them down closer to 500hz whereas horns closer to 1000hz. The other thing I noticed is that many people are running a tweeter with both their widebanders or horns to add that extra "sparkle". So I started thinking since I am going to run a tweeter anyways why not find a horn driver that will play as low as a widebander and essentially go 3 way with a horn on mid duty only. Here is what I am looking at.
> 
> Selenium D250-X 1" Phenolic Horn Driver 1-3/8"-18 TPI Pro Audio Compression Driver 264-204
> 
> Has anyone ever tried this idea or driver here. I will be using USD waveguides, will this driver even play down to 500hz on a horn that small. I am running 4 eclipse 8061 6 1/2" midbass made by Vifa and have a pair of eclipse 8001 silk dome tweeter on the dash almost on axis. Curious to hear thoughts on whether this is worth trying and any predictions on the output.


Some thoughts:


As Eric noted, 500hz is a stretch for conventional car audio horns
Run, don't walk, if someone tries to sell you a compression driver with a phenolic diaphragm. Yuck. When it comes to compression drivers, you should expect to pay about 4x as much as you would pay for a conventional driver. So if you'd typically spend $100 for a pair of tweeters, be prepared to spend $400 for a pair of compression drivers. Cheap compression drivers are truly horrendous, with a few notable exceptions.
I've been able to get down a full octave further - all the way down to 250hz - with waveguides and horns. The trick is *you must use something to extend the curve.*

Here's how this works:

At the lower end of our hearing (20hz) a soundwave is 1700cm long (55.7'!!!), but at the upper end (20khz) it's just 1.7cm long. That creates a couple of unique problems. At high frequencies, the geometry of a horn is absolutely critical. For instance, if the throat of your horn is off by a couple millimeters, it makes an audible difference.

Conversely, the wavelengths are so long at the mouth, even a large change doesn't make a heck of a lot of difference.









That's why I was able to 'get away' with such a large discontinuity in this waveguide that I had in my car. If you look at the waveguide, you'll see that it matches the curvature of the windshield and dash in the vertical axis, but in the horizontal axis there's a big gap.

That gap would 'break' things if it was at the throat, but since it's quite a distance from the throat, it's not a huge deal. *Measured in the car, this waveguide goes down to 250hz*


Oddly enough, this often means that ULTRA small waveguides and horns go lower than large ones. (Remember, the idea isn't to design a horn and stuff it in the car. *The idea is to take a look at your car, then make a horn that matches some existing boundary.*









For instance, in this pic of a Honda Accord, you'll notice that the dash makes a pretty nice horn.









A horn that's deep and short, like this one, will actually work worse than one that's extremely shallow. The reason is that you get a sudden discontinuity as the vertical angle changes, at the point where the mouth of the horn transitions to the dash.

Again, the idea is to look at the dash as a part of the horn itself.

Weltersys over at diyaudio did some interesting experiments with this stuff - he did some measurements on a horn-loaded array where he found that he could remove TWO of the four walls of the horn, and the frequency response barely changed(!)

If you see where I'm going with this, you'll understand that the dash of the car is basically acting like that - it's like a horn with one of the four sides missing.

That's how you get horns to do 250hz in a car.


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## Eric Stevens

Patrick,

Phenolic is one of the best materials you could use for a midrange compression driver, its just too heavy to play up high. Done right and used correctly it is a very good material for a compression driver.

Eric


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## Navy Chief

I really appreciate all the input, this is very valuable knowledge. Know that I know the how, the question really is why. Does running a horn low (500hz) with the need for a seperate tweeter perform better than a horn that picks up at a higher frequency (1000hz) but will fill all the way up to 20k. Just really trying to decide if this is even worth trying regardless of whether it is achievable. Are there any real gains in going this route. Also it looks like I am going to put the horns in my truck not my SUV. It is a 1979 Chevy truck with a curved metal lower dash so I am not sure how it will work out. I am considering a full custom dash just to make it work.


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## thehatedguy

Once you hear a good compression driver that can play midrange, it will be all that you think about wanting to put in your car.


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## Patrick Bateman

Eric Stevens said:


> Patrick,
> 
> Phenolic is one of the best materials you could use for a midrange compression driver, its just too heavy to play up high. Done right and used correctly it is a very good material for a compression driver.
> 
> Eric


I feel like the original poster is right where I was, when I first started down this path to madness, about 1997 or so. At the time, I'd basically heard a few cars with horns, and really like what I heard. But at the same time, I could tell that the gear that was out there was readily available for less. For instance, the USD Audio horns were obviously re-badged from someone else.

*At that point, I started trying to figure out how to make my own.*

But one of the first noob mistakes I made was that I used cheap compression drivers. I stand by what I said - *cheap compression drivers sound mostly awful.*

I think the original poster is on the right track. As Jason noted, compression drivers playing at midrange frequencies can sound amazing.

But it took literally YEARS to figure out why that is, and I'd hate to see the OP buy a pair of cheap compression drivers and give up on HLCDs due to the crummy sound of low-budget Selenium.

Then again, you never know... My first compression driver was a Selenium! (is this the pot calling the kettle black or what?)

I still have 'em in a closet somewhere... Bought them from Speaker City in Burbank. They're nowhere near as good as the ones I use now, but they were good enough to keep me invested in the hobby.


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## thehatedguy

Actually the Selenium D405 with the phenolic diaphragm is considered by many to be one of the best midrange use compression drivers in recent times. But they made "progress" and swapped it out to a titanium diaphragm.

Want a nice midrange compression driver? The Community M200 is one of THE best. but because it doesn't have a phase plug, you will need a tweeter for it past 4k or so.


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## Patrick Bateman

Navy Chief said:


> I really appreciate all the input, this is very valuable knowledge. Know that I know the how, the question really is why. Does running a horn low (500hz) with the need for a seperate tweeter perform better than a horn that picks up at a higher frequency (1000hz) but will fill all the way up to 20k. Just really trying to decide if this is even worth trying regardless of whether it is achievable. Are there any real gains in going this route. Also it looks like I am going to put the horns in my truck not my SUV. It is a 1979 Chevy truck with a curved metal lower dash so I am not sure how it will work out. I am considering a full custom dash just to make it work.


IMHO, the magic of HLCDs is due to a couple things. The first is huge headroom, the second is controlling the wavefront that's launched off the diaphragm of the driver. Basically eliminating early reflections, and putting that wavefront in a specific place (directivity control.)









Here's a TAD compression driver, sawed in half. Saw this at CES and had to take a pic. It goes down to 500hz. You'll see there's a small sealed chamber at the top, and a phase plug that takes the wavefront off the diaphragm and focuses it into the throat.

With a bit of work, you can get the advantages of a big expensive compression driver, *without dropping $2000 on a pair of TADs.*

First off, use the car to your advantage. For instance, a 500hz waveguide needs a mouth that's 68cm in diameter (about 27".) If you look at that cavity under your dash, you'll see it's just about perfect.* This is why people have such great results when they stick a high efficiency eight or ten there in the kicks. The cavity under the dash horn loads the woofer, especially if you located the kick panel so that it's deep in the corner of the car.

See where I'm going with this? You don't NEED a $1000 TAD, or a huge horn. Just get yourself some nice high efficiency mids, and stick 'em in the kicks. The car will do the rest.

Integration with the high frequencies can be tricky. The directivity will be different at the crossover point, and the sound from the HLCD will seem to emanate from a point that's about a foot forward of the mids in the kicks.

That's why I'm always screwing around with Unity horns.

As for the advantages of HLCDs, *yes*, they're very real. Once you hear a system with real headroom, and an ability to 'see' into the recording the way a good horn can, conventional loudspeakers will sound hopelessly artificial.

* if that doesn't make sense, it's perfect because the dimensions are right. You want a mouth that's about 68cm wide and about 68cm tall. It's not good enough that it's wide enough; it has to be both wide AND tall. If the mouth is too small, the group delay curve goes to hell and you get that 'horn honk' that's so nasty. You can hear that 'horn honk' on a lot of car horns if the xover point is too low. To do 500hz, you need a big mouth.


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## Patrick Bateman

thehatedguy said:


> Actually the Selenium D405 with the phenolic diaphragm is considered by many to be one of the best midrange use compression drivers in recent times. But they made "progress" and swapped it out to a titanium diaphragm.
> 
> Want a nice midrange compression driver? The Community M200 is one of THE best. but because it doesn't have a phase plug, you will need a tweeter for it past 4k or so.


I took a minute to read some reviews on the D250, and it definitely has it's fans on Lansing Heritage and Parts Express. My initial replay was definitely a blanket statement meant to scare anyone off from using a cheap compression driver. A lot of the cheap ones are just garbage. This one might be an exception to the rule.










One concern I'd have with this driver is putting together a horn that would work in the car. If you look at this graph of it's response, it would give you three octaves. From 500hz to 4khz. That's a great range - I hate having xovers in the midrange.

But the challenge would be finding a horn that would fit in the car. As noted earlier, it's going to be BIG. Perhaps as big as 68cm x 68cm.

You could horn load them in the kicks, but you'd have to cut a hole in the car. (Due to the depth.)









I've been having some very good results with these ridiculous Goldwood cone tweeters. As a tweeter, they're good to about 1500hz. But you stick an array of these on a Unity horn, and they'll do 250hz.

The reason these ridiculous looking drivers work well on a horn in a car is for a few reasons:


In our cars, we need small drivers, because there's limited space, and limited depth
The air mass in a horn interacts with the mass of our driver. These cheezy cone tweeters have a mass that's virtually nothing, because there's no surround, the diaphragm is ultralight, and there's no coating to weigh it down. What this means is that the cone tweeters behave almost like a ribbon, when they're mounted on a horn.

They're super cheap too. Four of them are less than $40 delivered. You might be shocked at how good they work - I was!


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## thehatedguy

You wouldn't get those large format drivers in a car very easily...and really take full advantage of what they could offer.

Agreed on the points about headroom, etc...that's why I am back looking at compression drivers and waveguides...maybe horns too, but definitely waveguides.

Having a HARD time not getting some BMS 4540Nds or that little Celestion Duke uses.


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## thehatedguy

Unity horns have caught my attention again too.

Having trouble figuring out how to put one high on my door though.


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