# What high-pass crossover frequency are you using?



## fish

I'm curious what everyone who's running or has run horns are using for your high-pass crossover frequency? Also slope, driver, & horn body.

If you would like to add any other crossover points & slopes you tried along the way & your comments feel free.


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## DanMan

I cross my ID Minibody Ultras at 1200hz 24db LR. My ID x69 drivers are lowpassed also 1200hz 24db LR. These points I never find a need to mess with, unlike the mids HP and subs LP.


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## [email protected]

Taking this a little more in depth...

Larger horns are supposed to reproduce lower frequencies. Is the bottom line always the manu spec xover frequency? Do you look at the response curve and choose a Xdb down point as the cutoff? I know power handling would be a variable, because at some point you would reach the mechanical/electrical limits of the driver...

So, how do you know the safest point?


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## Mic10is

JOey Knapp said:


> Taking this a little more in depth...
> 
> Larger horns are supposed to reproduce lower frequencies. Is the bottom line always the manu spec xover frequency? Do you look at the response curve and choose a Xdb down point as the cutoff? I know power handling would be a variable, because at some point you would reach the mechanical/electrical limits of the driver...
> 
> So, how do you know the safest point?


more about reaching the "mechanical" limits of the horn itself. some compression drivers will play lower, but the horn simply isnt large enough to reproduce that low.
an example, I once tried my mini horns at 850hz using the Cd1Pro and cd2 mylars. It sounded ok, but a few freqs REALLY jumped out and sounded like a freakin gun shot went off...not a comfortable thing to hear driving down the road...

Larger horns like the ID full body have been used as low as 500hz or so with a 24db slope. Typically crossed around 650hz.

Mini horns XO point typically start around 1000 and up, most commonly 1.2k

I used mini horns pretty much exclusively when using horns (won 2 world finals w horns and 3 2nd place without...)
and have always used the ID mini horns bc they have a much harder crossfire pattern to help really solidify the center image and crossover point was 1150 to 1200hz at 24db/octave.


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## req

ive been running my image dynamics CD2's with ID mini lenses at about 1200hz @ 24db for a while, i recently was messing around and put them down at around 900hz @ 30db to see if it changed much and i couldnt notice a whole lot. *shrug*


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## atsaubrey

currently I run my CD2 full bodies at 800hz at 24db, played them as low as 600hz and as high as 1200hz, 800hz for meseems to be the "sweet" spot.


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## wickedpsi

i ran my USD bc300's at 750hz 24db.


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## subwoofery

1.6kHz for me on CD1e V.3 full horns. Played with 1k and 1.2k but as Mic pointed out, some notes just JUMPED from the windshield and other notes had some cracking noise. 

I tried horns for the first time end of 2008 and I felt like a little kid. Worth every penny (bought MSRP from ID) IMHO. 

Bought a used CD2 neo to be used in my future car. 

Kelvin 

PS: hope this forum gets some interests. Would like to thank Mic, Aubrey, Jason and the other for my future stupid questions on horns


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## Horsemanwill

i've got my full size ultra's crossed at [email protected] i think may be lower.


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## raamaudio

Full size neo ID, [email protected] as well


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## Brian_smith06

Mine are on the floor looking at me asking why they are on the floor and not in my car:surprised:


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## Patrick Bateman

Mic10is said:


> more about reaching the "mechanical" limits of the horn itself. some compression drivers will play lower, but the horn simply isnt large enough to reproduce that low.
> an example, I once tried my mini horns at 850hz using the Cd1Pro and cd2 mylars. It sounded ok, but a few freqs REALLY jumped out and sounded like a freakin gun shot went off...not a comfortable thing to hear driving down the road...
> 
> Larger horns like the ID full body have been used as low as 500hz or so with a 24db slope. Typically crossed around 650hz.
> 
> Mini horns XO point typically start around 1000 and up, most commonly 1.2k
> 
> I used mini horns pretty much exclusively when using horns (won 2 world finals w horns and 3 2nd place without...)
> and have always used the ID mini horns bc they have a much harder crossfire pattern to help really solidify the center image and crossover point was 1150 to 1200hz at 24db/octave.


Good observation. One of the reasons that I run Unity horns instead of conventional horns is that the Unity horns aren't xmax limited like a conventional.

IE, a conventional horn may have a sensitivity of 110dB, but it's a moot point if the suspension on the compression driver can't accommodate more than a few micrometers of travel.

This generally isn't a problem with unity horns, since the woofers on the horn have more surface area AND more xmax than a compression driver.


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## fredswain

We had found that with the larger bodied ID horns, we could physically cross them over decently low, depending on the vehicle, but that power handling really suffered. Another problem was that at these lower requencies, below about 1200 hz or so, the frequency response peaks and dips really started to move around at varying distances off axis. In other words you might have a dip at 1000 hz on axis but move off axis 20 degrees and suddenly that dip might be at 900 instead and potentially move around more at different angles. This made it harder to equalize from any position other than a single point. This is why many judges complained that the sound stage would move if they did with horns. We tended to adjust the crossover until this effect was minimized and tuned from there. As a result our crossover points weren't based on how low the horn physically played but rather where the soundstage was stable and where power handing was good. Typically that was automatically resolved when the stage issues were taken care of. 3K was the next big hurdle.


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## Patrick Bateman

req said:


> ive been running my image dynamics CD2's with ID mini lenses at about 1200hz @ 24db for a while, i recently was messing around and put them down at around 900hz @ 30db to see if it changed much and i couldnt notice a whole lot. *shrug*












Horns only play over a narrow frequency, so that's why tweaking crossover points isn't as audible as it would be with a conventional driver. The output of the compression driver is dropping like a rock on the low end, so shifting the crossover point a quarter of an octave barely makes an audible difference. Due to the inherent rolloff, you're going from a 48db/octave rolloff to a 54dB/octave rolloff.

I'm toying with the idea of a three way Unity for my car, should be interesting to see if I can do 80hz-20khz on one horn :O


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## thehatedguy

Rule of thumb with horns is to keep them 1.5-2x above the flare frequency. A steeper crossover will let you get closer down to the Fc of the flare rate, and some horns can be run closer to the Fc than others (exponential can get closer to Fc than tractrix). Why? Like a ported enclosure, the horn will unload below that frequency providing to air load for the driver. Horns are impedance transformers. The air inside the car loads the horns which loads the drivers. Below the Fc of the horn there is no loading and the driver is essentially shooting straight through the horn.

With that said, I took my large body ID horns down to 600 on a 48 dB slope. I had plans on taking them down closer to the Fc (big bodies are about 380 hertz- notice the favorite spots are about 800 hz which is nearly 2x) at 450 with the large format drivers I had.


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## fury

Last night I measured my ID full bodies with BMS4550's, and they drop off steeply at 1200hz.
Granted they are running in my room and not coupling to the dash of a car.

I cant imagine running a car horn much lower then 1khz without a driver like a TAD2001 and a massive horn...


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## thehatedguy

Well some horns need certain degrees of boundary loading to further extend the mouth of the horn. This is taken into account in the design of the horn...that is how you can shrink the size of the horn. Usually in the house this is done with bass and midbass horns.


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## Patrick Bateman

fury said:


> Last night I measured my ID full bodies with BMS4550's, and they drop off steeply at 1200hz.
> Granted they are running in my room and not coupling to the dash of a car.
> 
> I cant imagine running a car horn much lower then 1khz without a driver like a TAD2001 and a massive horn...


Yep... Horns are bandpass devices. Grasping that really helped me understand how to make them small. Trying to squeeze four or five octaves out of a horn is like trying to get a bandpass subwoofer to play from 20hz to 500hz. It's *possible*, but you're going to have to throw away a lot of efficiency to do it.










This is the response of a waveguide... See how it's only flat from 1khz to 4khz? Just two octaves?

That's because a horn focuses that high frequency energy into a beam. So the horn may be flat on-axis, but it's only because it's beaming. The *power response* of the two devices may well be identical.

I'd also argue that this is why waveguides have such magical imaging.


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## fredswain

Since totally flat also sounds completely dull and boring, sloping downwards a little bit as frequency increases is a desirable attribute provided it doesn't slope off too quickly. That response as shown looks perfectly acceptable from about 1.8K all the way up. A super tweeter could perhaps be used up over 10K but with so little sound energy up there it probably isn't needed. I don't see anything wrong with that which eq couldn't take care of. It needs some adjustment but it definitely isn't only usable from 1K to 4K. Not by a long shot. This of course isn't taking response at different axes into account and I'm basing this purely on that graph alone for example sake.


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## pickup1

800 thru factory passive.


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