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How do you properly set up a horn speaker

Hi- I have a set of Classic audio T1.4 horns that I am setting up - Do horns get set up the same way as regular speakers- I was going to use the cardas method but want to be sure that is fine- Also my room is 15x28 but at the point where the speakers are is a bay window(treated) that jets out to 17 feet so when using the calculator from cardas do I use the 17 feet where the speakers sit or the 15 feet which is the rest of the room- Thanks for the input-
fluffers
millercarbon's avatar
millercarbon
12,531 posts
 
There's no one and done method of speaker placement. Horn or otherwise. Its a process of trying to reach the best (in your judgment!) balance of frequency response and timing. If you go through the process you will probably wind up as I did with pretty much the Cardas arrangement of speakers about 6 feet out from the back wall and about 3 feet out from the sides. But what about "about"?

The really thorough systematic way of doing it is to start somewhere like that, play some bass warble tracks at various frequencies and write down your Radio Shack SPL meter readings with the meter where you will be listening. Which where you will be sitting matters as much as where the speakers will be. So each speaker placement generates several readings as you vary the listening position a foot or so closer or further back for each speaker placement. Of which if you are thorough there will be a lot.

Imagine a grid on the floor under each speaker. You might start 6' out and 3' in. Then 3' 4" in. Then 3' 6". Etc. Then try 6' 6" out by 3' in. You get the idea. Don't forget to check the frequency response at each of your three listening positions for each speaker placement!

Tedious yeah, but you know a better way? There isn't one!

Okay now you got speakers positioned for frequency response. Next you work on imaging. This is where you have to get really nitpicky precise. If your room is symmetrical you can measure from the wall to a corner on each speaker. If not then you will need to use a framing square and straight edge or line. This is also the method you will have to use if your room is asymmetrical in any way. If this sounds beyond anal well sorry, it works. We struggled forever in the Talon Audio room at CES one year until I said hey these conference room walls are FUBAR lets forget them and go to the framing square tape measure method. Boom. Done.

Yeah folks I set up the Talon Audio room at CES one year. Consider that when second-guessing this advice.

Final step is to fine-tune the toe-in. Toe-in varies a lot by speaker type and listener preference. What does not ever vary is that it must be absolutely symmetrical. As little as 1/16" off and you start to lose it. 

The final final step is to double-check toe-in with a laser level. This is because its easier to measure the base (speaker base not speaker bass, oh never mind) but midrange/tweeter level is what counts and this will be off and everything becomes a lot harder if the floor isn't level. Then you get to tweak the speakers to get them level and double-check yet again.

What? You didn't do all this?

Whatever you have now, it will be a whole lot better when you do.
johnk's avatar
johnk
1,973 posts
 
3 of my in home front loaded horn systems are all near rear wall and or corner.  Its one of the benifits of horn ownership. But you wont listen and will just drek it all up by placing like a crazy audiophile and later sell and try something else hey its what most are doing so have at it.
phusis's avatar
phusis
1,118 posts
 
@fluffers --

It seems you've got wonderful speakers - congrats. 

Be pragmatic; pay special attention to advice from someone with actual experience with speakers very similar to yours (i.e.: poster @atmasphere ) or horns in general (i.e.: poster @johnk ). As an owner of horn speakers myself I'll concur with the suggestion to start out with your T1.4's close to the rear wall, and then work from there. Really, don't bother yanking those fine speakers way into the room or theorize too heavily on placement, both of which I believe will be strongly counterproductive. Keep them close to the rear boundary, and toe them in a bit. Then try and fine tune from this outset. 
t_ramey
632 posts
 
This link helped me with setup of my horn speakers. I played with toe in until I was satisfied. 

http://libinst.com/PublicArticles/Setup%20of%20WG%20Speakers.pdf
audiokinesis
2,710 posts
 

@fluffers , you have an absolutely magnificent set of speakers.  Very nice choice.

Here are some general principles that might be worth being aware of:

1.  Early reflections are detrimental to imaging and clarity, and can cause coloration.  The relatively narrow pattern of your T1.4's (in both the horizontal and vertical planes) works in your favor here. 

2.  Late reflections are generally beneficial as long as their spectral balance is similar to the first-arrival sound.   Again, the relatively uniform directivity of your T1.4's (resulting on smooth off-axis sound) works in your favor.

3.  As a general guideline, the "fuzzy dividing line" between "early" and "late" reflections is about 10 milliseconds, during which time a sound wave will travel about 11 feet.

4.  Decorrelation is your friend when it comes to the reverberant field.  If we can get the left speaker's reflections to arrive at the right ear before they arrive at the left ear, that would be great.  When the first reflections arrive at the opposite ear, the ear/brain system tends to interpret them as spaciousness.  When they arrive at the same ear (especially if they are "early"), the ear/brain system tends to interpret them as coloration. 

There is an unorthodox setup geometry that takes advantage of the beneficial radiation pattern of your T1.4's:  Extreme toe-in, such that the speaker axes criss-cross a foot or two in front of the center sweet spot.  I use 45 degrees as a starting point.  This results in negligible early reflection off the near-side wall; instead, each speaker's first significant sidewall reflection will be off the OPPOSITE side wall.  This not only gives a long time-delay, but also gives us decorrelation, as now the left speaker's first sidewall reflection arrives at the right ear, and vice-versa. 

An additional benefit of this aggressive toe-in is an unusually wide sweet spot, with decent soundstaging across a much wider area than you get from a more conventional setup.   You see, the ear localizes sound by two mechanisms:  Arrival time, and intensity.  For the off-centerline listener, the near speaker "wins" arrival time, but the FAR speaker "wins" intensity, because the listener is far off-axis of the near speaker but is very much on-axis of the far speaker, so the two localization mechanisms average out to a certain extent.  The KEY to this is, the response of the near speaker must fall off smoothly and quickly as we move off-axis, and a good horn or waveguide speaker does this (conventional cone-n-dome speakers do not).

So at some point as you are experimenting, you might give this extreme toe-in suggestion a fair chance to win you over.   You might need to adjust how far apart the speakers are, and you want to avoid having reflective objects in between the speakers. 

Regarding soundstage depth and distance out from the wall, your T1.4's will be far more forgiving than most speakers because their radiation pattern doesn't allow much early energy to reach the wall behind them, at least not in the mids and highs (which are what matter the most for imaging).   So you can focus more on what distance from the wall gives the best bass.   Also, as you move the speakers forward you will be increasing the ratio of direct to reverberant energy, and you may find that the imaging becomes more precise but the sense of envelopment is decreased.   So there may be tradeoffs, but my guess is there will also be a "Goldilocks zone". 

Duke

dealer/manufacturer/fan of Classic Audio speakers

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