Placement of Horizontal Tweeter

[raypenn]

I re-read Seadog's thread on his 511 k-horn project, and it looks like he placed the tweeters on the outboard side of each speaker.

For horizontal tweeters, is there any advantage to placing the tweeters inboard or outboard (or both left or both right)?

Thanks.

[Marvel]

My personal opinion (really) would be to put the tweeters on the inside. You might get more side reflections (from wall) with them on the outside, causing more smear.

My small Alesis bookshelk monitors says to put the tweeters to the inside when placing them horizonally, to improve imaging. I had them the other way for a long time. It seems counter-intuitive to put the most directional freqeuncies on the inside, where they are closer together. It was easy to move these as they only weigh about 20 pounds each. Khorns would be harder to move (even just moving the tops).

[D-MAN]

My opinion is to put the tweeters on the OUTSIDE to increase the width and depth of the soundstage. This also works quite well for smaller rooms, too.

The first-reflections from the near sidewalls need absorbtion treatment, usually.

DM

[DrWho]

Usually you get less side-wall reflections when you move the speaker closer to the wall because it's easier to get the speaker aimed away from the wall. If you were perfectly tucked into the corner and had a perfect 90 degree dispersion, you would get no reflections at all. I'm also a fan of putting the tweeters on the outside because it widens the soundstage (as already mentioned).

[Marvel]

I've had mine both ways... and you can do what you want. I have read this theory from more than one source, but here is the explanation from Alesis on their bookshelf monitors (they say tweeters in):

The classic studio monitor layout used to be that the tweeters be placed to

the outside of a horizontally-oriented speaker. In the past, this configuration was actually beneficial in time aligning the tweeter with the woofer if the cabinets were not toed-in toward the listener. However, this configuration is highly prone to comb filtering effects if the listeners head is moved from side-to-side while mixing. This comb filtering causes the mid-to-high frequency tones to get louder, then softer, then louder again as you move your head from side-to-side, making it very confusing when trying to mix with precision.

Some people still believe that stereo separation is improved with tweeters

to the outside, but this is advice left over from the early days (the sixties) of stereo recordings when correct stereo often meant a complete hard right or hard left placement of an instrument (or singer). As stereo mixing techniques changed toward placing the vocalist (for example) in the center, the old tweeters-out orientation would indeed widen the image if ones head were kept in the exact center position. But this set-up proves to be very tiring, very quickly for the recording engineer. And, to others who are listening to the mix from either side of the engineer, the sound will seem to be coming primarily from the speaker closest to them.

[D-MAN]

Well, I suppose that's ok for (gasp) direct radiators...

Actually, with ESN's comb-filtering pretty much becomes a non-issue. You'll be amazed...

I've tried it both ways, too, and believe me, with horns the thing changes because they have a more controlled dispersion characteristic than direct radiators.

I never could get my direct radiators to sound even half-way decent in my room regardless of the positions I tried. Hence, the horns. It's way, way better.

DM

[DrWho]

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On 7/7/2005 3:51:09 PM Marvel wrote:

As stereo mixing techniques changed toward placing the vocalist (for example) in the center, the old tweeters-out orientation would indeed widen the image if ones head were kept in the exact center position. But this set-up proves to be very tiring, very quickly for the recording engineer. And, to others who are listening to the mix from either side of the engineer, the sound will seem to be coming primarily from the speaker closest to them.

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But that example is true no matter which way you have the tweeter oriented...if you're off axis and something is mixed down the middle, then of course it sounds like it's coming from the speaker closest to you!

When in the studio, I usually place my speakers upright so that I don't have any variations in placement when I move my head around...but if something needs to be placed so specifically, then I'll just bust out the headphones and place it that way. In all seriousness, nobody is ever that exact in the studio (and if they claim to be, then they're full of crap).

I just wanted to mention that the listening done in the studio is way different from the listening being done at home (or when one is trying to enjoy the music instead of rip it apart). I would bet that 90% of the time putting the tweeters on the outside sounds better to most people...the rare times that it doesn't is probably when the speakers are so far apart that the middle starts to sound empty.

In an ideal world the tweeters would be mounted along the symetric line going down the front of the cabinet. Is there any reason the tweeters in question couldn't be mounted on the middle of the khorn, perhaps even directly below the midrange driver? Keeping the drivers as close to each other as possible is probably one of the most important details...it can even have a large effect on the crossover design.

[Marvel]

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On 7/7/2005 6:14:28 PM DrWho wrote:

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In an ideal world the tweeters would be mounted along the symetric line going down the front of the cabinet. Is there any reason the tweeters in question couldn't be mounted on the middle of the khorn, perhaps even directly below the midrange driver? Keeping the drivers as close to each other as possible is probably one of the most important details...it can even have a large effect on the crossover design.

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I was actually planning on putting a slot tweeter (like a JBL 2405) just below the mid horn on the cabinets I want to build this summer. Unfortunately, summer is going by pretty darn fast. The 2405 has a little bit better horizontal dispersion than the 'baby cheeks' 2404. Less vertical dispersion though.

...and you are right about the difference between mixing and listening for the fun of it.

[formica]

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On 7/7/2005 3:51:09 PM Marvel wrote:

The “classic” studio monitor layout used to be that the tweeters be placed to the outside of a horizontally-oriented speaker. ... As stereo mixing techniques changed toward placing the vocalist (for example) in the center, the old “tweeters-out” orientation would indeed widen the image if one’s head were kept in the exact center position. But this set-up proves to be very tiring, very quickly for the recording engineer.

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Just wanted to add that studio listening is done "near field"... so that relative distance differences between left and right channels are inherently greater than most in room situations.

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On 7/7/2005 6:14:28 PM DrWho wrote:

In an ideal world the tweeters would be mounted along the symetric line going down the front of the cabinet...

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I'd been curious about that. The physics seem to point to that conclusion, and even PWK chose placing the tweeters above ear level rather than off centre in the tall Khorn.

I was just wondering HOW MUCH is lost by placing them the side, like Dman and ALK have done? I can understand their decision... as it becomes more of a convenience / aesthetics factor, esp if someone wants to add a pair of baby-cheeks.

After all, people seem to love the vertical Cornwalls, even though it seems contrary to logic.

Rob

[D-MAN]

Rob, nothing is "lost" by tweeter side placement, IMO.

If I had my druthers, I would go for tweeter centered and diaphragm aligned with the midrange driver diaphragm, but that is another "animal" as far as top cabinets are concerned. And at the height determined by both bass and top cabinet, that can be problematic, also. The best approach would be to mount the tweeter on a rod that sticks up from the top cabinet at the appropriate point to effectively clear the top cabinet edges when viewed form the seated listening position. A "tilting" mechanism on the tweeter mount could allow for a direct line-of-sight to the tweeter for better dispersion. The further away one sits, the shorter the rod used and the less tilt required.

In side mounting the tweeter, the dispersion pattern source is just from another point, and that would of course effect the reflectivity issues of the room. The horns are horizontally aligned on the same axis.

Room treatments on the outer wall "first reflection points" are used to reduce reflections due to the close proximity of the tweeter. The effect is a wider soundstage presentation in the case of "outer-side" placement like mine.

DM

[DrWho]

It seems some of the specs regarding the drivers used in the verticle cornwall indicate that the driver has a wider horizontal dispersion when mounted vertically.

[formica]

I guess wall treatment becomes more essential with the side mounting. How about comb filtering around the x-over point?

I was considering eventually refinishing / modifying a Khorn similarly to the composite horned Jubilee, which I believe is the V. Klipsch home. Problem with the three way is it wouldn't look as elegant with the tweeter at the top, esp if I get my hands on some JBL baby-cheeks. Looks count too, you know...

I could always mock it up once I get there...

Rob

[D-MAN]

I skipped gleefully around the whole comb-filtering issue when I got the ESN's...

DM

[DrWho]

What's behind the front face of the khorn near the top? Wouldn't there be enough room to cut out a hole and put the tweeter flush with the midrange? I don't suppose any of you guys with khorns would want to chop them up to find out

[formica]

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On 7/14/2005 10:07:04 PM DrWho wrote:

What's behind the front face of the khorn near the top?

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It's actually part of the horn... there is a 45o splinter at this first fold.

and here is a closeup of the splinter... Qman (not Dman) actually surface mounted them at that level. Not as pretty, but definitely no compromises...

Rob

PS: BTW' picture credits to John Warren

[Marvel]

You could do this on the Jubilee style, where the horn goes horizontal. It would be like looing at the back of a LaScala. The corner horn I plan on building is done this way, and I am contemplating putting a JBL 2405 there. It is a ring radiator with a slot type of horn, with the cutout a circle. Has a little bit better repsonse than the baby cheeks 2404 as well. Unfortunately, the price is about the same.

[D-MAN]

I think that it is important to put the high-frequency horn (and the midrange horns) where it can be turned, that is, in the top cabinet (or just on top like a turret)so that you can adjust the dispersion angle and get better results in a less-than-perfect listening space.

Mounting these to the bass cabinet itself will lock you in to the room dimensions in a non-adjustable manner.

Some food for thought...

DM

[jim-analog]

Greetings,

Just an FYI, I had built up a pair of boxes as miniatures of the Khorn top hat to enclose my EV-T350 tweeters. This allowed them to be oriented vertically for better dispersion and also allows for front to back position adjustment in an attempt to time align them with the mid horn. Seemed to sound better to me, but I don't think there were any measurable differences. It does look cool though. I'll post a link to pix when I can get them up.

Regards, Jim