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Old 31st October 2003, 06:38 PM   #1
Ken L is offline Ken L  United States
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Default Center to Center of Drivers 29" apart in proposed config - Problems??

Well, my latest speaker system configuration is to use

http://www.ddshorns.com/eng1-90.htm

10" waveguides with Beyma CP385ND 1" compression drivers

along with the 38" wide Azurahorns with FE208EZ Sigmas.

Minimum center to center distance fo the drivers here is about 24" due to the size of the horns - to get full dispersion from the waveguides and move them back to time align adds another 5 inches or so.

Should this work OK in a room 14x24??

I realize this distance is pretty far apart and will cause certain nulls and dispersion problems.

Frankly, the calculations and processing of all the data I can find on this subject are beyond me at this point.

I plan to use the Digital crossover to select crossover points and slopes by trial and error, selecting them by ear.

As I review this prior to ordering the Beymas I realize that this is the only part of this that I don't understand and feel comfortable with.

So please let me know your thoughts on this - I know we've got some pretty sharp speaker people around here.

Regards

Ken L
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Old 1st November 2003, 03:09 AM   #2
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Ken,

Sorry I don't have direct experience with the Azurahorns, but some thought do arise if you don't mind.

The Rane AC22 (2-way) or AC23 (3-way) are often available on eBay selling between $100 and $200. They have an adjustable time delay you could play with to electronicly time align the two horns.

Another way to gain some time alignment is to mount the left upper horn at about 11:00 WRT the lower horn and the right upper horn at about 1:00 WRT the lower horn. Than face the speakers a little outboard of the center listening position. This will provide a few inches of offset between the upper and lower horns. You can also play with the fore and aft tilt of the speakers to adjust the effects of lobing.

Just some thoughts.
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Old 1st November 2003, 08:35 PM   #3
Ken L is offline Ken L  United States
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Quote:
Originally posted by roddyama
Ken,

Another way to gain some time alignment is to mount the left upper horn at about 11:00 WRT the lower horn and the right upper horn at about 1:00 WRT the lower horn. Than face the speakers a little outboard of the center listening position. This will provide a few inches of offset between the upper and lower horns
Thanks Roddy!

I hadn't thought of the xtra inches there, and those little things do add up.

GM sent me an e-mail where he suggested a slight tilt in the larger horn to also get better time alignment and less comb filtering - a little tilt will also let me overlap the edges of the horns and get the center to center distance down to about 22 inches, which seems far more acceptable to me

With both of these suggestions, I should be able to minimize the problem down to feasible levels -

Thanks for your input -

You and GM are putting me on the right track.

Now I've gotta finish getting the cash together. But I wanted to make sure I had it sorted out pretty well before I actually started buying the drivers -
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Old 1st November 2003, 08:58 PM   #4
GM is offline GM  United States
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Hey Rodd, since Ken referenced my response to his private request, here's my response:

This is what I hate about round horns, they wind up so far apart there's no
hope of a coherent sound until you're sitting so far away you need a small
auditorium. Installed prosound gets around it somewhat by placing the
drivers as close as possible and raising/tilting the array down at the
audience, but most homes don't have tall enough ceilings to do it.

The closest you can come is to array them either diagonally or horizontally
(HF/mids/LF--seating--LF/mids/HF) to give some time delay and blurr the
'marching' effect that drivers audibly displaced in time causes and hope
there's enough digital delay adjustment to make up the rest. What I'm
referring to is what my system or any big vertical array suffers from, when
the music has a rising or falling scale, it marches up or down the array,
all slightly blurred. Very distracting. Also, there's the excessive off axis
comb filtering that occurs. No biggie if you don't mind a narrow sweet spot,
like for one person only until you can get far enough away.

That said, if the bass/HF XO points are low/high enough to be outside our
keen hearing acuity BW, and steep slopes to keep them away, the room should
take care of the rest. Assuming 4th order, the Azura needs to be ~flat from
100-10kHz, so can it be EQ'd for this much BW and still have enough
efficiency?

GM
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Old 1st November 2003, 09:11 PM   #5
ronc is offline ronc  United States
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I have even noticed this on single driver horns.My first set of horns (Fe-167.not my design) had the driver mounted >18" from the mouth and no amount of changing stuffing would get rid of that mechanical crossover sound.
On GMs advice i design my horns now with the driver as being right at the upper flare of the mouth(too hard wih my design to get it in the mouth) and there is no crossover sound and any transision of mouth to driver sounds unified.
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Old 2nd November 2003, 02:07 AM   #6
Ken L is offline Ken L  United States
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Quote:
Originally posted by GM
This is what I hate about round horns, they wind up so far apart there's no hope of a coherent sound until you're sitting so far away you need a small auditorium. GM
Ummm, well - didn't mean to misquote you or leave anything out GM - when I read your e-mail the part about tilting stuck with me.

Anyhow, I've been playing with tilitng the Azura's/dds waveguides and trying to cluster the horns and the woofer on the sub - I've got something that appears somewhat better in terms of driver distances, but then the diaphragm on the 1" compression driver is about 14" forward of the dust cover over the voice coil - if I pull the DDS guide back that much, then I have to move it out 3 or 4 inches or the Azura blocks a goodly portion of it. No digital delay on this one, it'll have to be passive crossover.

Soooooo - I'm now wondering if this configuration is worth it -

And if I might not be better off just to put a pair of Lowther PM5A's in and be done with it.

Without doubt, the Azura's are _big_round_horns_, and were intended to be used with FR single drivers - perhaps I'm off on a bad tangent trying to do a three waveguide setup with one?

Regards

Ken L
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Old 2nd November 2003, 06:30 AM   #7
GM is offline GM  United States
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>Ummm, well - didn't mean to misquote you or leave anything out GM - when I read your e-mail the part about tilting stuck with me.
====
Understood. Some folks are 'funny' about the publishing of private responses, even if on-topic, but since you referenced it, I figured it might be of use to others and clarify my remark to Rodd if he was interested.
====
>Anyhow, I've been playing with tilitng the Azura's/dds waveguides and trying to cluster the horns and the woofer on the sub - I've got something that appears somewhat better in terms of driver distances, but then the diaphragm on the 1" compression driver is about 14" forward of the dust cover over the voice coil - if I pull the DDS guide back that much, then I have to move it out 3 or 4 inches or the Azura blocks a goodly portion of it. No digital delay on this one, it'll have to be passive crossover.

>Soooooo - I'm now wondering if this configuration is worth it -
====
I doubt it, as I implied, digital delay is required since AFAIK the horn mouths would need to be flush in your case.
====
>And if I might not be better off just to put a pair of Lowther PM5A's in and be done with it.

>Without doubt, the Azura's are _big_round_horns_, and were intended to be used with FR single drivers - perhaps I'm off on a bad tangent trying to do a three waveguide setup with one?
====
FWIW, if I were to do a system with a round FR horn, it would be a two-way with bass bins or horns, and the highest resolution driver available for the rest of the BW, loaded as low as the room permitted WRT length and EQ'd flat in-room rather than adding a tweeter or super tweeter.

GM
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Old 2nd November 2003, 07:30 AM   #8
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Quote:
Originally posted by GM

...clarify my remark to Rodd if he was interested.
GM
Always.

Ken,

I agree with GM, because I too have always had trouble with the idea of round horns. FR systems have their limitations as well. It isn’t easy to make a FR system sound as musical as a good multi-way system. I suspect there are a few reasons for this, but nothing I could quantify from direct experience.

Choosing a FR system over a multi-way system, or visa-versa is to accept one set of compromises over the other. Here again I would have to agree with GM that for a multi-way system, the path you’ve described would be a difficult one. Should you give it up before you get started? I’d say not if you’re willing experiment. Where’s a lot enjoyment in a system that comes together after a lot of hard work. It all depends on what you’re after.
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Old 2nd November 2003, 08:54 AM   #9
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Hi Ken, all

Back when I used Lowthers, I just let the Lowthers go as far up as they could ,
and used some cheap piezo tweeters on top.
Had the Lowthers ( PM2Amk2 ) on a big flat baffle with the
tweeters , and PM6s in big parabolic bass "horns" below 200Hz.
That setup sounded pretty good.

Since you have the Behringer why not use digital delay on the dds waveguides?
You could try putting the dds waveguides in the middle,
with the Azuras on top, or even try the dds inside the opening of the Azuras, might work , or it might not.

cheers

Hmm, tried to attatch a drawing here, didn't work
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Old 2nd November 2003, 09:01 AM   #10
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Here's a small hornpic for inspiration

Click the image to open in full size.
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