Center to Center of Drivers 29" apart in proposed config - Problems??

[Ken L]

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

 

[roddyama]

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.

 

[Ken L]

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 -

 

[GM]

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

 

[ronc]

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.
ron

 

[Ken L]

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

 

[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.
====
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

 

[roddyama]

...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.

 

[slowmotion]

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

 

[slowmotion]

Here's a small hornpic for inspiration

An externally hosted image should be here but it was not working when we last tested it.

 

[Ken L]

Since you have the Behringer why not use digital delay on the dds waveguides?

Could work if I was tri-amping - however, the amp is to be a GM70 "boat anchor" that is massive. I have now collected almost all of he parts. Not practical to add another amp. I am bi-amping with a Crown amp on the bass bins now.

I have thought a number of times about centering the waveguide in the horn - but what holds me back on that is the time alignment part - using the digital delay to time align the bass and the horns has me thoroughly convinced of the benefits of time aligning - Analog passive delay looks like it would be putting too many parts into the signal path.

Were this last year I would just buy the drivers, etc. and give it a shot. However, this year things are down considerably financially, hence the need to make my mistakes in theoretical discussion instead of with my pocketbook.

Which is why I am most appreciative of everyone's input to this thread.

regards

Ken L

PS, Slowmotion, is that your setup in the pics ? Ihave seen that before and thought it was pretty slick

 

[slowmotion]

Could work if I was tri-amping - however, the amp is to be a GM70 "boat anchor" that is massive. I have now collected almost all of he parts. Not practical to add another amp. I am bi-amping with a Crown amp on the bass bins now.


regards

Ken L

Hi Ken

Yes, I know what you mean, these amps tend to get pretty big, you run out of room in a hurry. Please tell us how your GM70 amp turns out, will you?

PS, Slowmotion, is that your setup in the pics ? Ihave seen that before and thought it was pretty slick

Ken, I wish I had something like that.
As far as I know that's a full Goto setup.
I think those horns belongs to someone in Japan,
but I'm not sure. Great inspiration, tho

cheers

 

[Ken L]

Please tell us how your GM70 amp turns out, will you?

Will do. I have heard a very similar one that others have described as a "sonic masterpiece"

I have seriously got to get some stuff completed - one reason I've been looking at drivers.

the Dowdy LLama is debugging hum from my long-humming 12b4 transformer volume control preamp - a proprietary Dowdy design - I have almost all of the parts for the GM70 amp except power transformer for the power supply and filament tranformers, will do initial build on scrap mdf

Finally picked up 75th driver tubes and spares just a few weeks ago -

And need to do updates to the Behringer DCX 2496

I plan to make appropriate interim reports/reviews, but I'm looking forward to that far-off day when it's all completed -

Now if I can keep from getting off on any other tangents - hopefully I can get over the hump and start getting some stuff completed.

Best regards to all who have participated in this thread

Ken L

 

[John Sheerin]

Ken,
I've had decent results with big messes of horns, just moving them forward or backward to get the alignment as close as I could. You always end up with the tweeter way behind the mids and spaced some distance away so you can see the thing around the midrange horn's mouth, but if you get it all aimed at one spot, it can work. I wouldn't want to be trying to do the aligning by ear, though...

For example:
http://ldsg.snippets.org/HORNS/images/4way/stack.jpg
http://ldsg.snippets.org/HORNS/5way.html
This second one should have the midbass horn (on the far right) a few feet forward of where it is, and the sub is something like 15 feet behind the midbass (acoustically), but it still manages to sound good. Hopefully I'll add some digital processing to my arsenal at some point and see what a truly 'aligned' system sound like.

John

 

[Ken L]

Hopefully I'll add some digital processing to my arsenal at some point and see what a truly 'aligned' system sound like.

Thanks for your comments John

For now, I think I'll go with Lowther PM5A's and be done with it. Partly because I don't have time, money and the mental clarity to tinker with it.

As to "truly aligned", I don't know about other frequency ranges, but when I set the delay on my current subs, the results were truly notable.

The Azurahorns sit on top of 14' by 18" by 14" sealed subs - the center to center of the drivers is about 29" apart - I'm crossing to the subs at 145hz 4th order L-R

I put on some tracks with a lot of bass parts and played them while I had my wife spin the knob setting the delay - Initially, you could locate the bass comming from the 12" drivers, as being a physically lower source

However, as more and more delay was gradually implemented - the woofers seemed to be moving upward physically - when the sound from the woofers seemed to be coming from the center of the Azura's, I stopped.

Presumably, this effect is due to the overtones being produced by the 8" in the Azura.

Had I not done it, I doubt that I would have believed how much effect there was.

Actually, I think that doing it by ear was better than measuing and calculating - FWIW, what sounded best was about 15% off from my original calculations and after correcting my calculations for actual distance to my ear, still about 7%

This effort was enough to convince me big time of the benefits of correct time alignment.

regards

Ken L