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[Brian Jojade]

No I dont and I'm still using Windows XP.

Sill using XP and want to see a graphical drawing of how NOT to deploy speakers ever?  I'm not sure I understand the end game here..

[Ivan Beaver]

The biggest comb filtering happens because of 2 speakers set one stage left and one stage right.  The angle the horns spread the sound mostly effects WHERE the comb filtering happens.

The REASON comb filtering happens is because of time delays between when the sound from one speaker hits a position to when the sound from the other speaker hits the same position.  If your speakers are right next to each other, it is of less consequence than when they are separated by 40 feet across a stage.

While the combing is frequency dependent (because different frequencies have different wave lengths) the most obvious filtering happens at lower frequencies.

Not exactly. 

It is not the distance between the horns that is the issue, but rather the LISTENERS distance between them.

The greatest cancellation happens when the levels are the same between the devices.  If 1 device is a good distance away, then it's level will be lower, so the effect of the combfilter will be not as deep.

Also the further away, the lower the point at which the first notch occurs, and the closer together the notches will be.

Here is the math.  The first (lowest freq) will be 1/2 of the difference in arrival times (in terms of freq).  So a 1' difference in arrival time would be a notch around 565 Hz (give or take for elevation etc). 

And each subsequent notch will be at the rate or 565Hz.  So the next ones would be @1130hz, 1695Hz, 2260 etc.

While the lower notches can appear as holes in the response, the higher ones appear as a "dulling" of the sound, as if a little boost on the top end will fix it.  But it doesn't.  You can't fix time issues with eq.

Even a small offset of arrival times (as in small parts of an inch or a few mm) can make a noticeable difference.

[Ivan Beaver]

24" center to center. DDS CFD 2-60X Pro horns.  Radian 850PB 2" drivers. Operating frequency 1500-16K. Cabinets are 24" square.

http://usspeaker.com/dds%20cfd-2-60x%20pro-1.htm

http://usspeaker.com/radian%20850pb-1.htm

I just noticed that you said in the original post that the horns were not splayed.

The combfiltering will be different at different distances (horizontal) from the horns.  So "it depends" applies a lot here. 

Different seats will have have different notches based on distance, and different notches based on freq, that is dependent upon the actual pattern control of the horn at particular freq and how much each horn contributes to the overall energy at a particular freq.

So for the particular horns you referenced, (using the basic horn pattern loss formula)   freq=1,000,000/pattern in degrees/horn exit in inches 

You have a pattern loss freq of 877Hz in the 60* part of the pattern and 1500Hz in the 40* part of the horn.  So with your 1500Hz xover, you should be good in general terms of pattern control being what it says, but it also depends on the ACTUAL pattern of the horn.  That can vary a bit.

What you are asking for is a lot of data points for somebody (who has a good bit of time) to calculate, or a bunch of different screen captures to show the different notching at different freq vs different seats.

But suffice it to say, if you have those horns, sitting next to each other, all facing the same direction, you WILL have noticeable combfiltering that will shift as you move around.

[Scott Holtzman]

Sill using XP and want to see a graphical drawing of how NOT to deploy speakers ever?  I'm not sure I understand the end game here..

How are you guys possibly using XP?  The browsers have not been upgraded in so long you must be incredibly limited in the web sites you can access, how are you accessing this one?  It uses a cipher that is not supported in XP.

[Jeff Bankston]

How are you guys possibly using XP?  The browsers have not been upgraded in so long you must be incredibly limited in the web sites you can access, how are you accessing this one?  It uses a cipher that is not supported in XP.

Firefox still works for web surfing. But there are programs that will not download to xp anymore. I didnt like 7 , vista , and 8. I was thinking of getting a 10 pc. Now I hear there is 11. 11 must be really loud.

[Scott Holtzman]

Firefox still works for web surfing. But there are programs that will not download to xp anymore. I didnt like 7 , vista , and 8. I was thinking of getting a 10 pc. Now I hear there is 11. 11 must be really loud.

11 didn't really deserve a new version number.  It is a nice visual upgrade but if you are not using Microsoft's SSO universe (microsoft.net) or advanced features like hypervisors and sandboxing there is not much to see.  You also have to buy pro if you want a local login.  I am not quite sure how that works on airplanes yet I was not interested enough to load the developers release.


Windows 10 without a doubt is Microsoft's finest effort.  It brought a lot of new technology and security forward.  It's easy and visually reasonable.  I personally don't understand the the angst of end users and OS's, they blend into the background.  When I upgraded my wife's computer from 7 to 10 it took her a week until she said I though it changed quite a bit. 


90% of what we do is in browsers today anyway,  I love the profiles that let me take my browser experience from computer to phone to work computer to tablet to laptop seamlessly. 

[Russell Ault]

{...} I am not quite sure how that works on airplanes {...}

As a Microsoft-hosted-SSO naysayer I've never tried it, but I would ASSume offline login works similarly to "old-fashioned" Active Directory (i.e. credential caching).

-Russ

[Scott Bolt]

Not exactly. 

It is not the distance between the horns that is the issue, but rather the LISTENERS distance between them.

The greatest cancellation happens when the levels are the same between the devices.  If 1 device is a good distance away, then it's level will be lower, so the effect of the combfilter will be not as deep.

Also the further away, the lower the point at which the first notch occurs, and the closer together the notches will be.

Here is the math.  The first (lowest freq) will be 1/2 of the difference in arrival times (in terms of freq).  So a 1' difference in arrival time would be a notch around 565 Hz (give or take for elevation etc). 

And each subsequent notch will be at the rate or 565Hz.  So the next ones would be @1130hz, 1695Hz, 2260 etc.

While the lower notches can appear as holes in the response, the higher ones appear as a "dulling" of the sound, as if a little boost on the top end will fix it.  But it doesn't.  You can't fix time issues with eq.

Even a small offset of arrival times (as in small parts of an inch or a few mm) can make a noticeable difference.

Ivan is (of course) correct.  The actual distance that matters is the distance from each speaker to the listeners ears.  He is also quite correct that you can't "fix" time issues with eq (although many have tried).

Still, it has been my experience that pretty much any indoor venue (with some few exceptions) reflections  and room dynamics are going to be a much bigger problem than comb filtering.  The utility of putting tops over subs stage left and right has always won out in my book.  Sure, there are more sonically pure ways to deploy a simple PA system; however, they are mostly not worth the lost utility and ease of setup indoors due to limited possible layouts of speakers.

Outdoors .... different story altogether.

[Craig Hauber]

How are you guys possibly using XP?  The browsers have not been upgraded in so long you must be incredibly limited in the web sites you can access, how are you accessing this one?  It uses a cipher that is not supported in XP.

I know quite a few folks who's PC is still XP
-it just sits in the corner collecting dust while they use an android/apple tablets and their phones!

But seriously, XP is dead for anything requiring online use.
I have a dedicated older laptop I use for older serial-port managed devices with all their control software loaded on it.  It never sees the 'net but I wish modern windows was as simple and responsive as that machine feels!

[Paul Johnson]

NONE of my computers here will upgrade to Windows 11 - my i7 4000 series chips that I'm very happy with, performance wise are not acceptable - so Windows 10 should apparently be fine till 2025. I still have XP on a Panasonic tough book for a specific purpose and Firefox seems fine?

[ProSoundWeb Community]