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Author Topic: What is it which makes a subwoofer "omnidirectional"?  (Read 2877 times)

Mike Henderson

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #10 on: May 17, 2021, 07:51:55 AM »


https://mehlau.net/audio/multisub_geddes/

The EV Eliminator i "Sub" has little low end, and it's 50Hz Fb (Frequency of Box Tuning)will result in "flapping" if you try to get much low end from it.

For additional subs using the same processing as your SB 1000, look for units that match's its Fb of around 30Hz.

Art

Yes guys, I see that now. This will explain why the full range and the sub both are giving the same results as it's the placement of the sub or speakers that's important, thanks for helping me narrow it down!

Than's a great article too [thanks] and it's funny that I just instinctively had followed it's procedures. You've tapped into my next hurdle Art. I realized that I was getting a lot of "punch" bass and not enough depth and I was thinking of adjust the eq and crossover for this but yes, I can expect flapping and vibration issues should I do so.

This is the sub I have had in mind for a while now and should be a good option I think? Or might it be best to get an 18" to get the deeper heavier bass and would a Bass Reflex work or would folded horn be better to push the bass further through the room?

https://eaw.com/wp-content/uploads/2014/01/SBX220_SPECS_rev1.pdf

If I can get it I will try it at the back wall under my stack as normal facing forward first, if that should not work then I will have it face the side wall as I am doing now with the EV full range. Then maybe I can see how it will interact with the EV Sub which is located in the middle of the side wall so I might get the depth from the EAW Dual 12" and the punch from the EV Sub.

« Last Edit: May 17, 2021, 08:01:14 AM by Mike Henderson »
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Tim Weaver

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #11 on: May 17, 2021, 11:40:56 AM »

There won’t be a sub, of any style, that can “push through he room”.

You are dealing with a sub placement issue, not a sub type or amount issue. The placement of the sub is the only thing that can be used to fix this. Well, I guess you could change the size or shape of the room, but other than that you can’t fix it by buying a different sub.


The sub creates a wave. That wave travels to the first big boundary it sees and is reflected back. Now you have two waves, the original and the reflection. They will add together in some spots, and cancel out in some spots. The only thing that can change this is moving the origination location to somewhere more favorable so that the “add together” spot is where you sit to listen.
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Tim Weaver

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #12 on: May 17, 2021, 12:03:58 PM »

Go here. https://www.falstad.com/ripple/

Select 2 sources and see what that does to the coverage vs 1 source. Unfortunately you can’t model stuff inside a room very well, but think of that second (or 3rd,5th, or 39th) source as reflections from your walls.
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Mike Henderson

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #13 on: May 17, 2021, 12:07:22 PM »

There won’t be a sub, of any style, that can “push through he room”.

You are dealing with a sub placement issue, not a sub type or amount issue. The placement of the sub is the only thing that can be used to fix this. Well, I guess you could change the size or shape of the room, but other than that you can’t fix it by buying a different sub.


The sub creates a wave. That wave travels to the first big boundary it sees and is reflected back. Now you have two waves, the original and the reflection. They will add together in some spots, and cancel out in some spots. The only thing that can change this is moving the origination location to somewhere more favorable so that the “add together” spot is where you sit to listen.

Very well explained, thank you very much!

So now my decision will be which will be the best Sub to get to replace the full range EV at the back wall. Should it be 12, 15 or 18" to get the deep bass or the size does not matter as long as the sub's frequency response as Art said goes low enough like close to 30hz?
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Dave Garoutte

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #14 on: May 17, 2021, 12:18:21 PM »

Also remember there are three basic dimensions to the room; L x W x H, all of which can generate modes.
This is why purpose built studios generally have non-parallel walls and ceiling.
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Tim Weaver

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #15 on: May 17, 2021, 12:22:57 PM »

Very well explained, thank you very much!

So now my decision will be which will be the best Sub to get to replace the full range EV at the back wall. Should it be 12, 15 or 18" to get the deep bass or the size does not matter as long as the sub's frequency response as Art said goes low enough like close to 30hz?

This a garage, right? Just for you?

A healthy home theater sub would work a lot better than anything pro audio (until you start spending mega-dollars). Go to Parts Express. Look through their diy sub kits and get the biggest one you can afford. It will play deep and get loud enough for you I’m guessing. It doesn’t matter what size the soeaker is.
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Tim Weaver

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #16 on: May 17, 2021, 12:28:53 PM »

Alternatively get one of Art Welter’s 212 subs which would blow you out of the room at 40 hz. It’s not built with typical “Pro Audio” drivers. It was a special driver built for the lab sub. It more in common with car audio subs than it does pro audio.

It just goes to show that you really need to match the tools to the job. Most PA cabs focus on being loud over everything else. Thats especially true about that really awful Eliminator “sub”. It’s a weird design that causes a resonant peak at 70ish hz which is good for thumpy disco, but todays music has deeper bass and less thump. So it’s an outdated design and you’ll turn it into confetti if you ask it to play Deadmau5.
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Bullwinkle: This is the amplifier, which amplifies the sound. This is the Preamplifier which, of course, amplifies the pree's.

Mike Henderson

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #17 on: May 17, 2021, 12:38:04 PM »

Alternatively get one of Art Welter’s 212 subs which would blow you out of the room at 40 hz. It’s not built with typical “Pro Audio” drivers. It was a special driver built for the lab sub. It more in common with car audio subs than it does pro audio.

It just goes to show that you really need to match the tools to the job. Most PA cabs focus on being loud over everything else. Thats especially true about that really awful Eliminator “sub”. It’s a weird design that causes a resonant peak at 70ish hz which is good for thumpy disco, but todays music has deeper bass and less thump. So it’s an outdated design and you’ll turn it into confetti if you ask it to play Deadmau5.

You are hitting the nail on the head with this all the way Tim. Short while ago I went into the garage to do some more listening and I noticed I was getting more "thump" than bass, like a kickbass on overdrive.

2 things, do you have a link to Art's 212 subs for me to look into it please? Also, I am trying to make sense of the instructions for that Applet in your previous link. Do I need to be playing music with it?
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Tim Weaver

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #18 on: May 17, 2021, 01:00:47 PM »

Requires some wood and some glue, but here you go.
https://soundforums.net/community/threads/free-sub-plan-dual-lab12-front-loaded-by-welter-systems.164/



The app is a 2d visual representation of waves. No music needed. Its for HS Physics teachers basically to show how waves interact. Just select 2 sources in the drop down menu on the right. This simulates having 2 wave generators (like subs) spread apart. You get to see the destructive interference patterns. Then select 3 or 4 or whatever sources and see how it changes. Imagine those extra sources as being your walls and ceiling.
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Bullwinkle: This is the amplifier, which amplifies the sound. This is the Preamplifier which, of course, amplifies the pree's.

Mike Henderson

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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #19 on: May 17, 2021, 01:11:39 PM »

Requires some wood and some glue, but here you go.
https://soundforums.net/community/threads/free-sub-plan-dual-lab12-front-loaded-by-welter-systems.164/

The app is a 2d visual representation of waves. No music needed. Its for HS Physics teachers basically to show how waves interact. Just select 2 sources in the drop down menu on the right. This simulates having 2 wave generators (like subs) spread apart. You get to see the destructive interference patterns. Then select 3 or 4 or whatever sources and see how it changes. Imagine those extra sources as being your walls and ceiling.

Oh I had thought it was something to help with knowing best placements for a sub in a room. Yes I can see how the waves interact, thanks.
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Re: What is it which makes a subwoofer "omnidirectional"?
« Reply #19 on: May 17, 2021, 01:11:39 PM »


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