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 Post subject: Subwoofer inequality
PostPosted: Sun May 07, 2017 11:25 pm 
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So over the weekend I had a couple of gigs. And during I noticed that some of my tubas are louder than their fellow brothers. Now I didn't keep track and notate which ones to check at my other gig but some still seemed a little off. It's hard to tell with them so close to each other.

I run them series 65v limiter
30-85hz and I run the input signal in mono and output signal for lows in mono as well. And I ran a splitter on each output on my lows on the driverack pa2 since I don't have an option to make the crest5.0s run as parallel inputs. Now I'm just curious as to why the levels are different at one gig it was almost insanely different volumes. i don't hear or feel any air leaks.

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10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

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 Post subject: Re: Subwoofer inequality
PostPosted: Mon May 08, 2017 4:15 am 
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Joined: Mon Nov 28, 2011 11:12 am
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Location: Ilfracombe Queensland Australia
Are they all the same width?

Are you sure you wired them up correctly when you changed to serial instead of parallel in cab?
Tell us what you did.

Did you measure output cab to cab?

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Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
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 Post subject: Re: Subwoofer inequality
PostPosted: Mon May 08, 2017 6:50 am 
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DJStubbs wrote:
some still seemed a little off. It's hard to tell with them so close to each other.
It's impossible to tell, when clustered they act as one and are heard as one. If you have doubts the only way to be sure is to measure their response, one at a time, with the exact same signal, cab position and mic placement, preferably outdoors. Keep cabs that aren't being measured well away, as they will affect the result.


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 Post subject: Re: Subwoofer inequality
PostPosted: Mon May 08, 2017 8:02 pm 
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Grant Bunter wrote:
Are they all the same width?

Are you sure you wired them up correctly when you changed to serial instead of parallel in cab?
Tell us what you did.

Did you measure output cab to cab?



I did not. no way to test the actual sound levels they are putting out.
And all same size and all wired in series. i run 2 per channel one master and one daisy chained.

_________________
10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

https://ibb.co/e0Uazv
https://ibb.co/bUxmJQ

Klarity Audio & Lighting
https://www.facebook.com/KlarityAudio/


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 Post subject: Re: Subwoofer inequality
PostPosted: Mon May 08, 2017 8:10 pm 
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Bill Fitzmaurice wrote:
DJStubbs wrote:
some still seemed a little off. It's hard to tell with them so close to each other.
It's impossible to tell, when clustered they act as one and are heard as one. If you have doubts the only way to be sure is to measure their response, one at a time, with the exact same signal, cab position and mic placement, preferably outdoors. Keep cabs that aren't being measured well away, as they will affect the result.


Now when you say clustered do you mean next to each other in a line or stacked on top of each other.
I ran it both ways it seems that stacked on top of each other 2 high the bass will be higher and travel a bit farther.
but the bass doesnt seem to travel far. maybe 10 feet or so.

attached are some pics
the very top 280 seems to be kind of useless at that high. It would not really be able to hit anyone i might try and figure out some way to angle the 280s.

https://ibb.co/ntiZwQ
https://ibb.co/gLAsi5

_________________
10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

https://ibb.co/e0Uazv
https://ibb.co/bUxmJQ

Klarity Audio & Lighting
https://www.facebook.com/KlarityAudio/


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 Post subject: Re: Subwoofer inequality
PostPosted: Tue May 09, 2017 5:48 pm 
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Joined: Mon Aug 14, 2006 5:08 am
Posts: 5372
Location: Warren, MI
DJStubbs wrote:
Now when you say clustered do you mean next to each other in a line or stacked on top of each other.
I ran it both ways it seems that stacked on top of each other 2 high the bass will be higher and travel a bit farther.
but the bass doesnt seem to travel far. maybe 10 feet or so.


The 2nd picture, with the 4 stacked 2x2, is correct. How many subs were you using, total, at this outdoor fun-fest?

DJStubbs wrote:
the very top 280 seems to be kind of useless at that high. It would not really be able to hit anyone i might try and figure out some way to angle the 280s.


You want the bottom-most DR280 centered and level ay around ear-height, approximately 65" off the ground. Because you are "ground-stacking", the DR280 stacked on it should be basically dead level, or a few (2-3) degrees tilted forward at the face of the cab.

As for the subs, if you are losing almost all bass at 10', there is a phase problem. 1 or more of your cabs are playing out-of-phase. You need to not only double check your cabs, but you also need to check your cords, DSP/crossover/limiter/whatever outboard gear you are running and the amps, for a phase switch. They should all be off. To find what cabs may be wired out-of-phase, hook 1 up, and play some bass or sine waves. Add a second cab and it should get louder. If it get softer, check the internal wiring of that cab. Do this for all the sub cabs you use.

_________________
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice


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 Post subject: Re: Subwoofer inequality
PostPosted: Tue May 09, 2017 8:45 pm 
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Joined: Wed Jul 30, 2008 10:18 am
Posts: 581
Location: Kankakee, IL
DJPhatman wrote:
As for the subs, if you are losing almost all bass at 10', there is a phase problem. 1 or more of your cabs are playing out-of-phase. You need to not only double check your cabs, but you also need to check your cords, DSP/crossover/limiter/whatever outboard gear you are running and the amps, for a phase switch. They should all be off. To find what cabs may be wired out-of-phase, hook 1 up, and play some bass or sine waves. Add a second cab and it should get louder. If it get softer, check the internal wiring of that cab. Do this for all the sub cabs you use.


(This might be getting into semantics, not sure.)

Is this describing a phase problem or a polarity problem? I guess if a speaker is out of polarity, then the entire output of that speaker is out of phase. I usually think of phase problems as a narrow band of frequencies.

In any event, I agree with DJPhatman's assessment of the problem and fix.

_________________
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!


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 Post subject: Re: Subwoofer inequality
PostPosted: Tue May 09, 2017 9:05 pm 
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DJPhatman wrote:
DJStubbs wrote:
Now when you say clustered do you mean next to each other in a line or stacked on top of each other.
I ran it both ways it seems that stacked on top of each other 2 high the bass will be higher and travel a bit farther.
but the bass doesnt seem to travel far. maybe 10 feet or so.


The 2nd picture, with the 4 stacked 2x2, is correct. How many subs were you using, total, at this outdoor fun-fest?

DJStubbs wrote:
the very top 280 seems to be kind of useless at that high. It would not really be able to hit anyone i might try and figure out some way to angle the 280s.


You want the bottom-most DR280 centered and level ay around ear-height, approximately 65" off the ground. Because you are "ground-stacking", the DR280 stacked on it should be basically dead level, or a few (2-3) degrees tilted forward at the face of the cab.

As for the subs, if you are losing almost all bass at 10', there is a phase problem. 1 or more of your cabs are playing out-of-phase. You need to not only double check your cabs, but you also need to check your cords, DSP/crossover/limiter/whatever outboard gear you are running and the amps, for a phase switch. They should all be off. To find what cabs may be wired out-of-phase, hook 1 up, and play some bass or sine waves. Add a second cab and it should get louder. If it get softer, check the internal wiring of that cab. Do this for all the sub cabs you use.


Just the 4 t60s and 2 280s. and ill run through the check list and check the amps and crossovers. the amps shouldnt be the issue as there is no dsp or switches. it only has a fullrange sub and highpass switch i use 2 crest audio 5.0 amps for the t60s.

_________________
10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

https://ibb.co/e0Uazv
https://ibb.co/bUxmJQ

Klarity Audio & Lighting
https://www.facebook.com/KlarityAudio/


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 Post subject: Re: Subwoofer inequality
PostPosted: Wed May 10, 2017 12:02 am 
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Location: Warren, MI
What are you using for EQ and Limiting? My bet is 1 or more T60 polarity is reversed.

Rich4349 wrote:
(This might be getting into semantics, not sure.)

Is this describing a phase problem or a polarity problem? I guess if a speaker is out of polarity, then the entire output of that speaker is out of phase.


Yes and no, Rich. Out of phase may be due to a series wiring cross. Then the internals are out of polarity, but the cab will be out of phase from the rest. It will output, but will be very reduced. But, yeah, I should have said polarity when referring to the wiring. My bad, but I try to over-simplify too much. The beatings may begin! :oops: :P :lol: 8)

_________________
I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
Accept the fact that airtight and well-braced are more important than pretty on the inside. Bill Fitzmaurice


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 Post subject: Re: Subwoofer inequality
PostPosted: Wed May 10, 2017 12:12 am 
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Joined: Wed Mar 25, 2009 7:07 pm
Posts: 1291
Location: Medicine Hat, Alberta, Canada
If you get confused over the terms remember that phase shift is caused by delay, polarity has no delay.

180° out of phase is different than 2 signals out of polarity because the signal out of phase is also delayed by some offset, the signal out of polarity is not delayed from the original.

You can sum 2 identical signals out of polarity and get zero.

You cannot ever sum 2 identical signals out of phase and get zero because of the time offset; one signal starts before the other and the other ends later than the other.

_________________
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience


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 Post subject: Re: Subwoofer inequality
PostPosted: Wed May 10, 2017 7:35 am 
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CoronaOperator wrote:
If you get confused over the terms remember that phase shift is caused by delay, polarity has no delay.
The main consideration isn't how but the result. A polarity flip will change phase by 180 degrees at every frequency. If you have two identical speakers placed close together with opposite polarity cancellation is across the entire passband. Time align, which can be the result of a few issues including placement, will cause a different degree of phase shift at every frequency. If you have two sources placed close together and there is a 180 degree difference in phase at a frequency that they're both producing there will be a cancellation, but only at that frequency. If they're not both producing that particular frequency it doesn't matter.


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 Post subject: Re: Subwoofer inequality
PostPosted: Thu May 11, 2017 2:58 am 
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DJPhatman wrote:
What are you using for EQ and Limiting? My bet is 1 or more T60 polarity is reversed.

Rich4349 wrote:
(This might be getting into semantics, not sure.)

Is this describing a phase problem or a polarity problem? I guess if a speaker is out of polarity, then the entire output of that speaker is out of phase.


Yes and no, Rich. Out of phase may be due to a series wiring cross. Then the internals are out of polarity, but the cab will be out of phase from the rest. It will output, but will be very reduced. But, yeah, I should have said polarity when referring to the wiring. My bad, but I try to over-simplify too much. The beatings may begin! :oops: :P :lol: 8)



I'm using a driverack pa2 that's inputs are mono and subs are mono output at the driverack. And I added a splitter on the left and right outputs to go into my sub amps. Since they can't run parallel settings.
limiting the subs to 65v and set from 30hz to like 85 hz sometimes 100hz

_________________
10x Tuba 60 - Dual 12" LAB
5x DR280 - Melded 22 piezo array
2x Crest Audio 5.0
1x Peavey IPR2 3000

https://ibb.co/e0Uazv
https://ibb.co/bUxmJQ

Klarity Audio & Lighting
https://www.facebook.com/KlarityAudio/


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 Post subject: Re: Subwoofer inequality
PostPosted: Thu May 11, 2017 9:04 am 
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Joined: Wed Mar 25, 2009 7:07 pm
Posts: 1291
Location: Medicine Hat, Alberta, Canada
DJStubbs wrote:
Now I'm just curious as to why the levels are different at one gig it was almost insanely different volumes.


Are you sure it wasn't just different venues having different acoustics or your subs were at differing locations? If they were loud at one location and not so loud at another that would be my guess.

_________________
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience


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 Post subject: Re: Subwoofer inequality
PostPosted: Thu May 11, 2017 1:24 pm 
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Posts: 219
Location: Tilburg, Netherlands
Both styles of grouping subwoofers should work, however if you ground stack and the left two subs are phase shifted from the right pair you get a lot of anomalies when walking over from left to right in front of the subs. I once had a problem with an amp where there was a broken capacitor in a preamp stage of a power amp which caused this.

Now I'm not saying you have this going on. Other more likely possibillities are mentioned before. But you really have to check every cab, cable, amp and so on to isolate the problem. Most probable cause is inverted polarity in one or two of the subs or speaker cords you're using. So connect every possible way you can and compare. If output goes down with two cabs combined, link (from one cab to another) with another cable to see if that solves the problem if it doesn't, link another cab. Does this solve the problem it's likely the cab which made output go down (or at least not up) has a polarity issue.

As I said before in Another thread or on facebook, a quad of dual 12" t60's is a mighty weapon and at ten feet at Max input you should be having trouble breathing. Even eighty to a hundred feet out you should have considerable chest thump. If that's not the case something is way off.

Good luck Finding the problem


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 Post subject: Re: Subwoofer inequality
PostPosted: Thu May 11, 2017 1:33 pm 
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Joined: Thu Mar 15, 2012 6:19 pm
Posts: 219
Location: Tilburg, Netherlands
Forgot one thing, subs should be ran mono. But when using two output channels from the driverack all settings should be the same. Could be you have polarity switched on one of the channels. Worth it to check that first. :wink:


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