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Author Topic: pas 2-18 subs  (Read 14550 times)

Greg g. Pierce

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Re: pas 2-18 subs
« Reply #10 on: January 24, 2012, 01:02:40 pm »

My choice of filters are purely a guess. Although it's an educated guess based on my 18 years of dealing with poorly maintained club systems like the one the OP has.

These filters are what I choose as a "starting point" when I'm faced with a situation like above. I choose lower order filters because there is less phase shift. Therefor you have a better chance of at least passable summation at the actual XO point.

I also spread the XO point out a little (80'ish for the subs, 100 ish for the tops) because most subs have a rising response as you get to the XO region. 100 hz can be 10-12 db hotter than 40 hz. Spreading the ELECTRICAL crossover apart means that you ACOUSTICAL crossover gets closer to being right. Remember, what you see on that little screen is not what is happening acoustically. The freq response of your cabinets means your cabs will not follow that little line perfectly.

If after a listen (I have specific tracks that will highlight the XO regions I pick) I don't like what I hear, I'll move the XO points up or down based on what I hear. You can also mute a cabinet one at a time (ie mute the subs, then the tops) to hear if that nastiness is produced by one cab or the other, or if the nasties are produced only by the combo together.

If your punchy kick drum isn't happening, try flipping polarity on subs or tops to see if it comes back.

If male singers sound too chesty, move the tops XO point up until it subsides.

If there's clacking in the subs from the cones bottoming out (over excursion) move the hi pass on the subs up, or change to a steeper slope.

Keep listening and tweaking until you like what you get!
Tim,
One more note that may help in diagnosing the duckquack sound I'm getting , the sound is not the same cabinet or speaker making it all the time, once it was top speaker on left, another bottom on right, not all the speakers at the same time, this is giving me a hard time wrapping my mind around why all of them are not making the same noise, we are running stereo, just because thats how it was set up when we got it, but keep the outputs on everything as equal as possible.
When I get there tonight I will change the crossover points and see what happens.

Thanks again for your knowledge, I truly appreciate your time.
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Tim McCulloch

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Re: pas 2-18 subs
« Reply #11 on: January 24, 2012, 01:31:18 pm »

Tim,
One more note that may help in diagnosing the duckquack sound I'm getting , the sound is not the same cabinet or speaker making it all the time, once it was top speaker on left, another bottom on right, not all the speakers at the same time, this is giving me a hard time wrapping my mind around why all of them are not making the same noise, we are running stereo, just because thats how it was set up when we got it, but keep the outputs on everything as equal as possible.
When I get there tonight I will change the crossover points and see what happens.

Thanks again for your knowledge, I truly appreciate your time.

Greg-

After reading your post again, are you referring to the the speakers in the sub cabinets?  If you're talking about the LF section of your top boxes, read on...  That sounds very much like an error in patching either the Driverack or amp-to-speaker cabling.  If you're sending the Sub signal to the the LF, it's certainly bottoming-out.  From your original post, it sounded like only the subs were giving you problems...

What we mean by that term is that the voice coil form (the cylindrical bobbin the coil is wound on) is striking the back plate of the pole piece.  It happens because of "over-excursion" which occurs when the speaker's mechanical limits of cone & suspension movement are being exceeded.  That usually happens because the transducer is being worked at a frequency below cut-off; with too much power; or a combination of both (the sub High Pass filter is an example of correction for this).

Make absolutely certain that the pass bands that make up your speaker system are getting only the signals they should.

FWIW, on several occasions over the centuries I have mixed on a PAS rig like you describe.  The tops weren't a problem, but the subs never were satisfying.  At one install the same sub box repeatedly exhibited speaker failures.  I chalked it up to an air leak in the cabinet, but the owner was never able to find one, or any other difference between the cabs... but the stage left subs went through a half dozen re-cones in 13 months.  At another install where I was the Band Engineer, the rig never got enough thump and the house guy freaked out at the amount of sub I wanted to use, the manager was worried about noise complaints... I figured out that there was a limiter in the rig between the PAS crossover and the amp inputs.  It was a long set.  OH, and this was in 1989.

I suspect that long term (and particularly outdoors on the Relay gigs) you will be disappointed with the PAS subs.  They weren't spectacular in 1985 and are much less so these days.  OTOH, if they have enough oomph (Highly Technical Term Alert) when they aren't self-destructing, they might be perfect for your band.

Have fun, good luck.

Tim Mc
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Bill Hornibrook

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Re: pas 2-18 subs
« Reply #12 on: January 24, 2012, 01:39:45 pm »

I was in a band that had PAS 18" subs back in the 1980s. Not knowing too much about the line (and what you have compared to what we had), I'd take that HPF and run it all the way up to about 45hz on your DRPA.

Those drivers really don't have a lot of excursion to them. It's old school stuff.
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Tim Weaver

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Re: pas 2-18 subs
« Reply #13 on: January 24, 2012, 03:22:58 pm »

Greg-

After reading your post again, are you referring to the the speakers in the sub cabinets?  If you're talking about the LF section of your top boxes, read on...  That sounds very much like an error in patching either the Driverack or amp-to-speaker cabling.  If you're sending the Sub signal to the the LF, it's certainly bottoming-out.  From your original post, it sounded like only the subs were giving you problems...

What we mean by that term is that the voice coil form (the cylindrical bobbin the coil is wound on) is striking the back plate of the pole piece.  It happens because of "over-excursion" which occurs when the speaker's mechanical limits of cone & suspension movement are being exceeded.  That usually happens because the transducer is being worked at a frequency below cut-off; with too much power; or a combination of both (the sub High Pass filter is an example of correction for this).

Make absolutely certain that the pass bands that make up your speaker system are getting only the signals they should.

FWIW, on several occasions over the centuries I have mixed on a PAS rig like you describe.  The tops weren't a problem, but the subs never were satisfying.  At one install the same sub box repeatedly exhibited speaker failures.  I chalked it up to an air leak in the cabinet, but the owner was never able to find one, or any other difference between the cabs... but the stage left subs went through a half dozen re-cones in 13 months.  At another install where I was the Band Engineer, the rig never got enough thump and the house guy freaked out at the amount of sub I wanted to use, the manager was worried about noise complaints... I figured out that there was a limiter in the rig between the PAS crossover and the amp inputs.  It was a long set.  OH, and this was in 1989.

I suspect that long term (and particularly outdoors on the Relay gigs) you will be disappointed with the PAS subs.  They weren't spectacular in 1985 and are much less so these days.  OTOH, if they have enough oomph (Highly Technical Term Alert) when they aren't self-destructing, they might be perfect for your band.

Have fun, good luck.

Tim Mc


I agree with everything said here, but make no mistake. It's not that you are using PAS subs, there's no sub in the MI market that would be satisfactory outdoors in the same situation. It's just physics. You have a lot more space to pressurize, and there are no walls to help keep all that noise contained. I will typically use around 4 times the subbage outdoors as I do indoors. Usually by taking twice as many subs and run them twice as hard.
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Tim McCulloch

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Re: pas 2-18 subs
« Reply #14 on: January 24, 2012, 03:36:39 pm »

Hi Tim-

I think your observation is spot on, they're trying to get indoor sound, outdoors.  This is a band-owned rig, so whatever they have, they'll use no matter what... particularly since the gigs are low/no pay.  If we can can keep them from blowing subs on every gig, they'll be fine.

Tim Mc


I agree with everything said here, but make no mistake. It's not that you are using PAS subs, there's no sub in the MI market that would be satisfactory outdoors in the same situation. It's just physics. You have a lot more space to pressurize, and there are no walls to help keep all that noise contained. I will typically use around 4 times the subbage outdoors as I do indoors. Usually by taking twice as many subs and run them twice as hard.
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Greg g. Pierce

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Re: pas 2-18 subs
« Reply #15 on: January 24, 2012, 07:05:42 pm »

Greg-

After reading your post again, are you referring to the the speakers in the sub cabinets?  If you're talking about the LF section of your top boxes, read on...  That sounds very much like an error in patching either the Driverack or amp-to-speaker cabling.  If you're sending the Sub signal to the the LF, it's certainly bottoming-out.  From your original post, it sounded like only the subs were giving you problems...

What we mean by that term is that the voice coil form (the cylindrical bobbin the coil is wound on) is striking the back plate of the pole piece.  It happens because of "over-excursion" which occurs when the speaker's mechanical limits of cone & suspension movement are being exceeded.  That usually happens because the transducer is being worked at a frequency below cut-off; with too much power; or a combination of both (the sub High Pass filter is an example of correction for this).

Make absolutely certain that the pass bands that make up your speaker system are getting only the signals they should.

FWIW, on several occasions over the centuries I have mixed on a PAS rig like you describe.  The tops weren't a problem, but the subs never were satisfying.  At one install the same sub box repeatedly exhibited speaker failures.  I chalked it up to an air leak in the cabinet, but the owner was never able to find one, or any other difference between the cabs... but the stage left subs went through a half dozen re-cones in 13 months.  At another install where I was the Band Engineer, the rig never got enough thump and the house guy freaked out at the amount of sub I wanted to use, the manager was worried about noise complaints... I figured out that there was a limiter in the rig between the PAS crossover and the amp inputs.  It was a long set.  OH, and this was in 1989.

I suspect that long term (and particularly outdoors on the Relay gigs) you will be disappointed with the PAS subs.  They weren't spectacular in 1985 and are much less so these days.  OTOH, if they have enough oomph (Highly Technical Term Alert) when they aren't self-destructing, they might be perfect for your band.

Have fun, good luck.

Tim Mc
Tim,
Your right the first assumtion, only the bottoms, tops are fine.
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Greg g. Pierce

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Re: pas 2-18 subs
« Reply #16 on: January 24, 2012, 09:58:49 pm »

Tim, I changed the xover to what you suggested. It was set on 35 instead of 30 for low pass and was set on bw 12 instead of 18, the high pass was set to100hz bw6, I changed it to 100hz LR this is how all three are set now
L 30 bw18 100hz lr12 the Drive rack also has another setting listed next to that, it says 0.0db
M 100 hz bw6 6.7khz bw6 and again the 0.0db
H 6.70 khz bw12   o.odb

I can still hear the speaker making the cracking, brrraaapp noise, but at extremely high level with bass exagerated. Still, just the one 18, in the one cabinet. another thing I noticed tonight is that that cabinet with the questionable 18 is noticeably quieter than the other cabinet. Stand in front of the other cabinet and you can feel the sound waves, in front of the one in question....not so much. All settings are equal on all components, levels on mixer, amps, everywhere I can see a level I checked to be sure.
The DRPA has a subharmonic synthesizer, it is off.
Compressor is set to on / overeasy level 5
So, I am open for your thoughts, besides shoving it off in the pond behind my shop and starting over....Another question, these cabinets have mismatched speakers, could this lead to other problems, if you were going to take all 18's out and replace with others, what would you suggest.
Again, I apologize for taking up your time on what was my mistake in buying, I just want to make the best of it, then start looking for another set of cabinets maybe.

Thanks to all for looking, listening, and contributing.
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Greg g. Pierce

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Re: pas 2-18 subs
« Reply #17 on: January 24, 2012, 10:04:55 pm »

The amps should not be run bridged into a 4ohm load.
http://www.crownaudio.com/pdf/amps/139440.pdf

Get 1 bigger amp (QSC RMX5050, Crown XTi6002, etc) and dial the DRPA to eliminate the possibility of over-excursion. Also, experiment with comp/limiters on kick and bass.
Thanks, I am looking into the compressor section and a compressor for the foh rack.
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Tim Weaver

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Re: pas 2-18 subs
« Reply #18 on: January 24, 2012, 10:19:18 pm »

OK, couple of things.

If one sub isn't putting out the same noise as the other one, then something is wrong. Take the drivers out of the quiet one and see A: if they both work outside of the cabinet, and B: if they are the correct drivers for this cabinet.

Two things might be happening. One, is there might be a dead woofer. In this case the other, working woofer, is going to beat itself to death eventually. You can't tell if one is dead simply by looking at the front of the cabinet. The good woofer will cause the bad oone to be moving about making you think it's (the bad one) is still working.

Secondly, if this box has the wrong drivers in it, it could be poorly tuned to the replacement drivers causing over-excursion. This is really common when a band blows something up they stick a cheap replacement in it's place and it never works right.

Third, the two drivers may simply be out of polarity with each other. Make sure they are both wired the same. Even better take a 9 volt battery and hook to the input and see which way the cones move. Both should move in the same direction at the same time.



Also in regards to the crossover, it sounds like you are triamping these speakers. Is this the case? What are the model numbers of the cabinets in question. 6.7 khz is waaaay too high to be crossing over a 15 into a horn. But we need to know if it uses a 1" or a 2" horn to give you further advice.

Also, the 0.0db section is simply your volume unit used to set the volume of that bandpass versus the volume of the next. It's how you turn the subs up relative to mids and hi's in other words.
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Greg g. Pierce

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Re: pas 2-18 subs
« Reply #19 on: January 24, 2012, 10:52:16 pm »

OK, couple of things.

If one sub isn't putting out the same noise as the other one, then something is wrong. Take the drivers out of the quiet one and see A: if they both work outside of the cabinet, and B: if they are the correct drivers for this cabinet.

Two things might be happening. One, is there might be a dead woofer. In this case the other, working woofer, is going to beat itself to death eventually. You can't tell if one is dead simply by looking at the front of the cabinet. The good woofer will cause the bad oone to be moving about making you think it's (the bad one) is still working.

Secondly, if this box has the wrong drivers in it, it could be poorly tuned to the replacement drivers causing over-excursion. This is really common when a band blows something up they stick a cheap replacement in it's place and it never works right.

Third, the two drivers may simply be out of polarity with each other. Make sure they are both wired the same. Even better take a 9 volt battery and hook to the input and see which way the cones move. Both should move in the same direction at the same time.



Also in regards to the crossover, it sounds like you are triamping these speakers. Is this the case? What are the model numbers of the cabinets in question. 6.7 khz is waaaay too high to be crossing over a 15 into a horn. But we need to know if it uses a 1" or a 2" horn to give you further advice.

Also, the 0.0db section is simply your volume unit used to set the volume of that bandpass versus the volume of the next. It's how you turn the subs up relative to mids and hi's in other words.
OK, I will take the speakers out of the cabinet and see what they do, also I was going to ohm them to be sure the one in question is reading close to 8 ohms

2* The drivers are missmatched, there is one old (reconed in 02 according to the info on the back) and one new B52 in each cabinet, so I was wondering if that was a problem, If I need to get 4 new 18s, what would be the correct speaker for the cabinet, Model no? I have no idea, cant find one on the cabinet anywhere. I am trying to put a photo on this

3* I have checked polarity with the battery, it's good, I will double check wiring on both cabinets to see they match

4* Yes, running three way, one crown 802 on each sub, two more amps running stereo for mids and highs

5* 2" horn
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Re: pas 2-18 subs
« Reply #19 on: January 24, 2012, 10:52:16 pm »


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