ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: 1 ... 6 7 [8] 9   Go Down

Author Topic: subs and deploying them 'in the round'  (Read 93891 times)

Dr. Don

  • Newbie
  • *
  • Offline Offline
  • Posts: 7
    • http://www.drdon.com
Re: subs and deploying them 'in the round'
« Reply #70 on: January 14, 2005, 07:15:00 PM »

I was system engineer/designer and FOH tech (in collaboration with Dan Healy) from 1979 until Jerry's untimely death in August of 1995, although during the last few years I worked the in-ear monitor system instead.

If you ask Jamie or Sam, they will both tell you we changed their lives and careers.

I have been approached to write a book, so ...

As far as the sweet spot on stage. For most musicians, especially the GD who didn't move around alot, the sweet spot was pretty well defined. Foot pedals and vocal mics were in a fixed position. The stage carpets were spiked marked so it all wound up being in the same position everyday. I personally set the carpet position with respect to the PA everyday.

Steering doesn't make sound disappear, it only moves it somewhere else. In this case, since we had steering speakers on both sides, the energy was directed off stage L & R and the sound on stage was  even. Steering is basically creating interference. With such a few number of interference components, FOH was mostly uneffected.
Logged
Dr. Don
Done WAY too many live shows

Mike Babcock

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1255
Re: subs and deploying them 'in the round'
« Reply #71 on: January 14, 2005, 08:17:14 PM »

Hey Dr Don

Thank you for posting. Thanks for the war story. Did you actually achieve thorax-rattling in the upper decks? And how bearable was it closer up?

Since you are here and it is relevant to this discussion. Are there any plans to go forward with your training classes, as seen at http://www.drdon.com/training/index.html When? Where? How much? After the SAC grounding seminar, I'd like to put yours next on the list.

Mike
Logged
http://www.themonitorguy.com/venue
Now with over 1000 venues!!!!!

Evan Kirkendall

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 6824
    • http://www.evankirkendall.com
Re: subs and deploying them 'in the round'
« Reply #72 on: January 14, 2005, 08:42:00 PM »

Cool. Thanks for the explaination. This thread it great!


Logged
Not all change is good change.

Dr. Don

  • Newbie
  • *
  • Offline Offline
  • Posts: 7
    • http://www.drdon.com
Re: subs and deploying them 'in the round'
« Reply #73 on: January 14, 2005, 11:36:44 PM »

Quote:

Did you actually achieve thorax-rattling in the upper decks? And how bearable was it closer up?


Maybe some posters out there who were at some of these shows should answer this question.
Logged
Dr. Don
Done WAY too many live shows

Liam Flynn

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 55
Re: subs and deploying them 'in the round'
« Reply #74 on: January 16, 2005, 06:34:38 AM »

Dr. Don wrote on Fri, 14 January 2005 23:36

Did you actually achieve thorax-rattling in the upper decks? And how bearable was it closer up?

Maybe some posters out there who were at some of these shows should answer this


I attended a number of shows during this time, sat just about everywhere, and had my thorax (and more) rattled many times, during song climaxes and some very memorable drums/space moments. Smile Almost levitating out of your seat as the band went from whisper-quiet to full throttle and the low-end kicked in was quite an experience. A couple nights in the upper back in Hartford and the floor of Foxboro Stadium really stick out.

The low-end never got unbearable, even very close. It just seemed to get bigger, fatter, and warmer. Part of that, I have thought, is that the Dead weren't a band led by the kick drum, or at least the mixes weren't. The other part, I know now, was the skill of the people at FOH, laying it on when appropriate, and knowing when to lay off as well. Knocking people over every second of every show with the kick just wasn't the point, and they knew it.
*Warning- flattery ahead*
Dr. Don, I always felt the PA was being played as another instrument at Dead shows, as a part of the experience rather than just the medium to bring the performance to the people. It was a revelation to me for the potential of SR. Dead shows stand out to me in terms of quality and dynamics like few others. The ability to bring so many people right onto the stage in an intimate way is a testament to the skills of all who made it happen. It changed the way I looked at SR. Thanks, and I feel lucky to be able to tell you in person.(Or whatever this is.)

This is an amazing thread. People have commented on it's content, comparing it to LAB of old. I'm gonna have to do some searching. Being new here, I have had plenty to read without even touching the archives.

Thanks, all.
Logged

Abdul-EQ

  • Full Member
  • ***
  • Offline Offline
  • Posts: 180
Re: subs and deploying them 'in the round'
« Reply #75 on: January 17, 2005, 12:18:21 AM »

Dr. D

Abdul does not know a thorax, Abdul does not know a lorax.
However, Abdul has experienced a few stadium shows at that time and will testify that your sub array shook his balls. Of hashish, right out of his pocket and onto the infield. Don't know if his pants were "flapping in the wind" as was your intent because Abdul is always pantless underneath the cloak.

Now that Abdul thinks about it, he is tempted to blame you for the loss, that was some righteous shit. Ah, maybe not, the statue of limitations has probably expired.

Happy to help,
Abdul

Logged
Abdul-EQ
Informative and entertaining

Mike Pyle

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 2485
Re: subs and deploying them 'in the round'
« Reply #76 on: January 28, 2005, 11:45:02 PM »

gtphill wrote on Thu, 06 January 2005 12:06


Actually, this a correct way of doing it.

Mike B's way:
You need to cancel the waves behind the front box.  So (for simplicities sake) if the front box is producing cos(x) then the rear box needs to produce -cos(x + D) where D is the time it takes for the sound from the front box to reach the rear.  The "-" comes from the polarity invert/box direction, and the D comes by delaying the rear box long enough from the sound from the front box to get there.

Alternative way:
Space the boxes 1/4 wavelength apart (90 degrees apart).  Now delay the front box another 1/4 wavelength (90 degrees).  The output from the the front box takes 1/4 wavelength to reach the rear box, and other 1/4 wavelength you added artificially, so cancellation ensues.  The undelayed sound from the rear box takes 1/4 wavelength to get to the front box, so it sums in phase out front.  Because sound diffracts around the rear box almost perfectly, it makes very little difference whether it is facing forwards or backwards, and you can't think of turning it around as a polarity inversion.

Note that the second method doesn't work as well as the first, because the individual box does provide some degree of forward directivity, and there is slightly less (3dB or so) less sound behind the box than in front.  This leads to a more hypercardiod-like pattern, which can be mitigated by turning down the rear sub about 3dB.  But, by turning down the rear sub 3dB you lose that energy in the main lobe:




One thing I still am not clear about:

If this array is set up like the first example you mention here, Mike B's way, is there still summation at the front of the array even though the rear sub is delayed? Or is the output of the rear sub substantially expended in cancelling the spill from the front sub?

If there is summation, how much is the sound affected by the delay in the rear sub? Is my thinking right that the combination of distance, signal delay and polarity inversion will make it a full cycle off?
Logged
Mike Pyle
Audiopyle Sound
707-315-6204
Dealer: Yorkville, EV, QSC, RCF, KV2, FBT, EAW, Danley, SLS, Turbosound, dBTech
 APB,A&H,Audix,Shure,Powersoft,RoadReady,K&M,Ultimate ,Global Truss,DENON,Chauvet,Elation...

Chris Davis

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1790
Re: subs and deploying them 'in the round'
« Reply #77 on: January 29, 2005, 12:07:01 AM »

Mike Pyle wrote on Fri, 28 January 2005 23:45

gtphill wrote on Thu, 06 January 2005 12:06


Actually, this a correct way of doing it.

Mike B's way:
You need to cancel the waves behind the front box.  So (for simplicities sake) if the front box is producing cos(x) then the rear box needs to produce -cos(x + D) where D is the time it takes for the sound from the front box to reach the rear.  The "-" comes from the polarity invert/box direction, and the D comes by delaying the rear box long enough from the sound from the front box to get there.

Alternative way:
Space the boxes 1/4 wavelength apart (90 degrees apart).  Now delay the front box another 1/4 wavelength (90 degrees).  The output from the the front box takes 1/4 wavelength to reach the rear box, and other 1/4 wavelength you added artificially, so cancellation ensues.  The undelayed sound from the rear box takes 1/4 wavelength to get to the front box, so it sums in phase out front.  Because sound diffracts around the rear box almost perfectly, it makes very little difference whether it is facing forwards or backwards, and you can't think of turning it around as a polarity inversion.

Note that the second method doesn't work as well as the first, because the individual box does provide some degree of forward directivity, and there is slightly less (3dB or so) less sound behind the box than in front.  This leads to a more hypercardiod-like pattern, which can be mitigated by turning down the rear sub about 3dB.  But, by turning down the rear sub 3dB you lose that energy in the main lobe:




One thing I still am not clear about:

If this array is set up like the first example you mention here, Mike B's way, is there still summation at the front of the array even though the rear sub is delayed? Or is the output of the rear sub substantially expended in cancelling the spill from the front sub?

If there is summation, how much is the sound affected by the delay in the rear sub? Is my thinking right that the combination of distance, signal delay and polarity inversion will make it a full cycle off?




It looks like not only the back waves get cancelled but the forward waves also get reinforced.  If I am thinking correctly, the front cabs may also cancel the rear spillage from the rear cabs?
Logged

Guest

  • Guest
Re: subs and deploying them 'in the round'
« Reply #78 on: February 10, 2005, 10:32:10 PM »

Logged

Guest

  • Guest
Re: subs and deploying them 'in the round'
« Reply #79 on: February 10, 2005, 10:42:48 PM »

Logged

ProSoundWeb Community

Re: subs and deploying them 'in the round'
« Reply #79 on: February 10, 2005, 10:42:48 PM »


Pages: 1 ... 6 7 [8] 9   Go Up
 



Site Hosted By Ashdown Technologies, Inc.

Page created in 0.034 seconds with 23 queries.