A Club Band PA system - Page 6 - diyAudio
Go Back   Home > Forums > Live Sound > PA Systems

PA Systems A forum for discussion of all parts of a sound reinforcement or DJ system: loudspeakers, mixers (desks) etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th April 2010, 03:33 PM   #51
taj is offline taj
diyAudio Member
 
taj's Avatar
 
Join Date: Feb 2005
Quote:
Originally Posted by col View Post
I don't expect to get cone break-up from a 12" driver that has a usable frequency range up to 4khz when I'm crossing out of it at 2.5khz with a 24db slope.
col,

You cannot avoid them. Cone breakup modes exist in all code drivers and is a permanent physical property; the resonant patterns within the cone material. The larger the cone, the lower the frequency of those modes. For a 15" driver, you can expect them to start probably around 500-700 Hz. For 6" drivers, they will start nearer to 3-5k, requiring less EQ or simpler crossover designs below that region.

You can easily see them on a driver's frequency response chart. It's where the response starts to go crazy on the way up near where it rolls off at the upper limit. The less cone damping there is, the more pronounced they will be. Check out the graph of any aluminum cone driver, and compare it with say a paper or Nomex cone driver.

For home stereo speakers with a passive crossover you will permanently deal with them in the crossover design. Some excellent speakers have pronounced BUMs that must be dealt with. But for pro audio the crossovers are typically active 'textbook' crossovers, you pick the frequency, slope, knee and you're done. You must then EQ the PA to correct those aberrations. (Digital crossovers [can] provide that custom tuned approach that passive crossovers provide -- one of their big advantages IMO.)

A good strategy for PA use, IMO, is to avoid BUMs rather than deal with them. You can look for drivers whose breakup modes are not too pronounced, or just work with smaller drivers where the modes are higher than the passband (or combine both approaches).

..Todd
  Reply With Quote
Old 27th April 2010, 09:55 PM   #52
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
more background reading:

Rod Elliot's article is very pro-horns, but then it comes from someone who was doing pro sound in the 70's. Does lay down some good basic facts to keep in mind though.

PA Systems

Also, Rog Mogale's article about using front loaded reflex boxes for small venues:

Speakerplans.com

col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 27th April 2010, 11:47 PM   #53
taj is offline taj
diyAudio Member
 
taj's Avatar
 
Join Date: Feb 2005
What are the links for, col? They don't seem relevant, and certainly aren't very insightful.

..Todd
  Reply With Quote
Old 28th April 2010, 12:08 AM   #54
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
Quote:
Originally Posted by taj View Post
What are the links for, col? They don't seem relevant, and certainly aren't very insightful.

..Todd
The articles are relevant background information for designing and setting up PA systems. Why would that not be relevant? The information helps to narrow down the decisions that need to be made before embarking on system building. I think both articles and the opinions they contain are a very good insight into PA design and they come from experienced, knowledgeable experts in this field.

col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 28th April 2010, 02:12 AM   #55
Variac is offline Variac  United States
diyAudio Editor
 
Variac's Avatar
 
Join Date: Dec 2001
Location: San Francisco, USA
Couldn't hurt..
  Reply With Quote
Old 28th April 2010, 05:24 AM   #56
taj is offline taj
diyAudio Member
 
taj's Avatar
 
Join Date: Feb 2005
col,

This thread is about getting input and feedback about a very specific purpose and very specific type of PA system, as described in the first couple of messages, from what I hoped would be folks with plenty of experience (like mine) in that field who understood those particular challenges. So far there's been some good information/ideas. But if it degenerates into a general DJ type PA design thread, with PA 101 chatter, then I'll bail.

Having said that, I would love to know more about those JBL PT waveguides. I read some of those other threads that were referenced, but real information was scant. Did Earl actually end up measuring them? Did anyone else? Are they actually good or are they, as Geddes suspected, just marketing hyperbole from JBL? They don't look like a waveguide as Geddes' AES papers describe. I am skeptical, but would love to learn they are decent. The noise/signal ratio in those other forums was too high to suffer through long enough to find that information.

..Todd

Last edited by taj; 28th April 2010 at 05:27 AM.
  Reply With Quote
Old 28th April 2010, 05:45 AM   #57
col is offline col  Australia
diyAudio Member
 
col's Avatar
 
Join Date: Feb 2008
Location: Melbourne, Victoria, Australia
Quote:
Originally Posted by taj View Post
col,

This thread is about getting input and feedback about a very specific purpose and very specific type of PA system, as described in the first couple of messages, from what I hoped would be folks with plenty of experience (like mine) in that field who understood those particular challenges. So far there's been some good information/ideas. But if it degenerates into a general DJ type PA design thread, with PA 101 chatter, then I'll bail.
No worries. I don't think any of my posts have deviated from that purpose though.

Quote:

Having said that, I would love to know more about those JBL PT waveguides. I read some of those other threads that were referenced, but real information was scant. Did Earl actually end up measuring them? Did anyone else? Are they actually good or are they, as Geddes suspected, just marketing hyperbole from JBL? They don't look like a waveguide as Geddes' AES papers describe. I am skeptical, but would love to learn they are decent. The noise/signal ratio in those other forums was too high to suffer through long enough to find that information.
The threads regarding the JBL PT waveguide (earl calls it a defraction horn) that are worth reading are here:

Horn vs. Waveguide

and here:

AK Design Collaborative - Econo-Waveguide Speaker - AudioKarma.org Home Audio Stereo Discussion Forums


col.
__________________
http://www.minirig.org.au
  Reply With Quote
Old 28th April 2010, 05:50 AM   #58
NEO Dan is offline NEO Dan  United States
diyAudio Member
 
NEO Dan's Avatar
 
Join Date: Jun 2008
Location: N.E. Ohio
Have you had a look at the Danley stuff?
__________________
Regards,
Dan
  Reply With Quote
Old 28th April 2010, 05:52 AM   #59
NEO Dan is offline NEO Dan  United States
diyAudio Member
 
NEO Dan's Avatar
 
Join Date: Jun 2008
Location: N.E. Ohio
The assistance audio brown bag kit would be another possible route.
__________________
Regards,
Dan
  Reply With Quote
Old 28th April 2010, 08:43 AM   #60
Xoc1 is offline Xoc1  United Kingdom
diyAudio Member
 
Xoc1's Avatar
 
Join Date: Nov 2008
Location: Devon UK
Quote:
Originally Posted by NEO Dan View Post
The assistance audio brown bag kit would be another possible route.
The BMS 2" 4950 driver in the brown bag system looks very interesting, being a coaxial compression driver 300 Hz to 22 kHz! (Not Cheap!)
The extended bandwith opens up a few more options.
Maybe 18" drivers on the bottom end crossing over to 12" drivers
(12" drivers seem to have the edge when it comes to comparing efficency)
Crossing over to the coaxial BMS at a low enough frequency to avoid any breakup - beaming on the 12"
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Band PA Question eddog Solid State 8 15th October 2007 04:53 PM
PA system for band practice DeadSpeaker PA Systems 5 10th August 2007 04:01 AM
Looking for a DIY PA system for my sons Garage Band airframe Instruments and Amps 24 30th June 2006 04:20 AM
PA system got me down.... xstephanx Multi-Way 27 28th April 2006 12:46 AM


New To Site? Need Help?

All times are GMT. The time now is 04:25 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2