The cheapest PA system - Page 2 - 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 2nd December 2008, 07:52 PM   #11
HK26147 is offline HK26147  United States
diyAudio Member
 
Join Date: Jan 2008
Does that 1st simulation graph you just posted assume a no Xmax limit of 99mm?
The prediction of the 2nd graph does not seem reasonable to me with a 4mm Xmax driver that will probably start to experience thermal compression @ 1/10 power and will have 2.5db loss @ 1/2 power, as typical for a pro driver
  Reply With Quote
Old 2nd December 2008, 07:55 PM   #12
diyAudio Member
 
Join Date: Nov 2008
Quote:
Originally posted by HK26147
Forum member Davygrvy built 6 horns each with an Eminence HL10 ( Total Driver cost $780 ). These horns formed a fairly small stack.
And when given enough power produced painful SPL.
I used to set up a parade float sound system myself, and I'm guessing his stack would fit your carnival wagon system.
But not as a 2 way.

thanks!


do you have a photo??

the 2way system is a too bad idea?
  Reply With Quote
Old 2nd December 2008, 07:57 PM   #13
diyAudio Member
 
Join Date: Nov 2008
Quote:
Originally posted by HK26147
Does that simulation graph you just posted assume a no Xmax limit of 99mm?


Quote:
Originally posted by andrew_87


my metod to have an approx of the max thoerical output,

Click the image to open in full size.


i use it to note the difference between different thorical project...
isn't correct but for approx the difference between project is good...



no scientist thoery... only an idea...
  Reply With Quote
Old 2nd December 2008, 08:01 PM   #14
diyAudio Member
 
Join Date: Nov 2008
Quote:
Originally posted by andrew_87
another simulation...

Click the image to open in full size.



140dB was refered to these simulations...



that's right! if i will have a real spl of 115-120dB is a great goal!



  Reply With Quote
Old 2nd December 2008, 08:16 PM   #15
HK26147 is offline HK26147  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
the 2way system is a too bad idea?
I have yet to hear a 2way PA that meets your goals, or an individual horn driver or horn/cab that would give a good response over 5 octaves for a high SPL PA.
Realistically I try to give each PA driver section a bandpass of approx 3 octaves, so each section can be optimized for it's bandpass, and any high frequency anomalies from each horn are filtered out electronically.

I don't have a pic of David's sub stack, but if you msg him, I'm sure he would sent you the couple I saw. I think his stack was up for sale.
  Reply With Quote
Old 2nd December 2008, 08:53 PM   #16
diyAudio Member
 
davygrvy's Avatar
 
Join Date: Mar 2007
Location: Oakland, CA
Blog Entries: 1
Here are a couple pics of my BFM AutoTuba (16" wide) sixpack.

Click the image to open in full size.

Click the image to open in full size.

and the response chart

They calculate to 134dB(SPL) @ 40Hz in half space at 300W input each. I chose to make six little horns to run as a group due to space restrictions. Six HL10C drivers in much bigger horns will of coarse be more efficient and deeper, but this was to solve a space problem and compromised on using more drivers, thus more power, to achieve the goal.

I don't think it is realistic to do a loud full-range system as a 2-way. Even 3-way takes compromises for beamy midbass drivers run too high.
  Reply With Quote
Old 3rd December 2008, 09:59 AM   #17
diyAudio Member
 
Join Date: Nov 2008
@ davygrvy:

thank you for the info!

good project the autotuba of BFM, is a phi/8 horn and in a stack can sound very smooth and goes low...

my initial project was developed to reduce costs:
- max 4 woofer--> 0.5phi design
- max 4driver (in particoular i find this driver with a low low cost! [circa 30])
- eventually piezo...

to extend the frequency of the woofer, enought for use the driver, i choosed a rearloaded bass horn: 40hz * 2^4 = 640hz (4octaves)
mid horn: 325hz (circa) * 2^4 = 5600hz

so:

12": 40hz to 500hz circa
mid driver: 500hz to 5000hz circa
piezo: 5000hz to 20000hz

i have choose 4 octaves because i readed that use horns for 3 octaves over the fb of the horn is wonderful for HIFi, 4octaves is for a compromise and 5octaves is not good!

but i have to test the driver and the woofer...
if they are **** I can create a system like yourse...

  Reply With Quote
Old 3rd December 2008, 11:49 AM   #18
HK26147 is offline HK26147  United States
diyAudio Member
 
Join Date: Jan 2008
Quote:
12": 40hz to 500hz circa
mid driver: 500hz to 5000hz circa
piezo: 5000hz to 20000hz
So it isn't really a 2 way...
IHMO: If you try to driver that compression driver hard it will blow quickly.
That compression driver strikes me as a cheap knockoff of similar screw-on drivers from Eminence etc.
It doesn't have a published Fs, nor a graph of frequency response to know how it performs near it's Fs.
And it's spelled KAPTON, not CAPTON ( that to me is a red flag when a manufacturer doesn't provide performance measurement and can't proofread it's copy )
Even with an active xover with an aggressive slope rate (48db) I would not attempt a 500hz xover and then drive it as hard as you intend.

As far as the use of piezo: The members of the BF forum ( David just mentioned ) use arrays of piezos. For the most part they find they work fine, with accepted limitations...
It takes a bunch of them ( dozens ). They need EQ. They should be limited to 27V max for protection. They need to be implemented with stability resistors to keep amps from oscillation. To also protect them and get the most SPL out of them, they need to have a xover ( regardless of sales hype ).
SEE DIYAUDIO wiki on this:
Those individuals who really require high SPL ( on the level you desire ) found piezos unacceptable and switched to compression drivers ( BMS drivers mostly ).
Things to consider...
Syd
  Reply With Quote
Old 3rd December 2008, 02:36 PM   #19
Speakerholic
diyAudio Moderator
 
Cal Weldon's Avatar
 
Join Date: Jan 2004
Location: Near Vancouver
Andrew, do not try and get around the language censor. We don't allow swearing here.
__________________
Next stop: Margaritaville
Some of Cal's stuff | Cal Weldon Consulting
  Reply With Quote
Old 4th December 2008, 07:26 AM   #20
diyAudio Member
 
Join Date: Nov 2008
Quote:
Originally posted by HK26147


So it isn't really a 2 way...
IHMO: If you try to driver that compression driver hard it will blow quickly.
That compression driver strikes me as a cheap knockoff of similar screw-on drivers from Eminence etc.
It doesn't have a published Fs, nor a graph of frequency response to know how it performs near it's Fs.
And it's spelled KAPTON, not CAPTON ( that to me is a red flag when a manufacturer doesn't provide performance measurement and can't proofread it's copy )
Even with an active xover with an aggressive slope rate (48db) I would not attempt a 500hz xover and then drive it as hard as you intend.

As far as the use of piezo: The members of the BF forum ( David just mentioned ) use arrays of piezos. For the most part they find they work fine, with accepted limitations...
It takes a bunch of them ( dozens ). They need EQ. They should be limited to 27V max for protection. They need to be implemented with stability resistors to keep amps from oscillation. To also protect them and get the most SPL out of them, they need to have a xover ( regardless of sales hype ).
SEE DIYAUDIO wiki on this:
Those individuals who really require high SPL ( on the level you desire ) found piezos unacceptable and switched to compression drivers ( BMS drivers mostly ).
Things to consider...
Syd

yes, the driver is an unknown quantity... probably i will use some 6" or some 8" horn loaded for the mid...
but i will take one driver, i will analyze the impedence, i will crox to 500hz... sound... i will try if it broke down or not
it's cheap, no problem...

yes piezos has limits but also advantage like, manly, no power loss... in particoular an array of piezos, lots of time, could help... i know that they need a good EQ and a specific filter but, fortunately, i haven't problems in it...
  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
Cheapest USB DAC kit? Spasticteapot Digital Source 0 16th November 2006 04:56 AM
Cheapest kit or project? yamski Tubes / Valves 14 26th May 2006 12:59 AM
Cheapest Solution bjackson Solid State 3 2nd August 2005 03:18 AM
Cheapest 12" Sub seangoesbonk Multi-Way 15 11th December 2004 08:15 PM
cheapest good sound system possible? r3n0 Car Audio 6 14th October 2004 05:28 PM


New To Site? Need Help?

All times are GMT. The time now is 07:13 AM.


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