Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

DIY powered mains
DIY powered mains
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
Thread Tools Search this Thread
Old 22nd May 2012, 01:12 AM   #1
SirNickity is offline SirNickity  United States
diyAudio Member
Join Date: Oct 2009
Location: Anchorage, AK
Default DIY powered mains

I'm working on a pair of BFM SLA Pros (4x Eminence Alpha 6 + piezo tweeter array) for mobile DJ work. Cabinet design is not my strong suite, so I'm looking for some advice on my plans.

Parts Express has some triangular corner ports that would give me almost exactly the area I need. The front baffle is already quite full, and I'm to understand placement isn't really a big deal, so I'd like to put these in the rear. Any inherent problems with this idea?

I have some home-designed PCBs for LM3886 chip amps. My plan is to run one chip per mid/woofer and one for the tweeter array. The Eminence 6Cs are 4-ohm drivers, and my transformer is 36vCT.

I seem to have botched my WinISD install, so I haven't quite gotten the box modeling down yet. I think this is about the right amount of power for the Alphas, assuming a 2nd-order high-pass at 80Hz. (This is mostly a fail-safe as my DriveRack already filters the tops at 100Hz, 4th order. But I'm building an internal active XO for the 2-way power anyway, so making the lower part bandpass is practically free.)

As for the piezos... well, I know next to nothing about piezos. They don't take much current, I'm told, and seem to need a sizable pad when used with a passive crossover, so I suspect a single 3886 will be plenty of power.

I have a rather large aluminum heatsink (about 5x7", with 1" extruded fins) that I would like to use. My plan is to put two of the ICs along each 7" side, and one (the tweeter IC) on bottom. Finally, I'll have an analog thermal sensor on the top side, monitored by an AVR uC, and enabling the mute pins if a thermal threshold is reached.

If it sounds reasonable, I'd like to have a metal plate on the back panel of the enclosure with all the inputs and controls, and have the heatsink on the INSIDE of the panel. (It's large and pointy. For a mobile system, that isn't so great.)

I have virtually no experience with this type of design, so I'm wondering if there's a snowball's chance of there being adequate cooling with the natural airflow one would get from a ported PA enclosure? If it's going to generate enough heat to warrant a thermally-controlled fan with additional vents and an air shroud around the sink, that's doable. I understand this may be difficult to predict without trying it, I'm just hoping to avoid two orders to the CNC place.

So, any thoughts? This is a learning experience for me, so I'm prepared for mistaken assumptions. I have built a computer sub with the 3886, and it's doing really well, but I stuck to the plans on the box and have a fairly traditional plate amp design there. This is a bit more ambitious.
  Reply With Quote


DIY powered mainsHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Class D amplifier? mains powered? ThyDntWntMusic Solid State 2 3rd February 2008 09:40 AM
D-class amp NOT powered straight from mains kubeek Class D 10 28th December 2005 02:43 PM
D-class amp powered straight from mains? kubeek Class D 1 26th December 2005 05:33 PM

New To Site? Need Help?

All times are GMT. The time now is 07:59 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio