Big 2-way

Dedicated to those large boxes at one end of the room
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#31

Post by chris661 »

Okay, so earlier I noted the large unbraced panels. It turns out that these have been a constant source of feedback at gigs.

So, I've done some measurements of different points on the panel to figure out what's going on. I used a clip-on piezo pickup feeding into a small mixing desk, which went into REW.

Without further ado, here's the diyAudio thread. All the images are embedded, so they should load okay if you're not a member there.
http://www.diyaudio.com/forums/multi-wa ... binet.html

Chris
SimonC
Old Hand
Posts: 545
Joined: Mon Sep 24, 2007 11:34 am
Location: West Yorkshire

#32

Post by SimonC »

Hi Chris,

This is over lapping with some work I'm doing on my tall multi-driver design and I have been running some modal (eigenmode) analysis on different bracing arrangements on them. (I'm lucky enough to have access to Ansys through work and can leave it chugging away after hours).

If you pm me the dimensions of your cab I can take a look to see if I can get a simulation to match your measured results, and once we have that we can very quickly test a whole range of bracing options overnight :-)

Simon C
chris661
Shed dweller
Posts: 2556
Joined: Mon Feb 22, 2010 7:29 am
Location: Sheffield

#33

Post by chris661 »

Ohh, that's very cool, thanks for the offer Simon!

Right, the big side panels are 420x760mm 18mm plywood, supported along 3 edges, 2 short, 1 long, and also supported around 35mm back from the other long edge, with a 18x70mm brace from the in-set baffle, around 40% of the way down. The long dimension of the brace is parallel to the short edge of the side.

There's also a handle and some screws into the side panel. The handle is made from thin-ish steel, so I think a near-uniform density would be maintained.

There are certain bits where braces can't really be added, due to the bass driver and horn. Here's a quick drawing - the numbers are fractions of the cabinet dimensions, and the red bits are where the drivers and horns live.



Image

Cheers
Chris
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