When it comes to setting up the active crossover which spot frequencies would you recommend ?
The crossover X's at 400Hz and 3800Hz. My aim was to just inject a sinewave input to the crossover and power amps and measure the output voltages at various frequencies.
The crossover X's at 400Hz and 3800Hz. My aim was to just inject a sinewave input to the crossover and power amps and measure the output voltages at various frequencies.
My crossover is different. I don't know the L values and the caps are the same but I have fewer resistors of different values! And my speakers are WA's old demo models. Btw the coverage of the damping material was a bit sparse and random - and differently applied from one cab to the other - and this was done by WA or their cab builders.
If the pads are the sort with a layer of rubber damping, then they are designed to add a bit of mass to the walls and lower resonance. The original BBC spec for this was that they only needed to cover 50% of the cabinet wall and should be placed centrally on the panel.
AFAIK, they are not required on the baffle, which already has the weight of the drivers.
Check with WA about the foam blocks. They should have supplied the right damping for the cabinet.
AFAIK, they are not required on the baffle, which already has the weight of the drivers.
Check with WA about the foam blocks. They should have supplied the right damping for the cabinet.
Yeah, a bit like small carpet tiles with a peel-off backing, that's what mine have too.
You can't double up those but I would try and add some more foam thickness.
There are some sellers on ebay which sell acoustic foam tiles for a lot less than Auralex costs in the shops.
Wilmslow also sell what I had in mind:
Acoustic Foam Panel Eggbox Profile
I would add at least one directly behind the woofer and may be extent that to cover the whole back panel.
There are some sellers on ebay which sell acoustic foam tiles for a lot less than Auralex costs in the shops.
Wilmslow also sell what I had in mind:
Acoustic Foam Panel Eggbox Profile
I would add at least one directly behind the woofer and may be extent that to cover the whole back panel.
Not enough to make a meaningful difference.
The idea is to damp out reflections from the back panel exiting through the woofer cone as much as possible without choking the system.
A little trial and error testing might be necessary.
I have noticed some LF vibration on the top panel of my cabs, these were treated with extra sticky damping from WA.
I think that is impossible to avoid without performing some major surgery on the cabs.
However I still would fit a foam panel like the ones I linked to behind the woofer. This doesn't do much to avoid the LF vibration you speak of but it reduces any upper bass/lower mid reflections (250Hz and up to xover frequency) bouncing off the back panel and exiting through the cone.
Anything reflected below around 250Hz should be within 1/4 wavelength on exiting and thus won't matter a great deal.
Now that is a good idea and makes a lot of sense, I must buy some, I guess a square foot would do it?
I think one or two tiles per speaker should do it but there is no harm in experimenting a bit.
I assume the rest of your cab is lined with those bitumen + foam panels.
I assume the rest of your cab is lined with those bitumen + foam panels.
I must look at the size of the tiles and order some, it's difficult to imagine a cleaner midrange than these PMCs are making but it's definitely worth a try. Yes, my cabs had a few (seemingly) completely randomly placed panels (by WA's builders) when I got them, I bought some extra and made them the same so at least it is a pair, it's probably overdone now but I doubt that makes any difference. It made me wonder just how much these panels do if all the people who demo'd them didn't notice they sounded different! Or maybe that's why the demo pair were sold!
It won't do much for the range covered by your mid but it should help cleaning up the octave just below ie the 200-400Hz range.
You won't get much help from foam panels below around 200Hz without filling the box so much that it suffocates but it will help covering the back and may be the sides.
You won't get much help from foam panels below around 200Hz without filling the box so much that it suffocates but it will help covering the back and may be the sides.
That is a very interesting thought, I'll have to try it, it does make sense, thanks for the tip. By "suffocation" I guess that you mean a stifling of the out-of-phase bass reflex effect? Would this depend somewhat on the material used for filling the box? This is possibly beginning to overlap with the ideas involved in TL design?
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