From rafael2pop@yahoo.com.ar Wed Nov 21 07:09:59 2012
Subject:Re: Speaker placement

Seen photo of VOX AC-30 stack on this permalink:

http://groups.yahoo.com/group/CloneWheel/photos/album/1779455190/pic/1245901405/view

Nice to see those legend cabs. Remember AC30 back in 1970 as the sweetiest guitar amp ever heard.

Cabs are not that hard to build for a cabinet maker but what is hard to get is the front grill cloth "diamond" like

tip: IIRC replacement can be got in a few places , eg

http://www.tubesandmore.com/products/S-G420

The coaxial stack seems to be a new approach if compared what it's used to see.

btw coaxial and  full-range speakers are hated
by crossover makers

Best,

Rafael

Re: Speaker placement

Wed Nov 21, 2012 5:52 am        (PST)        . Posted by:
"Bruce Wahler"         drawbars   

I kind of backed into my design, but here's where it started ...

I play keys and rhythm guitar, too.  Normally, I use an AC30, the
2-piece version with head and cab. 

I didn't like the new cab style (no  fascia on the top front),

so I had North Coast Music make me a '60s
style 'super twin' cab.  When it came time to make a stage monitor (and
smaller-room keyboard amp), I wanted another 'AC30' cab, so I could
stack them and save stage footprint. 

North Coast does *not* make custom
cabs; they are licensed by Korg only to make a few '60s-accurate
models. 

They do, however, sell them without speakers, and either open-
or closed-back.

So I decided to go the modern route.  If you do the math, an AC30 cab is
way too small to make good bass; it has a natural low end that rolls off
at about 100-110Hz, unless one puts tiny speakers (6" ?) in there.  But
sealed cabs can be EQ'ed to compensate for lack of low end, and will
work smoothly until they exceed their maximum throw.  So, I went with
coaxial 12's and excellent German-made compression drivers that roll off
about 30kHz.  Then I bought a Crown XTi power amp with built-in DSP,
took some room-compensation software I bought and a $300 recording mic,
ran pink noise through the speakers, and EQ'ed it until it was
reasonably flat from about 40Hz to 25kHz.  It sounds great with acoustic
piano, synth, Clav, and of course, the Vent.  It's probably not any
better sounding than a QSC or EV solution -- I haven't done any A/B
comparisons -- but it's slightly smaller, and completely camouflaged on
stage.  (Most players hear my rig and assume it's going through the PA,
even when it's not.)  It keeps up with my guitarist's 50W Rivera, but
just barely before the woofers start to 'blat' -- about like a pair of
K10s, I would think.

I've thought about building another one with subwoofers to use as a pair
for outdoors, etc. because system has plenty of 100-25kHz left; it's
just the low bass that runs out of headroom.  And I have a pair of
expensive subwoofers lying around from a home theater project that got
scrapped a couple of years ago.

I just put a photo of it in the Photos section (not Files).

Regards,

-BW

Bruce Wahler
Ashby Solutions.com^ (TM)
bw@ashbysolutions. com
http://music. ashbysolutions. com
877.55.ASHBY  (877.552.7429)