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Here are some pics of the 184 subs I built in various stages of
construction.
I used Fane 18XB drivers and have found them to sound very good (obviously
I don't have the PDs or RCFs to compare them to)
Here is some advice I would give to anyone thinking of building these
subs:
1) Cutting the circles for the port tubes was a bit hit and miss -
cutting such a tight radius with a jigsaw tends to bend the blade,
giving the cut a slanted finish, and making sealing the gap more
difficult.
2) Screwing the port tubes to the front panel was a bitch - we ended up
driving nails in, then taking them out and putting a screw into the
resulting hole.
3) Get the plywood cut by someone else with a wall saw - we got ours
done for 50 pence per cut at the B&Q warehouse, and all of the cuts were
spot on - within a millimeter - and this makes putting them together so
much easier
4) Put some handles in them - they're rather heavy to move around when
built, so taking some time to fit handles (or making your own) would be
time well spent - I'll definitely be fitting some on the next cabs I
build
Apart from that they were very easy to build - just have to follow the
rule of measure twice and cut once.
Thank you for these excellent designs, I can only wish that there were
more PA sites that had plans of this quality on.
Bob G
Rog's Reply:
Thanks Bob for those tips, just a quick word of how I go about points 1
and 2.
I always cut the 6” holes in the baffle with a router fitted with a
straight cutting bit and radius attachment. Even when I used to use a
jigsaw for cutting the holes I never found it difficult and never had
the problem of the blade slanting. I think the use of a better more
professional jigsaw and cutting more slowly would help here.
I have never screwed ports onto a front baffle. There are two ways to
attach the ports to the baffle, the first way is to always make the
baffle holes a very tight fit and use lots of grip fill (builders
construction adhesive) to hold the ports on to the baffle. Always leave
around 2 mm of port just proud of the baffle and then use a belt sander
to sand them down flush with the baffle. The second and better way is to
attach the ports to the baffle is to make the hole for the port in the
baffle smaller than the port, then use a router on the back of the
baffle to route out a channel the same size as the external diameter of
the port. The channel should be around 14 mm in depth, so that it does
not break though to the front of the baffle. Use lots of adhesive ‘grip
fill’ and push the port tightly into the 14 mm deep channel on the back
of the baffle. Now use a trimming bit in your router on the front of the
baffle to make the hole as seen from the front of the cabinet the same
diameter as in inside of the port. A trimming bit is a straight cutting
bit with a bearing at one end, make sure the bearing is touching the
inside of the port as you go around it, that way the hole will always be
the same size as the port. Lastly use a round over bit to put a radius
on the baffle hole. Fitting the ports this way will always make sure
that the hole you see from the front of the cabinet is the same size and
shape as the inside diameter of the port.
The last point I would like to make is that I never use any battens
around joints. If you use lots of glue and screw every 150 mm then I
don’t think that adding battens makes the cabinet any more air tight or
last longer on the road. It just adds weight and takes up internal
volume. I would rather the cabinet be really well braced from adjacent
and opposing panels than be battened just around the edge of the box.
And if you do use bracing don’t put it exactly half way along or in the
middle of a panel, always offset the brace, as if you divide the panel
into two equal sections you now have two panels that resonate at the
same frequency but just higher up in frequency.
Rog
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