FrankenHead and FrankenCabinet build

[Paul P]

Well I did a photo essay for the amp, why not for the head and cabinet...

Like the amp this is going to be unconventional. Since I play only in my
livingroom and won't have to move my gear around much I'm going more for
a piece of furniture than a traditional tolex or tweed style. The speaker is a
single 12" Eminence Red Fang.



I had just enough yellow birch lying around which was rough cut 1-1/2"
thick and wanted to plane that down to something reasonable like 7/8"
but my planer started to get tired when I got to 1" and I didn't feel like
sharpening the blades (a lot of trouble) so I stopped there. It does make
calculations easier. The cabinets will be pretty heavy.

Here's the stack of boards planed to thickness :



Glueing up narrow boards to make wider ones with my homemade panel clamps :



Panels sanded and cut to final dimensions :



Paul P

[black_labb]

the plan looks good, and the timber should go together well, even if it is quite thick.

[tubeswell]

Hi Paul P

That amp looks smaller than I thought it would (or is it just the thicker sides making it look that way on your drawing?) Have you thought about where you're going to put the handle(s) on the speaker cab?

[Bruce / Mission Amps]

Paul when I use to run our family's custom furniture woodshop, I also would also build all my own cabinets...
Here is what my ears would tell me... too thick and too hard of lumber (ie., real hardwoods) meant too clangy or dullish overtone ringing and brighter cabinet sound.
The best sound (again, to me) came from 4/4 s2s sugar pine and yellow pine, although some poplar cabs worked OK and some Alder cabs sounded good too.
Anyhow, I'd run the rips through our 15" planner, then the jointer and do the glue ups without biscuits.
When hard and the glue scraped off, I'd run them through the Time Saver to get about 3/4" slabs.
I used 13mm Baltic Birch for the baffles in the under 30 watt amps and 19mm for the larger powered amps.
The small, 5-15 watt amps would only get 3/8" 4 ply A/C fir baffles.

**********
And yes, I also hated pulling the three knifes out of my 15" planner for sharpening and reinstalling... seems like that was always a + couple hour job and then when I thought it was good to go, ...running a few test pieces would reveal one or two was still doing most of the work, requiring another knife set up... UGH!!

[Paul P]

That amp looks smaller than I thought it would (or is it just the thicker sides making it look that way on your drawing?) Have you thought about where you're going to put the handle(s) on the speaker cab?

Tubeswell, I think the amp may look small because the box is so big .
My reverb tank is above the amp on the front wall under the grill cloth
(a little cooling air should make its way into the amp through the cloth
and around the tank. The dimensions of the front are 21" wide by about
15" high, and the depth is 13".

I've decide not to have any handles for the time being. I'll be insetting
two casters at the rear of the cabinet with rubber feet at the front so
I should be able to tilt it back and roll it around by hanging onto the back
of the top. I don't plan on going anywhere with it.

Paul P

[Paul P]

Paul when I use to run our family's custom furniture woodshop,
I also would also build all my own cabinets...

Hello fellow (ex?)woodworker. A few years ago I planned on getting into
the business on an artisan-type level. I then got sidetracked into the world
of traditional cabinetmaking using authentic old handtools, no machines
at all, but that sort of petered out as I got interested in music, playing
guitar with my younger daughter. I sold a lot of my old tools to pay for
amp-building stuff. For the moment I'm back to doing everything by
machine (and choking on all the dust !).

Here is what my ears would tell me... too thick and too hard of
lumber (ie., real hardwoods) meant too clangy or dullish overtone ringing
and brighter cabinet sound. The best sound (again, to me) came from 4/4
s2s sugar pine and yellow pine, although some poplar cabs worked OK and
some Alder cabs sounded good too.

I was originally going to use pine but having quite a lot of wood lying
around about the house collecting dust these last few years it seemed
kind of dumb to spend a lot of money on more wood. [Most of the yellow
birch I'm using was to be my daughter's bed, a birthday present for her
second birthday. She's now 13, we finally bought her a bed last year...]
I realise that the sound is likely to be dull/dead in some ways, and as
you say maybe overly bright in others. I guess I'll find out soon enough.
I'll at least be able to play with the thickness of the baffle.

At this point I just want to get any speaker together so I can play my
guitar. I have this gorgeous brand new Heritage H535 that's been sitting
unused in a closet since last year waiting for my amp.

I'm not sure if you did but I sharpen my own planer blades, three HSS
blades for my 13" Delta planer. I have a Makita sharpener that works pretty
well but it takes me maybe two days to do the job.

Paul P

[tubeswell]

Fair enough!

Wow! - you've got an unused heritage 535! You're full of surprises! You'll have to share with us how you find it.

I played a (from memory think is was a?) 175 (- jazzy number) in a shop three or four years ago and was blown away by the quality. Incredibly even volume and action right across the fretboard. One-piece carved arch front and back. If only I could've both bought it and continued to live happily with my wife - I chose the latter (- one of those moments when your heart is ruled by your head).

[Paul P]

The boxes are put together with finger joints, also called box joints. They're
easy enough to cut on a table saw with a stacked dado blade and a simple
jig that's screwed to the miter fence. There are a few sites on the 'net with
details.

[ATTACH]2280[/ATTACH]

The hard part is adjusting the jig sideways and making a couple of spacers
for the first finger of a board. After that it's simply a matter of moving the
board over one finger at a time. My fingers are 1" wide which required two
passes over a 1/2" wide dado blade.

[ATTACH]2281[/ATTACH]

The cabinet, which hasn't had the front slope cut yet :

[ATTACH]2282[/ATTACH]

And the head box, which is really pretty huge :

[ATTACH]2283[/ATTACH]

They aren't glued up yet. The joints are pretty loose which is ok because
the glue takes up space and the wood swells a bit when it's wet. Putting
together tight fitting finger joints can be pretty stressing. As it is you have
to be quick because there's so much surface to apply glue to and it's drying
while you're busy glueing the other pieces so you have to go back over it
to moisten it. Can be nerve-racking, and these boxes are by far the biggest
I've done with these joints.

The nice thing about using wood joints other than butt joints is that the
pieces will hold together even without glue, and stay aligned during glueing
and clamping. Substantially more work though.

Paul P

[scole]

hey paul, what jig are you using to make the box joints? homemade?

[Paul P]

Hi scole, maybe you weren't logged in or something but if you go back to
my post right before yours there are two photos of my jig. It's really a simple
thing but it takes a bit of fine tuning to get it right, since any error is made worse
and worse as you move along from finger to finger (something that doesn't
happen if you use a router jig).

[Edit : After thinking about this a bit I don't think the error can get worse as
you move across the board, though it seems like it. Any error you make will
certainly be repeated as you go, though, so you have to have it adjusted
pretty well. It's worth it to cut fingers on many scrap pieces until the fit is
just right.]

Paul P

[trevorus]

Man, that's some nice cabinet work. On the couple of amp cabinet projects I did, I used butt joints that are reinforced with a small piece of square stock. Then I use a pneumatic brad nailer to tie it together as the glue dries. Doesn't look as pretty, but seems to be quite solid. As far as baffles go, I've pretty much used a scrap piece of OSB for now on a Valve Junior Combo rebuild, and it sounds really good. I was wondering if different baffle materials would have a big impact on sound.

[Paul P]

As far as baffles go, I've pretty much used a scrap piece of OSB for now on a Valve Junior Combo rebuild, and it sounds really good. I was wondering if different baffle materials would have a big impact on sound.

The minute that you let the baffle vibrate I'm sure it does.

I'm trying to get used to the idea that the behaviour of the baffle, and even
the entire cabinet, contributes to the overall tone. I can't help but think that
a vibrating box of wood will sound very much like a vibrating box of wood,
like an old tv set played too loud. Funny that sonic properties that are
associated with quality amps stem from the fact that the originals were so
cheap. Cheap amps with 10% distortion in cheap boxes of thin plywood that
rattled and shook.

It must take quite a bit of experimenting to get the knowledge necessary
to be able to design the sound of a cabinet so that it resonates just the
way you want it to over its frequency range. Bruce has this knowledge,
I certainly never will.

Paul P

[trevorus]

I'm in the same boat, Paul. I just have to throw it together, and hope it sounds good. In my particular case, it has, so I don't think I'll be fiddling with it, really.

[Paul P]

I rounded over some edges and cut the taper on the cabinet front
(still not glued up) :

I can't help but wonder about all the heads that must've fallen off
their cabinets and if they survived the experience. The shock must
put tremendous pressure on the chassis at the power transformer.

I'm going to rout some depressions in the cabinet top for the head's
rubber feet. This thing is so big the cable will probably break before
it falls over...

Paul P

[Bruce / Mission Amps]

I rounded over some edges and cut the taper on the cabinet front
(still not glued up) :

[ATTACH]2289[/ATTACH]

I can't help but wonder about all the heads that must've fallen off
their cabinets and if they survived the experience. The shock must
put tremendous pressure on the chassis at the power transformer.

I'm going to rout some depressions in the cabinet top for the head's
rubber feet. This thing is so big the cable will probably break before
it falls over...

Paul P

Right.. small 1/4" deep pockets for the rubber feet of the head to "drop" into but remember, if you do that you can't have a regular handle on the top lid of the speaker cab carcass.
I use 5/8" thick rubber feet on my Crusader heads and the Hiwatt style handles that fold down pretty tight.
http://www.mojomusicalsupply.com/ite...962&id=5220001