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.

2268

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 :

2265

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

2266

Panels sanded and cut to final dimensions :

2267

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.

2280

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.

2281

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

2282

And the head box, which is really pretty huge :

2283

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) :2289
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) :2289
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 PRight.. 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/item.asp?pid=17626&pg=44962&id=5220001

[Paul P]

I hate finger joints. They're about the only joint where you can't apply
clamping pressure inline with the glue joint so you have to resort to strap
clamps and cauls to keep the straps away from the joints. There's just so
much glueing surface that you have to apply copious amounts of glue so it
doesn't dry out on you, which then drips everywhere, especially where you
don't want it. Definitely not for the weak of heart.2310The box wasn't quite square at first, nothing a few whacks with a sledge
hammer couldn't fix...

Other than that, things are coming along nicely.

Paul P

[black_labb]

looking good.

[Paul P]

I glued up the cabinet which went quite well after practicing on the first box :2315While that was drying I rough sanded and rounded over the edges of the
head :2316Here's a close-up of a finger joint. To be honest they don't look this nice
everywhere but then, as the saying goes, a good craftsman is not one who
can do a perfect job but one who's good at fixing his mistakes... I repeat
this to myself everytime I do something stupid.
2317Paul P

[tubeswell]

Here's a close-up of a finger joint. To be honest they don't look this nice
everywhere but then, as the saying goes, a good craftsman is not one who
can do a perfect job but one who's good at fixing his mistakes... I repeat
this to myself everytime I do something stupid.Paul P

Hi Paul P, I have the same confession about using my new router, (its really easy to make tiny little slips when you get tired) so this time I'm going to cover the whole (5G9) box with tweed fabric again. :o

[Paul P]

I'm drowning in details... Besides the two boxes there are a bunch of small
pieces that go inside that have to be made. These are for the head, and
don't include the decorative faces :2342
I plan on using a piece of 1/8" plexiglass to cover the front and rear
panels which will be inset in rebates (rabbets) cut in the 1" square strips :2341
Starting to look like some sort of an amp :2340
The tape is holding on a patch to repair a chip that popped out while
rounding over the edges.

Now to do the same for the speaker cabinet.

Paul P

[trevorus]

What is the circuit you're using? knobs a'plenty

[Paul P]

What is the circuit you're using? knobs a'plenty

That's a long story :).

Here's the front panel with labels :2344
I originally planned to have reverb and tremolo on channel 2, so the panel
reflects this, but I've since put the reverb on channel 1. The range rotary
switches for the tremolo were so I could use quality pots which I could only
find in 1M and lower values.

As I mentioned somewhere else I plan to print out the panel on paper, glue
that to a piece of formica/arborite (countertop stuff), then put that behind
1/8" clear plexiglass (acrylic).

Paul P

[trevorus]

You might spray the paper/formica thing with laquer to seal it.

Of course, there is always this place: http://www.bnplasers.com/

They can do custom work.

[Paul P]

The cabinet with the baffle for my 12" speaker :2347 The baffle was cut from a piece of recycled 1/2" poplar
plywood that'd been painted beige. It'll be painted flat
black.

Still have to make the frame for the grillcloth.

Paul P

[Paul P]

I made the front and rear decorative frames out of cherry. The pieces were
doweled together then rounded over in a jig I threw together for the occasion.

2366 2367 2368 2369 2370

Paul P

[Paul P]

I got these really big rubber feet from Antique Electronic Supply when I
ordered my grill cloth. They're 1-3/4" at the wide end and 1-3/8" at the
small end. They're quite soft so they should offer the head at least some
isolation from the cabinet's vibrations.2377I routed some depressions in the cabinet top to receive the head's feet :2378Paul P

[Paul P]

The one thing that I've been pretty nervous about up until now has been
the grill cloth for my cabinet. My plan was to create a removable frame
that would hold the grill cloth sandwiched between two layers, a wider plywood
frame underneath with a narrower decorative frame on top.

I bought my grill cloth from Antique Electronic Supply, part number S-G297.
This is a pretty thick brown and black basket weave. One side is more black
while the other has large bands of brown visible (not shown in AES's picture).
I decided to have the brown on the outside. The brown doesn't show
well in the pictures below.

I've been afraid I'd have trouble getting enough tension in it to remove
wrinkles but it turned out to be pretty easy. I did a partial dry run of
assembling the frame without glue to see how it would go. I started
by marking the center of top, bottom and sides of the frame. I then
screwed one screw at the top center, followed the line in the cloth to
the bottom and screwed another screw in the center while pulling on the
cloth. I then did the same at the sides.

When I checked to see if the weave lined up with the frame at the ends
I found out that I had more of a parallelogram than a rectangle and redid
the sides. I put in a few more screws and found out that it was pretty
easy to tighten the cloth as I went, going back and forth to opposite sides
and ends working towards the corners.

I then traced around the plywood frame with chalk on the grill cloth and
disassembled everything. I then reassembled everything after having placed
a bead of glue on both halves of the frame.24192420
The cabinet itself is almost finished. I just have to trim the grill cloth and
put a partial panel on the back to hold the jack. The speaker will be installed
from the front of the baffle using machine screws with T-nuts on the inside.2421
Paul P

[Paul P]

Most of the woodwork is done. The rounding over of the panels has to be
worked by hand in the corners to blend the curves where they meet. I use
mainly half-round files for this :2426
The wood is yellow birch and I finished it with a sort of oil finish like that
found on scandinavian teak furniture where there isn't really any finish
visible. I use this on just about everything I make because it looks great
and is extremely easy to apply.

I first applied a quick coat of shellac (just the white liquid stuff you can
get at a hardware store) because of all the end grain due to the finger
joints which tends to turn really dark if too much oil is absorbed. I sanded
the shellac with 150 grit sand paper changing often because the shellac
quickly gums up the paper.

I then mixed up 1/3 mineral spirits (paint thinner), 1/3 pure tung oil (mine's
from LeeValley) and 1/3 satin polyurethane. I brush it on liberally and keep
all the surfaces wet for maybe 15-20 minutes. I then wipe it all off with
flannel cloths. I keep wiping until it feels almost dry. You have to wipe it
down often for a day or two because some of the oil seeps back out of
the wood and then it's hard to remove if it dries.

It would normally take about a week for the first coat to cure properly but
I didn't want to wait that long so I applied a second coat after two days
but this time I first added an equal part of polyurethane to what was left
of the mixture, greatly increasing its proportion. I applied as before but this
time it started to cure fairly quickly so I had to be quick in wiping it off
once it started. I wiped it down every hour or so until the finish stabilized.

That's all there is to it. It creates a fairly waterproof finish that is so soft
and smooth and has no visible film. It can always be waxed if you want
a more glossy surface.

One important thing : oily rags can catch fire by spontaneous combustion
if left in a pile. I believe what happens is that heat is generated by the
curing process and if this is concentrated in a wad or garbage pail it can
get hot enough to ignite, and there goes your house. I lay each rag out
on the concrete floor of my garage until it's dry.

My wood has a bit of figure to it, which shows up better under an incandescent
light :2422 2423 2424
Here's a close-up of the cherry frames for the front and back of the head :2425
I'm starting to think that I may just finish everything this weekend.

Paul P

[black_labb]

looking excellent, want to see it all together.

[Paul P]

Things are starting to move now that all the little pieces are done.

Here's the front frame with a piece of grillcloth to cover the upper
opening :2434 2435
The front control panel made from paper stuck to Formica for the labels
and plexiglass to protect it (I may do something a bit more elegant later
on) :2433
The front with the pieces installed :2436 2437 2438
I'm a little bit worried about static electricity from the plexiglass.

Paul P

[Paul P]

I installed the reverb tank. It's an Accutronics 9AB2D1D :2444
When I went to install the chassis I experience an "Oh xxxx !" moment when
I discovered that the output jack on the bottom of the reverb tank ended up
right over my reverb transformer and there was no way a plug was going to
fit in between. So I had to move the jack on the tank over a few inches. 2445
From the front : 2446
I'll be moving the footswitch jack back to its proper place and reinstalling
the intensity pot.

The speaker cabinet is now in my living room, though I still have to install
the speaker.

Paul P

[black_labb]

looks great. control panel looks great too.

[Steve Conner]

Looks great, the woodwork is beautiful :cool:

Shame to hear about the Oh xxxx moment, but I don't think you can avoid those. :( The last one I had was when I discovered the speaker magnet in my combo build stopped me from putting anything into the IEC mains socket on the chassis, and I couldn't relocate the socket.

I found that if I sunk it right into the chassis on spacers, I could just jam a particular brand of mains lead in. Eventually I blew the speaker, and the replacement had a smaller magnet that solved the problem :)

[Paul P]

Thanks guys. There is a "Part 2" to my "Oh xxxx" moment. I finished everything
yesterday (I'll post shortly with some pictures) and set the amp on top of
my cabinet in my living room and just left it there, figuring I'd try it out today
since it was late and I was exhausted, and I was kind of queasy about doing
it after all these months. Anyway I finally broke down and tried it out and
was disappointed to hear a buzz coming from the reverb circuit. Aaargh...

I was a bit concerned about how close the output coil of the tank was to my
reverb transformer and I guess it was too close. When I had the amp on the
bench I moved the tank real close and didn't hear any noise so I figured it was
going to be ok. I can move the tank up an inch or two which hopefully will be
enough (after I take everything apart again, which involves removing a pile of
screws and 13 knobs with two set screws each).

Oh well...

Paul P

[tubeswell]

Nice one Paul P!

I've had a heap of those moments in my recent build too. Seems I habitually take two steps forward and three steps backward at times. So if you've only made one small boo-boo, you're ahead of me mate ;-)

[Paul P]

I've actually played guitar the last couple of days, something I hadn't done
in months. Got to build those calouses back up...

With help from Casey4s for the idea I used some pieces of wood to attach
the chassis to the box. The strips are screwed to the chassis sides then
3" machine screws screw up from underneath into the strips :2472 2473
The rear control panel and frame are made the same way as the front,
except for the screws having to be on the outside. I'll probably replace
them with something a bit nicer sometime. Again it's paper on formica,
followed by 1/8" plexiglass, held in place by the frame : 2474 2475 2476 2477
A close-up of the power tube control center :2478
Paul P

[Paul P]

At last, the final installment...

Here's the front panel with the knobs installed :2483 2484Here is everything together :2480 2479
And the reason for all of this, my new guitar which has been hibernating in a
closet since last June. It, along with the amp, are to celebrate my fiftieth
birthday, which was last November.2482Thanks to all of you that shared the experience with me. I couldn't have done
it alone, that's for sure.

Paul P

[tubeswell]

That last one especially is a very pretty picture.
Now you should get practicing and post some sounds

[black_labb]

that looks excellent. great job