"Official" small box dimensions?

[WaZaK]

I searched and got 23 pages - mostly irrelevant: tightened up the search to "small box dimensions" and got zilch! Maybe it's hiding ......
So I checked the web: 5 manufacturers have 5 different sizes. Just to keep it interesting, some, including Swanson, Trinity and Vintage Head Box, don't seem to mention size other than "small box" or "18 watt".
26" wide seems popular (Mojo, Vintage Sound) but as small as 20" is quite common (Tube Amp Doc, Thunderbolt).
Height seems to be anywhere between 8 and 10", and depth between 8 and 9".
However, as most seem to agree on a 16 x 2.25" cut-out, I guess that is about OK.
Does anyone have a tape or ruler to stick next to a "real" small box (whatever one of those is) and tell me what it reads?
Yes, I know the box won't add tone or be louder (unless I use red tolex and gold handle covers plus a block M*rshall badge) LOL , but if I'm going to "recreate" an amp (and hopefully improve on it) I don't want to screw up on the dimensions. My handicraft skills do not need added avoidable errors! Also, I will want to match up to a 1 x 12" cab and need to know the head width to calculate the required cab volume (dimensions).
Any ideas?

[ChrisU]

If you look on the Marshall website http://www.marshallamps.com/product.asp ... Type=SPECS
the 2061x head and cab dimension are shown in the spec.

[Phil_S]

Funny that this should show up today. Just yesterday, I got out the saw and router to build a head cab for my 18W, which lives in a chassis 16x8x2.

For height, I like to have a little extra clearance both for heat and to allow a tube change without pulling the chassis. For this, I think ~8" interior height is appropriate with about 6.5" to the top of the tubes (highest point). I like a little extra width to allow for bracing blocks, etc., so I'd allow an extra .75" on each side; for a 16" chassis that's 17.5"

I used 1x10 #2 pine, which is 9.125" wide. Since I'm just cutting a one-off for personal use, and don't have a table saw (using a circular saw) I don't focus too much on exact dimensions. I'm happy when I can get the two sides the same length and the top and bottom the same length and for them to be square, too. I wasn't about to try to rip the width down with a circular saw. Even with a rip fence, it is a difficult cut and doing about 5' long is even more difficult to assure that it will be square.

I ended up with a box, exterior 19.5wx9.5hx9.125d, interior 18wx8hx9.125d. Interestingly, this isn't far from the Marshall dimensions, see below.

The Marshall site says 510x208x206 (mm) which is roughly 20x8x8 (in). I assume these are exterior dimensions.

In the end, it depends on the chassis and the tubes used.

OK, so here are 2 pix of the rough cab. I messed up as one of the dovetail cuts is uniformly too shallow by about 1/8" and I've been thinking about the best way to deal with it. I could be sanding it for months Wood filler and the roundover bit in the router probably.

[WaZaK]

Thanks ChrisU. I didn't think to look at Marshall - primarily because I didn't see any archive dimensions previously - and I have no idea how close the 2061x (reissue) is to what was previously used. I guessed that if they can throw out the tube rectifier, then why would they hang on to the original dimensions!
Anyway, 510 x 208 x 206 is what they say (now) - which converts to approximately 20 1/16w x 8 1/8h x 8 1/16d.
Nice pictures, Phil_S. Thanks for sharing. Also thanks for your thoughts on the dimensions. What is your cut-out going to be? (I see you have not got there yet!) I'd be interested to know your end radius dims, and what size roundover bit you will use on that material.

[Phil_S]

Oh, this is a whole new thing for me. I admit freely that I have not thought through all of the considerations of making a cab. I thought I'd allow it to evolve organically and see what I learn.

I had a little bit of time this morning and ran a 1/2" roundover bit on the corners. I probably would have used a 3/8", but those shallow dovetails need all the help they can get. I've still got to solve the problem of how to level the sides, lotta sanding to do .

I also ran a 1/4" roundover bit along the outer edge just to dress it a bit. I know it's just knotty pine, but I will probably give it a light stain and poly finish. I don't think I've got the patience to tolex it., but I could if I stumble on a cheap source.

My thinking is to install a couple of endblocks to take up the excess space between the chassis and the inner sides, then build a frame and stretch some grill cloth on it for the front. A couple of vertical blocks should facilitate mounting the grill and all it to be screwed in from there rear for a tidy finish. I've got a bag of T-nuts for speaker mounting and a couple here might work well.

I haven't begun to think about the treatment in the rear. I suppose I'll be needing a back panel that screws into the sides. I've enough depth to do it that way. I could use a rabbet bit to carve off some of the inside to make a slot if needed.

The chassis will be screwed in from the bottom. I'll countersink the screw holes. All that's required to get this right is a proper cardboard template that's been punched and tested.

I'm considering cutting some material out of top to do double duty as a heat vent/handle. The power tubes are very close to center, so I'm thinking this will work well.

[WaZaK]

Thanks for the update.
I'm still scratching my head with possible dimensions though. It seems there is simply no such thing as "standard" - because everybody seems to have their own "standard"!
Though it originated from this site, I didn't find it here even though I ran a search. I found it while trawling the web .......
http://www.uploadarchief.net/files/down ... d_rev1.pdf
This one is interesting because it has two head drawings: one an "18 watt" (24") and the other a "small box" (26"). Now this confuses me: Is an 18 watt not a small box head?
TurretBoards supply a chassis called "small box" chassis - which measures only 14' overall, while the "standard" seems to be 18 1/4" overall. Ironically, their chassis which matches the "standard" is called a "medium box" chassis!
I note many cabs say "will fit xyz's chassis" etc, which seems to confirm that there is no "standard" and the bottom line is that a "small box" is whatever rows your boat!
Still, the research has been interesting ........

[Phil_S]

I think your key here is not the amp chassis but the speaker cab. If you want it to match, and it isn't ridiculous, you can make the head box as wide as the speaker cab or smaller if you wish. Consider, the wider you make it, the heavier it will be. Personally, I wouldn't overdo it. 26" is just silly-wide for an 18" chassis. There is no "rule" that says the head width=speaker cab width. Just use your best judgment. No one in your audience is going to put a ruler on your amp.

[CurtissRobin]

What size cab would you like to have? That's the size it should be! You're hunting for information to "replicate" something that never existed. That's hard to do. Marshall never built the 18 watt amp as a head.

KennyO

[WaZaK]

My point exactly, KennyO!
And like no one is going to peel the Tolex away to see if the dovetails are the right size (LOL) Indeed, once covered, MDF will look like a classic masterpiece!
So in years to come, when this thread has dissolved into the ether, some other person will ask the question and I will have the definitive answer:
"Providing it is somewhere between the size of a matchbox and a London bus, then it will be an "authentic" small box ......."

[ReverendD]

Small box just means something smaller than the 30" (approx, don't have my big box super lead anymore to measure) wide marshall big boxes. Many like the narrower sizes for a more compact head and they fit a 2x12 a little better (if its standing up) than a wide head perched on top of a narrow cabinet. For a stack it hardly matters if your using the normal 30-31" wide stacks.

Regards,

Dyna

[Wayne_Alexander]

You are experiencing a vocabulary/terminology problem. To a Marshall person, the "smallbox" head is a very specific size - it's 660mm x 260mm x205mm, (or 26" x 10.25" x 8") and it's the headbox size for the JTM45 and many of the 50 watt Marshall amps. The "large box" head was used for the 100 watt and some 50 watt heads, and measures 750mm x 260mm x 210mm (or 29.5" x 10.25" x 8.25"). If you're using an 18 watt chassis from GDS or one of the other suppliers that uses a deeper chassis than 7", you need a headbox that's deeper than the 8" depth of a standard smallbox Marshall type cabinet. There are several cabinet makers who will build an "18 watt smallbox" cabinet, but it's NOT a standard/classic Marshall smallbox head cab. That's the difficulty you're having. The length and height of an "18 watt smallbox head cab" can be the same as the standard/classic Marshall smallbox head, but the exterior depth (front to back) needs to be 9" outside for most 18 watt chassis, about 1" deeper than your actual chassis depth. The chassis depth on a JTM45 or a 1987 is less than that, by an inch or so.

[WaZaK]

Thanks for the clarification, W_A. Very interesting.
My original comment was largely rhetorical: a question purely of aesthetics, I guess. You know, proportion; the "golden mean", etc.
Of course I realise (without being facetious) that a small box is smaller than a large box - and that as KennyO points out - recreating something that never existed is somewhat tricky ..........
But having seen (IMHO) some pretty ugly (in terms of proportion) small amplifier housings, I was simply interested to know if there were any strong feelings within the community as to what an 18w "small box" should be.
Personally, I like the "look" of the Swanson 18w box, but the dims. are not stated.
I have to conclude that for most people, an amplifier is utilitarian: something that amplifies music - and not intrinsically a work of art. Therefore the sound is really all that matters!
I must be getting too old. And seeing the youngsters going around with their dropped waistlines showing a "plumbers bum", I guess aesthetics will die with the baby boomers!
This is too philosophical: getting off-topic. I'll shut up!

[Phil_S]

My original comment was largely rhetorical: a question purely of aesthetics, I guess. You know, proportion; the "golden mean", etc.

I think you will find a width:height ratio of about 1.5:1 to 2.5:1 is aesthetically pleasing for a head box. Wider will look unwieldy (think 30x10). Narrower will start to become tipsy looking, peculiar, or will reach into combo land (18x18 will hold a speaker nicely--not saying it will sound good, tho'). Also, the wider it gets, the heavier it will be. People get heads to lighten the load.

[CurtissRobin]

I'd say Wayne's got it nailed.

Years ago I had a Fender Dual Showman amp. It came in reverb and non-reverb forms. The Reverb version's head cab looked a mile high due to the extra few inches of height for fitting the tank in there. Talk about an out of proportion and awkward appearance!

KennyO

[CurtissRobin]

If you're not intent on building a cab there are a few available on the Paul Ruby website. Go there and click Yard Sale or just click: http://paulrubyamps.com/BigCab.html He says it'll take a 22 x 8 x 3 chassis. $150

KennyO

[WaZaK]

At that price it's hardly worth bothering to make one! But unfortunately the cut-out is too big (at 3" high) for my plans, so if I'd have to remake the front and back, it's not so much of a bargain. Thanks anyway.

I have actually started throwing some scraps of wood together to make a prototype. I was going to use all 3/4" MDF as I had plenty. Then I realised I had made the top and bottom out of 11/16 material and had none left for the ends ..... So the ends are 11/16 birch ply. The front and back are 1/2" MDF.

I'm happy with the proportions now (see pic) so I think I'm going to go with this. But maybe tomorrow I'll change my mind ..........

[WaZaK]

Yep, I woke up and changed my mind!

I decided to take a break from the soldering iron and spend more time playing with cabs / sizes / construction methods / coverings.

This is the latest "try-out".

[drew]

You are experiencing a vocabulary/terminology problem. To a Marshall person, the "smallbox" head is a very specific size - it's 660mm x 260mm x205mm, (or 26" x 10.25" x 8") and it's the headbox size for the JTM45 and many of the 50 watt Marshall amps. The "large box" head was used for the 100 watt and some 50 watt heads, and measures 750mm x 260mm x 210mm (or 29.5" x 10.25" x 8.25").

A visual aid, courtesy of Jeff Beck:

[WaZaK]

I seem to have got side tracked with producing a plexi logo. I got the font right, but on an 18w Lite MicroBox, the standard 6"x2" seemed disproportionately large. Hence the paper mock-up scaled down. No point in laminating with the plexi till it looks right! I think it's right now.

This job seems to have become a "cost" challenge now, so I've got to be careful. It was the non-standard gold string that caused problems: 2 yds @ 21cents a yard! I'm running over $7 now, (at Home Depot type retail prices) and the logo will take it close to $8 ......

Maybe I'll see if Jeff Beck wants it for a couple of thousand when it's done .........

[WaZaK]

Paying the bills delayed immediate progress, but ....
I have completed my first attempt at a block logo. Now I know why those that sell them charge silly money!
Yes, I could buy one, but where is the fun?
Anyway, that is not quite true: I can't buy a small one. The original blocks were for the larger boxes, and I wanted to scale one to fit a MicroBox or LiteBox (whatever you want to call them!)
(Ignore the .jpg color in poor light. The color is not really too bad.)
I just know someone is going to say I know an easier way to make a block rather than hacking in fontmaker and photoshop.........