Cwmwenallt Musings

The remaining build activity for the Ghettocaster was to install the electronics, and I decided to take a somewhat unconventional apporach here. You might recall from the initial sketches and early posts, that I intended to put a telecaster like control bar on the front of the body, however after finishing the body a week or so back, I’ve more or less gone off that idea. Partly because I like the look of the wood, partly beacause I probably wouldnt use the controls that much anyway, and partly because it would mean opening a big hole in the front, which would then make the body entirely drilled through, which I thought might lessen its stability.

In the typical SG scenario the jack plug would emerge from the front deck of the body, again to preserve the wood finish, I dont want to do that, so nstead I’ve decided to route both pickup signals off the guitar unmodified, by using a stereo jack plug and route it out of the back-side of the body.

I bought a stereo jack plug for this, but unfortunately as you can see the there is quite a bit of wood between the cavity and the external surface, to get the jack plug to emerge at this point would have required taking a large amount of wood out, but all I wanted was to drill a small hole. So then I had a bit of a brainwave, I took a stereo minijack to jack adapter, and wedged it into the socket, like so:

Form the back of the guitar, all we see is a fairly neat mini jack socket. Obviously this means I wont be able to use the standard 1/4 inch jack plugs with this guitar, but I have a splitter cable which converts mini stereo into two quarter inch jack sockets (sorry forgot to take a picture of that).

So, then it was just a question of wiring it all up. I soldered wires to the stereo socket, but as there wasnt any pots to solder to for the remaining wires, I just screwed in a bit of block connector, which was handy as it allowed me to have a couple of goes until I got all of the wires in the right order.

So that was it, time to plug in and test. And it works!

Here is a small snippet of how it sounds, this is running both the neck pickup (as the left signal), and the bridge pickup (as the right) into Guitar rig, there are two overdubs here, one for the rhythm part and one for the lead. Both are using the “Jimi’s little wing” GR setting with a few tweaks. Apart from the dodgy quality of the playing, which hopefully we will be remedying over the next year, I think it sounds pretty good.

So thats it, basically done. All that remains is to get a couple of plastic covers for the rear chamber and the pick guard (when I finally settle on a shape!).

Toodle pip twangsters,

Sean.

The last couple of weeks, as time has permitted, I have mostly been focussing on the bodywork of the guitar. After cruising the guitar builder forums, I decided to finish the body in a product called tru-oil, which is a linseed oil based varnish intended for gun stocks; but makes a nice smooth and breathable finish for guitars. I also took the trouble to line the pickup pockets with a special conductive paint I got from stewmac. I was going to use copper foil, but this seems a lot neater.

Product placement:

After about 5 or 6 rounds of sanding, and rubbing on the varnish, the body looks pretty splendid, and smells like an old school desk. Hopefully the smell will wear off!

I didnt go to a really high gloss shine, although apparently the tru oil will do that, because I wanted it to look and feel like a piece of wood.

In this second picture I angled it so you can see it catching the light, which shows of the finish a little better.

here is a closeup of the pockets with a couple of coats of the conducting paint applied.

After assembling the guitar and a fair bit of fiddling with the little screws on the nut and bridge, it was finally set up and in tune.

And here she is in all her glory. Not quite done yet, still have the electrics to sort out, and the pickguard is roughly cut out of a bit of mounting card (and not the final shape either). But it does sound quite good, the card acts as a little sound board and it really holds a sustain well.

So. its official, I’ve built a guitar.

Next up is the electrics, where I’ve had a bit of a brainwave. So hold tight for that. Also in terms of practice, the black water side piece is coming together fairly well now, although I’m not going to be rivalling Bert any time soon, so I’ve added a new piece to the schedule. its called Andante in C by Mauro Giuliani; better known to the over 30’s in the audience as the “Tales of the Riverbank” Theme Music, the score is available here if you want to have a go, its fairly straightforward although there are a couple of tricky middle bits.

So thats it twang fans, until next time.

Hopefully the irony in the title translates, after you’ve read the article.

Today was quite a watershed day for the ghettocaster, I was going to post on the Sunday assessment, albeit a day late; but I just had to get this out there. The Sunday assessment for this week may go out a little late. If you are interested however, the practice piece for the coming few weeks is the traditional tune “black water side”, as played by Bert Jansch; a beautiful piece and probably beyond me, but I’ll be doing a separate post on it soon.

So – back to the ghettocaster. I’ve been stressing about whether this concept is actually going to work, as the profile and angle of the neck are set up for the higher Gibson style bridge. I wasn’t helped by the fact that the nut as supplied with the neck, not only is a rather ugly black, also has zero clearance for the string.

So, I thought, what I probably need is an adjustable nut so that I can dial in the height once the guitar is put together. A quick search revelaed more or less what I was looking for on eBay, and a few days later, here it is, in a rather fetching matching gold-bling finish:

So, barely pausing to think through whether this was a good idea, I proceeded to slice off the back of the nut slot to create a little platform for this nut to sit on:

And after a little sanding and cleanup with chisel, this is what it looked like.

Unfortunately, this is where the trouble started; the first problem was that when I tried to screw the block in place the little gold screw proved to be rather weak, and conveniently sheared off inside the wood. So that set me back a frustrating hour trying to extract it. Which entailed lowering the base of the platform by a couple of mm in order to get the grippers to attach to the stub of the screw

Then, blow me if the next one didn’t do exactly the same, Aargh! However by this stage I’d lowered the platform as much as I dared, but also I’d noticed another problem. When the height raising screws were engaged, they cause nut to angle slightly, which moves the leading edge of the nut back from the end of the fretboard by about a millimeter. My concern was that, even if I could compensate for this by moving the bridge, it would mess up the positioning of all the frets, making the whole thing impossible to tune.

So, I slept on it.

In the morning I resolved to fix both problems by a fairly radical step, which was to remove 1mm from the end of the fretboard. This solved both issues, by moving the screw hole away from the stub-end embedded in the neck, and allowing the nut to move back and preserve the original distance from nut to first fret.

And, seemingly it worked, however to check it out properly I really needed to actually attache the neck, so out with the drill (finally located it in the old piggery!), and whizz whizz, four neat holes:

And here they are form the back:

Then I bolted the neck on, unshimmed to see what the default angle would give, and after screwing down the bridge plate, I attached a string:

It actually became a guitar for the first time…. wow.

What’s more, after a little tentative tuning, taking it slowly in case anything gave; I actually got it up to concert pitch:

I fiddled around with the height of the nut to set the string clearance at the first fret to 0.09 , (midway between the recommended settings in my trusty Hanes manual for the telecaster), then I raised the bridge till the buzzing stopped, which was quite high, but still well within the prameters the bridge screw allows. You can see the height in this picture:

I had to dial in a little extra neck relief, which enabled me to lower the bridge a little, so now this E string is pretty playable the whole way up the neck. I checked the intonation at the 12th fret, and its pretty close, the notes at the other frets seem to be fairly accurate too. I still need to figure out what they actually should be based on equal temprament tuning, but I’m fairly confident now this is going to work.

Whew,

See you next time for the rest of the intial setting up, and more on actual playing.

toodle pip.
Sean.

[spot the obscure Led Zeppelin reference - answers on a postcard please]

So, another Sunday comes and goes with no assessment, have I given up entirely you’re all [not] wondering. Well no, thing is I’ve been travelling which has made regular practice something of a problem (although I did find a creative solution – more on that in a later post prhaps).

However the point of today’s missive is to update you on the progress of the ghettocaster, which has been sadly neglected of late, although still oft in my thoughts. I took the opportunity while in the US to visit a couple of guitar shops, and taking advantage of the exchange rate, purchased myself a nice little Seymour Duncan Telecaster bridge pickup. And here it is mounted in the Wilkinson bridge.

The pickup doesn’t need to be mounted directly to the guitar – see how it hangs off the bridge:

This means the bridge vibrations are transmitted to the pickup directly and so adding to that trademark twangy Tele sound.

But it does require a hole to accommodate that depth behind the bridge unit. And now the die is cast, I do have to whack out a little hole to put it in. So again out with the chisels (A router would probably be much quicker, but I don’t have one and am somewhat wary of losing a finger learning how to use one).

Anyway, before putting the pickup in the bridge unit, I carefully traced an outline on the body.

And then tap, tap tap…

…for about 45 minutes, until.

Ta. Da.

Well its a bit rough, I’m sure a router would have done a much better job, but the price was right, and the pickup fits. Most of the messy edges are going to be covered by copper shielding and the bridge pickup anyway so I’m satisfied.

Next issue is how to route the wire (that big black one in the picture above) out of the hole and into the cavity where all the controls will live. I can’t find my drill right now, so that will be an exercise for another day.

So. there we are, another small but significant step forward.

Oh and by the way I am practising still, if you recall the game-plan was to learn ‘Dee’ by Randy Rhoads; well I can just about play it all the way through now, but there are some tricky little changes in there, and its not that smooth. So I’m still working on it again all this week. Next week I’ll be getting back to the formal book plan.

So, thats it, keep on twanging,

Sean.

Morning campers…

Today was a bit of an important one in the life of the Ghettocaster.

For reasons I won’t go into here, (although the big freeze is certainly not helping), I’ve been a bit down for the last couple of days; so this morning I didn’t really feel like doing my morning practice. While moping over my second cup of tea though, I decided I was in exactly the right mood to tackle something I’ve been putting off – expanding the neck slot on the guitar body so that it would fit the Tele neck. This is a big step because getting the neck on straight is going to be critical on whether this project will result in a playable instrument or an evenings firewood. It’s also more challenging than the pickup pocket because this time any screw-ups are going to be visible.

So anyway, here was state of play at 10am.

And here we are at 11:15 – result!

It turned out to be a little tricky because the coping saw I originally bought for the occasion wasn’t able to give me enough of a stroke to make an effective cut once inside the neck pickup slot, this picture shows what I mean.

(sorry about the dodgy focus there).

So bouyed by my recent success with the chisel, and feeling gung-ho enough to have a crack, I carefully chiseled out the rest of the hole. I took it fairly slowly, and deliberately went for an undersized measure to give me room to maneuver later (always easier to take more off than to glue it back on).

What pleased me even more than not making a nasty mess, was the fact that once the neck is seated on the bottom of the slot, the middle of the neck lines up nicely with the middle line on the body.

So now it’s starting to look like an actual guitar.

But let’s not get ahead of ourselves. Here at the school of Cwm, in my role as acting head of the “making it up as we go along” department; I often find that I have launched into a project half cocked, with no idea how to proceed from a given point. Usually two options present themselves at this juncture, one is box the whole thing up and put it in the attic ‘for a rainy day’, hoping no-one will notice; the second is to rabidly consult the oracle of the internet for days on end, until I figure it out.

I find myself slightly in such a situation just now, but since I’m documenting the project for all the world to see, option one is out. In the ghettocaster project as we know, I’m attempting to merge the design of a telecaster and a Gibson SG, I’m using the Telecaster bridge on an SG body, not something I’ve ever seen before; so I’m a little off the map here. so the question is, what neck angle should I be aiming for so that I can set the thing up with a playable intonation; given that the angle pre-routed in the body was assuming it would be set up with a ‘tune-o-matic’ style bridge; which is considerably higher than that on the Wilkinson tele style one I’ll be using.

So ‘bing’ is my friend (being a Microsoftie, I have to eschew all things begining with G), and I located this fine resource, records from a man who has been there and lived to tell the tale. It apparently all comes down to trigonometry (you remember that far back right…),

So using his calculator the angle I need apparently turns out to be 0.89 degrees, which is actually a bit beyond my ability to measure accurately. According to my handy ‘angle finder’ though, the current angle looks to be around 2 degrees.

Angle of the body:

And the neck (assuming the frets are even, which they seem to be):

The difference looks like about 2 degrees, give or take.

I’m not sure how important this is going to be in the grand scheme of things, the bridge has quite a bit of adjustment ability; so my feeling is that I’m close enough now that packing with a bit of masking tape is going to suffice to sort out any discrepancy.

So that’s it for this session; next issue is making the bridge pickup pocket, and what to do about the front mounted controls. Hope you enjoyed it, cheered me up anyway.

Toodle pip.

Sean.

Today we were supposed to be going down to visit the in-laws for lunch, but a generous sprinkling of the white stuff in the night meant that the hill up the lane was too slippy to drive up.

So we got stuck halfway up, and I had a fairly hairy experience backing down the hill again, trying to avoid sliding off the side into the field 50 feet below. So, after strong a cup of tea to recover, I suddenly found myself with a free afternoon. And what’s this, a chisel in my hand, hmm….

OK, I’ve measured the distances about 50 times, and I’ve convinced myself where the additional pocket needs to be to accommodate my chosen pickup position as discussed yesterday. You can see in the picture that it will not quite double the width.

Well that was the before, and about 40 minutes later, this is how it looked.

and heres the pile of chippings extracted

OK, so not quite as neat as before, but I’m quite pleased with it actually, given that I probably haven’t whacked a chisel in anger since wood-work classes at school umptedum years ago, and once I install the copper sheilding and the pickguard no ones going to see it. Inspires a bit more confidence that I’ll be able to make a socket for the bridge pickup without screwing it up. So I think that’s that decision made. I haven’t been able to find the pickups I took out of beastie when she got a bit of an upgrade a few years back, although I’m sure they are in the loft somewhere, but actually since they are the original super 70’s, I probably would keep them in case I ever decide to return beastie to stock. And besides, Tele bridge pickups actually hang off the bottom of the bridge metalwork so they would be a bit wrong anyway; so it looks like shopping time again, these barenuckle pickups have had good reviews, so they are front runners unless an eBay bargain presents itself.

Here is a shot with the neck pickup held in place with a bit of blu-tac.

So first blood is drawn (well not literally you understand, although I did manage to whack the side of my thumb quite nicely with the hammer), onwards and upwards…

Sean.

Today is the first day of the new year, and I have been musing more on the Ghettocaster. In the previous article I described the overall design aesthetic I’m looking for. But if the thing is going to function as a proper musical instrument it also has to follow the design rules of a stringed instrument. The primary function of an electric guitar is to convert the vibration of a metal string into an electrical signal. Thus I need to understand a little bit about how a string behaves and how a pickup works. A couple of good reference articles I found which explain this in a lot of gory detail here and here. A general basic introduction is here.

I can’t pretend I followed everything in the Tillman articles, but the basic upshot it seems to be that a string vibration consists of a number of different segments which generate the fundamental tone, and a series of harmonics above it, and the type of pickup used, and more importantly its position with respect to those segments (as well as the mix between multiple pickups if present), is the main determiner of the sound of the guitar.

But whereas most guitarists are looking for a complex mix of higher harmonics, mixing bridge and neck, and sometimes middle signals; with single pole and humbucking arrangements to try and reproduce signature tones of classic electric guitar tracks, the Ghettocaster’s main role in life will be as a control device going into the computer. Thus I want to have a fairly strong and pure fundamental tone so that it works well with my Sonuus MIDI converter, and for actual guitar tones, I’ll be using my little Korg box, or Guitar Rig – which emulate classic guitar setups through complex signal processing and which will be providing most of the tonal variation. I’m not privy to how this software does it’s magic, but my assumption is it is primarily using a vocoder/convolution like arrangement multiplying the incoming clean guitar signal with stored waveforms, so it’s my theory that the purer the sound going in, the better these effects are going to work.

Thus, the Ghettocaster will have just one main pickup, I want to put it in the optimal position which emphasises the fundamental tone, and de-emphasises the higher harmonics (particularly the 4th and 6th which contribute the major third and dominant 7th, and everything above the 7th harmonic, which is where all the ‘jazzy’ tones get thrown in). This should give a nice rich pure fundamental, with a side of perfect 5th, which is basically a heavy metal “power chord”.

So where exactly is that ‘magic sweet spot’? Well of course it doesn’t really exist in any practical sense because as soon as you shorten the string by pressing down at a fret it’s going to move about; but for the open string, the response at 1/5th of the scale length (the total distance from the bridge to the nut) looks pretty promising. This will give a good strong dose of the fundamental, 1st, and 3rd harmonics; which are all multiples of the tonic. It will give a strong contribution too from the 2nd harmonic, which provides a perfect 5th. But it is a nodal point of the 4th harmonic, thus effectively eliminating the major 3rd. The harmonics after that up until the 8th harmonic yield either a repeat of the tonic or a perfect 5th. So, if we have the tone control set so that it attenuates the really high frequencies, this should give a fairly fat basic sound.

For the Ghettocaster dimensions, I’m working backward from the Tele style neck (I don’t think it has absolutely authentic Telecaster dimensions, but then I don’t have one to compare against), the distance from the leading edge of the nut slot to the 12th fret is 12 and 3/8ths of an inch, which means the overall scale length needs to be twice that: i.e. 24 and 3/4 of an inch; same as a standard SG I think. The Top Nut is 1 5/8″ across though, which I think is narrower than it should be.

If I butt the heel of the neck up against the back of the neck/first pickup pocket as currently routed in the body, the last few frets will occupy the space where the SG neck pickup would have sat, which will make it a bit less accessible than on a standard SG, but still relatively reachable and I doubt I’ll be doing a great deal of widdling around past the 16th fret anyway. Then if I measure off 4/5ths of the scale length (which is 19 and 3/4 inch if I have it correct), it means the pickup ends up needing to be pretty much neatly up against the leading edge of the second routed pickup pocket, not in the existing pocket of course; that would be too easy, but next to it.

So I need to extend the pocket for it, which will make for rather a large hole; however the custom pick guard will eventually cover it up and having all that space means I’ll be able to experiment with a few placings before committing to a final position. This extended pocket will probably actually make quite a large resonating chamber, and if I mount the pickup on the pick guard itself, then depending on the stifflenss of the material, the top plate will act a bit like the soundboard on an acoustic, and the pickup itself will move with respect to the strings. Quite what effect that will have on the sound (and my little theories above) remains to be seen.

The bridge pickup.

So, the remaining question is; whether to fit a bridge pickup? That is the one that gives that classic twangly Tele sound. For the basic role of the Ghettocaster as I’ve outlined it, it would seem superfluous; however it probably makes sense to add it, because mixing two filtered signals creates much more ‘interesting’ harmonic overtones (like the sound of an acoustic, where all of the overtones are heard), so in case I do ever get to feed the basic guitar into a monster stack of Marshall’s I may want that flexibility. Also, If I do add it, another interesting idea occurs to me, that it might be interesting to route both signals off the guitar unmixed and then combine them later in post processing where it would be possible to get much more creative in deciding exactly which overtones to add, an interesting topic for further investigation at a later date. So it makes sense to do the grunt work for it early on, before the body is finished, and then at least I’ll have the option to mess with the electronics later. On the other hand it means gouging yet another hole out of this nice mahogany. Good news is if I try it; any dodgy handiwork is going to be hidden by the bridge metalwork, but I’m wary of screwing it up.

Decisions, decisions…

Positioning wise, there is already a template slot in the bridge unit; and it seems churlish not to use it. I’m not sure why the bridge pickup is angled the way it is on a Tele; and I can’t be bothered to run all the mathematics to figure out what the harmonics generated would be. If it was good enough for Leo, it’s good enough for me. So that’s the theory anyway, let’s see what happens,

Bring on the twenty tens.

Sean.