Gibson Deluxe Tuners (part two)

Please note that this post is part two of four posts. I highly recommend reading all four posts in order before acting on any of the information.

The other parts are located here:

Part 1: http://diystrat.blogspot.com/2009/01/gibson-deluxe-tuners-and-why-they-suck.html
Part 3: http://diystrat.blogspot.com/2009/02/gibson-deluxe-tuners-fix.html
Part 4: http://diystrat.blogspot.com/2010/01/gibson-deluxe-tuners-revisit.html

Well, the Gibson Deluxe Tuners post certainly attracted some attention. Seems there are plenty of people out there with the same problem.

Before I talk about my repair options, I’d like to discuss a little further the design limitations of the Gibson Deluxe Tuners. I previously mentioned that the little tabs that attach the back cover to the main plate do not fold over once they go through the main plate, which I found strange. While exploring solutions over the past few days I noticed that a lot of replacement tuners from other (often cheaper) brands had tabs which DO fold over, keeping them very firmly attached to the main plate. I really do have to scratch my head at why the Gibson Deluxe Tuner designers decided not to do this.

Non-Gibson Deluxe Tuners with tabs that fold over:



Secondly, I have noticed that there is one more problem with these tuners, which is that the worm gear wobbles quite a bit, even when the tuner is working perfectly, with the back cover attached. It doesn’t wobble from side to side, but rather away from and towards the guitar head. I hope that makes sense. This is caused by the claws not gripping around the worm gear, but rather, just stopping it from moving from side to side. The alternative solution offered by the Gibson Deluxe Tuners is to make the cutouts on the back cover (which let the worm gear pass through the sides of it) limit the movement of the worm gear away from the guitar head. Unfortunately, these are quite imprecisely cut, so sometimes allow for far too much movement.

So given that second note, I have decided that I need to tackle the wobble problem before attaching the back cover, since once I attach it I don’t want to have to take it apart again.
What I will do is file a little bit off the bottom surface of the back cover (leaving the tabs intact), so as to move the cutouts closer to the worm gear and hold it in place better. This has the added benefit of effectively extending the length of the tabs (not enough to fold over, unfortunately, but maybe just enough for a little bit of extra purchase)
[Edit: In the end I found the reason for, and the solution to, the wobble problem, which I've documented at the end of part four. Please check it out before you start any work.]

So after a bit of thought, I figure I have maybe three realistic options:

1. Make a type of metal strap, which would hold the back cover on. It would be held down by the two screws that would hold the main plate to the guitar. The disadvantages of this are that the strap would be visible and the screws might need to be swapped for longer ones. The advantage would be that it would require no irreversible modification to the guitar or the tuner, and it might actually look quite cool.

2. Solder the back plate to the main plate. Advantages would be that it would be a quick and easy repair that should be quite strong and fairly reversible. Unfortunately I’m not convinced the metal used on the tuners would accept solder readily. Really, I should be looking at brazing, but unfortunately that's just not an option for me.

3. Similar to 2, but use glue, most likely 2-part epoxy. Quick and dirty solution, but may work well.

Whichever method I choose, I will still file a thin layer off the bottom first.

I’m off work all next week (for Chinese New Year), so I’ll decide what I want to do then.

Gibson Deluxe Tuners (a weak design?)

Please note that this post is part one of four posts. I highly recommend reading all four posts in order before acting on any of the information.

The other parts are located here:

Part 2: http://diystrat.blogspot.com/2009/01/gibson-deluxe-tuners-part-two.html
Part 3: http://diystrat.blogspot.com/2009/02/gibson-deluxe-tuners-fix.html
Part 4: http://diystrat.blogspot.com/2010/01/gibson-deluxe-tuners-revisit.html

I have a problem with one of the tuners on my Les Paul. It had the problem already when I bought the guitar a few years ago and I managed to do a temporary fix, but the problem has resurfaced.

Before you continue, please note that this is written from an engineering point of view.

Firstly, let’s have a look at a typical stamped (open-backed) guitar tuner.

There are several components and many names for those components, so my apologies if I use ones that you are not accustomed to. Firstly, the tuner can also be called the tuning head, tuning peg, or the machine head (and possibly other names). It has a main plate, through which the main cylinder (or capstan), passes. The capstan is the shaft that the string itself passes through. On the end of the capstan is a gear, sometimes called the pinion gear, and a screw/bolt holds that on to the end of the capstan. Then we have another shaft or pin with the tuner knob (or button) on the end of it. This pin has a gear on it too (in fact they are one part in most cases), and this particular gear is known as a worm gear. From now on I will just refer to this shaft as the worm gear.

As an aside, and for any non-engineer-minded people out there, the reason a worm gear is used is because turning the button/knob will rotate the worm gear, which will in turn rotate the pinion gear and the capstan, thus tightening or loosening the string, whereas no matter how much you tighten the string, the pinion gear cannot force the worm gear to turn. This is a really good way to keep strings in tune without making it really hard to turn the knob.

OK, back to the description of the tuner. There is one further feature that I have not yet mentioned and that is the retaining “claws” which are part of the main plate and hold the worm gear in place. The claws stop the worm gear from moving away from the pinion gear or falling away from the main plate. The plate stops the worm gear from falling against the guitar and the pinion gear stops it from falling out in the direction of the capstan. So hopefully you can see that the worm gear cannot possibly fall out unless the pinion gear is removed.

Now to the Gibson Deluxe Tuners (and why I think they are a weak design).

As you can see, the tuner has the same components as any standard open-backed tuner, but please note one subtle difference – although the claws stop the worm gear from moving away from, or towards the pinion gear (i.e. from side to side), they don't stop it from falling away from the main plate. Seriously, it can just fall right off.

“But wait!”, I hear you Gibson Deluxe Tuner fans shouting, “The Gibson Deluxe Tuners have a back cover which stops the worm gear from falling away from the main plate!”

Well, you are correct, but this leads me to the problem with my tuner... the back cover has fallen off. And this brings me to my second criticism of Gibson Deluxe Tuner design. You would think that, if the back cover was the only thing holding the worm gear in place, it would be held on in a way that would be very hard to move.
Let’s have a look at their design.

The back cover is held on with two little tabs (one of mine is slightly damaged, but this happened while I was trying to find a solution to keeping it in place. It originally fell off with the tabs intact). Now as an engineer, I would think that a tab should at least fold over to keep something in place, but these ones just go into slots and do not appear to be twisted, folded, or in any other way modified once they go through the slots. In other words they are held in by “interference fit” only, so that they can come out just as easily as they went in (edit: actually, this isn't 100% correct - they are "staked" in place [see the comments at the end of this post], although that doesn't add much strength in the direction they would fall off ). Now let’s think about what’s on the end of the worm gear. That’s right, a big knob/button that sticks out and is basically on the end of a lever. What do we often use levers for? Well, for prising things out of place for one. The longer the lever, the easier it is. So one accidental knock on the tuning knob and you can dislodge the back cover, letting the worm gear fall out of place.

In the course of trying to find a single replacement Gibson Deluxe Tuner (which, not surprisingly, cannot be bought separately), I have noticed many other people scrambling to buy single replacements off ebay or asking if anyone has a spare one on musicians’ forums. A full set is not cheap either; around £60 would not be unusual. I wouldn’t even mind paying that if I though it was a good strong design, but I think you can guess by my rantings how much I think of these things. Unfortunately replacing them with anything other than originals devalues the guitar, so there isn’t much choice.

Additionally, on the front face of the guitar head you need to use a bushing (also called a ferrule) which stops the capstan from rubbing on the wood of the guitar when it is being rotated, and whereas these are normally press-in bushings on tuners of similar design to Gibson Deluxe Tuners, on the actual Gibson ones, they are screw-in bushings. Now I have no complaints about this, design-wise, I’m just saying that there are very few replacements available other than the Gibson Deluxe Tuners.

Gibson Deluxe Tuner bushing (and washer)

Standard bushing

So stay tuned (no pun intended) for the next blog post, where I will try to fix mine.

The Chiquita Amp

You may think the name of this amp came about because of its size, but in fact it was simply because of what was printed on the wood used to make the box. You see, it was made with the thin wood from a Chiquita banana crate. Incidentally, this amp has no connection whatsoever to the wonderful Erlewine (and later Hondo) Chiquita travel guitar, as featured on Back to the Future, or the little amplifier that was sometimes included with it. In fact I didn't even know about that model name until years after I made this. Apologies for any confusion.

After finishing the DIY Strat, I decided I needed a little amp. I had next to no money to actually buy one, so I thought I might as well just make one. After a bit of research online, I settled on a simple audio amp using a TDA2030A. Let me just state right now that this was back in 2000, so the amount of information available online at the time was much more limited. I’m sure there are plenty of really good circuits available for fantastic mini guitar amplifiers these days.

Anyway, at the time I wanted to build something that was VERY portable and could run off a power adapter for a stomp box. This fitted the bill.

The circuit was just copied straight from one of the specifications documents for the TDA2030A, which are available on many sites such as the following: http://www.unisonic.com.tw/datasheet/TDA2030A.pdf

There are several circuits suggested, and I can't find the exact schematic on any sheets right now, so I've redrawn the one I did below (click on the image for a larger version):

As you can see from the finished veroboard circuit, it is a very simple design. The TDA2030A is at a distance from the board as I wanted to bolt it onto a small heat sink to help dissipate some of the heat. As I said, it can run off 9 volts, but the good thing about the TDA2030A is that you can easily bump the input voltage up to something like 18v and get much more power out of it.

The box was glued together, except for the back, which was bolted on. This way I could open it to fix any problems at any stage.

It’s a great little amp, considering its size.

My first ever electric guitar

Back when I was about 17 (so let’s guess 1987) I got my first electric guitar. I already had an acoustic, but it was time to move on to more exciting things. This one came courtesy of a friend of my brother’s, and cost me (if I remember right) either £40 or possibly £60. It had a red finish, with just a hint of orange, black pick guard, two chrome covered pickups with “Hofner” written on them and a maple neck with rosewood fingerboard. There was no name written on the head of the guitar, so I assumed it was rubbish, although I remember it played great and had a real ‘60s rock and roll tone to it.

At the time though, what I REALLY wanted was a nice red Strat, and I wasn’t too keen on that far-too-much-of-a-hint-of-orange finish on my no-name, so I sanded the body down (very badly) and resprayed it black (also very badly). I changed the old-fashioned-looking knobs to some modern black plastic things and painted the head black too. I also changed the tuners to black Gotoh-type things. After a year or so, I sold it to a school friend and forgot about it for a few years.

I thought about it a few times years later and tried to find out what sort of guitar it was, but had hardly any information to go on. Going on the shape alone, I simply couldn’t find the same guitar anywhere, even on Google, so gave up on ever finding out what it was. I also tried pretty hard to get back in touch with the guy I sold it to, in the hope that he would still have it and would be willing to sell it to me, but without success.

Forward wind to about 2005 and I found myself co-incidentally having a chat with the guy who sold that same guitar to my brother’s friend (before I got my hands on it). He told me a little more history. It seemed that the guy who had had it before HIM had stripped it down and resprayed it (very well, I might add). It was in fact a Hofner guitar, but the logo had been removed during the sanding process. This was enough info to really start my search.

It wasn’t very easy (due to limited production dates of this exact model), but I finally found out that it was a Hofner Colorama II, made in 1963. The final confirmation came courtesy of this page:
http://www.vintagehofner.co.uk/vintagehofner/solids/sol32.html
If you ever need to find out anything about old Hofner guitars, then I can’t recommend that site enough.

With this new-found knowledge, I just couldn’t stop myself from searching for one for sale. Finally, about a year later, I found one exactly the same (including the colour) on ebay and managed to stick in a cheeky last-minute bid, winning it for something like £130. It is fairly bashed up, but nothing that can’t be restored. Here are the photos from the ebay auction.

The moment I won the auction, I felt like I had corrected the 20-year-old mistake I had made when I sold my first ever electric guitar.


I will need to respray this at some stage, but that's fine. As far as replacing the hardware goes, well, I need to restore the machine heads to a vintage style. At some stage someone upgraded these to Gotoh-type tuners (I hardly have the right to criticise that, hehe), and I need to replace three of the knobs (two volume knobs and one tone knob), as they have lost their metallic labels, which can't be bought separately unfortunately.

I managed to find one volume and one tone knob on ebay from a similarly-aged Hofner, and here's the best bit; I still have one of the knobs I took off my old Hofner 20 years ago. I also bought a set of vintage-looking Kluson tuners, that will look very close to the originals, but will work much better than they ever did.

Here are the tuners and the knobs I bought:


Just one small problem though. The guitar is in storage at my brother's house in Ireland and I'm in Taiwan, so the restoration will have to wait.

The Mystery Box

A while back, I went to check out Tony's music shop in Taipei and noticed that they had this obviously home-made guitar pedal in the display case.


It was priced at NT$600nt (about US$20), and I was pretty much willing to pay that just for the parts I could use out of it.Anyway, I asked if I could try it out and they let me. It sounded superb.

There are two main amplifying components on it, a little 8-pin chip and a transistor.

The chip is marked:
OP275

And the transistor is marked:
C550B (This appears to be a BC550B)

There are three controls on it, labelled volume, tone and gain.
There are two toggle switches. The one on the side is a 3-way, with capacitors in 2 of the positions. It works as a tone filter I guess. At the back is a two-way switch, which appears to work as a kind of turbo overdrive.

Pot values are as follows:

VOLUME - A100K
TONE - B100K
GAIN - A50K (dual gang)

(A=audio taper, B=linear taper)

I traced the path of the dual-gang gain control. One gang connects between pins 1 and 2 of the OP275 and the other gang goes between pins 6 and 7 of the OP275. Shown below is an OP275. You can see that the gain control boosts BOTH amplifying stages at the same time. Serious boost there.


The circuit appears to be something between a Big Muff Pi and a Rat, and despite requests on 3 different sites for information, it appears to be a totally unique design. If you know otherwise, please do let me know.

Here's a couple of pics of the guts:



incidentally, they dropped the price to NT$500 while I was paying for it. Happy days.

The Volumizer!

Today I’d like to show you the booster pedal I made. It’s a straight clone of an MXR Microamp. The Microamp is a great booster pedal because it simply adds volume. You can use this to just increase the volume of your guitar for solos, or you can use it to overdrive your amp. The choice is yours.

The circuit diagram for the Microamp can be found at www.generalguitargadgets.com. General Guitar Gadgets asks that other people don’t post their circuits elsewhere, so I won’t. Just go to this page to get it: http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=70&Itemid=26 (click on “microamp schematic”).

The circuit is pretty simple, using a single TL061 as the amplifier. You can buy a ready-made PCB from General Guitar Gadgets, which would make life a lot easier, but I decided I would just build it on veroboard (strip board) since it was a pretty simple circuit. If this is your first time building a circuit, then just buy the PCB. You won’t regret it.

I made a quick veroboard sketch of the circuit (yes I know, it's rough, but it's been confirmed as accurate).


Anyway, here are a couple of pictures of the circuit during construction.



At first I built this into a much bigger enclosure, but then I decided to try to fit it into a much smaller box. To achieve this, I had to squeeze the components a little bit closer together on the veroboard and then cut a bit off the board itself, as you can see in the following photo.


It’s a really tight fit, but there’s just enough space to add a 9v battery (though I doubt I’ll do that).


I then added a bit of insulation to make sure the circuit board didn’t make contact with the metal enclosure.


I see a lot of people making their own stomp boxes, and doing a really good job, but then just leaving the box unpainted, or painted a single colour with no writing, or something scrawled on it like a child had done it. I figured I had done all this work on the electronics, so why not try and make the box look nice too? So, I painted the box black, then drew something up on the computer and printed it out on photographic paper (one side is sticky). I didn’t want to rip off the Microamp name, so I called it the Volumizer.

Here you can see it next to a standard-sized pedal (a Digitech DigiDelay) for size comparison. Just in case it’s not clear, the Volumizer is the smaller pedal.

Two-channel passive mini-mixer

Hello all,
Well, I didn't want to just stop after posting about the guitar. I have been known to dabble in other little projects after all. So don't be surprised if those other projects make it on here for time to time.
Today I'd like to show you the little two-channel passive mixer I made. I needed something that would let me plug two guitars into the same amplifier (and both be used at the same time). So, if someone were to come round to my house, we could both plug a guitar into the same amp. You can't just use a y-connector, since that's just amateur, and changing the volume on one guitar would affect the other. I'm pretty sure it could be unhealthy for certain amps too. Also, I wanted to be able to adjust the level of each guitar so that if one were more powerful than the other, this could be balanced out. Lastly, I wanted to make it as portable as possible, so that I could even stick it in my guitar case.
So, I searched for the simplest two-channel or multi-channel mixer schematics I could find and then came up with this:


Note that I don't claim to be the inventor of that circuit. Five minutes on Google and I'm sure you'll find a similar circuit posted on other sites. I have, however, drawn a nice clear circuit diagram for your convenience.

As you can see, the circuit is incredibly simple. Just three quarter-inch jack sockets, two 10k logarithmic pots, two 10k resistors and a box to stick them in (see notes just below).

NOTE: I've noticed several forums pointing to this post, and a lot of debate about the 10k values of both the pots and resistors as being too low (it has been suggested that 500k or even 1M pots would be better, for example). I've used this mixer a lot, as has a friend of mine who I made one for, and both of us have found that it does a perfectly good job, especially at home. My advice is to just give it a go and see how it works for you, rather that wasting too much time in advance theorising about how it might sound. If you find that it doesn't sound good to you, then by all means try different pot/resistor values, and report back in the comments below.

NOTE 2: See the comments at the bottom of this post for more discussion about this. 250Kohm pots and resistors seems to be a good choice by the looks of it.

I couldn't find a suitably-sized metal enclosure at the time of making this, so I settled on a plastic box with a metal bottom. My thinking was that I could always line it with tin foil (aluminum foil) if it picked up interference, but to be honest, it has never been an issue.
Here's a pic of how it looks inside:


And a closer pic of the resistors, etc.:


As you can see, it only just fitted in there. It may have been a better idea to put the two input jacks to the outside of the pots, but to be honest, I don't think it matters either way.
So, here's how it looks from the outside (front and back):



I've been able to use this little device on a few occasions, and it's been fantastic. The fact that it can fit into your pocket makes it incredibly handy too.
I haven't been in this position yet, but it could even save your ass if you were at a small venue with another guitarist and one of the amps stopped working.
And the cost? Pfft... maybe 200 Taiwanese dollars, which works out at about US$6.


Also, just one more comment from me - I ended up re-boxing this mixer. I never had any problem with interference, but I decided to re-box it in an aluminium enclosure anyway, since I found a size that was just perfect, and I liked the idea of it being more robust. Here's the re-boxed mixer: