After a bit of trial and error, it was clear that my ancient SKB PS-25 pedalboard power supply had finally keeled over.  I never use batteries, but fortunately a couple of the pedals had old 9V batteries still in them, so it was enough to scrape by for the rehearsal.

The following morning, just a few hours before the gig, I went through my box of old guitar gear to try to find a replacement 9V DC negative-tip power supply.  

Hey, here’s the power supply for my Digitech Jamman Delay which I’m not currently using in my live rig.   It says 9V, 1.3A.  Strange, it doesn’t show a polarity, but it’s a power supply for a guitar pedal, and the plug barrel fits, so it must be good, right?  What could possibly go wrong?

I plugged it in, powered up, and…  I’m not sure if I actually heard a pop, zap, or boom.  Maybe I just imagined the smell of electrical burning… 

It was with a sense of dread that I unplugged the power cables, and tried the pedals on battery. No lights, no sound- nothing.  They were all fried.  

So, there I was, with just hours before the gig was to start, with a miserable collection of dead pedals.  Fortunately, our bass player Ryan, had a Tube Screamer, Fulltone Full Drive 2, and Fulltone Fat-Boost in his old guitar gear bag.  I loaded em up with batteries and velcroed em down.  It all sounded different, and felt unfamiliar under my feet, but I made it through the gig ok.

I didn’t figure out until later that this Digitech power supply, part # PS0913B-120-B, is actually 9V AC, not 9V DC.   Ok, I’m an idiot for not realizing that the lack of polarity indicator was a clue.  And I only realized just now while looking at this picture, that the tilde next to the 9V must indicate AC.

But honestly, shame on Digitech for selling a pedal with a power supply that says 9V, has a standard pedal barrel connector, but is actually AC, not DC.  They should at least make the connector different so it won’t fit a standard pedal jack!

In the week following the gig, I took apart and fixed my pedals- blown diodes in my Speed Racer overdrive were about the worst of it.  No big deal.

My VOX Ice 9 was a more difficult nut to crack, since it uses a PCB with tiny surface mount components.  Using the microscope and a multimeter at the office, we were able to identify that both the 2SC4617 transistor (Q5) in the power section, and the 4558DR opamp (U1) in the overdrive section were fried.  You can actually see the PCB is blackened around Q5 (top-center in the picture)- maybe I did smell smoke after all!  I ordered parts, and thanks to my boss Charlie’s mad skillz soldering under the microscope, we were able to repair it.

Meanwhile, I stuck a big label on that Digitech power supply “9V AC – NOT FOR PEDALS”, and I repurposed an old Korg 9V DC 500mA power supply for the pedalboard.  It has been working ok, but I’m getting some hum from the boost.  I could get a Voodoo Labs Pedal Power Plus but it’s a bit pricey.  On the cheaper side, there’s always the Visual Sound One Spot, but it gets mixed reviews.  I’ve also been thinking of building a new DIY pedalboard, but actually, I am pretty envious of Ryan’s awesome pro pedalboard- the SKB PS45.

Our next Drop Daddies gig is tomorrow night, and we’re heading back to the Annex for a rehearsal tonight.  Note to self, pack some 9V batteries, just in case

In the US, solder is pronounced "saw-der" (ˈsɑːdər) without the L. My family is Australian- I grew up doing electronics projects with my Dad, pronouncing it with the L as "sole-der" (ˈsɒldər).  I have to really make an effort to say it the American way.

Here’s an interesting etymonline entry that shows the original mid 14th century word was “sawd” with no “L”.   It seems unlikely that this is the reason Americans pronounce it without an “L”, but it’s as good an excuse as any

For reference, here is the entry for "solder” in the Oxford English Dictionary, including recordings.  The pronunciation with the L is listed as British English, while the other is listed as American pronunciation.

And here’s a fun article about other words with missing L’s.

Good news- Apple rolled out an update to GarageBand yesterday which appears to resolve this. 

Thanks PaulB for letting me know!

These Rotomatics are different from typical locking tuners, like the Sperzel’s or Grover’s own Roto-Grips, where you lock and unlock the string using a thumbscrew around back.

On the Rotomatics, you just insert the string, and give it a wind, and an inner-cam rotates, locking the string into place under the string’s own tension.   I always feel a little uncertain when changing strings on these because the process is a bit different from other tuners.  Here are the instructions from Grover:

1. Turn tip of string post until it clicks into place. This aligns string post holes.
2. Note string hole is off center. Turn knob to rotate post until string hole is positioned away from knob. Thread string up through bottom of hole and pull firmly. See drawing.
3. Turn to begin tuning. At first, only inner “Locking Cam” is turning, securely locking the string. Once the string is locked, outer post will turn.
4. Bring string to pitch.

In this video, I apply this simple trick to the tuners on my Epiphone Riviera P93. Some of these screws have been loose since day one – the kind of loose where no matter how much you try to tighten the screw, it just spins freely in the hole. The wood fibers in the hole are stripped out and no longer gripping the screw threads. One simple toothpick, inserted in each hole and cut off flush, just like that carpenter had shown me- and now the screws go in nice and tight. The soft wood of the toothpick makes the perfect filler. No glue necessary.

That same carpenter also shared these fine words of wisdom: “Caulk and paint are what a painter ain’t”, but that’s a story for another day

"Until it’s recognized that the amplifier is AT LEAST 50% of the sound of the electric guitar, its full potential cannot be realized" Leo Fender

I couldn’t verify whether that quote is truly attributable to Leo Fender, but it’s a good point. 

We tinkerers spend all this time tweaking our electric guitars’ pots, caps, pickups, etc- when really the biggest factors in how your guitar sounds are the amp and pedals you play through.  Your guitar may be puttin out the most beautifully kickin tone in the world, but if you’re playing it through a crappy amp, you’re gonna hear crap.    

I found this interesting collection of FAQ’s about amps, tubes, etc (along with a ton of other tips) by Steve McKinley at Atlanta Tube Amp.  Check it out:

http://www.mindspring.com/~atlantatubeamp/id15.html

Thanks again to Pete for the permission to post this here!

January 2013

Howdy!

In this Tech Tips newsletter I would like to discuss the wiring options possible with a single humbucking pickup which has a four conductor output cable with an independent ground lead.

The following information applies not only to conventional humbucking pickups with side by side coils, but also to stacked humbuckers and humbuckers in other size formats or configurations.

In this newsletter I do not plan to cover the details of wiring one or more switches to accomplish the possible coil configurations described below. A great deal of useful information on this topic is provided on the Stewart MacDonald website, the Guitar Nuts website and on www.deaf-eddie.net

First, let’s start with the basics:

a humbucking pickup typically has two coils in which the effective winding direction in the two coils is opposite from each other; one coil is clockwise and the other counter-clockwise. For the purposes of this discussion I will only consider a balanced humbucking pickup in which both coils are wound with the same number of turns of coil wire and both coils are wound with the same gauge wire. The magnetic polarity of these two coils will be opposite from each other (one coil will have magnetic polarity which is north up and the other south up). It is helpful to remember that the signals generated by guitar pickups are alternating current (AC) waveforms, not direct current (DC). This is important because there are two and only two phase relationships possible for the signals coming from the two coils of a humbucking pickup:

In phase (zero or 360 degree phase shift)

Out of phase (180 degree phase shift).

When the two AC signals are in phase the voltage amplitudes add [ via constructive interference] to create a strong signal; when the two AC signals are 180 degrees out of phase the two signals cancel each other [through destructive interference] resulting in a relatively weak output signal.

The topic of phase relationship of two AC voltage signals is discussed and demonstrated on:

http://www.youtube.com/watch?v=30J5U0ThRUc

While some math is presented in this video, you can ignore it completely and just pay attention to the description of the AC signals and how these signals add when they are in phase and cancel when out of phase.
Back to our main topic: the output cable of a humbucking pickup as described above will have four leads:

Coil 1 start

Coil 1 finish

Coil 2 start

Coil 2 finish

There is no universally accepted standard for color codes used for the output leads in the pickup industry.  The color codes for many popular humbucking pickups is provided here.

Here are the output lead insulation color code assignments I use: 

Coil 1 start: black insulation

Coil 1 finish: white insulation

Coil 2 start: green insulation

Coil 2 finish: red insulation

There are six configuration possibilities for these two coils; let’s start with the most simple. In all of the examples below it will be assumed that the independent ground connection (often also serving as the output cable shield) is soldered to a known electrical ground such as the casing of a pot.

A: Coil 1 in single coil mode: the lead with black insulation (coil 1 start) would be connected to ground and the lead with white insulation (coil 1 finish) would be used as the hot output. The red and green leads are not used. This configuration will deliver a single coil like tone. If the humbucking pickup has balanced coil windings (the same number of turns on both coils and the same wire gauge used for both coils) the DC resistance (DCR) will be approximately half of what one would expect in series (humbucking) configuration and the output of this configuration will be approximately half of that which one would expect in series humbucking mode described in C below. The noise cancelation properties of a humbucking pickup in configuration C will be lost in this single coil mode. One could connect white to ground and use black as the hot output; this would reverse the phase of the output signal in configuration A by 180 degrees, but the tone and the strength of the signal from this one coil would be essentially the same as when black is connected to ground and white is used as the hot output.
B: Coil 2 in single coil mode: the lead with green insulation would be connected to ground and the lead with red insulation would be used as the hot output. The white and black leads are not used in this mode. This configuration will deliver a single coil like tone as described in A but with coil 2 functional. Recall that coil 1 and coil 2 have opposite magnetic orientations. If the humbucking pickup with only one coil operational is intended to be paired with a single coil pickup one might choose which coil of the humbucker is to remain functional so that the operational coil of the humbucker would have opposite magnetic polarity with respect to the single coil pickup to achieve noise cancelation.

C: Coil 1 and coil 2 in series and in phase: This is the usual humbucking configuration. The lead with black insulation would be connected to ground, the white and green leads would be connected to each other (this connection would be electrically insulated) and the lead with red insulation would be used as the hot output. The DCR of a humbucking pickup in this configuration will be approximately twice that of the DCR for configurations A and B assuming the coils of the humbucking pickup are balanced. The signals generated by vibration of the instrument strings above coil 1 and coil 2 will be in phase with each other and will add together. The output signal of a pickup in configuration C tends to be strong with a full rich tone; noise signals created in coil 1 tend to be canceled in coil 2. If the connection of the white and green leads at the free end of the output cable is shunted to ground the humbucking pickup will be coil split and coil 2 will remain operational as described in B. It is possible to wire the humbucking pickup with the two coils in series and in phase and have coil 1 remain operational when the humbucking pickup is coil split. To do this, at the free end of the output cable connect the green lead to ground, solder the red lead to the black lead and use the white lead as the hot output. To coil split one would shunt the connection of the red and black leads to ground leaving coil 1 operational.

D: Coil 1 and coil 2 in series and out of phase: The lead with black insulation would be connected to ground, the white and red leads would be connected to each other (this connection would be electrically insulated) and the lead with white insulation would be used as the hot output. The DCR of a humbucking pickup in this configuration will be approximately twice that of the DCR for configurations A and B assuming the coils of the humbucking pickup are balanced. The signals generated by vibration of the instrument strings above coil 1 and coil 2 will be out of phase with each other. The output signal of a pickup in configuration D tends to be weak with a somewhat thin tone; noise signals created in one coil will not be canceled in the other. If the connection of the white and red leads at the free end of the output cable is shunted to ground the humbucking pickup will be coil split and coil 2 will remain operational as described in B.

E: Coil 1 and coil 2 in parallel and in phase: The black and green leads would both be connected to ground, the white and red leads would be connected to each other and used as the hot output. The DCR of a humbucking pickup in this configuration will be approximately one fourth that of the DCR for configuration C (normal series humbucking) assuming the coils of the humbucking pickup are balanced. The signals generated by vibration of the instrument strings above coil 1 and coil 2 will be in phase with each other. The output signal of a pickup in configuration E tends to be moderately high output with a clear tone; noise signals created in one coil tend to be canceled in the other. Many instruments which have two reverse wound reverse polarity single coil pickups and a three position pickup selector switch (such as tele style guitars) connect the two single coils in parallel and in phase in the middle switch position.

F: Coil 1 and coil 2 in parallel and out phase: The black and red leads would both be connected to ground, the white and green leads would be connected to each other and used as the hot output. The DCR of a humbucking pickup in this configuration will be approximately one fourth that of the DCR for configuration C (normal series humbucking) assuming the coils of the humbucking pickup are balanced. The signals generated by vibration of the instrument strings above coil 1 and coil 2 will be out of phase with each other. The output signal of a pickup in configuration F tends to be weak with a somewhat thin tone; noise signals created in one coil will not be canceled in the other.

All of the configurations described above are also possible in instruments which have two single coil pickups which are reverse wound reverse polarity (RWRP).

I hope you find this information useful.

Best wishes,

Pete Biltoft

Vintage Vibe Guitars

I use clear waterslide decal paper, and print on my inkjet Canon Pro9000mkII.  After printing, and waiting a while to ensure the ink is dry, I spray on a few coats of Krylon Acrylic Crystal Clear acrylic to protect the ink during the soak.  Then, after the clearcoat dries for 30 minutes or so, I trim the paper to final dimensions and soak the paper in warm water.  When the decal starts to move freely from its backing, I wet the surface of the enclosure and slide the decal directly onto it.   I iron out the bubbles with wet fingers, and adjust the decal into its final position, being careful not to stretch the decal.

After drying for a few hours, I use a sharp razor to cut out the holes for the pots, switches, etc.  Then, I apply 4 clear top-coats of polyacrylic to protect the finish, waiting a few hours between each coat. 

I like water-based polyacrylic because it’s very easy to use and clean up, and is low-odor so it can be applied indoors. This stuff looks a bit milky when wet, but dries clear. You may also see some tiny bubbles in the wet finish, but these disappear while drying and the finish self-levels well. I find a foam brush to be easiest and very inexpensive- make sure your foam is reasonably dense – the very porous ones are harder to work with.

While the polyacrylic is wet and curing, I cover the project with a mixing bowl to prevent dust from settling in the finish – propping up an edge of the bowl to allow oxygen to circulate.  After every coat but the final one, I do a light sanding with 400-grit wet/dry paper, to provide some tooth for the next coat.  If you get finish pooling at the bottom edges, you can sand it down with a sanding sponge.  After the last coat, as a final optional step, I buff on a coat of paste wax for extra shine and durability.

As a side note, this video took a lot longer to complete than I had planned – I wasn’t happy with my first version of the video, so I started over from scratch.  And in the process, I finally started to pay more attention to my lighting and backgrounds, and I started using my DSLR for video instead of my camcorder.  I’ll write more about that in another post.

Here are some of the resources shown in this video:

• Clear inkjet waterslide decal paper
• Krylon Crystal Clear Acrylic Spray – Satin
• Carl Professional Rotary Trimmer
• Canon Pro9000 Mark II Inkjet Photo Printer
• General Finishes PolyAcrylic Water Based Top Coat – Satin
• Razor Blade
• Norton Very Fine Sanding Sponge
• 400 grit wet/dry sand paper
• Foam brush
• Minwax Paste Wax
• Stainless Steel Mixing Bowl or other suitable dust cover
• Jenga!

Thanks again to Pete for the permission to post this here!

October 2012

Howdy!

The topic for this tech tips newsletter will be Coil Splitting and Coil Tapping.

Coil Splitting and Coil Tapping are two methods which can be used to extend the range of tones on can get from a magnetic pickup.

First, a few definitions:

Coil splitting refers to disabling one of the two coils of a humbucking pickup by shunting that coil’s output to electrical ground.

Coil tapping is most often used to describe a single coil pickup which has a coil start and more than one coil end (output tap).

Because I intend to devote most of this article to Coil Tapping, let me start with Coil Splitting.

In many modern humbucking pickups each of the two coils of the pickup has a coil start and a coil end. One coil is typically wound clockwise and the other coil is wound counter clockwise. In the usual “PAF” style humbucker configuration a single bar magnet located under the two coils provides the magnetic field for both coils: one coil is north up and the other south up. When these two coils are connected together in series the signal generated by vibration of the instrument’s strings in each of the two coils is in phase and these two signals add together providing reasonably high output. An external noise signal (which can come from alternating current (AC) electrical devices in the environment) can also be present in each of the two coils of the humbucking pickup. These two noise signals (one noise signal in each coil) have the opposite phase from each other and subtract to effectively cancel the total noise signal. If a humbucking pickup has an output cable with four conductors (one conductor for the coil start and coil end of each of the two coils) one can “split” the humbucker by shunting the series connection of the two coils to an electrical ground. This Coil Splitting reduces the output of the humbucking pickup and also eliminates the noise cancellation effect. A humbucking pickup which is Coil Split tends to have a more single coil like tone and output.

Now, on to Coil Tapping.

Most standard single coil pickups have two leads: one connected to the start of the coil windings and one connected to the end of the coil windings. The lead associated with the coil start is often connected to an electrical ground in the instrument’s controls circuit (such as the casing of a volume or tone control potentiometer (aka “pot”)) and the other lead is considered the “hot output” which is often soldered to a lug on a pickup selector switch or volume control pot in the instrument’s controls circuit. A shielded pickup can have a third, independent lead which is soldered to copper shielding surrounding the pickup’s coil; this lead should be connected to a known electrical ground in the guitar’s circuit in order for the shielding to function properly.

Let’s explore the types of tapped single coil pickups starting with the most basic design. Imagine an unshielded strat style single coil pickup which is wound with 7,500 turns of 42 gauge wire in the usual way. This standard design single coil pickup has two brass grommets located on the bottom flange of the pickup: one grommet for the start of the coil windings and one for the end. Let’s call the first grommet where the coil windings start “S” and the second grommet where the coil windings end “E1” The DC resistance (DCR) of this coil (as measured between S and E1) will be approximately 5.5 k-Ohms. To this pickup we can add a second output grommet, E2. Assuming there is space on the bobbin one can  add more turns on top of the original coil by starting the new windings at the grommet where the first coil windings ended (E1) and finishing at a third grommet (E2). If we add an additional 2,000 turns to this pickup, the windings from the first coil plus those of the second coil will be in a series connection and will result in a higher output signal with perhaps a noticeable emphasis in the midrange frequencies. With an appropriate switch added to the instrument’s controls circuit one would be able to change between the first output lead (coil tap E1) which has a DCR approximately of 5.5 k-Ohms to the second output lead (E2) with a DCR of approximately 6.9 k-Ohms. It would also be possible to obtain a very under-wound tone from this simple coil tapped pickup by using the first output tap (E1) as the coil start and the second output (E2) as the coil end. This would result in a coil having effectively 2,000 turns of 42 gauge wire and a DC resistance of approximately 1.4 k-Ohms.

To this tapped single coil pickup we could also add another grommet (E3) and add even more windings.

Another option for this tapped single coil design would be to underwind the first coil and add additional coil windings for the second and third output taps (E2 and E3). Here is an example: wind the first coil with 5,500 turns of 42 gauge wire, the second coil with an additional 2,000 turns of 42 gauge wire and a third coil with an additional 1,500 turns of 42 gauge wire. The approximate DCR values would be: S to E1: 4.0 k-Ohms, S to E2: 5.5 k-Ohms and S to E3: 6.6 k-Ohms. As described in the previous example one could also access the intermediate taps having 2,000 turns (E1 to E2) and 1,500 turns (E2 to E3) for DCR values of 1.4 k-Ohms and 1.1 k-Ohms respectively. In this pickup with three outputs (E1, E2 and E3) one could also envision utilizing the coil windings between E1 and E3 for a coil having 3,500 turns and a DCR of approximately 2.5 k-Ohms.

Here is a brief, generalized summary of the effect on tone and output of under and over winding a single coil pickup:

1. Under wound: lower output than standard wound, brighter, clearer tone and more “airy” sounding.
2. Standard wound: higher output than under wound, more midrange emphasis than an under wound coil and in the case of a strat style single coil: bell like tone.
3. Over wound: higher output than standard wound, more emphasis on the midrange than standard wound and a “heavier” tone.

It is not necessary that all of the coil windings be made using the same coil wire gauge (42 gauge in the previous examples).

A tapped coil can have the first coil made with 42 gauge wire and the second and third coils made with 43 gauge wire. This design option might be chosen if space is limited on the pickup bobbin.

As a practical matter, the multiple output options available for tapped single coil pickups can be accessed using a variety of switches. Here are a few examples:

In a single pickup instrument the controls circuit might include a three-way toggle switch (as found on Les Paul style instruments), a blade style pickup selector switch (as used on many tele style guitars) or a push-pull pot to change between the output taps. Installation of a tapped single coil pickup and the appropriate switches in the controls circuit can give an instrument with only one pickup a wide range of useful tones.

In an instrument with two or more pickups one can include push-pull pots to access the output options of coil tapped single coil pickups. Each push-pull pot may be used to switch between two output taps of two coil tapped single coil pickups simultaneously. One could also use a two position on-on or a three position on-on-on mini toggle switch to control the output of coil tapped single coil pickups.

Custom tapped single coil pickup designs are available in many size formats including pickups designed for strat or tele style guitars, soapbar or dogear P-90 style single coil pickups, humbucker size single coils, pickups for lap steel instruments, bass guitars and many others. Please contact Vintage Vibe Guitars for more information on tapped single coil pickups.

I hope you find this information useful.

Best wishes,
Pete Biltoft

Vintage Vibe Guitars
website: www.vintagevibeguitars.com
email: info@vintagevibeguitars.com

In this tutorial, I will demonstrate how to compose your pedal artwork in GIMP, the free GNU Image Manipulation Program.  I’m using GIMP 2.8.2 on Windows, but it also runs on Mac and Linux.

I start with an overview of my Under Pressure compressor and Speed Racer Overdrive artwork, and then show how to compose your own pedal artwork from scratch.

I cover the basics of project setup, layout, working with the rulers and guidelines, the graphics and text editing and selection tools, sourcing artwork and fonts, retouching and removing blemishes, extracting components from a larger image, layer compositing with masks, and more.

Here are some of the resources shown in this video:

• GIMP – Free photo/image editing and authoring
• Urban Fonts – great resource for all kinds of fonts
• RGB Stock – free stock photos and artwork
• A brief clip of me using a Wacom tablet with pressure sensitive brushes in GIMP, excerpted from my JFET tutorial video.

Here’s a zip of the GIMP project file, and related fonts and images:

• A zip of the GIMP project file for this turorial, along with all source materials.  Note, you’ll need to install the BellBottom font in order to properly render the large text.

This project zip contains some materials that I didn’t create myself.  They are:

• Pressure gauge image:
  Air_Water_Pressure_Gauge_by_FantasyStock.jpg
  Posted by Fantasy Stock
• Blue waves image:
  2dRf60W.jpg
  Posted by Jana Kollárová
• BellBottom Laser font:
  Belbott0.ttf
  Posted by Iconian Fonts