
A client wanted her D-12-20 to fret in tune all along the fretboard. Can it be done?
Intonating a flattop’s bridge saddle is tricky, and that’s especially true when it comes to vintage 12-string guitars. Back in the day, it was rare to find an acoustic 12-string with a compensated bridge saddle. In fact for many players, the slightly out-of-tune jangle was a big part of a 12-string’s aural mystique. But times have changed, and as music and recording technology have evolved, most musicians and producers expect a 12-string to play reasonably in tune all along the fretboard.
Intonating a flattop 12-string with a straight bridge saddle involves filing unique break angle and intonation points for each string—an operation that requires skill and patience. Let’s investigate and see exactly what’s involved.
We’ll use a beautiful 1972 Martin D-12-20 as our project guitar. The guitar was in good shape when its owner brought it into the shop, but it didn’t play even remotely in tune and the action was uncomfortably high. Many old 12-strings require a neck reset (an expensive proposition), but I checked the neck angle and it was fine. Fortunately for the guitar’s current owner, the problem was rather simple. Somewhere along the line a previous owner or tech had installed a saddle that was both too high and incorrectly radiused (Photo 1).
My job was twofold: lower the action by reshaping the bridge saddle and then intonate each string. I knew that once I completed these tasks, the D-12-20 would play better than ever and sound more in tune at the higher frets.
Requisite tools. To intonate a 12-string, you need a few specialized luthier tools. These include a string action gauge, radius gauges, and a radius block (the latter must match the fretboard radius). You’ll also need a mechanical pencil, a capo, self-adhesive 80-grit and standard 400-grit sandpaper, and flat, single-cut miniature needle files.
You can estimate where each string should rest on the saddle, but it’s nearly impossible to get it perfect on the first try.
Preliminary check. Before starting this kind of work on a guitar, it’s important to tune to concert pitch and take measurements. These specs provide a baseline to help gauge your progress. You’ll be taking several measurements, so write them down as you go.
First, put a capo on the 1st fret and measure action at the 12th fret with a string action gauge. Take this measurement for both the 1st and 11th strings—the first of the doubled high Es and the low E string. (We’ll assume your 12-string has the standard octave-string configuration, i.e., the octaves in each pair are closer to you than their wound partners. Some electric 12s, notably Rickenbackers, reverse this order.) Measure the distance between the bottom of the string and the top of the 12th fret.
Next measure the relief: With the capo still on the 1st fret, hold the 11th and 12th strings down at the 14th fret and measure the greatest gap between the bottom of the 11th string and the top of the frets. Typically this occurs around the middle of the fretboard, somewhere between the 7th and 9th frets. You can identify this gap by tapping the 11th and 12th strings against the frets while still pressing them down at the 14th fret.
Now remove the capo and check the action at the 1st fret.
Finally, using a strobe tuner, check the intonation for each string. (Naturally, this is tricky on a 12-string because you have to pluck each individual string of the six pairs.) Starting with the 1st string, play the 12th-fret harmonic—make sure it’s in tune—and then fret the same note. If the fretted note is sharp or flat compared to the reference harmonic, write down how many cents it’s off and in which direction. Repeat the process until you’ve documented the intonation at the 12th fret for all 12 strings.
Our 12-string’s preliminary specs. Here’s how the D-12-20 measured up: The action at the 12th fret was 6/64" for the 1st string and 7/64" for the 11th string. Too high to play! The relief was .012"—perfect for my client’s playing style. At the 1st fret, the 1st string was 1/64" and the 11th string was just over 2/64" above the fret. Again, perfect action at the string nut. At this point, I knew my job would simply entail lowering the action at the bridge saddle.
When I checked the intonation with a strobe tuner, and compared the 12th fret harmonics to their corresponding fretted notes, I found most of the fretted notes were from two to six cents sharp, although the G and D pairs were flat by about three cents.
With these measurements in hand, I was ready to get to work.
Photo 2
Sanding the bridge saddle. My next step was to check if the saddle’s radius matched the fretboard radius. My radius gauge revealed what I’d suspected—it wasn’t even close. The fretboard had a 14"radius (Photo 2), but the bridge saddle was around 8". This meant the saddle had a much more pronounced arch than the fretboard. I knew if I didn’t reshape the top of the saddle to match the fretboard, the D and G pairs would be radically higher than the other strings.
Photo 3
Using a 14" radius block and self-adhesive 80-grit sandpaper, I sanded the top of the saddle until it matched the block’s radius. Here’s the most accurate way to reshape the top of the saddle: Place the radius block in a vise with the radius side up and affix the self-adhesive sandpaper to the block. Now remove the saddle from its bridge slot, turn it upside down, and gently sand its top in the block’s concave area. If you shine light behind the saddle, you’ll be able to see how much material you’re removing from the saddle and make sure its radius matches the block (Photo 3).
Since the action was pretty high on our 12-string, I removed about 1/32" from the top of the saddle at both E string pairs. I removed quite a bit more from the middle of the saddle to flatten out the arch.
Once the saddle is correctly radiused, slip it back into the bridge and grab your mechanical pencil.
Photo 4
Marking the saddle. Now it’s time to draw guidelines on the saddle crown for both the individual intonation points and the various angles needed to guide the strings as they emerge from the pin holes (Photo 4). But before you start drawing lines, let’s take a moment to discuss where the strings should sit on the top of the saddle. First we’ll deal with the intonation points, then the string angles.
Fair warning: Setting the intonation entails some trial and error. You can estimate where each string should rest on the saddle, but it’s nearly impossible to get it perfect on the first try.
For this task, it’s helpful to mentally divide the 12 strings into three groups:
• The six E, A, D, G, B, and E strings you’d find on a regular flattop. We know the lowest four are wound, and the top two are plain. So far, so good.
• The plain octave strings (E, A, D, G) that pair with the wound E, A, D, and G strings.
• The doubled unison B and high-E strings. Just like their mates, these are plain.
Okay, think about the first group—our standard 6-string. As a general rule, both the low E and B strings intonate best at the rear edge of the saddle (closest to the bridge pins). The G string’s intonation point is typically at the very front of the saddle (closest to the soundhole).
That leaves the high E, D, and A strings to be accounted for. The high E will typically fall between the B (remember, that’s at the rear of the saddle) and the G (at the front of the saddle). The D and A strings usually create a stair-step pattern between the G and low E strings, with the D closer to the G, and A closer to the low E.
The four plain octave strings are a different story. Both the low E’s octave and the G’s octave points will be at the front of the saddle. The octave strings for A and D will be further back toward the bridge pins.
As you’d expect, the unison B and E strings sit at exactly the same point as their siblings.
Now consider how each string travels from the pin hole in the bridge to the top of the saddle—the intonation point. On this Martin, the six primary strings—those that correspond to a standard flattop—are set back toward the rear of the bridge. The six additional strings, the four octaves and two unisons that make a 12-string such a beautiful beast, emerge through the soundboard and bridge right behind the saddle.
On the rear of the saddle, you need to file individual angles (think of them as ramps) that allow each string to reach its intonation point without encountering a sharp edge. Correctly filed angles minimize string breakage and maximize sustain. The angle for the primary strings will be shallower than the six extra strings.
Photo 5
On the rear of the saddle, you need to file individual angles (think of them as ramps) that allow each string to reach its intonation point without encountering a sharp edge. Correctly filed angles minimize string breakage and maximize sustain. The angle for the primary strings will be shallower than the six extra strings.
Filing the saddle. This is where your inner artist gets a chance to shine. Using a miniature flat file, carve each string’s intonation point and rear angle, based on your markings (Photo 5). Go slowly, and to prevent any sitar-like buzzing, be sure each string leaves the saddle from a crisp, defined peak as it heads toward the soundhole.
Checking intonation. As I mentioned earlier, there’s a lot of trial and error involved with intonating a 12-string. Once you’ve done the first pass of filing, put on a fresh set of strings, tune them to pitch, and check the intonation.
Photo 6
The goal is to have the fretted note at the 12th fret match the corresponding 12-fret harmonic. Use a tuner to keep track of how close the fretted note comes to its reference harmonic. If the string frets sharp, file the intonation point back toward the rear of the saddle. Conversely, if the fretted note is flat, carve the intonation point forward toward the front of the saddle. When you’re done, the saddle should look similar to Photo 6. Don’t be dismayed at how many times you’ll need to slacken and remove the strings, file the saddle, restring, retune, and recheck the intonation.
Wrap it up. When you’ve got the intonation dialed in to your satisfaction, take off the strings one last time, pop out the saddle, and then polish it with 400 grit sandpaper, followed with a polishing cloth. Restring, retune, and you’re good to go.
This process takes a long time to master, but in the end, it’s worth it when your 12-string plays in tune all the way up the neck.
The range of clean, dirty, and complex tones available from this high-quality, carefully crafted Dumble modeler make it a formidable studio and performance device.
Fantastic variation in many delicious sounds makes it a bargain. High-quality. Easy to use and customize. Killer studio path to lively, responsive guitar sounds.
Price may be hard for some to swallow if they don’t leverage the whole of its potential.
$399
UAFX Enigmatic ’82 Overdrive Special
uaudio.com
I’ve never played a realDumble. I’d venture most of us haven’t. But given my experiences with James Santiago’s UAFX modeling pedals, most recently theUAFX Lion, I plugged in the new Dumble-inspired UAFX Enigmatic confident I’d taste at least the essence of that very rare elixir. You could argue there is no definitive Dumble sound. Each was customized to some extent for the customer, and they are renowned nearly as much for dynamic responsiveness and flexibility as their singing, complex, clean-to-dirty palettes.
The Enigmatic nails the flexibility, for sure. To my ears, its tone foundation lives somewhere on a sliver of Venn diagram where a black-panel Fender and a 50-watt Hiwatt intersect. It’s alive, dimensional, snappy, sparkly, massive, and, at the right EQ settings, hot and excitable. But the Enigmatic’s powerful EQ and gain controls, multiple virtual cab and mic pairings, rock, jazz, and custom voices, plus additional deep, bright, and presence controls enable you to travel many leagues from that fundamental tone. The customization work you can do in the app enables significant changes in the Enigmatic’s tone profile and responsiveness, too. All these observations are made tracking the Enigmatic straight to a DAW—making the breadth of its personality even more impressive. But the Enigmatic sounds every bit as lively at the front end of an amp, and black-panel Fenders are a primo pairing for its saturation and sparkly attributes. The Enigmatic is nearly $400, which is an investment. But considering the ground I covered in just a few days with it, and the quality and variety of sounds I could conjure with the unit just sitting on my desk, the performance-to-price ratio struck me as very favorable indeed.
This month’s mod Dan’s uses a 500k linear pot, a 1.5H inductor (L) with a 0.039 µF (39nF) cap (C), and a 220k resistor (R) in parallel.
This simple passive mod will boost your guitar’s sweet-spot tones.
Hello and welcome back to Mod Garage. In this column, we’ll be taking a closer look at the “mid boost and scoop mod” for electric guitars from longtime California-based tech Dan Torres, whose Torres Engineering seems to be closed, at least on the internet. This mod is in the same family with the Gibson Varitone, Bill Lawrence’s Q-Filter, the Gresco Tone Qube (said to be used by SRV), John “Dawk” Stillwells’ MTC (used by Ritchie Blackmore), the Yamaha Focus Switch, and the Epiphone Tone Expressor, as well as many others. So, while it’s just one of the many variations of tone-shaping mods, I chose the Torres because this one sounds best to me, which simply has to do with the part values he chose.
Don’t let the name fool you, this is a purely passive device—nothing is going to be boosted. In general, you can’t increase anything with passive electronics that isn’t already there. Period. But you can reshape the tone by deemphasizing certain frequencies and making others more prominent (so … “boost” in guitar marketing language). Removing highs makes lows more apparent, and vice versa. In addition, the use of inductors (which create the magnetic field in a guitar circuit) and capacitors will create resonant peaks and valleys (bandpasses and notches), further coloring the overall tone. This type of bandpass filter only allows certain frequencies to pass through, while others are blocked, and it all works at unity gain.
“You can’t increase anything with passive electronics that isn’t already there … but you can reshape the tone by deemphasizing certain frequencies and making others more prominent.”
All the systems I mentioned above are doing more or less the same thing, using different approaches and slightly different component values. They are all meant to be updated tone controls. Our common tone circuit is usually a variable low-pass filter (aka treble-cut filter), which only allows the low frequencies to pass through, while the high frequencies get sent to ground via the tone cap. Most of these systems are LCR networks, which means that there is not only a capacitor (C), like on our standard tone controls, but also an inductor (L) and a resistor (R).
In general, all these systems are meant to control the midrange in order to scoop the mids, creating a mid-cut. This can be a cool sounding option, e.g. on a Strat for that mid-scooped neck and middle tone.
Dan Torres offered his “midrange kit” via an internet shop that is no longer online, same with his business website. The Torres design is a typical LCR network and looks like the illustration at the top of this column.
Dan’s design uses a 500k linear pot, a 1.5H inductor (L) with a 0.039 µF (39nF) cap (C), and a 220k resistor (R) in parallel. Let’s break down the parts piece by piece:
Any 500k linear pot will do the trick, in one of the rare scenarios where a linear pot works better in a passive guitar system than an audio pot.
(C) 0.039µF cap: This is kind of an odd value. Keeping production tolerances of up to 20 percent in mind, any value that is close will do, so you can use any small cap you want for this. I would prefer a small metallized film cap, and any voltage rating will do. If you want to stay as close as possible to the original design, use any 0.039 µF low-tolerance film cap.
(L) 1.5H inductor: The original design uses a Xicon 42TL021 inductor, which is easy to find and fairly priced. This one is also used in the Bill Lawrence Q-Filter design, the Gibson standard Varitone, and many other systems like this. It’s very small, so it will fit in virtually every electronic compartment of a guitar. It has a frequency range of 300 Hz up to 3.4 kHz, with a primary impedance of 4k ohms (that’s the one we want to use) and a secondary impedance of 600 ohms. Snip off the three secondary leads and the center tap of the primary side and use the two remaining outer primary leads; the primary side is marked with a “P.” On the pic, you can see the two leads you need marked in red, all other leads can be snipped off. You can connect the two remaining leads to the pot either way; it doesn’t matter which of them is going to ground when using it this way.
Drawing courtesy of singlecoil.com
(R) 220k: use a small axial metal film resistor (0.25 W), which is easy to find and is the quasi-standard.
Other designs use slightly different part values—the Bill Lawrence Q-filter has a 1.8H L, 0.02 µF C and 8k R, while the old RA Gresco Tone Qube from the ’80s has a 1.5H L, 0.0033 µF C, and a 180k R, so this is a wide field for experimentation to tweak it for your personal tone.
This mid-cut system can be put into any electric guitar not only as a master tone, but also together with a regular tone control or something like the Fender Greasebucket, or it can be assigned only to a certain pickup. It can be a great way to enhance your sonic palette, so give it a try.
That’s it! Next month, we’ll take a deeper look into how to fight feedback on a Telecaster. It’s a common issue, so stay tuned!
Until then ... keep on modding!
The two-in-one “sonic refractor” takes tremolo and wavefolding to radical new depths.
Pros: Huge range of usable sounds. Delicious distortion tones. Broadens your conception of what guitar can be.
Build quirks will turn some users off.
$279
Cosmodio Gravity Well
cosmod.io
Know what a wavefolder does to your guitar signal? If you don’t, that’s okay. I didn’t either until I started messing around with the all-analog Cosmodio Instruments Gravity Well. It’s a dual-effect pedal with a tremolo and wavefolder, the latter more widely used in synthesis that , at a certain threshold, shifts or inverts the direction the wave is traveling—in essence, folding it upon itself. Used together here, they make up what Cosmodio calls a sonic refractor.
Two Plus One
Gravity Well’s design and control set make it a charm to use. Two footswitches engage tremolo and wavefolder independently, and one of three toggle switches swaps the order of the effects. The two 3-way switches toggle different tone and voice options, from darker and thicker to brighter and more aggressive. (Mixing and matching with these two toggles yields great results.)
The wavefolder, which has an all-analog signal path bit a digitally controlled LFO, is controlled by knobs for both gain and volume, which provide enormous dynamic range. The LFO tremolo gets three knobs: speed, depth, and waveform. The first two are self-explanatory, but the latter offers switching between eight different tremolo waveforms. You’ll find standard sawtooth, triangle, square, and sine waves, but Cosmodio also included some wacko shapes: asymmetric swoop, ramp, sample and hold, and random. These weirder forms force truly weird relationships with the pedal, forcing your playing into increasingly unpredictable and bizarre territories.
This is all housed in a trippy, beautifully decorated Hammond 1590BB-sized enclosure, with in/out, expression pedal, and power jacks. I had concerns about the durability of the expression jack because it’s not sealed to its opening with an outer nut and washer, making it feel more susceptible to damage if a cable gets stepped on or jostled near the connection, as well as from moisture. After a look at the interior, though, the build seems sturdy as any I’ve seen.
Splatterhouse Audio
Cosmodio’s claim that the refractor is a “first-of-its-kind” modulation effect is pretty grand, but they have a point in that the wavefolder is rare-ish in the guitar domain and pairing it with tremolo creates some pretty foreign sounds. Barton McGuire, the Massachusetts-based builder behind Cosmodio, released a few videos that demonstrate, visually, how a wavefolder impacts your guitar’s signal—I highly suggest checking them out to understand some of the principles behind the effect (and to see an ’80s Muppet Babies-branded keyboard in action.)
By folding a waveform back on itself, rather than clipping it as a conventional distortion would, the wavefolder section produces colliding, reflecting overtones and harmonics. The resulting distortion is unique: It can sound lo-fi and broken in the low- to mid-gain range, or synthy and extraterrestrial when the gain is dimed. Add in the tremolo, and you’ve got a lot of sonic variables to play with.
Used independently, the tremolo effect is great, but the wavefolder is where the real fun is. With the gain at 12 o’clock, it mimics a vintage 1x10 tube amp cranked to the breaking point by a splatty germanium OD. A soft touch cleans up the signal really nicely, while maintaining the weirdness the wavefolder imparts to its signal. With forceful pick strokes at high gain, it functions like a unique fuzz-distortion hybrid with bizarre alien artifacts punching through the synthy goop.
One forum commenter suggested that the Gravity Well effect is often in charge as much the guitar itself, and that’s spot on at the pedal's extremes. Whatever you expect from your usual playing techniques tends to go out the window —generating instead crumbling, sputtering bursts of blubbering sound. Learning to respond to the pedal in these environments can redefine the guitar as an instrument, and that’s a big part of Gravity Well’s magic.
The Verdict
Gravity Well is the most fun I’ve had with a modulation pedal in a while. It strikes a brilliant balance between adventurous and useful, with a broad range of LFO modulations and a totally excellent oddball distortion. The combination of the two effects yields some of the coolest sounds I’ve heard from an electric guitar, and at $279, it’s a very reasonably priced journey to deeply inspiring corners you probably never expected your 6-string (or bass, or drums, or Muppet Babies Casio EP-10) to lead you to.
Kemper and Zilla announce the immediate availability of Zilla 2x12“ guitar cabs loaded with the acclaimed Kemper Kone speaker.
Zilla offers a variety of customization to the customers. On the dedicated Website, customers can choose material, color/tolex, size, and much more.
The sensation and joy of playing a guitar cabinet
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A guitar cabinet that provides „that“ well-known feel and gives you that kick-in-the-back experience. Because guitar cabinets can move some serious air. But these days cabinets also have to be comprehensive and modern in terms of being capable of delivering the dynamic and tonal nuances of the KEMPER PROFILER. So here it is: The ZILLA 2 x 12“ upright slant KONE cabinet.
These cabinets are designed in cooperation with the KEMPER sound designers and the great people from Zilla. Beauty is created out of decades of experience in building the finest guitar cabinets for the biggest guitar masters in the UK and the world over, combined with the digital guitar tone wizardry from the KEMPER labs. Loaded with the exquisit Kemper Kone speakers.
Now Kemper and Zilla bring this beautiful and powerful dream team for playing, rehearsing, and performing to the guitar players!
ABOUT THE KEMPER KONE SPEAKERS
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