
The CAT scanning process helps luthiers better understand the material properties of the tonewoods used almost a century ago.
When reconstructing the sound of a vintage instrument, a data deep dive may be in order.
My interest in the science of sound stemmed from my inability to understand most modern luthiers’ theories or philosophies. One issue I’ve struggled with is why so many of the best examples of vintage guitars that are awesome on so many levels are now approaching 100 years old. Why doesn’t the same abundance of excellent sounding instruments exist in the modern era? Something was definitely spot-on with these older guitars. But when the tonewood stars are aligned, modern makers do occasionally come close to hitting that mark, so I don’t think it’s totally a question of those older instruments maturing through aging. I feel these guitars were good from the start.
So, what do I have to do to replicate the sound of those older guitars? And, most importantly, which sound is my primary goal? I’m sure I’ve said this before, but, just in case, I’ll say it again: The sound of world-class musical instruments is not subjective. They either fall into that category or they do not. However, there are still slight variables at play.
When I was developing my acoustic guitars, I had a blank canvas. All I had to do was make alterations until the instruments’ voice made me happy, and that became my sound. This method is called “form follows function,” because I altered the components until the instrument worked for me.
Reconstructing the sound of existing instruments is a more difficult task. In order to righteously pull it off, you have to replicate all of the components dimensionally, inside and out. Then, you can manipulate the tonewood to adjust the sound. This is “function follows form,” which is a much different, and ultimately more difficult, style of musical instrument making. In my shop, we call this style of backdoor guitar making “reverse profiling.”
Back in the day, I successfully pulled this off with vintage Gibson Advanced Jumbos and J-45s, but the Martin’s sound was more elusive. The added mass of the larger bracing and thicker tops can easily become lethargically dark and less responsive. But if correctly balanced, it’s a pretty special sound. Recently, I decided to move to the next level of reproducing the sound of vintage Martin guitars, specifically the late-’30s Martin D-18.
Unlike a modern sound that is commonly described as wet or lush, the vintage tone is clear and dry.
The first order of business was to locate an accurate example that had the desired sound and feel. There are varying sonic examples from any time period, so a marker was needed to keep the project on track and to compare for accuracy. This kept the project honest. I chose two models to compare: a 1937 D-18 with advanced bracing and wide string spacing, and a 1939 D-18 with non-advanced bracing and narrow string spacing. These were both iconic examples that had unique tones and folklore associated with their bracing patterns.
The next step was information gathering. Reverse profiling is trickier than a fresh build, and we need to understand the materials used a century ago. The data we compile plays a major role in the instrument’s tonal development and is absolutely necessary before we can develop any profiles. To achieve this, I worked with fellow luthier Tom Nania to CAT (Computed Axial Tomography) scan our vintage marker guitars. This way, we could calculate the density of the vintage tonewoods. Then, we physically mapped out the guitar’s weights and thicknesses inside and out. This generated the preliminary formula that was a key step in reverse engineering an existing guitar for reproduction. We established a definite path or, in other words, a recipe. When we make a change, which is inevitable, we will have accurate markers for each attempt.
I have always been impressed with the sound of vintage guitars. Unlike a modern sound that is commonly described as wet or lush, the vintage tone is clear and dry. If we can nail down this sound, we’ll gain a better understanding of tonewoods and their stability. This is only the beginning of a much bigger picture that will unfold over the next few years, and this 1937 D-18 is only one of the projects in the works. So far, our findings and progress are encouraging. I can’t wait to see where it ends up, but I expect good things.
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- Martin’s Joe Silvius: For the Love of Exotic Tonewoods ›
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Xotic revamps a classic Vox-boost-in-a-box pedal, creating a new one in the process.
Smart, feature-packed update on a classic. Nice size and price.
Small boost knob.
$180
Xotic Effects AC Booster V2
Xotic Effects newest version of the Vox-flavored AC Booster, the AC Booster V2, adds a second, footswitchable boost circuit (tweakable via a small, clear knob tucked among the four main-channel controls), plus a set of four dip switches on the box’s righthand side which engage compression, modern or classic voicing, low-mid boost, and high-mid boost.
This new suite of features packs significant extra functionality into V2’s still-diminutive enclosure. The Vox sounds are all there, and with the high-mids juiced and treble nudged, you’re squarely in clanging Top Boost territory. The modern voicing trades some furry mid-range chunk for a bit more aggression and clarity, while the compression is useful for leveling leads and smoothing out unruly playing.
The boost knob is a little difficult to access, situated as it is in the center of the primary four-knob array. I don’t have particularly big fingers, but even I had trouble twiddling it. That’ll annoy some. But it’s a small price to pay for such a pedalboard-friendly footprint. The boost doses you with a healthy bump in level and gain that’s great for stand-out leads and solos. And speaking of standing out, the upper-mid boost switch is a treat. I found that creating a greater disparity between the high mids from the low mids made for a more precise and satisfying tone-shaping experience than I would experience using a standard mids knob.
There are no shortage of pedals that ape Vox AC30 mojo, but I haven’t seen many that will give you the range of utility that the AC Booster V2 will, for less for $200. Xotic nailed a smart and versatile redesign here.
Nashville luthier and guitar tech Dave Johnson shows us the baker's dozen of tools he thinks any guitar picker requires to be a guitar fixer.
3. Guitar Tech Screwdriver Set - 3000
4. Nut File Set (for medium guitar strings) - 0882
8. String Spacing Ruler - 0673
9. Nut and Saddle Files - 4556
The Ultimate Guitarist's Tool Chest Giveaway
Whether you're setting up your first guitar or fine-tuning a custom build, these are the 13 tools every guitarist needs. Now you can win them all. We've partnered with our friends at StewMac to give away a complete pro-level toolkit valued at over $750.
Click here to enter
Paul Reed Smith cradles one of his company’s Charcoal Phoenix limited-edition guitars in front of a PRS Sonzera amp.
The storied guitar builder reflects on his dozen months sharing his experience, knowledge, and perspective with PG’s readers.
Over the past year, I’ve written a series of articles in Premier Guitar going over some of my, and our industry’s, views of guitar making. You can find all of them all online (and for those reading this online, the articles are collected here). What I am going to attempt to do for this final piece is boil down each of these articles to a “sort of” conclusion. I have enjoyed the process of writing and editing each one. For the most part, it’s been a lot of fun. So:
Tonewood Doesn’t Matter. Wood Does (August 2024)
We don’t use the word tonewood in conversation at PRS. It doesn’t capture a lot of my experience of which combinations of wood make good instruments. First and foremost, we are looking for qualities of wood over species, and we make sure we dry and treat each one appropriately.
What Makes a Guitar Worth the Price? (September 2024)
Very often, the price of a guitar does reflect how good an instrument is—and very often the price of the guitar has nothing to do with how good an instrument is.
What You Can and Can’t See When Buying a Guitar (October 2024)
This one’s a pet peeve. When making a purchase, you can clearly see the color of a guitar and how beautiful it is, but you have no idea if the neck is going to warp over time because of many factors, including wood drying and truss rod installment design. Trust your experience.
Does Where a Guitar Is Made Really Matter? (November 2024)
There are really good, really smart, really talented people all over the world. While I won’t deny it’s helped our career here at PRS being in the United States, I do not believe it is a truly defining factor of our quality. A good example would be the PRS SE Series.
The Complicated Beauty of Electric Guitar Pickups (December 2024)
We’ve taken so many good stabs at humbucking design, and I’m getting incredibly good feedback on our new McCarty IIIs. But making pickups is a complicated art. There are a lot of ingredients in the recipe.
“I hope these articles have had some positive impact on you as a group.”
In Guitar Making, It’s the Details that Matter (January 2025)
Well, that title says it. What’s interesting for me is that all guitar makers believe that different types of details matter more than others. At PRS, we have our own beliefs.
When Building Guitars—Or Pursuing Anything—Go Down All the Rabbit Holes (February 2025)
This one’s about learning. It’s a process I really enjoy. Whether your passion is guitar making, guitar playing, or something else entirely, there is always more to keep discovering.
Paul Reed Smith on Buying Gear (March 2025)
Very often at a clinic, the people who don’t play guitar have a less calcified view of the sound of the instruments being demonstrated than those players who have already developed strong ideas. On the other hand, one time a very experienced player was at one of my clinics and heard something he’d been looking for for a long time and did not expect it out of the guitar he got it from. Trust your experience—not your predetermined views.
Learning from the Mistakes of Guitar Building’s Past (April 2025)
I think my beginnings as a repairman gave me a lot of insight on this one. Even still, just the process of defining a past guitar-making mistake is its own art.
Paul Reed Smith on Where Amp History—and Tone—Begins (May 2025)
This one I love. It’s a greatly exaggerated version of mods you could do to a TS808 Tube Screamer, which has a history on the web. Amplifiers are “modulated power supplies” and can have so much impact on your tone.
The Lifelong Rhythm of Learning (June 2025)
In some periods of time, there’s a lot to be learned, and in some periods of time, you can barely hold what you had before. It’s different for everyone, and for me, it’s been up and down. No matter where you are in the process, there’s always good work to do.
I hope these articles have had some positive impact on you as a group. I know some things resonate with some people and not others, and the opposite as well. I haven’t gotten a lot of feedback from these articles except that there’s not an overwhelming chorus saying “what an idiot,” which I assume means there’s been some meat on the bone of some of the views shared. It’s been a joy. Thanks for listening.
Kemper updated the entire product range introducing the all-new Kemper Profiler MK 2 Series. More Power. More Flexibility.
KEMPER PROFILER - The all-new PROFILER MK 2 Series
Kemper today announces the immediate availability of the all-new KEMPER PROFILER MK 2 Series. Kemper continues to raise the bar with the upcoming Profiler MK 2 Series — a bold evolution of the Profiler lineup (All PROFILERs: Head, Rack, Stage, the Player, and the powered versions), delivering more power, more flexibility, and more creative potential than ever before.
At the heart of the PROFILER MK 2 Series works an upgraded processing engine, unlocking faster performance, with boot times clocking in around 20 seconds, and a host of new features that expand the boundaries of what a modern guitar or bass rig can do.
A New Era of Effects:
20 Blocks in Series, the most powerful effects architecture ever found in a Kemper unit - The PROFILER MK 2 Series now offers seven additional effect blocks, raising the total number of simultaneous audio effect blocks to an incredible 20 — all running with zero added signal latency. It’s like having an entire, fully integrated pedalboard with pedal essentials at your feet — but one that boots in seconds, never needs rewiring, and always remembers your settings.
A new Era of Profiling:
Kemper announces a new profiling technology for the MK 2 series. Availabilty is expected during Summer. Currently in extended testing with some selected third-party profile vendors the new profiling offers:
- More than 100,000 individual frequency points meticulously analyzed for the most precise amp recreation ever achieved.
- Next-Level Speaker & Dynamically adjustable Cabinet Resonance – Capturing the true dynamics of your setup with the longest and most complex impulse responses in the industry.
- Liquid Profiling Technology – Seamlessly integrate the original amp’s gain and tone controls, transforming a single profile into a fully dynamic, living amplifier.
- Unparalleled Precision & Feel – A cutting-edge hybrid approach combining precise, deterministic analog measurement with Kemper’s industry-leading profiling intelligence.
Overview - All that’s new in the PROFILER MK 2 in more Detail:
All-New FX Section – 7 Additional FX Slots - ThePROFILER MK 2-Series introduces an expanded FX section with seven dedicated “pedalboard essential” FX slots, featuring: A new second Noise Gate (Palm Ninja), Compressor, Pure Booster, WahWah, Vintage Chorus, Air Chorus, and Double Tracker.
Adding these to the pre-existing 10 audio blocks, Spectral Noise Gate, Transpose Effect, and Volume Pedal - in total this provides users with 20 simultaneous audio effect blocks, setup gig-ready right out of the box while maintaining full flexibility for customization.
This new layout makes it convenient to cover all the bases and offers 8 flexible FX blocks available for the acclaimed tone shapers and studio-grade unique FX the KEMPER PROFILER is famous for.
Performance Meets Portability - With a smarter internal design and new lightweight aluminum components, the Profiler Stage Mk 2 has shed excess weight — making it even more gig-friendly without sacrificing the tank-like build quality musicians rely on. Whether for touring the world or heading to a local session, this is the most travel-ready full-featured Profiler yet.
Mk 2-ready Player! - For all guitarists and bassists already rocking the compact PROFILER Player, there is good news: it’s been “MK 2”-ready from day one, meaning it’s fully aligned with the power and potential of the new series, and now, on LVL 1 already, it features 16 simultaneous FX in total. This new extended signal flow becomes available for all Player owners as a free update, and yes, it will get Profiling, too. Making the PROFILER Player out of the box the features richest and most professional performance and recording solution - with its travel-friendly footprint and convenient price point!
8-Channel USB Audio Support for the new Mk 2-Series - Native 8-channel USB audio support to all KEMPER PROFILER MK 2 Series units, enabling seamless multitrack recording and reamping directly into your DAW – no external interface required.
Loop Longer, Play Harder - The integrated Looper also gets a serious upgrade. With up to two full minutes of recording time, the MK 2 Series lets you capture extended phrases, build layered soundscapes, or craft entire performances — all on the fly. (Looper available from LVL 3 for the Player)
Speed and Responsiveness Upgrades - Major improvements under the hood. Boot times, preset switching, and UI responsiveness are noticeably faster and smoother, especially in Performance Mode.
Christoph Kemper, Founder & CEO:
“The new PROFILER MK 2-Series makes the PROFILERs feel more like a complete rig than ever before. With instant access to essential FX, full USB audio integration, and improved playability, we’re giving our users a platform that adapts and grows with them.”
Pricing & Availability:
The new KEMPER PROFILER MK 2 Series models are available now from dealers worldwide and directly from the Kemper Online Store. All the new features require a KEMPER PROFILER MK 2 Series device. Visit www.kemper-amps.com for downloads and release notes.
PROFILER Head $1,348.00
PROFILER Rack $1,398.00
PROFILER Stage $1,498.00
PROFILER Player $ 699.00
PROFILER PowerHead $1,798.00
PROFILER PowerRack $1,798.00
PROFILER Remote $ 469.00
At a glance!
The Kemper Profiler MK 2 Series isn’t just about doing more. It’s about doing it better, faster, and without compromise. With unmatched tonal power, surgical precision, and effortless usability, this is the most complete and forward-thinking Profiler platform yet.