I recently traded my Vox Valvetronix VT50 for an old Gibson Duo-Medalist. Although the online comments I initially found about the Duo-Medalist were lackluster, I’ve come across articles that tout the untapped potential of this old tube amp—they even cite [legendary Trainwreck amp builder] Ken Fischer to support this claim. Though I’m a novice, I have a friend who is capable of performing electronic surgery. I was wondering if you could shine additional light on this amp and weed out fact from fiction concerning its mod potential. For your reference, I’ve attached information I’ve found online about the Duo-Medalist, including its schematic. By the way, the amp’s footswitch is MIA, so I can’t engage the tremolo. I’m curious whether we can perform a miracle on that, as well.
Sincerely, Tommy Kirst
Hi Tommy:
I’m glad to see you’ve found a cool old tube amp! But simply having tubes doesn’t guarantee an amp will sound great. Some amps need a bit of help before they can ascend to the “pretty cool” category. Let’s see if we can raise the cool factor of your Gibson Duo-Medalist.
The 2-channel Duo-Medalist in all its ’70s glory. Photo by David Hilts
In your email, you supplied me with some posts and links that mention information supposedly supplied in The Trainwreck Pages by the late, great Ken Fischer. I knew Ken and was familiar with the original Trainwreck Pages published in the Angela Instruments catalog of many years ago (this fantastic parts catalog was obviously a true labor of love for Steve Melkisethian at Angela Instruments). There’s no mention of Gibson amps in that publication, but that’s not to say that Ken didn’t supply this information somewhere at some point in time.
The bottom line is that the modification mentions removing a few resistors and capacitors to improve the amp’s performance. I’ve taken a look at the schematic, and it’s my opinion that this modification should definitely improve the frequency response and increase the gain of your amp. Let me explain the modification and then give you a better way to execute it. We’ll then also look at a few other potential modifications that can make your Duo-Medalist even better.
This schematic for a vintage Gibson Duo-Medalist can also be downloaded at
gibson.com/Files/schematics/duo-medalist.jpg. Image courtesy of Gibson Guitar Corp.
In the initial modification, we will be removing an RC (resistor/capacitor) network in the preamp stages of the Normal and Reverb channels. It appears that this was incorporated to set the frequency response of the amp. Removing this will definitely change its tonal characteristics, but since you aren’t happy with the performance of the amp anyway, we’ve got nowhere to go but up.
In looking at the schematic, we can see a network of three resistors (470k, 220k, and 220k) and three capacitors (330 pF, 470 pF, and .0068 μF) attached to pin 5 on both V1 (the Normal channel) and V2 (the Reverb channel). Since this is a multi-chassis amp, your friend will need to remove the Duo- Medalist’s preamp chassis—the chassis containing all the preamp tubes—to locate these parts.
Now, although I said we would be removing these components from the circuit, that doesn’t mean we need to completely remove them. I’m going to give you a way to execute this that’s both substantially easier and reversible, should you ever wish to return the amp to its stock circuitry.
Locate the tag board terminal where the wire from connector S2 Pin 1 attaches. This should be the start of the RC network. Now locate Pin 5 of V1 (the 6EU7 closest to the side of the chassis). This is where the RC circuit connects to the preamp tube. Run a short wire from the S2 Pin 1 connection to V1 Pin 5. Now locate the .0068 μF capacitor that is part of this network. One side of it should be connected to a grounded terminal. Leave that lead connected and disconnect the lead that’s attached to the junction of the two 220k resistors. Lifting this lead will eliminate any additional noise from being injected into the signal path.
That’s it for the Normal-channel mod. By today’s standards, this should really lead to an improvement in the amp’s sonic performance, but if you ever wish to return the amp to stock, simply remove the wire and reconnect the .0068 μF capacitor.
But we’re not done yet. Next month, we’ll continue with our Duo-Medalist makeover by focusing on the Reverb channel, as well as a mod to improve the amp’s top end. We’ll take a look at your tremolo-pedal question, too, so stay tuned.
Special thanks to amp fanatic David Hilts for sharing a photo of his Gibson Duo-Medalist. Look for additional cool photos from Hilts in the April 2011 issue.
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EBS BassIQ Blue Label Triple Envelope Filter Pedal
The EBS BassIQ produces sounds ranging from classic auto-wah effects to spaced-out "Funkadelic" and synth-bass sounds. It is for everyone looking for a fun, fat-sounding, and responsive envelope filter that reacts to how you play in a musical way.
Overall, they encompass the historic arc of stompbox technology from fuzz and overdrives, to loopers and samplers, to tools that warp the audio end of the space-time continuum. Click on each one to get the full review as well as audio and video demos.
DigiTech JamMan Solo HD Review
Maybe every guitarist’s first pedal should be a looper. There are few more engaging ways to learn than playing along to your own ideas—or programmed rhythms, for that matter, which are a component of the new DigiTech JamMan Solo HD’s makeup. Beyond practicing, though, the Solo HD facilitates creation and fuels the rush that comes from instant composition and arrangement or jamming with a very like-minded partner in a two-man band.
Click here to read the review.
Warm Audio Warm Bender Review
In his excellent videoFuzz Detective, my former Premier Guitar colleague and pedal designer Joe Gore put forth the proposition that theSola Sound Tone Bender MkII marked the birth of metal. TakeWarm Audio’s Warm Bender for a spin and it’s easy to hear what he means. It’s nasty and it’s heavy—electrically awake with the high-mid buzz you associate with mid-’60s psych-punk, but supported with bottom-end ballast that can knock you flat (which may be where the metal bit comes in).
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Walrus Monumental Harmonic Stereo Tremolo Review
Among fellow psychedelic music-making chums in the ’90s, few tools were quite as essential as a Boss PN-2 Tremolo Pan. Few of us had two amplifiers with which we could make use of one. But if you could borrow an amp, you could make even the lamest riff sound mind-bending.
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MXR Layers Review
It’s unclear whether the unfortunate term “shoegaze” was coined to describe a certain English indie subculture’s proclivity for staring at pedals, or their sometimes embarrassed-at-performing demeanor. The MXR Layers will, no doubt, find favor among players that might make up this sect, as well as other ambience-oriented stylists. But it will probably leave players of all stripes staring floorward, too, at least while they learn the ropes with this addictive mashup of delay, modulation, harmonizer, and sustain effects.
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Wampler Mofetta Review
Wampler’s new Mofetta is a riff on Ibanez’s MT10 Mostortion, a long-ago discontinued pedal that’s now an in-demand cult classic. If you look at online listings for the MT10, you’ll see that asking prices have climbed up to $1k in extreme cases.
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Catalinbread StarCrash Fuzz Review
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Red Panda Radius Review
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Electro-Harmonix LPB-3 Linear Power Booster and EQ Review
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JFX Pedals Deluxe Modulation Ensemble Review
This four-in-one effects box is a one-stop shop for Frusciante fans, but it’s also loaded with classic-rock swagger.
Origin Effects Cali76 FET Review
The latest version of this popular boutique pedal adds improved metering and increased headroom for a more organic sound.
JAM Fuzz Phrase Si Review
Everyone has records and artists they indelibly associate with a specific stompbox. But if the subject is the silicon Fuzz Face, my first thought is always of David Gilmour and the Pink Floyd: Live at Pompeii film. What you hear in Live at Pompeii is probably shaped by a little studio sweetening. Even still, the fuzz you hear in “Echoes” and “Careful With That Axe, Eugene”—well, that is how a fuzz blaring through a wall of WEM cabinets in an ancient amphitheater should sound, like the sky shredded by the wail of banshees.
Fishman EchoBack Mini Delay Review
As someone who was primarily an acoustic guitarist for the first 16 out of 17 years that I’ve been playing, I’m relatively new to the pedal game. That’s not saying I’m new to effects—I’ve employed a squadron of them generously on acoustic tracks in post-production, but rarely in performance. But I’m discovering that a pedalboard, particularly for my acoustic, offers the amenities and comforts of the hobbit hole I dream of architecting for myself one day in the distant future.
RJM Full English Programmable Overdrive Review
Programmability and preset storage aren’t generally concerns for the average overdrive user. But if expansive digital control for true analog drive pedals becomes commonplace, it will be because pedals like the Full English Programmable Overdrive from RJM Music Technology make it fun and musically satisfying.
Strymon BigSky MX Review
Strymon calls the BigSky MX pedal “one reverb to rule them all.” Yep, that’s a riff on something we’ve heard before, but in this case it might be hard to argue. In updating what was already one of the market’s most comprehensive and versatile reverbs, Strymon has created a reverb pedal that will take some players a lifetime to fully explore. That process is likely to be tons of fun, too.
JHS Hard Drive Review
JHS makes many great and varied overdrive stomps. Their Pack Rat is a staple on one of my boards, and I can personally attest to the quality of their builds. The new Hard Drive has been in the works since as far back as 2016, when Josh Scott and his staff were finishing off workdays by jamming on ’90s hard rock riffs.
Keeley I Get Around Review
A highly controllable, mid-priced rotary speaker simulator inspired by the Beach Boys that nails the essential character of a Leslie—in stereo.
Cusack Project 34 Selenium Rectifier Pre/Drive
The term “selenium rectifier” might be Greek to most guitarists, but if it rings a bell with any vintage-amp enthusiasts that’s likely because you pulled one of these green, sugar-cube-sized components out of your amp’s tube-biasing network to replace it with a silicon diode.
Vox Real McCoy VRM-1 Review
Some pedals are more fun than others. And on the fun spectrum, a new Vox wah is like getting a bike for Christmas. There’s gleaming chrome. It comes in a cool vinyl pouch that’s hipper than a stocking. Put the pedal on the floor and you feel the freedom of a marauding BMX delinquent off the leash, or a funk dandy cool-stepping through the hot New York City summertime. It’s musical motion. It’s one of the most stylish effects ever built. A good one will be among the coolest-sounding, too.
Or you can check out the Reverend Billy Corgan Drop Z. At a glance, the Drop Z may not look like much of a cure for the 6-string doldrums. But pick it up and you’ll feel the difference fast. The Drop Z is built around a 26 1/4" scale and a 24-fret neck that makes this Reverend feel like a very different instrument. Designed and optimized for use with drop tunings, it opens the doors to whole palace ballrooms full of new musical possibilities.
Beastly Blue and Easy To Use
If the feel of the Drop Z alone doesn’t dislodge you from a guitar rut, there’s a good chance that its pretty profile would compel you to pick it up and play. It’s a handsome instrument. The conservatively chambered alder body (it’s routed at the bass and treble horns) is clad in a very pretty twilight-blue-meets-ocean-turquoise glossy finish, which is complimented perfectly by the brushed-aluminum pickguard. The chambered body definitely helps with the weight; the Drop Z is a little less than eight pounds. It also helps the guitar feel very balanced. There’s not a hint of neck dive. And if it weren’t for the discernibly longer stretch you make to reach the first fret, it would feel as familiar and comfortable as a nice Stratocaster.
The medium-oval neck, which is satin-finished maple with a maple fretboard, is a pleasure. It feels substantial and fast, and getting around its expanse is facilitated by a perfect setup. The 12" fretboard radius and jumbo frets also add to the Drop Z’s easy-breezy feel. Big bends require little more effort than they would on a normal scale, and I never felt the urge to squeeze a note to compensate for the weird intonation issues big frets and long scales can cause. From first fret to 24th, playing the Drop Z is an easy glide.
The Drop-Z pickups are a modified version of the Railhammer Billy Corgan Z-One pickups in his other Billy Corgan signature Reverends. The pickups’ impedance is rated at 14.5 ohms, which suggests a pretty hot unit. In this incarnation, the Z-One pickups are tuned for even more output and smoother treble. That’s a good idea for a pickup designed with heavy musical settings in mind.
Fangs on Cue, but Mellon Collie, Too
Though the Drop Z is easy to play in a getting-around-the-fretboard sense, plugging and turning up may take adjustments in approach and attitude. As the pickups’ impedance rating suggests, the Railhammer Z-Ones have a lot of hop, and as the expansive lengths of string resonate impressively, you’ll hear a lot of very present treble overtones. I spent most of my time with the instrument in a C# modal tuning or C–G–D–G–B–B, and in each tuning the Drop Z rumbled impressively (particularly through a late-’60s Fender Bassman head, which is a beautiful, burly match for this instrument). But unless I wanted to linger among the peaky resonances of the highest two strings (and I often did), I needed to attenuate both tone controls.
The good thing is that each of these controls has a very nice range. And while the guitar can start to feel stripped of its essence with too much tone or volume attenuation, there is wiggle room for softening transients and taming unwanted overtone blooms. These pronounced peaks are easy to hear in both the neck and bridge pickup, depending on your approach. I worked a lot more with open strings and drones than Billy Corgan might on songs like “Zero,” which the guitar was tailored for. But for those keen to explore the mellower side of the Drop Z’s personality, the combined pickup setting is a magic bullet. It’s airy, open, and makes it easy and rewarding to navigate slow-moving chord changes with strong bass foundations. It’s also fun to take advantage of the fretboard’s whole expanse in this setting—darting and dashing from toppy treble-note clusters to growling bass harmony notes—and enjoying the detail and string-to-string balance. By the way, the Drop Z, as you might guess, sounds positively massive with distortion, though you should be careful to choose your gain device carefully. The pickup’s midrange emphasis will make a similarly mid-heavy distortion sound harsh. A Sovtek-style Big Muff, with its scooped midrange and round low-end resonance, is an ideal fit if you want to get extra large.
The Verdict
The Korea-made Drop Z is a beautifully crafted instrument and a silky, easy, balanced player that will make you forget, in moments, about the expansive fretboard and extra scale length. It feels completely natural and effortless. How you relate to the tones here will depend on your musical mission. The hot pickups make it a perfect fit for outsized, aggressive tones. I, for one, would prefer to explore the wealth of overtones this well-constructed instrument generates via less aggressive pickups. But players like me will still find much to love in the combined pickup settings and the pickups’ impressive capacity for detail, which, depending on the tuning you use, can highlight harmonic interplay between notes and chords that would be much less prominent and less fun to explore in a more conventional guitar.
Reverend Billy Corgan Drop Z Signature Electric Guitar - Pearl White
Loopers can be complex enough to make beginners cry. They are fun if you have time to venture for whole weeks down a rabbit hole. But a looper that bridges the functionality and ease-of-use gap between the simplest and most maniacal ones can be a sweet spot for newbies and seasoned performers both. The JamMan Solo HD lives squarely in that zone. It also offers super-high sound quality and storage options, and capacity that would fit the needs of most pros—all in a stomp just millimeters larger than a Boss pedal.
Fast Out of the Blocks
Assuming you’ve used some kind of rudimentary looper before, there’s pretty decent odds you’ll sort out the basic functionality of this one with a couple of exploratory clicks of the footswitch. That’s unless you’ve failed to turn down the rhythm-level knob, in which case you’ll be scrambling for the quick start guide to figure out why there is a drum machine blaring from your amp. The Solo HD comes loaded with rhythm tracks that are actually really fun to use and invaluable for practice. In the course of casually exploring these, I found them engaging and vibey enough to be lured into crafting expansive dub reggae jams, thrashing punk riffs, and lo-fi cumbias. Removing these tracks from a given loop is just a matter of turning the rhythm volume to zero. You can also create your own guide rhythms with various percussion sounds.
Backing tracks aside, creating loops on the Solo HD involves a common single-click-to-record, double-click-to-stop footswitch sequence. Recording an overdub takes another single click, and you hold the footswitch down to erase a loop. Storing a loop requires a simple press-and-hold of the store switch. The sizable latching footswitch, which looks and feels quite like those on Boss pedals, is forgiving and accurate. This has always been a strength of JamMan loopers, and though I’m not completely certain why, it means I screw up the timing of my loops a lot less.
Many players will be satisfied with how easy this functionality is and explore little more of the Solo HD’s capabilities. And why not? The storage capacity—up to 35 minutes of loops and 10 minutes for individual loops—is enough that you can craft a minor prog-rock suite from these humble beginnings. Depending on how economical your loops are, you can use all or most of the 200 available memory locations built into the Solo HD. But you can also add another 200 with an SD/SDHC card.Deeper into Dubs
Loopers have always been more than performance and practice tools for me. I have old multitrack demos that still live in the memory banks of my oldest loopers. And just as with any demos, the sounds you create with the Solo HD may be tough to top or duplicate, which can mean a loop becomes the foundation of a whole recorded song. The Solo HD’s tempo and reverse features, which can completely mutate a loop, make this situation even more likely. The tempo function raises or lowers the BPM without changing the pitch of the loop. As a practice tool, this is invaluable for learning a solo at a slower clip. But drastically altered tempos can also help create entirely new moods for a musical passage without altering a favorite key to sing or play in. Some of these alterations reveal riffs and hooks within riffs and hooks, from which I would happily build a whole finished work. The reverse function is similarly inspiring and a source of unusual textures that can be the foundation for a more complex piece.
HD, of course, stands for high definition. And the Solo HD’s capacity for accurate, dense, and detail-rich stacks of loops means you can build complex musical weaves highlighting the interaction between overtones or timbre differences among other effects in your chain. I can’t remember the last time I felt like a looper’s audio resolution was really lacking. But the improved quality here lends itself to using the Solo HD as a song-arranging tool—and, again, as a recording asset, if you want a looped idea to form the backbone of a recording.
The Verdict
With a looper, smooth workflow is everything. And though it takes practice and some concentration in the early going to extract the most from the Solo HD’s substantial feature set, it is, ultimately, a very intuitive instrument that will not just smooth the use of loops in performance, but extend and enhance its ability as a right-brain-oriented driver of composition and creation.
