Hello Ask Amp Man fans. While I’ve been answering your questions for many years now, the last few columns have been about interesting amps I’ve come across, and this column follows that path. I still very much enjoy servicing amps when possible—and occasionally a really cool and unusual piece will cross my bench. Over the years, I’ve seen plenty of vintage Marshall, Fender, Ampeg, Vox, Hiwatt, and Gibson amps. They’re all cool, of course, but sometimes there’s a genuinely unusual one. This month’s featured SVT was one of those. The customer hadn’t played the amp for years and wanted it brought up to spec.
At first glance, it looked like a typical Saint Louis Music-era SVT (Photo 1). It was dressed in black, maybe late-’80s or early-’90s, and possibly an offshore-manufactured unit. But then I saw a commemorative plaque (Photo 2) attached to the rear grate. What could this be? Time to do some digging.
Photo 2
In disassembling the amp, I noticed the transformers looked to be old-school, U.S.-made and not the later-period SVT offshore transformers, which to me are pretty recognizable. The lower power-amp chassis also looked to be of original U.S. manufacture. It had the same multi-pin chassis connector and same tube location and callout as classic SVTs. It looked from a time warp to the late-’60s/early-’70s—not a typical SLM-era Ampeg. So, it was time for some research.
The first thing I sought to learn about was the plaque on the rear. Surely “1987 SVT Limited Edition 019 of 500” means something! Turns out it does. This amp is part of a production run known as “Skunk Works” and was, indeed, built by SLM.
Here’s the bloodline: Ampeg was sold to the Magnavox Corporation in 1971. Magnavox then sold Ampeg to Music Technologies Inc. in 1980. SLM bought the rights to the Ampeg name in 1986 and took possession of any Ampeg inventory left at MTI. That inventory contained enough of the old major parts (transformers, chassis, etc.) to build 500 SVTs! These amps were built in-house by the Skunk Works crew at SLM. They were supposedly the first SVTs made in the U.S. since Magnavox had the brand. SLM built and covered all the wooden cabinets and used some stock typical of their ’80s/’90s SVTs for the vinyl, knobs, grille cloth, etc.—which is why, at first glance, they look to be standard SLM-era products.
Photo 3
That perception is quickly put to rest once these units are disassembled. The layout and circuit boards look pretty much identical to the ’70s units I’ve serviced over the years (Photo 3 and Photo 4). Now that I knew what an interesting piece I had on the bench, it was time to see what condition it was in.
Photo 4
Since the customer hadn’t used the amp for years, the first procedure was to bring the amp up slowly over the course of the day to re-form the filter caps. So, I pulled the chassis, removed all the tubes, checked the mains fuse’s condition and value, hooked the amp to a Variac, and started to bring it up slowly while monitoring the DC voltage. In cases like this, during the course of the day I’ll bring up the Variac until the voltages are close to the voltage rating of the capacitors. If the amp doesn’t blow the fuse, we can at least be sure that none of the filter caps are shorted.
Next, I discharged the caps and checked the components known to fail. There are six 5-ohm, 5-watt resistors on the power amp circuit board (Photo 5). Each is attached to the plate of one of the 6550 output tubes and is actually used as a safeguard. If one of the output tubes shorts out, the resistor will open up instead of the amp blowing a fuse, allowing the amp to continue to function through the gig. Pretty ingenious, but there is no indicator to let you know that a tube has blown, so unless you’re very familiar with the feel and response of the amp, you may be running with only five working output tubes for quite a while. The only downside to this feature is that the amp will need to be disassembled and serviced for replacement of the bad resistor before the bad tube is replaced.
Photo 5
Anyway, these resistors checked out fine, so it was time to clean all the jacks, pots and sockets, install a new set of tubes, and see if the amp behaved. I chose the new reissue Tung-Sol tubes because, if memory serves, some of the mid-’60s SVT amps came stock with the original Tung-Sol 6550s. That was a bit of a nod to the past—plus, these tubes sound nice!
I always set up and test amps prior to reinstalling the chassis in the head shell, in case there are any problems. With all new tubes installed, I fired up the amp and set the bias with the very friendly biasing scheme on these amps. Test points and adjustment pots on the front of the power amp chassis, along with instructions, allow for proper biasing, even when the chassis is mounted in the head box. That’s pretty slick. The amp biased up properly and the output on the scope looked great. It was time to put all the screws back in and send this historically significant amp back to its owner—a big ol’ sweet skunk.
Revv G3 Purple Channel Preamp/Overdrive/Distortion Pedal - Anniversary Edition
The Revv G3 revolutionized high gain pedals in 2018 with its tube-like response & tight, clear high gain tones. Suddenly the same boutique tones used by metal artists & producers worldwide were available to anyone in a compact pedal. Now the G3 returns with a new V2 circuit revision that raises the bar again.
It would have been easy for Wampler to simply make a Mostortion clone and call it a day, but they added some unique twists to the Mofetta pedal. While the original Mostortion had a MOSFET-based op amp, it actually used clipping diodes to create its overdrive. The Mofetta is a fairly accurate replica and includes that circuitry, but also has a toggle switch for texture, which lets you choose between the original-style diode-based clipping in the down position and multi-cascaded MOSFET gain stages in the up position.
Luscious Low Gain and Meaty Mid-Gain
The Mofetta’s control panel is very straightforward and conventional with knobs for bass, mids, treble, level, and gain. The original Mostortion was revered for its low-gain tone and is now popular among Nashville session guitarists. Wampler’s tribute captures that edge-of-breakup vibe perfectly. I enjoyed using the pedal with the gain on the lower side, around 9 o’clock, where I heard and felt slight compression that gave single notes a smooth and silky feel. I particularly enjoyed the tone-thickening the Mofetta lent to my Ernie Ball Music Man Axis Sport’s split-coil sound as I played pop melodies and rootsy, triadic rhythm guitar figures. The Mofetta has expansive headroom, and as a result there’s a lot of space in which you can find really bold, cutting tones without muddying the waters too much. Even turning the gain all the way off yields a pleasing volume bump that would work well in a clean boost setting.
There’s a lot of space in which you can find really bold, cutting tones without muddying the waters too much.
Switching the texture switch up engages the MOSFET section, introducing cascading gain stages that elevate the heat and add flavor the original Mostortion didn’t really offer. Classic rock and early metal are readily available via the MOSFET setting. If you need to stretch out to modern metal sounds, the Mofetta probably isn’t the pedal for you. Again, the original Mostortion was, first and foremost, a low-to-mid-gain affair, so unless you’re using it as a boost with a high-gain amp, the Mofetta is not really a vehicle for extreme sounds.
One of the Mofetta’s real treats is its responsiveness. Even at higher gain settings the Mofetta is very touch sensitive. You can tap into a wide range of dynamic shading just by varying the strength of your pick attack. I enjoyed playing fast, ascending scalar passages, picking with a medium attack then really slamming it hard when I hit a high climactic note, to get the guitar to really scream.
The Verdict
Wampler is a reliably great builder who creates pedals with a purpose. I own two of his pedals, the Dual Fusion and the Pinnacle, and both are really exceptional units. The Mofetta captures the essence of the Mostortion and makes it available at an accessible price. But even if you’ve never heard or played an original Mostortion, you’ll appreciate the truly versatile EQ, touch sensitivity, and the bonus texture switch, which expands the Mofetta’s range into more aggressive spaces. The wealth of dirt boxes on the market today can make a player jaded. But Wampler pushed into a relatively unique, satisfying, and interesting place with the Mofetta.
Filthy, saturated fuzz is a glorious thing, whether it’s the writ-large solos of Big Brother and the Holding Company’s live “Ball and Chain,” the soaring feedback and pure crush of Jimi Hendrix’s “Foxy Lady,” or the sandblasted rhythm textures of Queens of the Stone Age’s “Paper Machete.” It’s also a Wayback Machine. Step on a fuzz pedal and your tone is transported to the ’60s or early ’70s, which, when it comes to classic guitar sounds, is not a bad place to be.
Catalinbread’s StarCrash is from their new ’70s collection, so the company is laying its Six Million Dollar Man trading cards on the table—upping the ante on traditional fuzz with more controls and, according to the company’s website, a little more volume than the average fuzz pedal, while still staying in the traditional Fuzz Face lane.
The Howler’s Viscera
Arbiter Electronics made the first Fuzz Face in 1966. The StarCrash is inspired by that 2-transistor pedal, but benefits from evolution, as did almost all fuzz pedals in the ’70s, when the standard shifted from germanium to silicon circuitry to improve the consistency of the effect’s performance. The downside is that germanium is gnarlier to some ears, and silicon transistors don’t respond as well to adjustments made via a guitar’s volume control.
While Fuzz Faces have only two knobs, volume and fuzz, the silicon StarCrash has three: volume, bias, and low-cut. Catalinbread’s website explains: “We got rid of that goofy fuzz knob. We know that 95 percent of all players run it dimed, and the remaining 5 percent use their guitar’s volume knob to rein it in.”
I suspect there are plenty of players who, like me, do adjust the fuzz control on their pedals, but the most important thing is that the core fuzz sound here is excellent—bristly and snarling, with a far girthier tone than my reissue Fuzz Face. It’s also, with the bias and low-cut controls, far more flexible. The low-cut control allows you to range from a traditional, comparatively thinner Fuzz Face sound (past noon and further) to the StarCrash’s authentic, beefier voice (noon and lower). Essentially, it cuts bass frequencies from 40 Hz to 500 Hz, resulting in an aural menu that runs from lush and lowdown to buzzy and slicing. And the bias control is a direct route to the spitty, fragmented, so-called Velcro-sound that’s become a staple of the stoner-rock/Jack White school of tone. The company calls this dial a “dying battery simulator,” and it starves the second transistor to achieve that effect.
Sweet Song of the Tribbles
Playing with the StarCrash is a lot of fun. I ran it through a pair of Carr amps in stereo, adding some delay and reverb to mood, and used a variety of single-coil- and humbucker-outfitted guitars. While both pickup types interacted well with the pedal, the humbuckers were most pleasing to my ears with the bias cranked to about 2 o’clock or higher, since the ’buckers higher output allowed me to let notes sustain longer before sputtering out. Keeping the low-cut filter at 9 o’clock or lower also helped sustain and depth in the Velcro-fuzz zone, while letting more of the instruments’ natural voices come through, of course.
With the low-cut filter turned up full and the bias at 10 o’clock, I got the StarCrash to be the perfect doppelganger of my Hendrix reissue Fuzz Face. But that’s such a small part of the pedal’s overall tone profile. It was more fun to roll off just a bit of bass and set the bias knob to about 2 or 3 o’clock. Around these settings, the sound is huge and grinding, and yet barre chords hold their character while playing rhythm, and single-note runs, especially on the low strings, are a filthy delight, with just the right schmear of buttery sustain plus a hint of decay lurking behind every note. It’s such a ripe tone—the sonic equivalent of a delicious, stinky cheese—that I could hang with it all day.
Regarding Catalinbread’s claims about the volume control? Yes, it gets very loud without losing the essence of the notes or chords you’re playing, or the character of the fuzz, which is a distinct advantage when you’re in a band and need to stand out. And it’s a tad louder than my Fuzz Face but doesn’t really bark up to the level of most Tone Bender or Buzzaround clones I’ve heard. In my experience, these germanium-chipped critters of similar vintage can practically slam you through the wall when their volume levels are cranked.
The Verdict
Catalinbread’s StarCrash—with its sturdy enclosure, smooth on/off switch and easy-to-manipulate dials—can compete with any Fuzz Face variant in both price and performance, scoring high points on the latter count. The bias and low-cut dials provide access to a wider-than-usual variety of fuzz tones, and are especially delightful for long, playful solos dappled with gristle, flutter, and sustain. Kudos to Catalinbread for making this pedal not just a reflection of the past, but an improvement on it.
Catalinbread Starcrash 70 Fuzz Pedal - Starcrash 70 Collection
The release of a newRed Panda pedal is something to be celebrated. Each of the company’s devices lets us crack into our signal chains and tweak its inner properties in unique, forward-thinking ways, encouraging us to be daring, create something new, and think about sound differently. In essence, they take us to the sonic frontier, where the most intrepid among us seek thrills.
Last January, I got my first glimpse of the Radius at NAMM and knew that Red Panda mastermind Curt Malouin had, once again, concocted something fresh. The pedal offers ring modulation and frequency shifting with pitch tracking and an LFO, and I heard classic ring-mod tones as the jumping off point for oodles of bold sounds generated by envelope and waveform-controlled modulation and interaction. I had to get my hands on one.
Enjoy the Process
I’ve heard some musicians talk about how the functionality of Red Panda’s pedals are deep to a point that they can be hard to follow. If that’s the case, it’s by design, simply because each Red Panda device opens access to an untrodden path. As such, it can feel heady to get into the details of the Radius, which blends between ring modulation and frequency shifting, offering control of the balance and shift ratios of the upper and lower sidebands to create effects including phasing, tremolo, and far less-natural sounds.
As complex as that all might seem, Red Panda’s pedals always make it easy to strip the controls down to their most essential form. The firmest ground for a guitarist to stand with the Radius is a simple ring-mod sound. To get that, I selected the ring mod function, turned off the modulation section by zeroing the rate and amount knobs, kept the shift switch off and the range switch on its lowest setting. With the mix at noon and the frequency knob cranked, I found my sound.
From there, by lowering the frequency range, the Radius will yield percussive tremolo tones, and the track knob helped me dial that in before opening up a host of phaser sounds below noon. By going the other direction and kicking the rate switch into its higher setting, a world of ring-mod tweaking opens up. There are some uniquely warped effects in these higher settings that include dial-up modem sounds and lo-fi dial tones. Exploring the ring mod/frequency shift knob widens the possibilities further to high-pitched, filtered white noise and glitchy digital artifacts at its extremes.
There are wild, active sounds within each knob movement on the Radius, and the modulation section naturally brings those to life in more ways than a simple knob tweak ever could, delivering four LFO waveforms, a step modulator, two x-mod waveforms, and an envelope follower. It’s within these settings that I found rayguns, sirens, Shepard tones, and futuristic sounds that were even harder to describe.
It’s easy to imagine the Radius at the forefront of sonic experiments, where it would be right at home. But this pedal could easily be a studio device when applied in low doses to give a track something special that pops. The possible applications go way beyond guitars.
The Verdict
The Radius isn’t easy to plug and play, but it’s also not hard to use if you keep an open mind. That’s necessary, too: The Radius is not for guitar players who prefer to stay grounded; this pedal is for sonic-stargazers and producers.
I enjoyed pairing the Radius with various guitar instruments—12-string, baritone, bass—and it kept getting me more and more excited about sonic experimentation. That feeling is a big part of what’s special about this pedal. It’s so open-ended and controllable, continuing to reveal more of its capabilities with use. Once you feel like you’ve gotten something down, there are often more sounds to explore, whether that’s putting a new instrument or pedal next to it or exploring the Radius’ stereo, MIDI, or expression-pedal functionality. Like many great instruments, it only takes a few minutes to get started, but it could keep you exploring for years.
Red Panda Radius Ring Modulator/Frequency Shifter Pedal
