Hey there from Argentina! Love your articles!
I have a 1966 Super Reverb amp, all original. I’m looking to mod it lightly to have early breakup (now it’s at about 7). I don’t like pedals, so wanted to ask you for advice.
Thanks so much,
Martin
Hello Martin,
Glad you’re diggin’ the column … in Argentina! And, might I say, nice amp. The Super Reverb is definitely one of my all-time favorites. It has great midrange content, which we all know (or should) is where a guitar belongs in the mix, because, well, a guitar is a midrange instrument. And at only 40 watts, it can be pushed into overdrive easier than higher-powered amps (although not as easily as, say, a Deluxe), and sometimes that’s the power range we need for smaller venues. That sounds like the situation you’re currently looking to solve, so let’s see if I can help you with some options. You mentioned you’d be open to modification, so let’s start with suggestions there, and then I’ll give you other options, too.
Mod 1: Install a master volume. Master volumes come in a few different styles and affect the signal differently. A standard type of master volume is one where the signal from the preamp is attenuated in the circuit prior to reaching the phase inverter. This can work fine in many instances where the preamp is designed to achieve distortion, and is the case with most mid- to hi-gain amplifiers. The drive is developed in the preamp and that signal is fed to the output stage via the master volume at whatever level necessary, with the output stage being used, for the most part, as a source of clean power.
There is another type of master volume—the simplest of all, actually—that acts to combine the two out-of-phase signals from the phase inverter before they reach the output tubes. And what happens when two out-of-phase signals are combined? For those who don’t know, they cancel out. Therefore, the signal being sent to the output tubes is shut down in varying degrees, from not-at-all to full.
Unfortunately, neither of these would work well for you, in my opinion, as there is not much in the way of overdrive that can be achieved in the preamp section of a typical Fender amp. What I would recommend is a master volume that actually changes the signal prior to the output tubes to simulate a bit more drive—and yes, they do exist. They’re called post-phase inverter master volumes, or PPI’s. There are two different types that, when reduced from maximum volume, begin to actually flatten out the peaks of the signal being fed to the output stage, which tends to mimic an overdriven output stage. This is one way to get more “apparent” overdrive from your amp at a lower volume. These master volume circuits can be found by you or your tech on the internet. I would suggest searching "The Trainwreck Pages" online for more background. This is an article written by the late Ken Fischer of Trainwreck Circuits in the mid 1980s. You’ll enjoy it.
The Brown Box was developed to run vintage amplifiers at the voltages that were present when the amp was designed, which in the U.S. was closer to 110 or 115 volts.
Mod 2: Convert to a quasi-triode mode. Have your tech either convert your amp, or install a switch, so you can run your output stage in a quasi-triode mode. This can reduce the output power by approximately 40 percent and generally causes the amp to have a somewhat smoother response. This can be done by simply disconnecting the screen grid voltage from pin 6, which is being fed to the screen grid of the tube via the 470-ohm resistor connected between pins 6 and 4 in a Fender amp.
Simply connect the pin 6 connection of that resistor to pin 3 of the socket, which is the plate connection of the tube. Connecting the plate to the screen grid through that 470-ohm resistor causes the tube to run in a quasi-triode mode. This can also be accomplished with a heavy duty DPDT switch so you can run the amp in either standard pentode more or triode mode for those smaller venues.
Non-mod 1: Swap rectifier tubes. If you’re running a 5AR4 rectifier tube in the amp, try a 5U4. While the 5U4 draws a bit more filament current than the 5AR4, Super Reverbs have vacillated between them over the years while using the same mains transformer, so this should not be an issue. As far as the difference, the 5U4 should lower the plate voltage by 10 to 15 volts, and it seems to compress a bit more. So, if you’re looking for merely a subtle change, this may be all you need.
(Left) If you’re running a 5AR4 rectifier tube in the amp, try a 5U4. Super Reverbs have vacillated between them over the years while using the same mains transformer. (Right) Removing the 6L6 output tubes, installing Yellow Jackets in the tube sockets, and inserting a pair of EL84 tubes into the adaptors reduces the output by 20 watts.
Non-mod 2: Install a Yellow Jacket tube converter. This allows you to convert the output stage from 6L6 tubes to 6BQ5s. You simply remove the 6L6 output tubes, install the Yellow Jackets in the output tube sockets, and insert a pair of 6BQ5 (EL84) output tubes into the adaptors. The output is now reduced to approximately 20 watts, but because the EL84 is the baby brother to the EL34, the tonal characteristics of the amp will change and have a bit more mids with less top and bottom. But hey, vive la différence.
Non-mod 3: Use an external attenuator. There are certainly plenty out there. Just be sure it’s impedance specific: You purchase a 2-ohm model for the Super Reverb.
Non-mod 4: Use an external voltage reduction unit. Try something like a Variac or a Brown Box. The Brown Box was developed to run vintage amplifiers at the voltages that were present when the amp was designed, which in the U.S. was closer to 110 or 115 volts, as opposed to the typical 120+ volts currently supplied. If you decide to use a Variac-style device, lowering the wall voltage 10 to 15 volts may get the results you’re looking for.
I hope that makes your Super Reverb super for all applications.
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.
Reverend Vernon Reid Totem Series Electric Guitar - Shaman
Silos features six presets, tap tempo, one full second of delay time, and three voices—two of which are styled after bucket-brigade and tape-delay sounds. In the $150 price category, it’s not unusual for a digital delay to leave some number of those functions out. And spending the same money on a true-analog alternative usually means warm, enveloping sounds but limited functionality and delay time. Silos, improbably perhaps, offers a very elegant solution to this can’t-have-it-all dilemma in a U.S.-made effect.
A More Complete Cobbling Together
Silos’ utility is bolstered by a very unintimidating control set, which is streamlined and approachable. Three of those controls are dedicated to the same mix, time, and repeats controls you see on any delay. But saving a preset to one of the six spots on the rotary preset dial is as easy as holding the green/red illuminated button just below the mix and preset knobs. And you certainly won’t get lost in the weeds if you move to the 3-position toggle, which switches between a clear “digital” voice, darker “analog” voice, and a “tape” voice which is darker still.
“The three voices offer discernibly different response to gain devices.”
One might suspect that a tone control for the repeats offers similar functionality as the voice toggle switch. But while it’s true that the most obvious audible differences between digital, BBD, and tape delays are apparent in the relative fidelity and darkness of their echoes, the Silos’ three voices behave differently in ways that are more complex than lighter or duskier tonality. For instance, the digital voice will never exhibit runaway oscillation, even at maximum mix and repeat settings. Instead, repeats fade out after about six seconds (at the fastest time settings) or create sleepy layers of slow-decaying repeats that enhance detail in complex, sprawling, loop-like melodic phrases. The analog voice and tape voice, on the other hand, will happily feed back to psychotic extremes. Both also offer satisfying sensitivity to real-time, on-the-fly adjustments. For example, I was tickled with how I could generate Apocalypse Now helicopter-chop effects and fade them in and out of prominence as if they were approaching or receding in proximity—an effect made easier still if you assign an expression pedal to the mix control. This kind of interactivity is what makes analog machines like the Echoplex, Space Echo, and Memory Man transcend mere delay status, and the sensitivity and just-right resistance make the process of manipulating repeats endlessly engaging.
Doesn't Flinch at Filth
EarthQuaker makes a point of highlighting the Silos’ affinity for dirty and distorted sounds. I did not notice that it behaved light-years better than other delays in this regard. But the three voices most definitely offer discernibly different responses to gain devices. The super-clear first repeat in the digital mode lends clarity and melodic focus, even to hectic, unpredictable, fractured fuzzes. The analog voice, which EQD says is inspired by the tone makeup of a 1980s-vintage, Japan-made KMD bucket brigade echo, handles fuzz forgivingly inasmuch as its repeats fade warmly and evenly, but the strong midrange also keeps many overtones present as the echoes fade. The tape voice, which uses aMaestro Echoplex as its sonic inspiration, is distinctly dirtier and creates more nebulous undercurrents in the repeats. If you want to retain clarity in more melodic settings, it will create a warm glow around repeats at conservative levels. Push it, and it will summon thick, sometimes droning haze that makes a great backdrop for slower, simpler, and hooky psychedelic riffs.
In clean applications, this decay and tone profile lend the tape setting a spooky, foggy aura that suggests the cold vastness of outer space. The analog voice often displays an authentic BBD clickiness in clean repeats that’s sweet for underscoring rhythmic patterns, while the digital voice’s pronounced regularity adds a clockwork quality that supports more up-tempo, driving, electronic rhythms.
The Verdict
Silos’ combination of features seems like a very obvious and appealing one. But bringing it all together at just less than 150 bucks represents a smart, adept threading of the cost/feature needle.
EarthQuaker Devices Silos Multi-generational Time Reflection Delay Pedal
