7 Ways to Get High-Volume Tube Tone Without Being Too Loud: Attenuators, Load Boxes, and More

Within the realm of tube-based guitar amps—and there are still a lot of us who play them—the most common how do I...? question posed still revolves around obtaining fat, juicy, cranked-up tone at reasonable volumes. Volume levels on stage seem to have declined steadily since the glory days when big full-stack amps ruled the world, and anyone who regularly plays small- to medium-sized clubs in particular will tell you how restrictive many venues are regarding room volume these days. Yet, we all still like to sound big, even if we're not pegging the needle on the decibel meter.

Plenty has been written about using smaller amps to reduce volume levels while still hitting the amp's "sweet spot" tone-wise, and there's some sense to that. But plenty of us just like the sound of our bigger 30-, 50-, and 100-watt amps. We'd rather stick to that amp, and that sound, and help it fit the room better, rather than change up our rig entirely. In other cases, we're already using smaller amps in the sub-20-watt, but those can still be too loud for some smaller clubs or to be satisfying for home or studio use.

Fortunately, we've had a solid five decades of clever engineers puzzling out excellent solutions to the problem of achieving cranked-amp tone at suitable volume levels, and there are more great ways of getting there today than ever before. Below, we'll check out seven of the most reliable means to the end.

The Quietly Cranked Reality Check

It's important to acknowledge right up front that no amp will sound exactly the same at lower volumes as it does at higher, regardless of how transparent the volume-reduction technique used. This is for several reasons, and usually for a combination of reasons, but chief among them are these:

  • The strength with which the speakers are driven also contributes to any amp's overall sound, causing compression, the enhancement of certain frequencies (which displays any particular speaker's character), and speaker distortion in and of itself. If you reduce the power to the speaker (as master volume controls, output attenuators, and reampers do)—even if the tone and distortion content remain the same—you change that sound. Period.

  • The human ear perceives frequencies differently at different volume levels. Reduce the volume, and any amp will sound different to us, regardless of how much it "sounds like itself when loud" in terms of distortion content and frequency parameters.

As such, most players find that many of the volume-reduction solutions discussed here are excellent for knocking off enough decibels to make an amp that usually suits a 250-capacity venue sound good in a 100-capacity venue, for example, or for making their soundman and lead singer just that much happier on a large concert stage. But there are few, if any, that can really knock a 100-watt amp down to "bedroom volumes" with entirely satisfying results. That being said, many will still do the trick just fine for a little low-volume, late-night jam.

With all of that in mind, you'll find among these units discussed some truly outstanding ways to make your big amp viable again (or make any amp, small or large, function well in a small, constricted venue). For many players, one or the other of these solutions has proved a real game-changer in the volume wars.

Master Volume Controls

Most guitarists will already be familiar with this one. It's perhaps the most obvious solution, and it has been with us the longest. A handful of inventive makers started putting master volume controls on their amps as early as the late '60s, but this simple knob really came into its own with the Mesa/Boogie Mark I amps of the early '70s, and then the Marshall Master Model amps—the 2203 and 2204 heads—of the mid-'70s. Soon, it was difficult to find a serious guitar amp that didn't have a master volume there at the end of the control panel.

What They Do

1978 Mesa Boogie Mark I

Much as the name implies, a master volume control is a potentiometer (pot) placed later in the amp's circuit to rein in the overall output level, regardless of how you set the first volume control (which itself might be labeled "gain", "drive," or something similar). This allows the player to drive the preamp hard to achieve distortion from the tubes in that stage, while still reining in the volume created by the output stage—which is what's ultimately sent to the speaker. The master volume isn't a "product" as such, of course, but a relatively simple network that any competent amp designer, manufacture, or repair person can cobble onto an existing circuit.

Popular Examples

There are several different ways of achieving master volume controls, and some have earned more followers than others. Many early master-volume controls were placed in or at the end of the preamp, to rein in the signal after the first gain stage(s) or tone stage, as was done in some Mesa/Boogie designs, and Marshall designs such as the JCM800 2203 and 2204, and others of that ilk.

These can still sound great (and those names tell you they are associated with some classic amps), but many guitarists have come to prefer a configuration called the post-phase-inverter master volume (PPIMV for short), which places the pot (or often two ganged pots in one) after the phase-inverter. The phase-inverter is technically part of the output stage, so in this position the MV allows for more of the overall sound of the circuit before reining it in.

1979 Marshall JMP 2203

The Drawbacks

Thousands of players have been entirely happy with their master-volume controls for going on 50 years now, so they clearly do the trick just fine as far as many guitarists are concerned. Detractors will say, however, that the nature of this control means that even at their best they can only reduce what's happening in the circuit before the output tubes, and don't allow for bringing those big tubes' essential contribution to an amp's sound, or that of the output transformer.

For that reason, they do often seem to work best in amps that generate the majority of their signature tone in the preamp stages already. Also, using a master volume to achieve extremely low volume levels—but with a heavily cranked-up overdriven sound from a maxed-out gain control in the preamp—can often result in a fizzy, bees-in-a-tin-can tone.

Output Attenuators

The output attenuator first saw the light of day in a commercial sense in the '80s, and in the '00s and '10s this has become one of the more popular solutions to cranking up a big amp. Output attenuators most commonly take the form of a box (from the size of a brick, to about the size of a shoebox) that is connected between the amp's speaker output and the speaker or extension speaker cabinet, to reduce the power flowing from the former to the latter. Some amp makers have also added built-in attenuators to their amps in recent years.

What They Do

Universal Audio OX Amp Top Box Attenuator

Whatever its housing, an attenuator contains either resistive or reactive elements that "soak up" the amp's output power (something also known as a "load box") to reduce the level that is passed on to the speaker, usually by increments selectable by the player via notched switches or rotary dials.

Given the size of the components necessary to achieve this (which also can produce a lot of heat while absorbing your amp's wattage), these are heavier and more cumbersome solutions than the simple master volume. But many players prefer output attenuators because they move the level-clamping potential two stages further along in the amp: since the unit is plugged in between the amp's output and the speaker, it's also receiving (and reducing) the sound of the output tubes and the output transformer alike.

Popular Examples

Prices of output attenuators vary widely, depending on the cost of components inside and the complexity of the design. Simple resistive units like the Weber Mass and Dr. Z Air Brake and Brakelite won't break the bank cost-wise and have satisfied plenty of discerning players.

More complex reactive units like the Rivera Rock Crusher or Universal Audio OX Box use elements that purport to interact with your amp the way an actual speaker does, and are more expensive as a result. (Note that these also contain a lot of other "quietly cranked" solutions within the same box, which will be covered again in the Speaker Emulators section below).

The Drawbacks

While they have proved one of the more satisfying products for many players, attenuators still have their detractors. Simple criticisms include that they can be big and heavy and require you to carry yet another thing to the gig. The more complex units can also be expensive. Sound-wise, many attenuators—however good they might be—will still leave your amp sounding a little fizzy and choked if used to extremes. And often, even when used only to notch off a few decibels, they can add some darkness and compression to your tone.

Re-Amping Units

Like the attenuator, the reamper is connected between your amp's output and your speaker or cab and in that sense they can perform some of the same functions, although they are constructed quite differently. Newer to the game, relatively speaking, and fairly popular in recent years, the reamper is actually two (and sometimes more) solutions housed in one box, to the end of transparently clamping off your amp's full output power, and converting it into something less—and easily controllable. These are also relatively big and somewhat heavy devices, and they require AC power to function.

What They Do

Bad Cat Unleash V2 Re-Amplifier / Attenuator

Think of a reamper as a load box (as contained in an attenuator) set to one fixed level of full attenuation, and a power amp contained in one unit. The device receives your amp's output and fully clamps it down in the load box, where it derives from it a line-level signal (much like an amp's DI output) which it sends along to its internal power amp. The power amp then sends a signal to the unit's speaker output—with volume/level and tone controls for the user interface—which can be dialed in for a wide range of volume levels.

In addition to reducing an amp's natural volume level (which is often their primary purpose), most reampers can also increase it, being used, conversely, to make a small, low-powered amp louder, for example. Since they are converting a high-wattage speaker signal to a low-voltage line level signal, these units are also capable of including effects loops, which standard power attenuators cannot.

Popular Examples

Released in 2012 and more recently updated in an updated V2 edition, the Bad Cat Unleash is a simple but effective reamper with the functions described above (achieved via a solid-state Class D power amp capable of a 100 watt output), along with two footswitchable output levels and an effects loop. A bigger, heavier, and a little more expensive option—but one that has been extremely popular in recent years—the Fryette Power Station couples a quality reactive load with a 60-watt tube power amp, along with an effects loop and other useful functions such as a line in and DI out.

The Drawbacks

Since they derive their initial attenuation from an internal load box, reampers can get some of the same accusations as those leveled at passive output attenuators: fizzy overdrive tones when used at extremely low volumes and some sonic artifacts regarding compression and dynamics. Some players balk at the prices, others at the notion of using an external amplifier to control the volume of their primary amplifier (along with the heat and extra power consumption involved).

Speaker Cabinet Emulators/Simulators

Although viable professional speaker emulators (also called "simulators" and "cab emulators") have been around since the late '80s, this category has really come into its own in just the past few years. Combining elements of the output attenuator and reamper discussed above, the speaker emulator clamps your amp's output, and injects it into an additional circuit that emulates the sound of a speaker cabinet to send to the house PA and stage monitors, or direct into a recording setup in the studio. The benefits are that you can get the sound of a classic speaker cab—from small combo, to full stack—without lugging the thing around, and that this can be reproduced at any desired volume, with consistent sonic results.

What They Do

Mesa Boogie Cabclone 8 ohm Speaker Cabinet Simulator

Although some speaker emulators are separate units unto themselves, most contain some form of internal load box which functions much as that in the reamper above. This load box receives your amp's full-power speaker output and taps it off to a line-level signal that feeds the speaker-emulation circuit. That's where things can be done very differently: Some units use an analog filter network to simulate the sound of a speaker cabinet, while others carry advanced digital emulations derived either from complex reactive modeling (much like that used in modeling-amp technology), or from impulse responses (IRs) created by recording actual speaker cabinets. Note that these devices require an external power amp and speaker (such as a PA system) to reproduce the speaker-emulated signal.

Popular Examples

German company Palmer kicked off this category in 1989 with the PDI-03 Speaker Simulator, which offers very convincing analog emulations that countless pros have put to use. Smaller modern units like the Mesa Boogie Cab Clone and bigger, like the Rivera Rock Crusher (which also includes an output attenuator to send a reduced signal to a standard guitar cab) have used similar analog technology.

The Torpedo Studio and Torpedo Live from French company Two Notes include digital emulations based on IRs to reproduce the sounds of hundreds of classic speaker cabs, and they've been very popular with professionals for the past several years.

Newer to the category, but winning fans fast, Universal Audio's OX Box incorporates that company's acclaimed approach to studio software plugins to create reactive-modeling digital cab emulations, along with studio-quality compressors, delays, and reverbs, plus a six-step attenuator that can also be routed to your traditional "live" guitar cab.

The Drawbacks

The better speaker emulators are expensive (as in, more than $1,000 USD new), and most require the help of an external amplification system, so some players might feel they're only part of the solution.

Voltage Regulators

Several engineers have designed roughly similar systems that provide an alternative master volume of sorts by regulating the internal voltages within a guitar amplifier to naturally "dial down" the overall output level. These are internal solutions that are either built into an amp to begin with or that can be added to an existing circuit by a qualified tech.

What They Do

65 Amps Tupelo 20-Watt

Voltage regulators (also called "power scaling," "master voltage," and "xxx") are achieved via a network of components within the amp's power supply, governed by a potentiometer that allows the player to reduce the DC voltages that feed the tubes. These components are responsible for how efficiently they operate and, therefore, how much they amplify the guitar signal that passes through them. Some such systems operate exclusively on the output stage, while others operate on the output and preamp stages alike. Fans of this solution uphold that it provides a natural-sounding way of reducing your volume level, since you aren't changing the gain and tone settings by some external means, only reducing the amount of amplification that the tubes deliver.

Popular Examples

Perhaps the best-known version of the voltage-regulator circuit is that devised by Kevin O'Connor of Canadian company London Power, a system he dubs Power Scaling, and which involves adding a comprehensive internal voltage regulator to almost any existing tube amp circuit. Other popular types are those included as factory-standard equipment in the amps from several specific manufactures, such as Suhr, Mojave, 65 Amps, Morgan, and others.

The Drawbacks

While many such systems can indeed provide significant volume reduction while retaining a reasonably accurate rendition of your fully cranked tone, most do also introduce some artifacts, which are often felt as much as heard. These include added compression and a sort of "looseness" to the playing feel, and they are frequently heard, too, in a softer, spongier, less articulate sound from the amp. Also, the addition of any such system to an amp that doesn't already have it requires and invasive procedure to which some players might object.

Iso Cabs

This rather obvious solution has been with us for several decades, both as a manufactured product, and as a popular DIY project. The principle behind the iso cab (short for "isolation") is simple: Stick a speaker in an enclosed, soundproof box, put a microphone in there with it, and you can play as loud as you like—with no artificial attenuation between amp and speaker—while governing your in-house volume levels precisely via the PA and monitor system or into your recording interface.

What They Do

Randall USM-ISO12C 60-Watt Isolation Cabinet

Loud speaker... In a box... You can't hear it, but if you put a mic in with it then you can. That pretty much covers it. See above.

Popular Examples

Amp maker Randall was an early proponent of the commercial iso cab, and they still have the Isolation 12 on the market. Jet City offers the very affordable Jetstream Iso U cabinet, and Rivera offers the very well-engineered Silent Sister. Amp maker Morgan also has an entrant to the market in the form of the Chameleon convertible isolation/extension cabinet. The principle behind all is roughly the same, although they differ according to the number and types of inputs and outputs provided, and—more crucially—to the engineering that has gone into the effort to keep them sounding natural and in-the-room-like.

The Drawbacks

Detractors say that the mic'd-up sound of a speaker within an iso cab can often be compressed, dark, and overly boomy, because there isn't enough air space within to let the speaker react naturally, and for the soundwaves to travel naturally as they would in a larger room. That can certainly be the case with poorly (or indifferently) designed units, but makers of the more complex cabs have put a lot of thought and engineering into re-creating a room-like sonic space in a smaller environment. In addition, of course, many are heavy and cumbersome, but they might supplant a traditional extension cab, so it's often six of one, half a dozen of the other.

The Plexi Shield

And the simplest way of reducing the eardrum-piercing sound of a loud guitar amp on stage? Block it with something, of course. Engineers have long created such baffles (often called "gobos") in the studio to help isolate one instrument from another, and the procedure has often been taken to the stage with the use of folding Plexiglas isolation shields, which help to rein in the direct projection of specific sound sources, without entirely cutting off the visual element of the instrument or amplifier in question.

What They Do

ClearSonic Plexi Shield

Such shields are most commonly made from clear Plexiglas panels—generally at least three, of the required size—which are joined together with hinges. This configuration allows them to be self-standing in front of the amplifier when correctly angled and to be folded flat for easy transportation. In most situations, the amp or cab positioned behind the shield is mic'd and then re-amplified through the PA. Such shields are good for taming the directionality of an amp (to avoid that "taking the heads off the audience in the front row" phenomenon, for example) and will also somewhat reduce the overall perceived volume in front of the stage, but another of their primary use is for isolating amps and instruments on stage from bleeding into each other's mics, rather than purely for volume reduction.

Popular Examples

ClearSonic is likely the best-known name in such products, and they make folding shields suitable to all sizes of guitar amplifiers, as well as drums, entire vocal isolation booths, and more. Control Acoustics offers some relatively affordable solutions, as do other companies from time to time, and guitarists have also made their own.

The Drawbacks

As in the "what they do" section above, these aren't purely volume-reduction devices, although they can help contribute to such solutions when used carefully, and without lofty expectations. They don't dramatically decrease the overall ambient stage volume (since the volume is still there, it is just being blocked and deflected), and they can sometimes create odd and undesirable reflected sounds from the amp-side of the shield.


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