One of the side benefits of the widespread use of in-ear monitoring is that stage volume for many acts has dropped significantly. A sort of domino effect resulting from this phenomenon has been that — as there are few or no wedges on stage — the need for high-volume guitar and bass rigs has decreased. Of course, there will always be musicians who want two Marshall double-stacks barking at maximum volume, but the presence of loud guitar and bass rigs is in fact counterproductive to using IEMs, because the ability of earpieces to reject stage sound can only go so far.
Many guitar and bass players have sought alternatives to traditional amp rigs, experimenting with setups that produce little or no stage volume. The quandary is in the player’s ability to reduce volume without sacrificing tone. This time out, we’re talking about alternatives that don’t require the traditional speaker cabinet blasting in the face of the audience and the FOH engineer. Let’s take a look at speaker load boxes and speaker cabinet simulators.
Amplifier Loading
You can’t run a guitar or bass amp without connecting a load. A load is something that draws power or requires electricity to do work, in this case the loudspeaker(s). In theory you could disconnect the speaker from a guitar amp and replace it with a DI box, but that creates two issues. First, the power output from a guitar or bass amp is probably sufficient to smoke the components in a DI. Second, amps (in particular tube amps) won’t deliver their best tone and could be damaged when connected to an improper load. So a “normal” DI connected to the amp’s output is probably a no-no.
Any guitar player will tell you that the tone of their amp depends upon its interaction with the speakers. Many amps have a “sweet spot” where they react with the speakers to produce optimal tone (thus the description of a speaker as a reactive load). In some cases, that sweet spot is loud enough to blow back your hair, so the trick is to get the amp to the sweet spot without damaging the hearing of small animals that might live nearby. This is typically done by connecting a load box, or “power soak,” between the output of the amp and input to the speaker cabinet. As the name implies, a power soak absorbs power from the amp and turns it into heat, enabling you to crank the amp to the sweet spot while not blowing all that sugar into your eardrums and your neighbor’s yard. A power attenuator is not intended to replace the loudspeakers in a guitar rig. Its purpose is to allow the guitarist to run the amp at settings that yield the desired tone while reducing volume. In a live situation, you’d still need to place a mic on the (now very quiet) speaker cab.
The natural evolution of the power attenuator is the speaker simulator. This enables the amp to remain connected to a proper load while producing absolutely no acoustic output; the signal is patched directly to the mixing console. This concept is life-changing for both FOH and monitor engineers. Executed properly, speaker simulation keeps musicians happy by getting their tone, keeps the amplifier happy by tricking it into thinking it’s connected to a reactive load, and keeps the engineers happy because they no longer have to deal with loud amps on the deck.
Problems Caused by Loud Stage Amps
In order to build a mix in a small venue, the FOH engineer must run the P.A. system louder than the on-stage volume. This can be uncomfortable for the engineer and the audience — especially since the typical 4×12 speaker cab is very directional. People sitting or standing in front of a guitar player’s cabinet will hear it fine while people on the other side of the stage may not hear it at all.
The need to overcome stage volume can be a big issue in casinos where stage sound may spill into gambling areas (no one wants to miss the sound of a croupier taking their money), or there may be patrons who are not there for the music, or there may be strict SPL limits.
Spill from the stage is often out-of-phase with sound from the P.A. system (see last month’s column).
Loud amps — especially bass rigs — produce significant spill into other microphones. Guitar and bass players who sing may notice that their amps get louder in their monitors when they move away from their vocal mics. The FOH engineer may notice the same thing in the house mix.
Musicians may have trouble discerning parts when the stage is awash in sound.
Speaker simulators solve all of these issues and come in various shapes, sizes and prices. Connecting a speaker simulator is relatively simple, but you do need to pay attention to a few details. Some simulators such as the Palmer PDI-03 are manufactured in impedance-specific versions. Others, such as the Sequis Single Channel Motherload, are intended for use specifically at one fixed impedance (typically 8 ohms). Two Notes’ Torpedo Reload has user-adjustable impedance settings.
All of these devices take signal from the amplifier, do their emulation magic, and output a low-level signal for direct connection to the mixing console. A bit of homework may be needed to determine the nature of the output signal. The Motherload provides XLR and TRS balanced outputs at line level while the Palmer PDI-03 outputs at mic level. We use Two Notes Torpedo Live in Buck Dharma’s guitar rig for BÖC shows. Output of the Torpedo Live is patched to a DI, which feeds the mic input to a mixing console. Not all speaker simulators are designed for connection to the output of an amp. The GCS-2 from ADA (adaamps.com) operates more like a DI box, taking the signal from a guitar preamp and providing a balanced XLR output that can be switched between line or mic level.
There are key features to look for that can be invaluable. First and foremost, the guitar player needs a variety of cabinets emulations. Typical options include modern versus vintage speaker tones, a variety of speaker sizes, open- or closed-back cabinets, EQ, mic selection, and microphone distance and angle. From a practical standpoint, a ground lift switch is a must, and a level control for the simulated output can be handy in helping the unit play in the sandbox nicely with a wide variety of DIs and mixing desks. A line output can be useful for situations where you might want to record a direct feed to a DAW as-is or for later reamping. Emulators that employ modeling or convolution techniques should provide USB ports so that you can upload new cabinet simulations or firmware updates as they become available.
A speaker “thru” jack facilitates temporary connection of an onstage cabinet so that players can tweak their sound — particularly useful at the start of sound check when their in-ear mix may not yet be ready. When the ear mix is up, the cab can be disconnected, rendering the stage silent once again. Beware that some simulators will disconnect the internal load circuitry when a TS plug is inserted in the thru jack. If you operate the guitar amp with one end of a speaker cable connected to the simulator and the other end disconnected from the speaker cabinet, the amp will be operating without a load and may suffer damage.
The front few rows of audience will no longer be hearing the direct sound from a guitar or bass amp blowing in their face so it’d probably be a smart move to run a front fill where you can dial in some guitar and perhaps vocals if needed. I’ll usually set up a post-fader aux send for front fill, place the fill speakers along the downstage edge, and feed in the vocals and guitars, plus maybe a bit of effects so that the premium seats don’t get cheated. This is less of an issue with bass because low frequencies tend to be much less directional.
