The speaker in a guitar amp doesn't just reproduce that amplifier's tone. Its tonal characteristics and limited frequency range make it an integral part of the sound. The interdependence of amplifier and speaker is what makes it difficult to simulate a guitar cabinet.
FIG. 1: For those recording with instrument amplifiers, the Sequis Motherload offers speaker simulation, speaker load, and attenuation functions.
Sequis successfully takes on the challenge of cabinet simulation — and more — with its Motherload device (see Fig. 1). The 1U unit has three main functions. The first is as a speaker simulator. In the studio, you can patch it in after your amp or modeling processor and record direct with an authentic speaker sound.
The second function is as a speaker load (aka “dummy load”), letting you run your amp safely with no speaker plugged in. In a DI-recording scenario, it lets you run your guitar through your amp's circuitry, into the Motherload's speaker simulator, and then into the multitrack, without any sound coming from your speakers.
The Motherload's third main function is as an attenuator. It lets you crank your amp (and get the sweet tone that often comes from doing so — especially with a tube amp), yet send a fraction of its normal output to the speakers. As a result, you can get ultimate tone for miking without blowing the walls out. The Motherload can also work in tandem with Sequis's standalone attenuator, the Richter Control (see the sidebar “On the Richter Scale”).
Although the Motherload's primary application is to work in conjunction with electric guitar or bass amplifiers and hardware modelers, the company stresses that its filters sound great with acoustic-electric guitars, synthesizers, organs, loops, and so on.
A Load of Options
On the right of the rear panel (see Fig. 2) is the Input/8 Ohm Load jack, where you plug in the speaker output of your amp. From there, it feeds the Motherload's line-level speaker simulator. If you also want your amp's signal to continue unmolested to your speaker cabinet, you can use the provided Thru Out. If you use the Thru Out, your amp and speaker cabinet must have impedances that match each other, or you risk blowing an output transformer.
FIG. 2: In addition to all of the unit''s I/O, the rear panel of the Motherload also features a volume knob that adjusts the output of the attenuator.
If you want to attenuate the signal going to your speaker cabinet, you can feed your cab with the Attenuator output rather than the Thru Out. The Attenuator output is rated at 8Ω, with a maximum power-handling capability of 100W RMS.
Keep in mind that a 4Ω speaker cabinet will double the perceived volume and load on the Motherload. That means you won't be able to turn the volume up past 50W, or you'll risk overloading the Motherload. A 16Ω amp's speaker output will be overloaded by the Motherload's 8Ω input, which may damage the amp, the Motherload, or both. A 16Ω speaker cabinet may be used with the Motherload's 8Ω speaker output without worry, but it will seem quieter.
The rear panel also includes a volume knob to adjust the Attenuator output's signal to any value between 0 and 2.5 percent of your amp's normal output. This is probably the most useful volume range for the personal-studio recordist. For stage use, you might want a cranked amp sound with just a small amount of attenuation. I would have liked to have seen a larger range of attenuation options. The minimum attenuation is 97.5 percent.
Tapping the Load
The Motherload includes a line-level Send and a jack called Return/Line In. You can use these to connect a line-level effects device or processor between your amplifier and the speaker simulator. You can also use the Return/Line In for the Richter Control, or to insert a line-level signal from a synthesizer or amp modeler. You could even use it to patch in the line-level output from your audio interface in order to access the Motherload's filter-compensated outputs. It is that filter that shapes the amplifier's direct tone to sound like it's coming through a speaker cabinet.
The impedance of the Send is 150Ω, while the Return/Line In impedance is 2 kΩ. Depending on the impedance of your line-level device, you may need to use a direct box to properly match it.
The Motherload offers both balanced XLR and balanced TRS line outputs. You can adjust the level of the XLR output from the Line Out knob on the front panel. The full XLR level is approximately -18 dB, dependent on control settings. You cannot adjust the level of the TRS line output, but its signal is about 10 dB hotter than that at the XLR. I found that when recording with the Motherload, I got the best results using the XLR input into my audio interface and setting my interface's input level to -10 dB.
If you're getting hum through the balanced out from an unbalanced device such as an amp-modeling processor, the Motherload includes a stud for a chassis ground, and a 3-way ground switch. I didn't experience any hum at all, but Sequis claims that for those who do, these built-in countermeasures are successful in virtually every case.
Mother of All Filters
The Motherload's speaker simulator offers five presets intended to cover a variety of typical cabinet sounds. Presets 1 and 4 aim for a modern-rock sound; 2 and 3 for a more woody, Fender-style tone; and 5 for a more open, scooped sound.
Each preset has a miniscrew that trims the harmonics of its filter. I would have preferred small rotary knobs, but Sequis feels that screw shafts are more effective for preventing accidental adjustments. My favorite presets for high-gain sounds from my Randall RM100 and THD Flexi-50 amplifiers were 1 and 5, while I liked preset 4 for lower-gain playing.
The real fun is when you build your own custom simulation using all the Motherload's filter controls. Unfortunately, the terminology Sequis has used is more akin to that used with a synthesizer filter than anything a guitarist typically deals with.
The Filter knob offers five preconfigured settings to trim the harmonics. The resonance is controlled by two knobs: one for boosting and one for cutting. The higher the resonance, the more open the sound. The lower the resonance, the more closed or woody. I like the more open sound of high resonances. Keeping the resonance too low results in a rather muffled tone. Perhaps lower settings would work better with a bright amp.
The Mid Shift knob lets you adjust the midrange emphasis. Lower mid-shift settings sound good for capturing a woody, jazz- or blues-style cabinet sound. Higher mid-shift settings give you a brighter sound.
The Bass and Treble knobs adjust the lowest and highest frequencies that a typical guitar cabinet can reproduce. These tone controls let you tailor the overall sound of the simulated cabinet. The key to success with them is subtle settings. You don't need high Bass-control settings to achieve the Motherload's convincing and impressive emulation of the thump of a real speaker cabinet. If you set the Treble control too high, it can add unpleasant harmonics.
Hitting the Motherload
Overall, the Motherload has a lot to offer. It's versatile and it sounds great (see Web Clip 1). It's certainly not inexpensive, but considering that you get an attenuator, speaker load, and cabinet simulator in one package, it's an excellent value — especially when compared with buying separate components for each function.
Although the attenuation and speaker load features are easy to use and intuitive, grasping the parameters of the speaker simulator is not so simple. It doesn't help that the included documentation is scanty at best. Because of these factors, I gave the unit a low rating in the Ease of Use category. (According to Sequis, an expanded version of the manual will be available by the time you read this.)
If your aim is to get the best-sounding recorded tones you can, and you don't mind dealing with an interface that takes some effort to learn, you're sure to be satisfied with this product. I've tried most of the current crop of hardware and software speaker simulators, and the Motherload's simulation is among the best.
Orren Merton likes to simulate being a guitar player when he's not writing.
ON THE RICHTER SCALE
The Richter Control ($399; see Fig. A) is a dedicated attenuator that's similar to the one in the Motherload (the sound and controls are the same) but able to put out ten times as much volume. This makes it useful for a gigging situation in which you want to crank a really loud amp while keeping your stage volume under control. The unit's minimum attenuation is 70 percent, which might not leave you enough volume on a large or loud stage.
Caption goes here
The Richter Control's line-output impedance and signal level are an exact match for the Motherload's line in. So if you want to have an attenuator box near your amp, and a Motherload at a distant mixing board or studio control room (to be controlled by an engineer), you could connect the two Sequis units directly and they'd be a perfect sonic and electrical match.
To me, the Richter Control is not that compelling as a standalone attenuator. It doesn't allow for light attenuation, nor does it have an adjustable line out like the less expensive THD Hot Plate, or a variable impedance switch like the less expensive Weber Mass. However, if you need a separate attenuator to use in conjunction with the Motherload, the Richter Control is the logical choice.
PROS: Excellent sound quality. Speaker load for silent recording. Highly configurable. Five presets with adjustable filter settings. Send/return loop. Chassis ground and lift. Balanced XLR and TRS simulator outputs.
CONS: Complicated interface and inadequate documentation. Limited attenuation range. No level adjustment for TRS output.
EASE OF USE
Sequis/Motherload USA (distributor)
Amplifier Input (1) ¼" TS speaker cable Attenuator Output (1) ¼" TS speaker cable Return/Line In (1) ¼" TS; 2 kΩ; 2-24.5V Send (1) ¼" TS; 150Ω 0-2V Speaker Simulated Outputs (1) balanced XLR, (1) balanced ¼" TRS Maximum Input Wattage 100W RMS at 8Ω Maximum Attenuator Output 2.5W RMS at 8Ω Dimensions 19" (W) × 1.7" (H) × 11.4" (D) Weight 12.1 lbs.