Two Notes Torpedo Reload

Could the Two Notes Reload be the last word in studio guitar amplification?

The best amp and cab simulators are pretty much sonically indistinguishable from the real thing, but most attempts to replicate the unique interaction between guitarist, guitar, amp and speaker that defines the physical experience of playing have been less successful. Two Notes Audio Engineering are specialists in overcoming this obstacle through hybrid hardware/software products — and their Torpedo range of amp, cab and mic simulators has dug a few deep holes in my wallet already!

Given the hybrid approach, smaller spin-off devices were almost inevitable. First came the Torpedo Wall Of Sound, a power amp, cab and mic plug-in for Mac and Windows, now in its third generation. More recently, the Torpedo CAB put their amp and cab sims in a software-programmable stompbox. Their latest product is the Torpedo Reload active attenuator, which combines the company’s Re-Act resistive/reactive multi-impedance load and attenuator (developed for the Torpedo Live) with a power amp, a load-box output, an instrument DI and a re-amp loop. While the Reload is a hardware device, it comes with a ‘lite’ yet very capable version of the Wall Of Sound III plug-in. This offers 24 cabinet simulations, and more can be purchased from Two Notes’ online store.

Overview

The Reload’s impressive weight is thanks to the chunky toroidal mains transformer, a pair of hefty heatsinks, the thick brushed-metal fascia and the solid steel casing. An optional rackmounting kit is available. Simple controls and indicators occupy about 60 percent of the front panel. In the lower section there’s a power switch, the instrument input to the DI, the controls for Replay, Speaker and Contour, and a switchable 15dB pad that acts on the output of the Re-Act Loadbox. The upper section has LED indicators for the chosen ioad impedance, signal/clip levels for the instrument in, replay and speaker inputs, and the status of the Match function, which allows you to ensure a guitar-level signal is sent to any connected amp.

A slotted aperture, through which a large, rear-mounted and commendably silent exhaust fan pulls cooling air over the Reload’s internal heatsinks, occupies the remaining panel space. Since I’m no fan of internal dust build-up, I’m a little concerned that there’s no facility to fit a filter to this inlet.

A large fan is joined on the rear panel by jacks for the switchable 4/8/16 Ω speaker in (from your amp) and two speaker outs (to your cabs), the balanced XLR connectors for the Loadbox and DI output, and the Replay facility’s balanced TRS line in and unbalanced TS amp out jacks. The two XLR outputs and TRS line input are each equipped with ground-lift switches. The analogue power supply is fed via a fused single-voltage IEC connector — the European review model was set to 230V.

Active Reactive

To understand how this device mimics the behaviour of a loudspeaker, it’s important that you understand something about the nature of impedance — I’ll try to keep it brief! Impedance is the measurement of how much a device ‘impedes’ the flow of alternating current (AC), such as an audio signal, passing through it, and it is affected by both electrical and mechanical factors. Like resistance (to direct current), impedance is expressed in Ohms (Ω). However, unlike resistance, impedance varies with frequency, and the extent to which it does so is what we term reactance.

A loudspeaker is a highly reactive device, because its impedance varies significantly in accordance with the frequency of the signal delivered to it by an amp. The impedance of a nominally 8Ω loudspeaker may reach a peak of 40-50 Ω at its resonant frequency (typically around 100Hz), which will then drop to the rated impedance at between 400-600 Hz before rising in a relatively smooth arc (due to increasing inductive reactance) to perhaps 30Ω at 20kHz. However, its resistance will remain constant at approximately 6Ω throughout.

This changing impedance affects solid-state and valve amplifiers differently. In very simplistic terms, the power output of a solid-state amp decreases as the loudspeaker’s impedance increases, but for a valve amp the situation is more complex, as it will attempt to deliver a constant current to its output transformer’s secondary winding. As a result, the power output of a valve amp increases as the loudspeaker’s impedance increases. It’s this interaction between a valve amp and the impedance curve of the loudspeaker connected to it that determines the tone and dynamics of the sound produced — this is why your choice of loudspeaker (not forgetting the cabinet in which it’s mounted) can have such a profound effect on your experience as a player.

Although a valve amp sounds best when it’s being worked hard, volume level issues, in domestic and gig settings, led to the development of variable ‘passive resistive’ attenuators. These designs employ simple resistors to provide the necessary load — resistors have a very low reactance, so although they’re effective at reducing the volume to zero if required, they also affect the interaction between valve amp and loudspeaker, and therefore the playing experience.

To obtain more realistic results, manufacturers began developing passive attenuators (often incorporating a DI output) that combined reactive and resistive loads, in order to mimic loudspeaker impedance curves while providing adequate attenuation. Some manufacturers included an actual loudspeaker voice coil or even a lightbulb as part of the reactive load, whilst others added EQ and filters to the DI output, to approximate either generic loudspeaker cabinets or a more specific combination of loudspeaker and cabinet (and sometimes even the microphone too).

The Torpedo Reload follows a more recent trend towards ‘active’ attenuators, in which the output of the valve amp is terminated by a reactive/resistive load, and a sample of that signal is sent to an internal power amp that drives a speaker cabinet. The advantage is that the valve amp drives into a consistent impedance curve, but the disadvantage is that the cabinet is isolated from the amp and therefore the individual interaction between amp and cab is lost. But the benefit of a consistent impedance curve for the amp to drive into is much more preferable than the negative effects of a passive attenuating resistance.

In Practice

You can treat the Torpedo Reload hardware very successfully as four separate sections — speaker attenuator, load, DI and re-amp loop — but in tandem with the Wall Of Sound III plug-in, it’s a powerful and flexible front end.

In its role as a valve-amp attenuator, the three impedance settings (4/8/16 Ω) allow you to match the Reload to your amp and, should you wish, you can plug any combination of cabinet impedances into the two speaker output jacks, as long as the resulting impedance is no less than 4Ω. The speaker input will accept amps rated at up to 150W, so there’s the potential to clip the feed from the load to the internal amplifier and Loadbox, and this can be monitored on the speaker section’s front-panel LED. The Speaker knob sets the output level of the 70W into 4Ω internal amp, which then feeds the Contour stage that acts as a variable loudness control. This last control can be used not only to compensate for our perception of low and high frequencies at lower volume levels, but also for creative effect: the Vintage side of the dial moves towards a mid-range tonality, with a lot of presence, while the Modern side gives the boosted treble and bass (or scooped-mid) guitar tones that are beloved of those playing in heavier musical genres.

The input to the Loadbox is taken from the same point as that of the power amp, and the signal is then balanced and travels directly to the balanced XLR Loadbox output, to give you a dry sampling of your amp’s output as it drives into the Reload’s Ra-Act reactive/resistive load. This can be sent to an effects unit, audio interface or PA system or some such device.

The signal from the front-panel instrument input passes directly to the balanced XLR DI output, and its only internal interaction is with the Replay section’s Match facility, where the instrument input acts as the reference level for the outgoing re-amp signal. The Replay section itself is simply a balanced line-level TRS input that’s then unbalanced and attenuated before being level-matched with the instrument input via the Replay control and sent to the amp output TS jack.

The Torpedo Reload can accommodate any combination of speaker cabinets, down to a minimum combined impedance of 4Ω.

The various inputs and outputs make the Reload an attractive proposition for a studio setup, since you could plug a guitar (or bass), with or without a preamplifier, into the instrument input, feed the DI output into the Replay’s line in, feed the amp out to your amplifier, plug your amplifier into the Reload’s speaker input, connect a cab to the speaker out and mic that, then run the Loadbox output to your DAW. I feel that Two Notes have missed a trick, though, in not including the possibility of simultaneously feeding the DI output and the Replay input from the instrument input — that would enable you simultaneously to record a completely dry guitar signal for re-amping, plus the Loadbox output and the miked cabinet. That said, you could split the DI output to get there.

With the Loadbox and/or DI guitar signals routed to your DAW, the Wall Of Sound III plug-in comes into play. This version provides simulations of single-ended Class-A and push-pull Class-A/B power amplifiers, each with a choice of 6L6, EL34, EL84 or KT88 output valves (a total of eight overall), 16 guitar cabs, eight bass cabs, a mix of six dynamic, condenser and ribbon guitar-cab mics, plus two bass-cab mics. The thinly disguised names hint heavily at the originals and, as I mentioned, you can purchase others should you wish. You may also load your own (or third-party) impulse responses.

The plug-in provides two parallel audio paths that can be configured as stereo, mono-to-stereo, or mono-to-mono, and thus allows you to choose either two identical or different combinations of power amp, speaker and mic. Having chosen your power amps (which you’d possibly want to turn off if you were using the Loadbox output), cabs and mics, you can position the mic inside a virtual room to taste. You might, for example, choose to use the same cab in either channel with a close, off-axis dynamic mic on one and a condenser slightly further back on the other. You can then refine the sound in each path using the low-cut filter, five-band EQ (with switchable centre frequencies for guitar and bass), exciter and compressor. If your computer and DAW can handle it, you can run up to 50 of these parallel pathways, giving you the option of building a 100-speaker wall — with a bit of luck you might well manage to recreate the sound of the Grateful Dead’s original Wall of Sound PA rig!

Loads Of Performance

As an attenuator, the Reload is impressive, producing consistent feel, tone and dynamics into my 1x12 and 2x12 cabinets throughout the volume range, as you might expect given its active attenuation approach. I felt much more comfortable playing through the Reload than with my original Torpedo VB-101 or the other purely resistive attenuators that I own.

Playing my 1964 Vox AC50 through my studio monitors via the Loadbox output sounded and felt more realistic than I’m used to experiencing, and compared very favourably with the feel I get from my miked-up silent cabinet. Driving that cabinet from the Reload, slightly tweaked in the Vintage direction by the Contour control, and mixing the result in with the Loadbox output produced great results. I could push the silent cab hard to get a bit of speaker break up, whilst keeping the AC50 held back to avoid any nasty incidents (such as the one that cost me my original Mullard rectifier and output valves...). With the 1x12 miked up and added to the mix, I felt in a really good place playing-wise, in terms of both sound and feel.

Setting the Reload up to re-amp a straight DI guitar track from my DAW was extremely simple, courtesy of the Match facility. Feeding the amp out re-amp signal into my Ethos Overdrive preamp pedal and back into the Wall Of Sound plug-in gave me access to all that program’s power amps, cabs and mics; it didn’t take me long to find sounds I was more than happy with. And that was before I ran those in combination with a Loadbox track and the miked silent cab!

Fully Loaded?

The Torpedo Reload produces an extremely close approximation of the sound and feel of playing an electric guitar through a hard-driven valve amplifier at a heavily attenuated loudspeaker level. It is the first speaker attenuator to get me excited about playing through it, and that would be more than enough to justify its asking price, even if the Reload were just an attenuator. But the Loadbox output, DI, re-amping facility and bundled software open up a whole range of possibilities, on stage and in the studio. What’s not to like?