Bassic Review – Quilter Labs InterBass Pedalboard Preamp/Amp

Amplifiers are required to produce DOUBLE their wattage for a modest 3 decibel volume increase. To demonstrate in reverse, a 1,000 peak watt amp may put out that much wattage in a short burst with the volume all the way up, but back off the SPL a mere 3 dB, and now the amp is only producing 500 watts – at just a slight volume decrease from max. Back off another 3 dB and you’re at 250 watts. Six more dB and you’re at around a 62-watt output, but at only 12 decibels lower than the max volume of that 1 kW behemoth. So, if you don’t need to play extremely loudly, and you have a good number of speakers with which to push air and increase perceived volume, 45 watts doesn’t look or sound too shabby.

The Inter-View

The InterBass is built to survive, featuring a solid, rolled-metal casing, in a footprint comparable with the MXR Bass DI. It does utilize and ship with a very hefty 3 Amp (24V) power supply that you don’t want to confuse with any of your others, so it won’t run off your paltry +9v DC pedalboard supply. But at least the proprietary PSU is supplied with the pre/amp at purchase, and isn’t likely to be confused visually with your others. One interesting choice regarding the system’s power management is that Quilter didn’t include an on/off switch; the amplifier’s output is active whenever the PSU is plugged in and powered. This seemed a bit odd and detrimental at first, but I have to admit, I didn’t necessarily miss a power switch in practice, turning the Master volume down each time before plugging/unplugging the unit.

A basic 3-way EQ section is provided with a fun, colloquial naming scheme per frequency band, but I would have liked to see the 1kHz Snap control centered about two to three octaves higher. [Editor’s Note: according to Pat Quilter, the Snap control is a high-frequency shelfing filter, so it’s not really “centered” on anything; in fact, the hinge point is an octave lower than usual at about 500Hz, so the “action” tends to occur at 1kHz and above] The EQ section sounded very usable at all settings through my reference Genzler Amplification, relatively flat-response speaker cabinets (both the Bass Array type, one employing a single main 12″ and the other two 10″s). A cabinet emulation voicing is also available via the FR / Vint switch when set to the Vint side, which – not surprisingly – seems to produce a vaguely SansAmp-ish, Ampeg fridge kind of vibe, if you’re going direct. An Active/Passive switch is also offered to optimize your input level.

Focusing on the direct out signal, it’s a bit disappointing that an industry standard balanced XLR type output was not provided on the InterBass. However, a balanced quarter inch output is included, and it is switchable between a headphone-appropriate level and DI signal for when you’d prefer to play silently with ‘phones. Other outputs comprise the Effects Loop’s send and return. As you may or may not expect from a pedal/amp of this size (if it’s possible to have many expectations at all from such a new class of bass gear), Quilter decided to forego Speakon outputs in favor of a ¼” speaker output. This almost caused a problem for me – in a demonstration of rapidly changing industry norms, I realized it had been many years since I needed to use a ¼” speaker cable for my own gear and needed to do a bit of searching for one still in good shape. I’m glad I still had one – my last! So not quite the seamless integration with my existing, regularly used gear that I had at first assumed the Interbass would be, but also not a deal-breaker by any means.

InterBass in Action

“But really, Sean, how can 45 measly watts really sound, especially when I’m used to playing an 800-1,000w bass head?” Well, my fellow bass amp stat cork sniffer, a whole lot better than I’d expected! The wattage breakdown is 45w at 4 Ohms, 33w at 8 Ohms, and 17w at 16 Ohms. Bass cabs and bass cab hookup scenarios don’t often come in 16-Ohm variants these days, so that may show a touch of naiveté on behalf of the manufacturer for the bass market (a 16-Ohm total impedance is much more common in the guitar world), but that’s not of much consequence. The fact is, if you have a few speakers to push the full 45 watts through at a 4-Ohm total load – and even if you have a very efficient single 8-Ohm cab – this thing gets surprisingly loud. But not just loud in a cheap ploy of manipulated wattage for sheer volume’s sake at any tonal cost – it gets super deep, too! The InterBass sounds indistinguishable from a typical, modern bass amp, right up to its max output, and does it in an ultimately useful, heavy hitting manner. It sounds like a bass amp! Even without much preamp coaxing. I’ve been fortunate to play a lot of interesting and surprising bass gear toys and tools over the years, but this one frankly has surprised me, and in the best possible way.

In my estimation, the InterBass is cleared for up to medium-sized performances when used with enough speaker cones moving enough cubic inches of air (or very high efficiency/Xmax drivers). If Quilter were to find a way to bump the pedalboard-friendly amp up to 200 watts (roughly adding another 6 dB of additional volume), it might even compete for large format gigs! Although I’m not privy to what (if anything) Quilter does on the DSP side, I’m tempted to believe there’s some pretty well-executed and potentially judicious application of limiting and parallel compression to achieve such impressive output from such low wattage (the TC Electronics RH750 amp comes to mind). [Editor’s Note: the InterBass is all analog, no DSP is involved; according to Pat Quilter, we may refer to this as “ASP” (analog signal processing), and there is a “virtual subwoofer” being controlled by the Depth knob] If that output could be quadrupled – which in this technological space is not an outlandish idea – the InterBass may actually start replacing full-fledged, cabinet-topping amp heads.

The Bottom Line

As the product currently stands, I find it more of a travel, “small gig” alternative, or lower stakes power supplier in comparison with a concert grade amp head. Still, the InterBass serves as a highly useful tool and an incredible proof of concept item. Expect to be seeing more of this sort of thing, from Quilter and likely others as well, until perhaps cabinet-specific, integrated amps and DSP profiles are found married to a majority of our bass and guitar speaker cabinets … if we can ever deal with that kind of change! Until then, pedalboard users can potentially cross one major item off their gigging gear inventory list, opting to leave that old-fashioned amp head at home.