Arsenal Audio by API R24 V14 and R20

Arsenal Audio provides reasonably priced, yet “fantastic” mic preamp and EQ modules.
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The Arsenal Audio line provides a sonically creative outlet for API’s design team to innovate and expand beyond their deep roots with 2520 discrete op-amp based products. Each unit is hand-assembled and designed to provide years of greatsounding analog audio performance at a surprisingly reasonable price.

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Features—R24 and V14

Although quite rare today, American based APSI manufactured consoles and equalizers were built during the late 1970’s and early 1980’s. The APSI 562 was a 4-band parametric EQ that was manufactured by APSI, but distributed through API. The R24 and the V14 are both re-engineered versions of the classic APSI 562 equalizer. The R24 is a 2-channel, self-contained unit that contains two identical equalizer channels in one 2U chassis with a built-in power supply; the V14 is built around the popular 500 VPR format. Both equalizers have high headroom with the R24 having a +23dB clip level and the V14 a +24dB clip level. The R24 provides XLR connectors and 1/4-inch balanced connectors for both input and output.

Both equalizers cover from 20Hz to 20kHz in four EQ bands of overlapping frequencies: 20Hz to 200Hz, 100Hz to 1kHz, 500Hz to 5kHz and 2kHz to 20kHz on the R24 and 2.2kHz to 20kHz on the V14. Each band has a continuously variable control of frequency and gain (+/- 12dB) and provides peaking response characteristics. Two separate pots control the R24’s frequency and gain while the V14 utilizes a set of dual concentric pots for each of the four bands. When using the V14, I initially found that when I made adjustments on the outside knob. Otherwise, adjustments on both units are quick and easy. Both the R24 and the V14 have an EQ in/out switch that places the circuit into the active audio path via a silent relay. In the “out” position, there is no active circuitry in-line.

The two equalizer variations offer almost identical performance with a bandwidth of 20Hz – 20kHz +/- 0.5dB and a THD+N @ 1kHz, +4dBu of 0.01%. The R24 has a signal-to-noise ratio of - 100dB and the V14’s signal to noise is - 102 dB. Both have a 12K ohm input impedance and a 300 ohm transformer balanced output impedance.

Features — R20

Unlike the Arsenal Audio R24 and V14, which are based on a classic design, the Arsenal Audio R20 was designed from the ground up by API’s design team. This dual-channel, high-quality microphone preamplifier offers a flexible, high-quality front end for microphones and instruments. The dual mic preamps provide up to 55dB of gain and the front-panel, highimpedance instrument inputs each provide up to 31dB of gain. The R20 is a single 12-pound, 10-inch-deep 2U chassis. The two mic pres are completely independent, sharing only a common power switch. Each channel features both mic and instrument inputs and switches for phantom power, phase reverse, and pad. Each of these functions includes an indicator LED to easily inform the user of the current status of the devise even in a dark control room. The pad switch attenuates the microphone signal by 20dB and the instrument signal by 10dB. The output levels are monitored via a custom analog VU meter and a peak LED located above the gain control knob. The rear panel includes a pair of female XLR connectors for microphone input and pairs of both balanced male XLR and balanced 1/4-inch jacks for audio output. The two output connectors are wired in parallel.

The R20 utilizes the THAT 1512 Mic Preamp IC, which produces near-discrete performance. The microphone input offers 54dB of gain and the high-impedance instrument input offers 45dB. The mic input has a 6.8 kilohm input impedance and a bandwidth of 20Hz – 50kHz, +/- 0.5dB. The THD+N @ 1kHz, +4dBu is 0.013% and the maximum output level is +20dBu with a -90dB signal-tonoise ratio. The instrument input has a 500 kilohm input impedance and a bandwidth of 20Hz – 20kHz, +/- 0.5dB. The THD+N @ 1kHz, +4dBu is 0.002% and the maximum output level is +20dBu. The unit’s instrument path has an -80dB signal-to-noise ratio.

In Use

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The mic pres are smooth, punchy, and full. They are slightly less aggressive and more natural-sounding than the standard API pres, but they still sound great on drums and guitars. I’ve used them on kick (AKG D 112), snare (Heil PR 20), and overheads (Royer SF-12); in every instance, I had great results. I recorded loud, distorted guitars with a Royer R-122 through the R20 and had great results without using any EQ or compression. The instrument inputs also work sonic wonders on keyboards and bass.

I don’t have fond memories of the APSI console I worked on while I was still in college, perhaps it was before I could tell what sounded good and what didn’t. Regardless, I can say that the R24 and the V14 sound absolutely amazing. They are astoundingly musical and work well in every situation. I’m used to working with equalizers with a Q control, and I was certain that I would miss the Q on the Arsenal Audio pieces, but there has only been one instance (a squeaky acoustic guitar) where I found myself needing to add an EQ with Q adjustment to get the desired results. I recorded a Taylor 514 CE acoustic guitar with an AKG C28 through the R20 mic pre, the V14 EQ and a Tube Tech CL1B compressor and had great results. I used the same signal path with a Brauner VM1 KHE to record vocals and, again, had great results.

I’ve been strapping an analog EQ across my in-thebox Pro Tools mixes for several years now with great results. I typically use the A Designs HM2EQ Hammer — a tube EQ—and have loved what it does. I gave the R24 a shot and found that it performs in the same league.


API’s new Arsenal Audio line provides three great new products that all sound fantastic, yet are priced amazingly within reach. Anyone in the market for expanding their mic pre or equalizer arsenal—pun intended!—should give these products serious consideration.

Review Setup: Apple Macintosh 2 GHz Dual Processor G5 w/2 GB RAM, Digidesign Pro Tools 7.4, Lynx Aurora Converters, PMC AML-1 monitors, Focal Twin6 Be monitors

Russ Long is an producer/engineer in Nashville and a regular contributor to Pro Audio Review.