Much as it did with the compact TD-100 direct box and TLA-50 tube leveler, Summit Audio has packed an astonishing number of quality features into the half-rackspace 2BA-221 Mic & Line Module ($695). The 2BA-221's mic preamp section provides a -20 dB pad, phase switch, adjustable highpass filter (20 to 200 Hz), and a continuously variable impedance control (100ž to 10 kž). Because a microphone's output impedance might range from 50 to 600ž or more, the Mic ž knob grants control over the preamp's impedance match to the mic, affecting gain and timbre.
The 2BA-221 also offers a Line/Hi-Z direct-input section, with a single gain control for both inputs and a ¼-inch input jack mounted on the front panel. The line-level and high-impedance inputs can be used simultaneously. By internally mixing the line and mic input stages and running the summed output through a single vacuum-tube (12AX7A/ECC83) output stage, the 2BA-221 is an innovative, multipurpose audio-engineer's helper.
The panel layout is easy to grasp, with the Line/Hi-Z input section on the left, the mic preamp on the right, and the output gain knob and meter at center. A three-LED meter indicates signal present, average level, and clipping. A three-way switch combines AC power and 48V phantom switching.
On the back panel are an IEC power connector and fuse, an XLR mic input, a ¼-inch TRS balanced line input, and a ¼-inch insert that accesses the summing signal. Two separate tube-stage outputs are provided — a +4 dBu balanced XLR and a -10 dBV balanced 1¼4-inch — and you can use them simultaneously for a variety of signal-splitting duties. An additional input and output on the back allow you to link multiple 2BA-221 units, creating a modular monophonic mixer with multiple outputs, inserts, and one final tube output stage.
In studio testing, I found each section of the 2BA-221 to have unique and very useful characteristics. The line-in had plenty of gain, even with a -10 dBV CD-player input. Line-level signals were processed cleanly, with subtle smoothing of the high end and a beneficial mid-bass boost heard on a range of music mixes.
The 2BA-221's DI input contributed a warm, thick tone to electric bass that compared favorably to favored DI/preamps such as the Peavey VMP-2 and Langevin DVC. For guitar, however, the DI was rather dull and certainly not as exciting as the Langevin or Grace 101.
In contrast to its mellow DI input, the 2BA-221's solid-state mic preamp sounded bright and aggressive. Compared with the relatively uncolored Grace 101 and FMR RNP, the 2BA-221 exhibited a hefty bass punch as well as incisive highs that never got too harsh. Compared with stock mixing-board preamps, the Summit was definitely lively, dynamic, and detailed.
Paired with an AEA R84 ribbon mic (ribbons being especially sensitive to preamp impedance), the 2BA-221 even came surprisingly close in character to an expensive Focusrite Red-series preamp. The Summit's major differences were its higher noise floor and a bit of harshness in the upper midrange.
Practically speaking, the Tube Output control functions as a boost, passing clean, useable gain at its counterclockwise setting and adding subtle gain and coloration up to the knob's one o'clock position. When turned further clockwise, output increases dramatically, reaching roughly +20 dB at maximum. In this overdrive range, tube distortion will vary according to the level of the input signal. The 2BA-221 never sounded fuzzy or unpleasant when driven hard, even when the red clipping indicator was continuously on.
This 2BA-221 was a lot of fun to put through its paces, though the lack of decibel or unity-gain calibrations on the knobs was frustrating. In addition, with the condenser and ribbon mics I tested, the impedance control had just two operative settings — rather dull below a threshold around nine o'clock, and uniformly focused throughout the rest of the clockwise range — instead of a spectrum of timbre adjustments.
Sonic Hand Warmer
Minor quibbles aside, the 2BA-221 is a bargain and a versatile problem solver for studio or stage. Consider the unit's potential for submixing with electric cello, bass, acoustic guitar, or other instruments that combine miked and direct outputs. As a mic preamp, Summit's latest creation has a lavish set of features and impressive audio credentials. It can also be used as a tone box for mild and effective tube coloration when processing any of its input sources. With the 2BA-221, Summit Audio has proved yet again that great things do indeed come in small packages.