For more than 15 years, Summit Audio has been a leading U.S.-based maker of high-end tube gear. The company's latest offering, the TLA-50 Tube Leveler

For more than 15 years, Summit Audio has been a leading U.S.-based maker of high-end tube gear. The company's latest offering, the TLA-50 Tube Leveler ($695), breaks new ground by packing Summit's acclaimed compression technology into a compact frame. Furthermore, in keeping with its “less is more” design philosophy, Summit has kept the price of the TLA-50 accessible to all levels of the studio market — without sacrificing pro quality.

In many ways, the TLA-50 is like a little brother to the venerable Summit TLA-100A. Like its elder sibling, the TLA-50's selling points include smooth soft-knee compression, classic two-knob simplicity, transformerless circuitry, and a chunky vacuum-tube vibe. The TLA-50 and TLA-100A also share nearly identical front-panel features. Separate three-position switches (fast, medium, and slow) govern attack and release parameters, as well as stereo link/in/bypass status for the unit. In Bypass mode, the tube is still in the signal path. Switches for AC power and meter status (output and gain reduction) are also found on the brushed-aluminum front panel, flanking large output gain and gain-reduction knobs. A retro-looking cylindrical (also known as edgewise) VU indicator, backlit in orange, incorporates overload lights that bathe the meter in a red wash when levels hit 6 dB before clipping (+20 dBm).

Inside the unit's sturdy metal chassis, a 12AX7A/ECC83 vacuum tube imparts a glow to the Tube Leveler's signal path; the output amplifier stage, however, is solid-state. Unlike pricier Summit gear, the TLA-50 does not employ a custom 990 op-amp stage.

Rear-panel connections are comprehensive, with a +4 dBu balanced XLR/-10 dBV unbalanced ¼-inch combo input jack, and separate +4 dBu balanced XLR and -10 dBV unbalanced ¼-inch outputs. A ¼-inch insert jack allows sidechain and send/return functions, and another ¼-inch link jack facilitates the use of two Tube Levelers on, say, a stereo mix. A standard IEC power-cord connector and fuse are also rear mounted. The compact TLA-50 is one rack unit in height and half a rackspace wide, and it can be mounted on standard rack trays.

Listen Up

The TLA-50 performed well during commercial sessions at Guerrilla Recording studio, and my overall impression is that this little compressor definitely has a big tube attitude. In tracking duties, the unit excelled on bass, baritone sax, and other sources that typically benefit from a slow, smooth attack, long release time, and hefty low-end response.

The Tube Leveler also worked well on some male vocals. I did, however, opt for another compressor when the Summit contributed a grainy high-end characteristic to one particular male vocalist singing into a Lawson tube mic.

On full-frequency mixes while running signal through the unit with the bypass switch on (tube in circuit), the audio quality was clean and uncolored. Switching the compression circuit on (unity gain, no gain reduction) dulled the high end slightly and added a significant increase in punchy bass response.

Dialing in 2 to 3 dB of compression on program material produced a thickening of the bass and midrange and some attenuation of airy upper frequencies. Though I try to avoid such words, I have to admit that the Summit TLA-50 delivered an unquestionably “fat” sound here. However, some mixes treated in this fashion became murky in the 200 to 300 Hz range. At 5 to 7 dB of compression, the Tube Leveler was still smooth and musical and evidenced no bass pumping. At this extreme setting, midrange boosting and high-end attenuation were more noticeable.

Summit Audio mentioned to me that the TLA-50 does some high-end boosting of its own as gain-reduction increases. I found this to be true with the aforementioned vocalist, but to my ears this characteristic was largely program dependent. I also determined that the two TLA-50s I reviewed had internal wiring anomalies that reversed the polarity of signals routed through the XLR connections. According to Summit Audio, though, this problem has not been found in any of its other TLA-50s.


If you're looking for flat and transparent compression, Summit Audio's TLA-50 Tube Leveler may not be your ideal tool. But for convenience and a vigorous tube vibe at an affordable price, I have yet to see a comparably priced contender that can stay in the ring with Summit's little giant.

Overall EM Rating (1 through 5): 4
Summit Audio, Inc.; tel. (831) 728-1302; e-mail; Web