Boulder Amplifiers 2110 line preamplifier

Founded in 1984, Boulder Amplifiers is a conservative audio company that goes quietly about its business, choosing not to call attention to itself with marketing flash or acronym-laden features. Change comes slowly to such companies, which is why the just-retired 2010 preamplifier enjoyed a 17-year run.

On the outside, with the exception of the new, front-panel–spanning display band of mirrored glass, the 2010's replacement, the 2110, looks little different from its predecessor, though changes inside and out are many. And the price has risen, from $48,000 to $54,000.

The 2110's basic physical building blocks are the same as the 2010's. The 2110 is a modular design with a main chassis comprising a control module that includes the front-panel; sitting on and behind it are separate housings for the left and right channels. This three-part chassis sits on the massive 2100 outboard power supply, which comprises four separate, isolated supplies connected by three umbilicals: one supply each for the left- and right-channel analog sections, one for the logic and user-interface circuits, and one for standby and power-up, which Boulder claims substantially decreases power consumption when the preamp is not in use.

To keep noise at vanishingly low levels, there are no electrical connections between the audio and user-interface sections. Control is effected through a system of optical transmitters and sensors that trigger functions within each channel's housing.

Switching Capabilities and Functionality
To the right of the 2110's centrally positioned and optically controlled, infinite-spin volume control are buttons for Balance, Mute, L(eft) and R(ight) Polarity, Display (intensity), Program, and on/off.

Like the 2010, the 2110 can be switched among its six inputs via a row of hand-polished, stainless-steel pushbuttons on the left of the front panel and labeled One through Six. A seventh button, Aux, lets you set the input routed to that output for recording or other purposes. You can program the 2110 to automatically route all inputs to the Aux output, as most preamps do. You can also configure any input to function as a tape monitor and, to prevent feedback, set the 2110 to block the chosen input from sending its signal back to the Aux output, which would otherwise produce some nasty feedback. The tape-monitor system is complex and ingenious, but Boulder's instructions about how to use it are unnecessarily complicated and obtusely described.

Any input(s) can be configured for Theater Mode, which bypasses the volume and balance controls to produce unity gain from that input(s) at the 2110's output. This will be useful for those who combine two-channel and surround-sound systems, but Theater Mode must be used with great caution. Boulder's strong warning sows needless panic by stating, in red ink, "there is no way to control the volume of the 2110 while in Theater Mode." Of course you can control the volume of the 2110 while in Theater Mode—just not the volume of the particular input set to Theater Mode. If Boulder thinks that's too obvious to mention, they need to talk to more consumers.

Other things the 2110 lets you do: invert the polarity of either or both channels, adjust the muting level, set the display to one of eight levels of brightness, change the volume control's default scale (–100dB to 0dB; as set-up for review, the 0dB setting was equivalent to 20dB of gain) and resolution (increments of 0.5dB) to various other options. You can even set the main and Aux output polarity, depending on your choice of power amplifier and/or recording gear. You can program input names, and set individual input levels to produce equal output levels among your inputs. I'll stop there. The 2110's configurability and adjustability are what you'd hope for and expect for $54,000.

I hear you: "Yeah, but much of that is available in any $600 home-theater receiver." True enough. However, the 2110's sound quality and build quality are most definitely not available for $600. And all configurations and adjustments that can be made using the front panel can also be easily done with Boulder's ergonomically excellent, full-function remote control.

All of the 2110's connections are via balanced XLR input and output jacks. Single-ended components can easily be accommodated using RCA-to-XLR adapters. (In Boulderese: "The negative input (pin 3) should be wired to ground only at the RCA phono connector.") Of course, to take full advantage of the 2110, you should use differentially balanced source components and a differentially balanced power amplifier. The 2110's three sets of XLR outputs can be used with special splitters to drive up to six power amps.

2110 vs 2010
The 2010 was differentially balanced at its inputs and outputs; its volume control was not. The 2110, however, is fully differentially balanced from input to output. The 2110 replaces the 2010's Boulder-engineered, unbalanced, CMOS-controlled resistor ladder volume control with one that's fully differentially balanced and said to improve signal/noise ratio and eliminate step noise.

The 2010 used Boulder's proprietary 993 gain stage, which had through-hole, hand-soldered boards potted and encased in an extruded housing. This module has been completely reengineered and redesigned. The new 993S features surface-mount technology, with all boards "stuffed," assembled, and finished in-house, then potted and enclosed in a machined housing. The 2110 also features new bias-injection and ground- topologies.

Along with the all-new circuit design, the 2110's aluminum case is machined from stock and its surfaces are all bead-blasted and clear-anodized. The 2010's case was a combination of bead-blasted, machined aluminum, and powder-coated sheet stock. The labels on the rear panel are now engraved, not silk-screened. All of Boulder's metalwork is CNC-machined in-house, which in high-end audio is unusual. Boulder also does its own bead blasting while the clear anodizing is performed by a subcontractor.

External control has migrated to the Internet age, with full IP control and two-way feedback, a 12V trigger via a mini-jack, as well as Boulder's Boulder Link via RJ-11 connector. All of this is familiar to home-theater geeks, less so to the rest of us, for whom an on/off switch is less threatening.

There are other, less significant changes. More important is a shift to a more sophisticated protection circuit in which each power-supply is microprocessor-controlled and monitored. Should operating temperatures exceed the correct range, the 2110 will mute until the affected supply returns to normal.

Boulder's Game Plan
The foundation of the 2110 is its massive power supply for each channel. These feature big, made-in-USA toroidal transformers potted with a resin of mineral glass and epoxy, and encapsulated in custom, magnetically shielded steel enclosures. Each assembly weighs more than 8 lbs. The power supplies for the logic circuits are equally well endowed.

The four interlocking chassis that comprise the 2110 are well damped, to eliminate microphonic resonances. This is accomplished with a combination of damping materials and the fact that the vibrational resonances of the entire structure are both higher than those of the individual housings and well above the audioband. I could devote half a page to the design and construction of the multilayer feet that support the 48-lb power supply and the 63-lb main housing.

The 2110's input selection is logic controlled, with signal routing to the six 993S gain modules via sealed relays. The 2110's input circuit transistors are bipolar, which Boulder says makes them lower in distortion and more reliable than FETs. The 2110's direct-coupled design includes a servo capable of eliminating up to 50mV of source-produced DC offset voltage.

Boulder has paid maximal attention to even the most minimal issues. The display window is made not of plastic but of hand-ground, mirror-coated Pyrex, to prevent warping and/or scratching and to maximize legibility. The mirror finish is produced to Boulder's specs to avoid halo effects and blurring, while maintaining the mirror finish in standby mode.

Speaking of mirror finishes, the 15 buttons on the infrared remote control are cut from stainless steel and hand-polished in-house, in a nine-step process that matches their looks to that of the front panel's buttons and mirrored display.

Boulder Amplifiers, Inc.
3235 Prairie Avenue
Boulder, CO 80301
(303) 449-8220

shp's picture

Hi Michael

I notice you are using both products as digital sources. Which do you prefer?


dchk's picture

I am wondering why you did not compare it to Audio Constellation Altair II, Vitus MP L201 or Soulution 725, which are also marketed as high price tag high ends.