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Universal Audio 2-610 Microphone Preamplifier

I was practically teary-eyed when I pulled the brand new Universal Audio 2-610 Mic Pre from its shipping container. Since the announcement of its release nearly a year ago, I have been excited about putting this piece of audio history to work.

I was practically teary-eyed when I pulled the brand new Universal Audio 2-610 Mic Pre from its shipping container. Since the announcement of its release nearly a year ago, I have been excited about putting this piece of audio history to work.
Product PointsApplications: Studio recording

Key Features: Dual-channel, vacuum-tube mic, line and instrument preamplifier. Dual-triode tube stages (12AX7A and 6072A) in a Class A single-ended configuration; XLR mic/line inputs, 1/4″ instrument in, XLR line output.

Price: $2,295

Contact: Universal Audio at 831-466-3737 Web Site


+ Great tube sound

+ Tons-o-gain


– Some tube noise when recording quiet instruments

The Score

The Universal Audio 2-610 is the vintage-lover’s dream come true. It packs a great- sounding tube mic/line/instrument amplifier with basic EQ into an affordable package.
The Universal Audio 2-610’s inspiration is the 610 console, which was designed by Bill Putnam Sr. in 1960 for his United Recording facility (now Ocean Way) in West Hollywood. This rotary-controlled console was the first desk-to-employee modular design (a precedent still in use today) and its fat warm sound made it a mainstay for decades. From Frank Sinatra and Sarah Vaughan to The Doors and Van Halen, hundreds of classic recordings were made on the 610 console. The Beach Boys’ Pet Sounds album, arguably one of the greatest recordings of all time, was recorded through the 610. The 2-610 ($2,295) has all the unique character and warmth of the original 610 combined with the functionality required by the modern studio.


The two-rackspace, 11.75-pound Universal Audio 2-610 is a dual-channel, vacuum-tube mic/line/instrument preamplifier. Both channels have two gain stages that utilize a dual-triode tube (one stage uses a 12AX7A and the other a 6072A) operating in a Class A single-ended configuration. The circuit’s gain, distortion and frequency response are determined by the variable negative feedback that is applied to the two gain stages. The balanced inputs and outputs are transformer coupled. The device has a maximum microphone input level of +3.5 dBu, a maximum output level of +20 dBu, signal-to-noise ratio >82dB and a whopping maximum gain of 61 dB.

The box’s rear panel has identical connections for both channels of operation. Mic Input and Line Input are provided via XLR connectors and Line Output is provided via an XLR connector. In addition, the rear panel is equipped with an IEC jack for AC power via the included cable; a voltage selector switch allows the unit to be configured for either 115 V or 230 V operation.

With the exception of the power switch, the unit’s two channels have identical controls. The five-position Input Select switch determines signal input as 500 ohm or 2 k-ohm microphone input (via the rear panel Mic Input), line input (via the rear panel Line Input) or 47 k-ohm or 2.2 M-ohm Hi-Z input (via the front panel 1/4-inch Instrument Input jack). The 47 k-ohm setting works best with -10 dBV line level signals and the 2.2 M-ohm setting is usually best suited for instruments with passive pickup systems.

The five-position Gain switch adjusts the gain of the input stage in 5 dB increments (-10, -5, 0, +5, +10). Turning the switch to the right reduces negative feedback, which in turn raises the gain. The Gain switch also alters the amount of the tube’s harmonic distortion (one of the main contributors to the warm sound characteristic of tube equipment).

The Polarity switch determines the Line Output polarity. When switched to In, the output is Pin 2 hot. When switched to Out, the output is Pin 3 hot. The +48 V switch activates the channel’s phantom power.

The Level knob is the master volume control. It determines how much signal from the preamplifier gain stage is sent to the output stage. Level can be adjusted on a scale of 0 to 10 (nominal gain is somewhere between 7 and 10).

The 2-610 has both high- and low-frequency shelving equalizers. The Frequency switch determines the corner frequency (4.5, 7.5 or 10 kHz for high frequency and 70, 100 or 200 Hz for the low frequency) and the amount of boost or cut (0, +/-1.5, +/-3, +/-4.5, +/-6 or +/- 9 dB).

In Use

Though the 2-610 does not spec as well as some more modern microphone preamplifier designs, it sure does perform. The contraption is an amplification masterpiece. I found that the higher the gain the more aggressive the resulting sound. I had great results achieving vocal textures varying from warm, fat and round to in-your-face with a hint of distortion.

The variable impedance allows for easy matching with ribbon microphones. I had exceptional results recording strings and horns with my Royer SF-1s through the 2-610. I also had good results using the box with Royer R-121 to record electric guitars.

I was able to get a great acoustic sound using the 2-610 along with the Sennheiser MKH 800. There were a couple of instances when recording a finger picking part that the mic pre’s noise became noticeable, but not to the extent of being unusable.

The Hi-Z inputs sound wonderful. They perfectly capture keyboard textures and add a hint of tube warmth to balance out the digital edge present with so many modern keyboards. I also had fantastic results recording bass guitar, which sounds absolutely gigantic through the 2-610’s Hi-Z inputs.

The more I use the 2-610 the more I understand why all of those classic sounds recorded through the Universal Audio 610 console sound so good. It is simply a good sounding, musical piece of gear.


If you are looking for the most precision microphone preamplifier on the planet, the 2-610 is not the right box for you, but if you are looking for a versatile preamp with plenty of gain and a load of personality, this could very well be what you have been waiting for.


Sennheiser MKH 800, Sony C-800G, Royer R-121, SF-1 and SF-12, AKG D112 & Shure SM57 microphones; Mogami cabling; iZ Technologies RADAR 24 and Pro Tools recorders; PMC TB1 monitors with Hafler amplification.