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Field Test: Little Labs Lmnopre Mic Preamp


The basis for the LMNO’s discrete circuit topology was originally a limited-run mic pre designed by Jonathan Little in the late ’80s. This single-channel pre was an insider choice among top engineers, producers and artists, and offers unique features and operating modes not available in any other mic pre. One unique feature is the built-in IBP phase-alignment tool. Phase alignment is crucial when using two mics placed on the same source or combining the mic and DI signals on bass or guitar. This set of passive, all-pass analog filters allow rotating the audio phase 360 degrees. For external use in a mix, this section is also available separately from the preamp via line-level XLR inserts.

I liked the ability to instantly toggle between the front panel XLR mic jack and a second XLR on the rear. This let me A/B mics on a singer or two mics that were placed differently on the same source. I also liked the low-frequency resonance control, which blends in an adjustable, musical LF peak without adding a specific equalizer circuit.

For added sonic color, you can overdrive the output transformer without distorting the rest of the all-discrete circuit. For a pristine, transparent sound, bypass the output transformer for transformerless operation. If you don’t need to ride level, then you can switch the master output trim pot out of circuit. With the master output off, the bypass acts as an output mute. Inside the chassis, space is provided for installing your favorite mic input transformer, or you can temporarily connect one using the 5-pin XLR on the rear panel.

To establish full gain potential (+74 dB) and avoid switching transients, the manual recommends stabilizing the unit for an hour before use, but mine seemed fine in 20 minutes. It’s powered by an external, linear 47-volt “line-lump” supply.


My first test involved a female vocalist singing into a Mojave MA-200 tube mic. The Lmnopre has two mic gain controls — low gain (+20 to +48 dB) and high gain (+40 to +74 dB) — for adjusting its fully differential Class-A gain stage. This singer required the low-gain mode (about 40 dB), as did most of my recording projects. The unit offers a tremendous amount of gain (+31dBm max output), making it viable for Foley or ambient recording. The sound was extremely clean, neutral and quiet — clean enough for me to hear the mic’s output compress on louder levels and the inherent noise floor of the mic’s 5840 tube. For this mic and singer, I preferred using the transformerless output, but I made sure I was driving a fully balanced input on the next piece in my recording chain. I found no differences in the noise floor in either mode; high gain simply gives you a cleaner-sounding level.

The Lmnopre’s LF resonance effect was most pronounced on vocals, sounding just like the LF proximity effect that occurs when a singer hugs the mic. My female singer “pops” easily, even with a screen, so she prefers to sing further away from the mic. I cranked up the LF resonance effect, and it sounded like she had moved within inches of the mic.


Lmnopre has two ¼-inch DI input jacks labeled “A” and “B.” I recorded a Fender Precision bass direct using A and miked a Fender Bassman amp with a Neumann U47 FET mic going through the mic pre in the studio’s API console. Input A is best suited for passive pickups. It has a 10-megohm active buffer amp before the custom DI input transformer, while B connects you directly to the 50k-ohm primary of the custom DI input transformer (giving you 6 dB less gain). I used this input for synths and guitars with active pickups. If you use the same DI path all the time, then you can set jumpers to configure the other DI’s ¼-inch jack as a thru to feed a guitar amp.

The IBP phase-alignment tool was handy when I combined the DI and mic signals to one track. The bassist played each string separately while I rotated the IBP knob until all notes were at about the same dynamic level. The DI bass sound was very clean and clear. I wanted more “hair” on the sound (like on a guitar amp with master volume), so I turned the master output knob down and boosted the gain. Saturating the output transformer produces an extreme sound with more attack than a tube-based preamp breaking up. You can do this on any source, but instruments with more sustain, such as guitars and basses, sounded best.

On electric guitar, I used the API console and the Lmnopre with two Shure SM57s on a single amp. Both mics were four inches away, with one aimed at the speaker cone’s exact center and the other off to the side but pointed at the center. The IBP control let me change the tonality of the mics’ combined sound — anywhere between thin and phase-cancelled to big and fat in which most of the frequencies were in phase and summing together. When panning the two guitar signals left and right, rotating the IBP to about 90 degrees produces a very wide stereophonic image; be sure to check it in mono!


Priced at $1,680, this unit offers control over sound quality by providing options and customized touches that begin at the circuitry level. With its excellent construction, I’d have no worries about taking it on the road in a tracking rack. And Lmnopre’s useful features such as the IBP, dual XLR mic inputs, dual DI inputs, LF resonance control and variable gain staging make it a perfect choice for those who are picky about their signal path.

Little Labs, 323/851-6860,

Barry Rudolph is an L.A.-based recording engineer. Visit him at