Real World: The “Black Art” of Microphone Preamps
Choosing one over another? Sorry, no standard answers
Editor’s Note: We asked Fletcher (of Mercenary Audio and ProSoundWeb Rec Pit fame) and LSI Microphone Editor Ty Ford for their “takes” on mic preamps for live and recording applications. They have worked with each of the selected units and offer commentary based on this experience. At the same time, the only hard-core fact about preamps as Fletcher clearly indicates below is that there are no absolutes. Troll around the web and check out the descriptions and specifications of any preamp, and you’ll find remarkably little consistency between any two. Even by sound reinforcement standards, the selection and preferences of preamps involves a bit of the “black art”.
What makes a good microphone preamplifier? What makes one mic preamp better
for an application than another? Why even bother with “outboard” preamps?
Frankly, there are no standard “correct” answers to these questions, it’s
all about a subjective sense of aesthetic that users have to determine
their own bad selves.
Mic preamps like wine, cars, guitars, and the brand of cigarettes you
smoke are all a very personal decision. What I may find remarkably mundane
and boring may be absolute perfection to another user. Just as some men
make perfect mates for some women, other women may consider these same
men to be psycho-losers from hell. It’s all that subjective.
There are tools that have made my life a miserable ball of living nightmare,
while others I’ve found over the years have served me well. The latter
have enabled me to give my audio a sense of “three dimensions”, a sense
of character and texture that help me to get the various tones that comprise
music to work and play well with each other.
Sometimes my choice of preamp will enable tones to blend with each other
in a way I find musically pleasing, other times my preamp choices will
enable the tones to gain greater independence and separation within the
context of the musical presentation. Other times I have found that trying
to get any kind of clarity or dimension from these same tools is probably
a little easier than wringing blood from a stone.
I tend to gravitate to preamps with a distinct and unique personality.
I have found that some mics work better with some pre-amps than with others.
This is a whole other can of worms that doesn’t really need to be opened
at the moment. And I’ve found that there are fewer than zero rules when
it comes to mic-pre selection.
Poll 100 engineers on their favorite tools, and you’ll probably get 100
different answers. What we often fail to realize is that we are indeed
in show business, and that often a product will have more “show” than
substance to it’s capabilities. There are a myriad of myths that permeate
our industry, certain tools are for certain applications, “X” is incapable
of doing a decent job on a “Y” kind of sound, etc.
Besides the normal subjectivity selection, we have to realize that all
of these various tools have to work together as a cohesive unit to obtain
any (desired) result. Just as you’re not going to have the same ‘tuning’
on a system in football stadium as you would with a system in a soft seat
venue, it’s also true that often, outboard preamps will work better in
some venues as opposed to others.
The whole is always the sum of its parts, and the various parts seem to
change from night to night, show to show. Perhaps the musician is playing
differently than the night before, perhaps the venue evokes need for a
different set of textures, perhaps you (the operator) have a different
impression of how to present the performance on any given evening.
With all of this said, skip the grain of salt and instead pick up a huge
bag of it as you peruse the following views regarding a selection of mic
preamps. While some of these assessments may turn out to be of use to
you, they may be relatively useless for your applications, tastes, aesthetics
and etc.
Much like 1,000 lawyers chained together at the bottom of the ocean, take
these evaluations simply as a “start”. Just as there will inevitably be
more lawyers to take the place of our drowned friends, so too with preamps.
And each of you will come to your own conclusions about what hardware
is cool and what isn’t for your musical aesthetic, regardless of my or
anyone else’s experiences and opinion.
Bon Appetite.
Aphex Systems 1100
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Channels: 2 List price: $2,495
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Its MicLim circuit prevents short overloads from causing digital distortion.
Stepped input and LF filter pots aid in setup. A built-in tone generator
helps with setups.
Ty’s Take: I use this preamp a lot because even though it uses
a tube, it’s very open sounding. The step-switched low-frequency roll-off
circuit lets me pull out the low frequencies before it gets to the second
amp stage and the MicLim optolimiter allows me to keep my record levels
just a bit hotter.
ART Pro MPA
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Channels: 2 List price: $457 |
Manufacturer Take: Circuitry is a hybrid design utilizing solid
state and tube technology. The Active balanced input utilizes a hybrid,
triple-differential transistor design. A second stage 12AX7A tube running
on a regulated DC voltage provides an additional 40 dB of gain. The design
causes the tube to overload before the input or output stage and allows
the user to manipulate the tube gain.
Fletcher’s Take: Somebody actually seemed to have a decent idea
for an inexpensive, reasonable sounding preamp when they decided to market
this thing. The only problem is that somebody else thought that putting
“firebottles” in the thing was going to make it sound “toobey”. It’s a
nice sounding pre-amp, but don’t let the “toob” stuff fool you.
ATI 8MX2
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Channels: 8 List price: $2,995 |
Manufacturer Take: The 8MX2 offers eight proprietary ATI High Voltage mic-preamps in a single rack space, and a stereo mix buss with full monitoring capabilities. Each channel also has a variable threshold limiter as well as full cueing capabilities with metering of level and limiter attenuation.
Fletcher’s Take: This is a wonderful unit for those with less than enough inputs on a real rig, or for those with a budget rig to employ as a main mix buss to add the more “audio critical” aspects of a mix to a main mix. The mix buss has a wonderful depth of tone, headroom, and a couple of cool bells and whistles thrown in for good measure. In these days of wanting everything in to fit in one RU, with truck space at more of a premium than ever, who can blame ATI for making the knobs small and closely spaced. Frankly, the thing sounds good enough to put up with the tight spacing.
Bellari Rolls RP-220
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Channels: 2 List price: $500 |
Manufacturer Take: The RP220 is a dual tube preamp with transformer balanced inputs, XLR and 1/4-inch inputs and outputs, +48-volt phantom power and mic/line level switching. Thermal harmonic distortion is 0.1 percent (typical). Signal-to-noise ratio is 107 dB.
Fletcher’s Take: As a lower-priced addition to a writing rig for the back lounge of the artist’s bus, this is kind of in the same league with the ART unit. A tube change (talk to the guitar tech, he probably has one in his workbox) often helps, but they’re not at all horrible sounding at the price point.
Benchmark Media MPS-400/2000
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Channels: 4 List price: $1395.00 |
Manufacturer Take: Consists of four MP-4 microphone preamplifiers, each with balanced inputs and outputs, switchable phantom power and 20 dB input attenuator. Two gain control options are now available: switched gain option (+15 to +65 dB in 5 dB steps or +30 to +50 dB in 2 dB steps), and gain potentiometer (continuously variable gain from +18 to +73 dB).
Fletcher’s Take: The quality of the audio available at the price point may make this one of the best values on the market. I found it to sound quite similar to the Millennia HV-3, but far less expensive.
Crane Song Spider
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Channels: 8 List price: $7500 Manufacturer Take: It’s an amplifier/mixer with two types of digital outputs: stereo and eight channel. Stereo is for recording engineers who do live stereo or multi-channel recording. The eight-channel output allows the system to function as an analog front end for DAW’s, digital mixers, and modular digital recorders. |
In addition, the stereo bus can be assigned to digital channels seven and eight.
Fletcher’s Take: If you have an artist that is trying to record master quality product in the back lounge of the bus, or are considering doing some incredibly high quality (as in album-quality) “understage recordings”, this thing goes beyond versatile, and far beyond good sounding.
dbx 286A
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Channels: 1 List price: $299.95 |
Manufacturer Take: A mic preamp and and five processors that can be used independently or in any combination. It includes wide-ranging input gain control, switchable 48V phantom power and an 80Hz high-pass filter. A redesigned OverEasy compressor can be used to transparently smooth out uneven acoustic tracks or deliver that classic “in your face” rock vocal.
Ty’s Take: In reviewing the dbx 286A some years back, I was very impressed by how clean and clear the mic pre sounded. I made a point to call the technicians to ask them how they had gotten the SSM 2017 preamp chip to sound as good as it did. They said they spent a lot of time moving components around on the circuit board to minimize noise and maximize performance. That was time well spent. This box rates higher than most on the price/performance curve.
Drawmer 1969 Mercenary Edition Tube
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Channels: 2 List price: $2,995 |
Manufacturer Take: Burr-Brown op-amps have been chosen for a ‘silkier’ sound for the mic amp. The ‘DI’ input has limited ‘tone control’ function as well for ‘minor touchups’ (or real radical alterations). The compressor works on a ‘J-FET’ compression cell, which sounds a bit smoother than a VCA, and has the potential to be faster than an “opto-attenuator”.
Fletcher’s Take: Well, I definitely have no business commenting on this one... If I didn’t think it was great I’d have to kill myself. That said, the pre-amps in this unit were devised almost as an afterthought to the compressor, which is a versatile, musical tool that was designed mostly with two-buss applications in mind. The pre-amps were made to sound clear and full.
Focusrite Red 1
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Channels: 4 List price: $2,795 |
Manufacturer Take: Includes four preamps in a single unit, with custom-wound input transformers, custom potentiometers and sealed relays enhance performance and reliability. General features include switchable phantom power, phase reverse, an easily read illuminated VU meter, and a handy scribble disc for denoting channels.
Ty’s Take: I always think I sound “nekkid” when I hear myself through a Red. At first, that can be a little disconcerting and may make you try harder, but you can bulk up with the usual amount of processing afterwards and end up sounding clean and big.
Grace Designs 801R
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Channels: 8 List price: $4,995 |
Manufacturer Take: Frequency response is rated at 40 dB gain ± 0.2d B, 20 Hz to 300 kHz, while thermal harmonic distortion plus noise (THD+N) is 40 dB gain, +25 dBu out, <.001 percent. Crosstalk specification is -109 dB for any given channel. Maximum output level is +28 dBu for balanced lines and +22 dBu unbalanced. The 801RCU remote control ($995) can control up to 64 channels at a distance of up to 1,000 feet.
Ty’s Take: Another of the exceptionally clear preamps. No attitude. You get what the mic hears. Put the preamps on stage and run line level back to the console. This alone will improve your sound.
Great River MP-2NV
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Channels: 2 List price: $2,499 |
Manufacturer Take: Based on the preamps found in old Neve 1073 modules but with a twist. While the circuit is basically the same, different components were chosen for a lower noise floor, an extended frequency response and better bass clarity. While the unit sounds similar to a 1073, the user experiences a larger, more open sound field that is helpful if you are storing audio in the digital domain.
Fletcher’s Take: The intention was to build a pre-amp that had the size and the thunder of an original Neve, but with a level of clarity (especially in the low end) that often finds itself getting “hazy” with original Neve modules. A secondary output is for “no latency monitoring” when used with a digital audio workstation, and the ability to add a load to the input and output transformers.
Jensen Twin Servo 990
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Channels: Expandable from 1 List price: $1,550 (1 ch), $900 (per add. ch) Manufacturer Take: Each channel uses two precision 990C operational amplifiers modules, developed and patented by Jensen, to achieve one-tenth the distortion and twice the bandwidth of a single stage design. |
The Jensen Twin Servo 990 has a 19-inch wide mainframe rack-mount chassis and can be ordered with one to four channels. Additional channels can be added later up to the total capacity of the mainframe.
Ty:’s Take: I used one of these a few years back on front line vocals and kick drum in a live venue. They made the board preamps sound broken. I also heard them sound very nice in the studio on drums and micing an Acoustic 150 bass rig with an (EV) RE20. This is one of my personal favorites; an exceptionally clean preamp for any mic in your closet, especially low-output ribbon mics.
Manley Labs VoxBox
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Channels: 1 List price: $4,000 Manufactuer Take: The preamplifier of the unit is based on the well-regarded Manley preamplifier. |
High-current 48V Phantom power is switchable from the front panel. A simple passive bass cut switch kills rumble and reduces popping. The music passes through only clean Class A vacuum tube circuitry.
Fletcher’s Take: The sound reinforcement market seems to have embraced the VoxBox for many “audio critical” applications (like vocals). The unit employs a 3:1 opto compressor before the mic pre (which is often very useful) and another opto compressor that can be “frequency selectable” for de-essing purposes, or used as a full-range limiter (again, quite useful). There is a four-band equalizer section that is remarkably musical, and the mic pre has always struck me as being very clear, yet full and robust sounding.
Millennia Media HV-3D
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Channels: 4 or 8 List Price: $2,994 (4 ch), $3,995 (8 ch) Manufacturer Take: Uses the straight HV-3, solid state, fully-balanced, discrete, hybrid, high voltage mic preamp in four or eight channel multiples. Minimum input gain is at 8 dB. Optional B&K (DPA) +130 volt inputs and dc-coupled “ribbon inputs” on all channels. |
With +23 dBu input headroom, the HV-3D requires no input pads or switch points as found on “textbook” preamp designs. Standard audio cables over 1,000 feet in length have been driven from HV-3 mic preamps with no immediately detectable signal degradation.
Ty’s Take: Very clean, very open. A very real sense of extended top end without sounding hyped.
Pendulum Audio Quartet
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Channels: 2 List price: $3,250 |
Manufacturer Take: Combines four elements - mic/DI preamp, opto-compressor, equalizer and de-esser into one package. It’s the mic pre from an MDP-1A, a channel of compression from the OCL-2, with a brand new equalizer design and a very inoffensive de-esser.
Fletcher’s Take: Has the ability to perform pretty much any task thrown it’s way with a complete, full and rich tone. The added bonus to the unit is that any of the sections, mic pre, compresser/de-esser, or equalizer can be used entirely independently of each other, allowing the user to use the mic pre on vocals, the equalizer on a kick drum, and the compressor on a bass. These are not necessarily the best applications for each of these sections, just an example of the unit’s versatility. Each user will find their own applications, and there are many!
TRUE P2 Analog
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Channels: 2 List price: $1750 |
Manufacturer Take: Includes two active high-impedance DI’s, as well as a Mid-Side decoder for creative special image control. Stereo phase correclation display speeds mic positioning. Also includes selectable high-pass filters, relay-switched signal routing and dual gain range.
Fletcher’s Take: The P2 seems to have a depth and dimension to its tone that can compete with some of the world’s best preamps. There are two “gain ranges, which for some reason sound different (one fuller, one thinner). The unit has a nice versatility not often found at this price point. One of my favorite features of the unit is the “phase correlation meter” which has proven itself to be a very useful tool when employing stereo microphone techniques.
February 2003 Live Sound International