(Written in the late 1990s; sorry it’s so non-comprehensive)
I compared several condenser mics and mic preamps in my home project studio. I’m sharing the results to help anyone else considering similar purchases in the semi-pro to pro price range.
My studio was based around a Mackie SR24x4 board (for monitoring and mixing) and a Tascam 488 cassette-based Portastudio multitrack tape deck. (It runs the tape at double normal speed and uses dbx noise reduction to improve the frequency response and noise floor.) I’ve since moved on to Pro Tools hard disk recording.
I compared two mics for recording acoustic guitar: an AKG C460B with the cardioid capsule, and a Neumann KM184. I also recorded my voice (a baritone) through an Audio Technica 4050 large-diaphragm condenser mic while testing preamps. I tried the Mackie’s builtin preamps and several outboard preamps, in order of increasing price: an Aphex 107 Tubessence, a Bellari (Rolls) RP220, a Peavey VMP 2, a Symetrix 202 rebuilt by Audio Upgrades, and a Neve 1272 refurbished and rackmounted by Brent Averill. Mercenary Audio also sells Neve 1272 modules; if you don’t get them rackmounted, they were under $500 per channel. I also compared the mic preamps in two other mixing boards I had access to: a Ramsa S840 series, and an Allen & Heath Syncon.
Acoustic Guitar Mics
The AKG 460 and the Neumann 184 are both small-diaphragm condenser mics, about the diameter of a magic marker; the AKG is about twice as long as the Neumann. They’re in the $580-$650 price range, retail, with the Neumann costing about $50 more than the AKG at my dealer.
I set up the two mics side by side in front of my acoustic guitar, pointed toward the neck-body joint. I recorded them simultaneously, first through the Bellari tube preamp and then through the Mackie preamp (they were just what I had around at the time). Then I swapped the positions of the mics left and right and repeated the tests, because the mic position nearer the guitar neck picks up more high harmonics and the mic position nearer the body picks up more low harmonics.
Both sounded very good on my acoustic guitar. However, the 460 has some midrange honkiness compared to the 184, which sounds almost magically well balanced. The relative sounds of the mics came through no matter what the mic position or preamp used. The 184 is amazingly realistic sounding on acoustic guitar. It would probably sound great on most stringed instruments. It has a significantly higher output than the 460, which helped the signal to noise ratio when using the noisy Bellari preamp.
Tube Mic Preamps
I compared a builtin preamp in my mixing board with several rackmounted preamps in the $300-$1000 range.
The Mackie preamp is very clean, crisp, and quiet. It sounds unflatteringly strong and honky in the upper-midrange, and somewhat strident and brittle.
The Aphex 107 is a solid-state dual-channel preamp with a tube stage tacked on, and sounds like it. Its sound resembles the Mackie preamp but has more midrange grit and detail and less harshness on the top. It’s fairly quiet.
The Bellari RP220 dual-channel preamp is more of a real tube circuit. It colors the sound much more than the Aphex; it sounds smooth and warm, with a rounded-off top end. The effect struck me immediately as Beatley. Listen especially to Rubber Soul-era Beatles and you may notice that it sounds like there’s something between you and the performers: a delicate veil of subtle tube distortion. It sounds like they may be nearby in the next room with the door open, rather than the modern clear “right there in your living room” sound. The Bellari has a similar sound, but with even less airiness. Although I like its smoothness, I want more immediacy than it gives. If you want to make your recordings sound like they were made in the 1960s, the Bellari preamp might help.
The RP220 adds significant hiss. It’s quite noticeable when soloing the channel with headphones, though in a full band mix it might be covered up. When I turned the Bellari’s gain up to about 75% to try to get a little more bite to the sound, the hiss got so loud that it kept my noise gate open when I had it set to open on my taking a loud breath (for effect) in the vocal mic. That’s too much hiss to be usable, in my opinion.
The Peavey VMP 2 sounds silky in the lows and has some grit in the highs. It sounds kind of narrow and lower-midrangey. It’s in between the Aphex and the Bellari in its treble and hiss levels. It has treble and bass knobs; by putting the bass at 11:00 for acoustic guitar, or the treble at 12:30 and the bass at 1:00 for vocals, I was able to lessen the midrangey effect and give the sound more presence and openness. I found that if I turned the treble even as high as 1:00, it started to add too much upper-midrange in addition to the airiness, increasing the nasal effect. The Peavey’s hiss is audible but not unusably so.
Channel 2 in the Peavey VMP 2 I got had a constant crackle that was very apparent in headphones while tracking a part. Reseating, then swapping out the tubes one at a time confirmed that the problem was a bad tube, and replacing it fixed the problem. I didn’t check the other units, but the Peavey contains Chinese tubes: six 12AX7 and two 12AT7. To open the box you have to remove 13 Phillips screws.
Solid State Mic Preamps
Audio Upgrades replaces components in other manufacturers’ products to improve the sound. They make their own solid state mic pre-amp circuit which can be installed in a variety of different systems; the one I tested was in a Symetrix SX202 mic preamp box. The Audio Upgrades mic pre sounds very clean, precise, and flat. It doesn’t sound either especially exciting or especially bad in any particular way.
The Neve 1272 is also not a tube circuit; it’s class A discrete. The one I got was from the early 1970s. Brent Averill replaced the dried out electrolytic capacitors and the styrene capacitors, mounted the preamp on a 1U rack faceplate, and added a high-impedance 1/4″ DI input and a passive output trim to fine-tune between the 5dB click stops of the Neve gain control.
The Neve sounds very smooth, punchy, and fairly clear; it has none of the grit (distortion) of the tube preamps, though it does distort (fairly musically) when turned up most or all of the way. It has a lower-midrange hump, giving a built-in proximity effect (“warmth”), and a dip in the mid-midrange, where voices tend to sound nasal; this gives it a more flattering, musical sound than any of the other preamps I tried. Neves are famous for their “larger than life” presence, which I heard too. With the KM184 on the acoustic guitar, the Neve sounded fairly well balanced but didn’t capture the higher harmonics quite as well as the Peavey and Audio Upgrades preamps did. EQ might help that, but a Neve preamp with EQ costs about twice as much as the 1272.
The Ramsa mixer’s mic preamp is noisier than the Mackie or Neve preamps. It’s midrangey, with a little woof, without the stridency of the Mackie.
The Allen & Heath Syncon mixer’s mic preamp sounds similar to the Neve, only less so. There’s less top and bottom–less proximity effect and up-front presence–while still having some of the Neve’s pleasant nasal dip.
Out of the group of equipment I tested, my favorite units were the most expensive ones in each class. The Neumann KM184 mic for acoustic guitar, the Peavey VMP 2 for a tube sound, and the Neve 1272 for a clean sound. There are even more expensive products on the market for each of these applications; I stopped where my budget stopped.