D-Mac's Stuff

(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.

Conclusion

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.

(Written in 1996)

What does it mean to be playing music in a certain key?
Well, let’s start from the beginning…

What is sound?

A moving object exerts a force on air molecules, compressing them closer together under greater pressure. Delicate bones in our inner ears are moved (less than a thousandth of an inch) by the air pressure, and nerves pick up their motion and interpret it as sound. Vibrating objects like guitar strings, guitar soundboards, and speakers (or vocal cords) create periodic changes in air pressure, where it is alternately increased above the normal value (when there’s no sound) as they move toward you, and then decreased below the normal value as they move away from you. A periodic sound is also called a tone.

What is pitch?

The number of times that the air pressure changes in any given period of time determines what pitch we hear the tone as–how high or low the tone is. Each movement back and forth is called a cycle. Usually pitch is measured in cycles per second, also known as Hertz (named after a 19th century physicist). The pitch of a tone is also called its frequency, because it is determined by how often (frequently) the air pressure is changing, which is determined by the frequency at which the part of the instrument that created it was vibrating.

The middle A key of a piano is a string vibrating at 440 Hertz; that is the standard pitch that orchestras tune their instruments to, so tunings based on it are said to be in concert pitch.

What is an octave?

When a tone has a frequency that is twice as high as another tone, we hear it as being “the same note”, only an octave higher. The next A above the middle A on a piano is vibrating at 880 Hertz, and the next A below the middle A is 220 Hertz.

If one vibrating object (such as a piano or guitar string, or a reed) is half as long as another one that has the same thickness and is tightened to the same tension, that shorter object will vibrate at twice the speed as the other one–one octave higher than it. (I don’t know why it happens that way.) Therefore, the 12th fret of a guitar, which is one octave higher in pitch than the open string, is located in the middle of the string.

What is volume?

The amount of difference in the air pressure determines how loud we hear a sound as being. If the pressure changes are large, we hear a loud noise. So if the air molecules (and thus our eardrums) are vibrating rapidly but only a short distance, we hear a high-pitched but quiet sound.

Why do different kinds of instruments sound different?

The strings (or whatever is making the sound) aren’t only vibrating at one frequency. Although there is one fundamental frequency for each tone, the motions of the air particles are actually composites made up of vibrations of several frequencies. The frequency that has the biggest impact on the resulting air particle (and ear drum) motion is the fundamental frequency, which we perceive as being the pitch of the sound.

The other frequencies mixed in with it to varying extents are what give the instrument its timbre (pronounced “tamber”) — what makes a guitar sound different from a trumpet or a violin. Many of these other frequencies that are mixed in are actually multiples of 2 of the fundamental frequency, and the one an octave above is called the first harmonic, the one two octaves above is called the second harmonic, etc. When we play a guitar string while touching it at its halfway point, we are muting the fundamental frequency while emphasizing the first harmonic; similarly for one-quarter of the string length and the second harmonic, and so on.

How are octaves divided up?

In the music of Western civilization, an octave is divided into 12 notes; the exact locations of the divisions were decided on by J.S. Bach. These 12 notes together are called the chromatic scale, perhaps because they are the distinct “colors” with which we “paint” to create music (“chroma” usually refers to shades of pigment or light). Other civilizations, such as India and China, have developed systems of music that divide octaves into other numbers of notes. Why do we use 12 notes? Perhaps because 12 can be divided into half, and also into fourths, which makes writing melodies using that scale easier. But we actually use more notes than those 12; we make in-between notes when we bend strings for added expressiveness using our fingers or a vibrato bar.

Does a song use all of the chromatic notes?

Not usually, except in some experimental jazz music. Normally, a piece of music uses a subset of the chromatic scale. The notes of the chromatic scale are also called semitones; the intervals between them are called half steps. The notes on a guitar are all a half-step away from each of the two notes on the frets next to them on the same string. Going from one semitone to another, while skipping one semitone between them, is called a whole step (yes, it’s made up of two half-steps). That’s skipping a fret on a guitar.

Certain patterns of whole and half steps are commonly used; the most common is the major scale, which has the pattern “whole-whole-half-WHOLE-whole-whole-half”. To make it easier to remember the pattern, you can think of it as two “whole-whole-half” patterns separated by a whole step, which I capitalized to make it stand out. This organization within the major scale has no significance that I know of besides making it easier to remember the pattern. Why is this particular set of semitones used? It just seems to sound good. It has a “stable” feel to our ears. Some other popular scales are the harmonic minor scale and the pentatonic scale, which use different subsets of the notes of the chromatic scale.

How were the note names chosen?

The 8 notes of the C major scale (not A major, for some unknown reason) are referred to using the names of the first 7 letters of the alphabet (A through G), with the octave note having the same letter name as the root note (C). The remaining notes of the chromatic scale each have two names; you can think of them as being sharp (higher in pitch) compared to the chromatic note just below them in frequency, or flat (lower in pitch) compared to the note just above them. So the note between C and D can be called both “C sharp” and “D flat”.

Because of where the half steps happen to be in the major scale starting on C, there is no note between E and F or between B and C. So there is no “B sharp”, for example. Other scales, and the major scale starting in keys other than C, do contain some of those “sharp/flat” notes. The word “sharp” is usually abbreviated “#”, and “flat” is written as “b”, or a symbol that looks a lot like a “b”.

So, what is a key, then?

A key is the notes of a particular scale (e.g., major), starting on a particular note (e.g., C). A piece of music that is in a particular key, such as “C major”, has a melody that uses only (or mostly) notes in that scale. For unusual effects, it might have an occasional note that is not in that scale; these notes are called accidentals.

Where do the chords in a key come from?

A chord is just three or more notes played simultaneously. (Playing just two notes at once is called a double stop.) The chords that are naturally part of a given key are the chords that contain only the notes in that key’s scale. The intervals between the notes in a chord determine what kind of chord it is–the feeling that the sound of the chord has to our ears, as well as what name we give the chord.

If you start with the root note of the scale (C for the key of C major) and add the third and fifth notes of the scale, you have what’s called a a major chord. That is a three-note chord with a two-whole-step interval between the low note and the middle note, and a one-and-a-half step interval between the middle note and the high note. For example, a C major chord contains the notes “C E G”. Since a guitar has more than three strings, when we play a major chord on it we can double some or all of those three notes on different strings, perhaps in different octaves, for a fuller sound.

If you start on the third note in the key’s scale and add the third and fifth notes of that scale above the note you started with, you end up with a minor chord, which is a three-note chord with a one-and-a-half-step interval between the low note and the middle note, and a two-whole-step interval between the middle note and the high note. For example, in the key of C major, if you base a three-note chord on the third note of the C major scale (E) and count that note as “1”, then the “3rd” note is G and the “5th” is B. That’s an E minor chord, containing the notes “E G B”, and written “Em”.

You can occasionally use chords that contain notes that are not in the song’s key, when you want a sound that is less normal sounding. For example, a dominant 7th chord contains four notes, one of which is the flattened 7th scale note above its root: a G7 chord contains an F note, not the normal F#.

Why do we skip notes, and not play chords that consist of, say, the first, second, and third notes of a scale? Playing all those close-together notes doesn’t sound very good. But we do sometimes use one close interval by including an even-numbered note, for example in the C6 chord (C E G A). Perhaps the most common type of chord where this is done is Csus4 (C F G), in which the third is “suspended” (omitted) and the fourth is added.

What is Ellipsis?

el.lip.sis \i-‘lip-s*s, e-\ \-‘lip-.se-z\ n or el.lip.ses
[L, fr. Gk elleipsis ellipsis, ellipse, fr. elleipein to leave out, pl fall short, fr. en in + leipein to leave]
1a: the omission of one or more words that can be obviously understood and supplied to make a construction seem more complete (as in “the man he sees” for “the man that he sees”)
1b: a leap or sudden passage without logical connectives from one topic to another
2: marks or a mark (as … or *** or -) showing omission esp. of letters or words

Who was Ellipsis?

Ellipsis was a basement band, pretty much… (Originally Suki’s… then Sri’s… then Eric’s… then Suki’s again…) We met at the University of Maryland in the early 1990s and got together to form a consulting company, and to relax after the meetings we brought our instruments along. Eventually we all got different jobs so the company never materialized, but a band sort of appeared in its place. And then we all got new instruments.

And then Sri went to Alaska, then Massachusetts, then Washington state, then California, so we don’t play together much any more.

What did they play?

David MacKenzie: vocals, guitar, keyboards, bass

Sridhar Rao: drums, keyboards

Suki Hirata: guitar, bass, drums

Eric Poh: bass, guitar, keyboards, vocals

Keith Barteck: bass, vocals

As you can imagine after looking at the above list, figuring out who does what on any given song can be… interesting. We find that arranging songs for 5 amateurs can be pretty difficult, not to mention getting everything mixed audibly above the drums without provoking the neighbors to have us arrested, or finding times when everyone can get together all at the same time. So we often break into factions of 2-4 people instead and sidestep the question.

Everyone in the band is a Rush fan, so most of the covers we do end up being Rush songs. We’ve also tried some Smashing Pumpkins and Police stuff. Usually we get part way through the song and can’t remember the rest… thus the band’s name.

The style of our original music is sort of updated classic rock with an ambient twist… Sri describes it as “folk-thrash”… maybe “folk-Rush” would be more appropriate if we keep adding keyboards…

Recordings

Our first album was going to be called “Obscure”, for reasons that are, uh… never mind. But we never made it, just some demos and jams. We eventually compiled a 2-CD set “Jams ’97” which isn’t available anywhere.