Archive for the ‘How To’ Category

DIY Audio Mixing Circuits

Saturday, November 24th, 2012

For a while now I have been interested in summing in the analog as opposed to the digital domain and I built a 16 channel summing mixer with Daking-style amplifiers. I haven’t been very happy with the usability of summing mixers without linear faders and pan controls. It just doesn’t feel right. If you’re mixing with rotary knobs, you can only turn two knobs at once, but when you mix with faders you can do at least 8 at a time.

I basically started doing some research about the kinds of circuits that I need to build and I wanted to post links to the stuff that I found to be the most helpful.

Simple Mixer Schematics from All Electric Kitchen:

Slightly more complex mixer circuits (Pre’s, EQ’s, Line Drivers):

Elliott Sound Products (ESP) Article on Audio Mixing:

I will add information as I read more!

Do You Need A Demo?

Sunday, February 6th, 2011

When a band or artist is first starting out, many choose to make a demo recording of their music. While some find that recording a demo is essential in getting their musical career off the ground, others find that it has little benefit to them in the long-term. Here are just a few things to consider when thinking about recording a demo.

If you’re a new artist or band, then you might not have the financial backing which is often required to record a whole album, which can require a larger of time to be spent in the studio. Once you have a recording contract, it is also unlikely that your original recording will be used – usually they will be professional rerecorded before public release. In this sense, recording a whole album simply to allow music executives to listen to a short sample can seem like an unproductive use of time and money – it can be a better idea to simply record a short demon to show what you can do.

It is also worth bearing in mind that demo recordings do not always give a true representation of your musical ability. After all, those who like your music won’t simply want to listen to your recordings as they play online games or on their headphones during their commute to work. They’ll also want to hear you play live – and so will record companies and producers. Although the fact that broadband internet is now widely available from companies such as O2 can mean that a large number of people will listen online to digital recordings of your music, this will not negate the need to be able to play live. Whilst a demo can act as a good taster of your sound, but you should make sure you are able to recreate that sound for a live audience should you be invited to.

Lastly, it is worth bearing in mind that unsolicited demo tapes rarely get much attention. Only record a demo if you have a clear plan on how you want to use it – other than just blindly forwarding a copy on to every record company which you can think of. Otherwise you may be better off recording a full album, which you may be able to see at gigs and performances.


Black Walnut Branches into Lumber

Wednesday, August 18th, 2010

As many of you already know, I love to build things out of wood: guitars, acoustic treatments, furniture, and assorted house-oriented projects.  What you probably didn’t know is that there’s a black walnut tree in my backyard.  For years and years the squirrels have been denting the hood of my car by throwing walnuts at it. You can’t blame the squirrels.  The walnuts do sound great when they bonk my car, but it still sucks. Partially from my frustration that cars are made out of aluminum foil instead of actual steel, I have been fantasizing about cutting down the two large branches above my parking space in the driveway. And I have been fantasizing about how great it would be if I could then mill the logs from the branches into usable lumber.

Last week my dreams came true and the next door neighbor hired a tree company to remove the branches because they were also above their parking spaces and creating a wonderful super-highway for the squirrels nests in the roof of their house. I then convinced the guys gutting the trees to give me all of the large branches from the walnut tree for free. Score! I was so excited.  Black walnut has an incredibly beautiful grain with a dark brown heart wood and a creamy tan sap wood.  Walnut makes amazing guitar necks, great furniture and is just generally really cool looking and feeling.

I ended up finding out about Roy from A.W. Woodworking (phone: 401-219-1258) through Craigslist and he gave me a quote for driving all the way from Rhode Island up to Medford, MA to mill my black walnut into usable lumber. The price was about 1/4 – 1/3 what the lumber would have cost from a lumberyard locally. Hurray!  The following is a short photo story of the process:

Black Walnut Tree

The Black Walnut tree after the branches have been cut down

Black Walnut Branches

Black walnut branches waiting to be milled

Branches are somewhat less than ideal for milling because they aren’t straight and they aren’t very big. It makes is harder on whoever is milling the wood. Roy did a great job!

Log Section and Walnuts

A cross-section of a log and 4 fresh walnuts before the soft outer shell dries and falls off

Cross Section

Another cross section of a log with the bark still intact

Baby Walnut Tree

A tiny black walnut sapling growing from the neighbors' foundation

Waxed Log End

The waxed end of a cut branch

The Arrival

The saw mill has arrived and is backing into the driveway

The Portable Mill

The portable saw mill is in position and ready for work

The First Branch

Garfield places the first (and smallest) branch on the mill to rip it into planks

Blade Against Branch

The blade of the mill is lined up with the first branch ready to remove the first slab

The First Slice

The first slice comes off the first log while the saw exhausts on the driveway

Cranking the Mill

Roy cranks the handle pulling the saw blade through the log


Garfield rotates the log into position for ripping off the top slab

Squaring Off

Ready to rip off the top slab to create two square edges

Two Clean Edges

Now with two clean edges the log can be ripped into planks

Top View

A bird's eye view of Roy and Garfield working

Arched Grain

This ripped log shows the beauty of black walnut's grain


Discarded slabs of bark and pieces that are too short to mill


Black Walnut planks after milling waiting to be stacked and dried

Wood Grain

Top view of the black walnut wood grain showing both the lighter sap wood and the darker heart wood

Embedded Metal

This piece of embedded metal ruined the band saw blade

Detail of Wood Grain

A close-up view of the grain of the black walnut plank

Studio Construction Photos: Con-Fusion Entertainment

Saturday, June 12th, 2010

Several months ago I was approached by two former students (Evan Schlosser and Robie Rowland) at the New England Institute of Art to help them to design a studio in a rented space in Allston.  They introduced me to their partner Arjun Ray and I started consulting with them.  The space was being converted into rehearsal  spaces and construction was already underway in the space to convert it from an office building into a rehearsal room.  We would convert that into a fully-functional professional studio.

After measuring the space and investigating the existing construction, I came up with a design that would isolate the studio from their 3 neighbors as much as possible and that would provide them with 2 large and functional live rooms and  a good sized and well proportioned control room.  My initial design follows but had to be altered some to address problems such as sprinkler and HVAC locations.

Original Studio Design

The Original Design for Con-Fusion Entertainment's Studio

One of the things that is very nice about the space is the two large windows allowing natural light into the studio’s control room.  I designed all of the spaces to avoid parallel wall to help prevent problems with standing waves and the accumulation of low frequencies in less-than-ideal locations.  The rectangular space is broken up in such a way that the control room gets larger the further away from the mix position.  Both the live rooms have site-lines to the control room as well.  The control room, where the most time will be spent, is the largest room and will allow for comfortable seating for producers, engineers and their clients.

Here are some of the early construction photos.  In the pictures are Arjun Ray, Robie Rowland and Evan Schlosser (The 3 partners of Con-Fusion Entertainment), and Mike, Rick and Robie the Elder.  I tried to create some order to the photos to create a narrative.  At this point, nearly all of the metal studs are in place and drywall is starting to be hung.

Looking at control room from inside the large live room

Looking at control room from inside the large live room

View out of the control room door

View out of the control room door

View into the corner of the control room

View into the corner of the control room

View out the main control room window

View out the main control room window

The wall makes a slight job at the studio entrance

The wall makes a slight job at the studio entrance

Exterior walls filled with 703 fiberglass insulation

Exterior walls filled with 703 fiberglass insulation

Detail of the double wall construction

Detail of the double wall construction

3 Layer studio window in progress

3 Layer studio window in progress

Detail of finished studio window

Detail of finished studio window

Cutting metal studs makes sparks!

Cutting metal studs makes sparks!

Placing the first piece of gypsum board

Placing the first piece of gypsum board (from the left: Evan, Robie and Arjun)

Arjun sealing the top edge of the drywall

Arjun sealing the top edge of the drywall

Signatures of the builders on the first drywall

Signatures of the builders on the first drywall

So those are some of the pictures of the progress.  I would love to hear your thoughts!

Tracking an 8-Piece Drum Kit for 5.1 Surround

Monday, February 1st, 2010

The Project: Drums in 5.1

I am currently working on a recording of music that I have been writing with Penny Larson, the awesome-est drummer ever. We tracked the drums at U. Mass Lowell’s wonderful Rm 114, which is by far the best room I have ever worked in. Big enough to make great drum sounds with lots of diffusion and enough low frequency absorption to prevent the room from being boomy or rumbly. It’s just totally delicious.

Penny and I first worked together recording Bryan McPherson’s “Fourteen Stories” and then subsequently on Sierra’s EP “Rocks.”

Penny Larson's 8 Piece Drum Set

Penny Larson's 8 Piece Drum Set

The record will be released in 5.1 Surround at 24bit 88.2kHz so there is a lot of opportunity to use the 360 degree soundstage to allow the kit to be heard in all of its glory. There are lot of issues that arise when recording a really large drumset and I will talk a little about these types of issues.

mkit from the Front

8 Piece Drum Kit from the Front

Problems Micing a Large Kit

More Drums = More Mics = More Problems

As you add microphones to a drum setup, the potential for phasing and bleed problem increases exponentially. More drums usually means closer together drums, so isolating the drums becomes difficult. When sounds bleed into unintended microphones the possibility of phase cancellation or other problems increases as well. Adding to the mix problems are a zillion cymbals that will cause physical problems with mic placement as well as bleeding problems. Two objects can not be in the same place at the same time.

Microphone Selection and Techniques

Surround Microphones

Although I love recording with omni’s and a Jecklin Disk, I decided to try something different for this particular drum tracking session. The Jecklin Disk technique creates a very nice realistic stereo image, but I am not going for realistic in this case. I want drums that are bigger than life and over-the-top.

Used a variation of spaced cardioids very similar to that used in the Decca-Tree style employed in the Fukada tree. In this case I chose to use 2 Neumann KM140 Cardioid Small Diaphragm Mics for the left and right speakers and an AKG 414 XLS in Cardioid for the center channel. I used a pair of Neumann TLM103 for room mics facing into an RPG Schroeder Diffusor away from the drum set.

Front 3 Microphones: Neumann KM140's with AKG 414 XLS in Cardioid in Center

Front 3 Microphones: Neumann KM140's with AKG 414 XLS in Cardioid in Center

Rear Surround Left Neumann TLM103 toward RPG Diffusor

Rear Surround Left Neumann TLM103 toward RPG Diffusor

To recap the surround microphone setup: Left, Center and Right “overheads” are actually in front of the kit to enable better balance between cymbals and drums. Rear surround large diaphragm cardioids point away from the kit into the corners of the room.

Kick Drums (plural, as in two!)

I have always been a fan of the delicious warm thump produced by micing the front hole in the kick with an AKG D112. It always provides a great tone, but can lack a little bit in fast transient response and clarity. I have been using Earthworks TC25’s and SR25’s for the kick and snare drums. The tiny diaphragms offer a tremendously accurate transient response and can handle very high SPLs. I use the Kick Pad which ships with the SR25 to pad the mics output and scoop out the middle frequencies to create a great kick sound. With most double kick players, one drum is the main drum and the other is used for accents and kick fills.

First Kick Drum: AKG D112 and Earthworks TC25

First Kick Drum: AKG D112 and Earthworks TC25

Second Kick Drum: AKG D112 and Earthworks SR25

Second Kick Drum: AKG D112 and Earthworks SR25

The Earthworks TC25 is an omni-directional microphone while the SR25 is Cardioid and provides a little bit of isolation with the pickup pattern. I used the SR25 on the second kick drum and employed the Kick Pad in the signal chain, while I used the TC25 turned off axis on the main kick drum. The TC25 has a flat response all the way down to earthquake, so I chose it for the main kick drum, while the second drum was happy with the slightly tighter sounding SR25.

Snare Drum

The first secret to a good snare sound is a good drummer and a good snare drum. For this particular recording Penny brought 5 snares to choose from and I selected the one that sounded the closest to my ideal of the Al Green and Fleetwood Mac snare sounds: excellent attack, white noise snare sound, warm woody tone (sometimes obtained from Brass and Copper drums!), good tonal variation (rim, sidestick, center, flam, rim shot, etc), and a lot of low midrange (150 Hz – 300 Hz). Again I used a two microphone technique using a traditional snare mic, Sennheiser 421, and an Earthworks TC25 omni. The 421 provides the traditional proximity effect low mid whap (technical word) while the omni fleshes out the toal tone and timbre of the snare. I place the omni pointing at the shell of the snare drum so that it picks up both the top and the bottom of the snare.

Snare Drum: Sennheiser 421 Over the Head (Warning: Never Try This Without A Great Pro Drummer

Snare Drum: Sennheiser 421 Over the Head (Warning: Never Try This Without A Great Pro Drummer

Snare Drum: Sennheiser 421 (View 2) DANGER! Amateur/Intoxicated/Drunk/Average Drummers WILL Destroy Mics in this Position!

Snare Drum: Sennheiser 421 (View 2) DANGER! Amateur/Intoxicated/Drunk/Average Drummers WILL Destroy Mics in this Position!

Snare Drum: TC25 Pointed at the Shell of the Drum

Snare Drum: TC25 Pointed at the Shell of the Drum

Toms (All Five of Them!)

There’s really no super secret tracking technique here, just 5 Sennheiser 441’s. Currently the 441 is my favorite dynamic microphone period. It has a wonderful pickup pattern rejecting sources to the sides and a very small rear lobe behind the microphone. The 441 has fantastic tone, a great bump in the lows and low mids from the proximity response and rejects the other toms, drums and cymbals in the vicinity. The hardest part of micing the toms on Penny’s ginormous kit was getting around the cymbals and other hardware. Obviously the 441 is a large microphone and this does make it hard to use in tight spaces.

Tom No. 5: Sennheiser 441

Tom No. 5: Sennheiser 441

Tom No. 4: Sennheiser 441

Tom No. 4: Sennheiser 441

Tom No. 3: Sennheiser 441

Tom No. 3: Sennheiser 441

Tom No. 2: Sennheiser 441

Tom No. 2: Sennheiser 441

Tom No. 1: Sennheiser 441

Tom No. 1: Sennheiser 441

Notice in the Tom No. 1 photo that I had to use a mic clip from a 421 and LOTS of GAFFER’S TAPE to fashion a mic clip. Sennheiser makes great sounding microphones but by far the absolute stupidest microphone clips EVER. EVER.

Flat Ride Cymbal Spot Mic

After doing a few test takes, it became evident Penny’s flat ride cymbal just wasn’t cutting through the rest of the drum kit. The tone of the flat rides is superb, but they become inaudible with a large or loud kit. I used an AKG 452 under the cymbal to get it to push through the masking. Even though the mic is pointing up, the cymbal isolates the mic from the other sounds so phasing wasn’t much of a problem.

Flat Ride Spot Mic: AKG 452

Flat Ride Spot Mic: AKG 452

Again, I cannot stress enough how important a great drummer and good drums are to getting the sound of a great kit. Thanks Penny!

Penny Larson: The Great Drummer in the Center of the Sound

Penny Larson: The Great Drummer in the Center of the Sound

Audio Quality: How to Build a Listening Room (Part 1)

Saturday, October 24th, 2009

At this year’s AES meeting in New York City, the AES Educators took up the topic of how to teach our students to recognize and strive for the highest quality audio possible.  In order for us to teach  techniques to attain the highest audio quality,  students must have access to good listening environments. The traditional concept behind building a great listening room is to build a room which is essentially a studio control room.  Unfortunately this is extremely expensive, usually requires an acoustician and often an architect and is way out of the price range of most learning institutions.   What is needed is a clear set of guidelines to convert existing horrible sounding rooms into adequate critical listening spaces as cheaply as possible.

Gone are the days of the listening party, where people would come together and listen quietly to music together.  But the listening party teaches us a lot about what a listening room should be like.  Here are some ideals that we should strive for in the listening room:

  1. As Quiet as Possible
  2. As Symmetrical as Possible
  3. Use DIY Acoustic Treatment to Control Problems
  4. The Best Loudspeakers that Can Be Afforded in Good Positions
  5. Use the Creation of a Listening Room to Educate the Students

I teach Audio Technology 2 at the New England Institute of Art in a concrete box, which arguably the worst possible environment to do critical listening in.  If memory serves the dimensions are about 17 x 19 feet with 10 foot ceilings with a drop ceiling at about 8 feet.  I will try to use this room as the guinea pig room to talk about these issues. With any luck, I will get permission and a small budget to improve the room’s acoustics so that it becomes a better environment both for listening and for teaching.

– Hendrik

In the spirit of using my blog as a great way of complaining about the general state of the world I offer the following whine:

Today we have a great many adversaries to high quality audio, some of which I have outlined below:

  1. The dominant listening device is an iPod with Apple-made earbuds. (eew!)
  2. Most modern music productions are over-compressed so that they sound as loud as the other over-compressed recordings. (grody!) This is usually referred to as The Loudness Wars. (Also check out: The Death of High Fidelity)
  3. The second most dominant listening device is the car. (very noisy!)
  4. The third most dominant listening device is the craptop computer. (Noooooo!!!!)

Before You Come to the Studio to Record an Album…

Sunday, August 2nd, 2009

Many potential clients ask me the same questions before they come into the studio to work on their albums or EPs:

What should I do to prepare myself to make a great recording?

Should I record a demo myself first?

I almost always answer the questions with more questions:

1.  Why do you want to make a recording?

Is it to get gigs?  Sell at gigs?  Try to get licensing for TV or movies? Is it to finally hear the music the way that you hear it in your head? Is it to document your songs accurately to the way you play them or is it to fully realize the full arrangements with drum, bass, strings, urdu?

2.  Who is the audience of the recording?

Record label executives  or your friends and fans?  Are you the audience for your own music or are you trying to sell this stuff?  Are you planning on giving it away as a promotional tool to help build your following?

3.  Are you ready to record in a studio now or do you want to demo the songs to figure out how they should be arranged and performed?

Usually demoing the songs yourself will help you figure out what you haven’t practiced enough, and force you to think about the dynamics and the tempos and the form in a way that you haven’t already.  I always want artists to know the tempos of the songs before they come to the studio.  If they can bring lyric sheet with chord changes that also really helpful as well.

If you have a way to record yourself, I would always do at least some recording yourself to help you figure out what you are trying to do.  The recording equipment can be very simple, like GarageBand, a 4-Track or 8-Track cassette or digital recorder, or something a little more sophisticated like a full-blown DAW like Sonar, Logic,  Cubase or ProTools.

After you have had a chance to record simple versions of the tunes with piano or guitar and voice, then you can think about adding other instruments in a much more concrete way.  Some music might start with a drum pattern or loop and build from there.

After you you have done all this pre-production, it will be time to start talking to a good producer or engineer to help really get the recording process planned and started.  As a engineer, it’s much easier for me to do my job when the music is more fully formed before I start my work.  As a producer, I like to be involved in the music process as early as possible so I can help to shape the form, dynamics and feel of the song while the song writing is in process.

How to Become a Hip Hop Producer

Saturday, July 4th, 2009

Their is difference between someone who makes beats – meaning composing and performing (or programming) original instrumental music, someone who is really a producer, and a recording engineer that specializes in hip hop tracking and production.

The fastest way to learn to beat making is to make beats with whatever you have available. I have worked with a couple of heads who were complete geniuses with the Playstation software from MTV. Their music was simply amazing. Software that is highly under-rated is FL Studio or FruityLoops. The step sequencer is the easiest way to make music quickly. Read the manual! Watch videos online.  Start working with as many other beat makers that you can find on the net, in your home town. For me, competition made me write stuff that was much better than working by myself in a vacuum. The three big instruments to learn would be keys, drums, and bass. You did not need to work in a studio to do this kind of work. You need a computer, a decent audio interface (Not an M-Box), and a couple of nice monitors. If money is a factor, don’t get a Mac. You get a lot more computer in the PC world and there’s tons of software available.

A real producer puts the whole show together. They hire everyone, often write songs with the artists, choose the studio to work in, find live musicians to fill out the sound. Sometimes that means doing everything yourself. A lot of the time the producer FUNDS the project and gets the biggest share of the profit (if any).  A producer is a big picture person usually with an excellent understanding of the psychology of creative people, motivation, fear, competition and excellence. This is something that comes with lots of experience, a strong musical background, charisma and usually fame or money.

An engineer deals with the tiniest details of tracking and mixing. Moving a mic a half inch, rotating a mic off axis, how to attenuate the peaks of the kick to get it to sound bigger, without making it wimpy. Attack and Release time minutia for compressing drums, bass and vocals. How the sound stage can be used to the best advantage, how to either avoid masking or use it to create new timbres. You need to learn this either in a studio as an apprentice, in a good audio school that has great facilities (I teach at New England Institute of Art in Boston and at U. Mass Lowell both have great facilities) and then leverage that into getting good internships.

Sometimes there are people who really are all three. Sometimes you will find yourself in one role or the other depending on who you’re working with.

The best job to get to learn audio engineering is working for live sound companies as a grunt. You will carry the bass bins, mic stands and a 43 foot console. But you will get to watch the FOH and monitor guys throw down. Live is good because it forces you to learn to do things quickly and it puts you around dozens of musicians every weekend. Not wanting to be embarassed is a very powerful way to learn.  You are always on stage being watched from the time you load in, to the time you strike the stage.

(posted to GearSlutz 7-4-09)

How To Use a Compressor: Understanding Dynamics

Saturday, June 27th, 2009

One of the hardest audio processors to understand is the compressor.  Even after several years of using compressors many of my students and readers still have lots of questions about how to dial in the sound that they are trying to get.  Compressors are in the Dynamics Processors family which also includes limiters, expanders, gates and noise reduction.  Dynamics processors work in the Amplitude Domain.  Compressors work on the amplitude of an audio signal, which is basically the loudness of the signal.  Look at a waveform view of an audio signal:

Graph of a Sine Wave with Amplitude and Frequency

Graph of a Sine Wave with Amplitude and Frequency

The vertical axis shows Amplitude, which in analog (electrical)  audio refers to the amount of voltage in an analog signal. When the wave is above the center line, then the voltage is positive and when the wave is below the line the voltage is negative. Audio (in the electrical analog sense)  is AC or Alternating Current which means the voltage goes from positive to negative and then back again. The further away from the center line, the higher the voltage and the louder the wave will sound.

The Dynamics of music is generally thought to be the differences between the loud parts of music and the quiet parts of the music.  The dynamics of audio includes all of the differences in amplitude along the waveform.  In most pop music, for instance, the loudest parts of the music are the snare drum hits, followed by the lead vocal, then the background music. Notice in the following image the red dots above the waveform.  They are marking the locations of the snare and kick drum hits in the music.

The red dots mark the locations of the snare and kick drum hits.

The red dots mark the locations of the snare and kick drum hits.

Notice that there is audio in between the loud hits as well, but that it just has a lower amplitude. Compressors and all dynamics-based effects work on the amplitude of the audio, to adjust and change the differences in voltage.  The loudest level in digital audio is 0 dB Full Scale or (0 dB FS) which means that anything above that level will be distorted or simply just an error.  We can’t change the loudest possible level, but we can change everything that is below that level.

What a compressor does:

A compressor attenuates (decreases amplitude) audio that is above a threshold by a ratio.  The attack time is how quickly the compressor starts to attenuate the signal after the threshold is exceeded and the release time is how quickly the compressor stops attenuating the signal when the audio drops below the threshold level.

Probably the most common use of a compressor is to make an audio signal sound louder without peaking out the signal and causing clipping and distortion.  In a nutshell, the loudest parts of the audio signal (the peaks) are made a little bit quieter so that all of the signal can be boosted by the amount that the peaks were attenuated.