Archive for the ‘audio’ 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!

JBL L100T: Speaker or Food Storage?

Sunday, July 17th, 2011

I was recently given a pair of JBL L100T speakers from the late 80’s.  They needed to have the foam surround replaced because the originals had started to rot away. I ordered new surround from Speaker Works ( so that I wouldn’t have to pay an arm and a leg for the repair.

In order to replace the foam surrounds, I needed to first remove the woofers from the cabinet so that I could work on the speaker more easily.  After removing the speaker, I discovered a large pile of what appeared to be cat food in the bottom corner of the speaker.

Here are some of the photos taken on my phone. Apologies for the poor quality, the room was dark and I had to use a flash for up close photos…

Inside JBL L100T Speaker

Cat food carefully collected and stored by a family of mice.

Underneath the fiber glass absorption...

More cat food and mice dropping found under the fiberglass insulation

Bag full of cat food pulled from speaker cabinet

I pulled the bag's worth of cat food out of the speaker cabinet.

More later when I get the speaker surrounds replaced!


Classic Gear: Distressor

Wednesday, October 27th, 2010

By Carlton Meriwether (from the New England Institute of Art AKA AI New England)

Distressor EL8-X

Distressor EL8-X

Distressor EL8-X

The Distressor EL8-X is a mono digital compressor/ limiter produced by Empirical Labs. A highly adaptable machine they’re considered one of the industry standards for compression and distortion. They have a multitude of compression ratios ranging from 1:1 to 20:1 and a Nuke setting for brick wall limiting. Two types of distortion can be applied focusing on 2nd or 3rd harmonics.  Time based features like attack and release are calibrated to keep consistency between machines when stereo linking.

The Distressor was built with not only modern compression but with vintage emulation in mind. The Distressor has a soft parabolic knee when set to ratios less than 6:1 giving a more natural sound to compression. Setting the unit to 6:1 or greater applies a more sharp vintage knee to simulate tube, FET, or  optical compressor machines from the past. There are specific settings listed by the manufacturer to emulate the LA-2A, 3A, 4A; the dbx160; the Fairchild IGFET and 670.

With a frequency range of 2Hz to 160kHz and a 110dB dynamic range the Distressor is a complete all around compressor. With an MSRP of $3000 for a pair ($2295 through dealers like SweetWater) the Distressor is a reasonably affordable replacement for multiple vintage compressor/limiter rack modules. An over all well built machine utilizing all metal film and Roeder resistors, the craftsmanship is well above average in American made electronics. The hand connected input and output ports allow for consumer changing of the “hot” pin in the xlr connectors to match any gear already in use and the A/C power source can run on 110 and 220 volt inputs giving the Distressor superior compatibility on a global scale.


Classic Gear: dbx 160

Monday, October 25th, 2010

Written by Joe Cenedella (New England Institute of Art AKA A.I. New England)

dbx 160 (1976) Designed by David Blackmer, using early Overeasy circuit and RMS detection

The dbx 160 was introduced in 1976 as a professional quality compressor/limiter.  The brainchild of David E. Blackmer (founder of dbx) it quickly became a must have for studio engineers of the time.  Besides being one of the earliest compressors, the dbx 160 introduced to the market features that allowed for a much smoother and more natural sounding compression.  The 160 uses voltage controlled amplifiers (VCAs) which adjust gain settings to fluctuate with the voltage creating smooth and natural sounding compression that closely simulates how the human ear interprets sound. Along with the VCA the dbx 160 introduced true RMS detection paired with feed forward gain reduction. This allows the model to achieve an infinite compression ratio (120:1) without excessive gain levels, and without excessive distortion, which causes oscillation in the feedback loop. All models of compressors at the time the dbx 160 was introduced gave the user some control over compression in the form of preset ratios (10:1, 20:1). (source) this is where the VCA’s come in allowing the attack and release to fluctuate with the input signals envelope. This allowed for more of a set it and forget it approach instead of constantly adjusting the ratio throughout a performance.

The Features:

Auto detected/attenuated 40dB for ground loop hum

Introduced “over-easy” compression, or soft knee compression

Adjustable threshold 10mV-3V

LEDs for input level, output level, or gain

First to have fully adjustable compression up to 120:1

RMS detection, VCAs, and Feed Forward gain reduction

VU origin adjustable 20dB (+/- 10dB input)

Mono inputs, two required for stereo tracking

Output level of +/- 26dB Hi-Z, +/-24dB Lo-Z

Cost New: $300 in 1976

Cost Now: pair sells on ebay for $1600

Link to user manual:

Official dbx Pro Audio Info:

Other Sources:,_Inc.

Cheaper Alternatives for Audio Cabling?

Tuesday, December 22nd, 2009

The following is a Facebook exchange that I had with a former student outfitting his new studio.  He raises some great questions about what makes a cable compatible with audio.

if i were to put an audio snake through 1 1/4 conduit and i were to use cat5 as a temporary cheap(free) way to do this would it work for 16 channels?

I know it will fit in the conduit.. at least thats what the electrician told me.
I am more interested in how well cat5 will work as a temporary audio cable

CAT5 unfortunately will not work as audio cable unless you convert all the audio to digital first and then shoot it down the line. This would be REALLY expensive. CAT5 isn’t shielded, though the “twisted pair” nature of it does help a little. CAT5 has 4 pairs of very thin solid core wire, so that you would only get you 4 channels, even if there was a shield.

Your best cheap option for 16 channels is to buy 16 channel snake cable and solder the ends without the breakout box. Redco does sometimes have used snakes for sale.
Do you need all 16 channels? What else is in the conduit? If there’s any power there don’t run any audio into it!

I like Clark Wire’s cable because of the color coding and a very convenient drain wire

Do you mind if I post your question anonymously on my blog?

Go right ahead and put it on your blog. I figured the lack of shield would destroy me. I am just in a situation where i can get way more than a hundred feet of it for free and was wishing it would work. i only need to go about 50-60ft so i would have done 4+ runs of it.

The conduit is going to be along the baseboard and the power is going to be ran through the ceiling and come down where needed about 12-18inches up the wall.

My parents have a mid sized barn(closer to small i guess) that they currently rent out. The renters have told my parents they will no longer need it after January. I was hoping to get a little project space for when i am not busy over the summer. i might “steal” some of the “broken” dmx/XLR from work and see what i can do with that before buying stuff i can’t afford ha ha.

on a side note…
Will 5 wire DMX work if i just don’t use a wire?

DMX Cable has higher impedance than audio cable because it’s for data. DMX is around 110 Ohms while audio cable is around 70 Ohms. I also think DMX cable has thicker shielding. You could probably use DMX cable for digital connections like AES-EBU which also uses an XLR connector.

It’s possible that you could send audio on a DMX cable but you might get signal loss because of the higher impedance. I wouldn’t risk it personally. I would see if you could find a used snake somewhere and fix what needs to be fixed.  Sometimes companies have short lengths of cable that they will sell for a discount.

Good luck!

Please let me know if anyone finds out some new cheaper ways of doing our work!

Review: PreSonus Faderport with Sonar PE

Sunday, November 8th, 2009
The Faderport by Presonus

The Faderport by Presonus

This week I purchased the Presonus Faderport for use with my DAW, Sonar Producer Edition 8.31.  I have been finding that I really like the immediate control and hand/ear coordination that a real fader provides because I have been working a lot on the API Vision at U. Mass Lowell.  I read a zillion comparisons between the Faderport and Frontier Design’s Alphatrack, a similar single fader automation encoding device. Here’s a very interesting video that compared the speed of the faders on both units.

As you can see from the video, the Faderport’s reaction time is significantly faster than the Alphatrack.  It should be noted that fades as fast as the ones in the video are pretty rare.  For something this fast, most of us would do a mute automation and not a super fast fader move.  The fader on the Faderport is very nice feeling.  It’s quite smooth and although it is a little noisy, it is clearly the highlight of the unit.

The pan knob frankly sucks.  It is a detented pot, so it clicks as you turn it.  There is no specific center detent and in Sonar after you move the pan control the closest you can get to center is +/- 1%.  You also need to rotate the knob completely several times before you get a hard pan left or right.  The pan control is actually more cumbersome than doing fade automation with a mouse.

The instructions for install are really poor.  For individual DAWs you can’t use the included CD-ROM for the installation.  Rather you need to go to the PreSonus website and download a specific driver/plugin for your DAW, but they don’t tell you this in the instructions.  The Sonar driver doesn’t include the feature of being able to program the single user-assigned button with a task and the PROJ button (which is supposed to open the track/edit view in Sonar) doesn’t work at all.  You can open the Mix window and the Transport control, but not the Edit window which is the most commonly used window in Sonar.

It also isn’t clear if you can assign the fader or the pan control to anything other than volume or pan, so you are REALLY limited as to what you can control and automate from the device.  All in all I found the Faderport pretty disappointing and I plan on returning it and getting an Alphatrack.

Here’s the video overview of the PreSonus:

Daking FET II Compressor Review: Super Fast and Transparent

Monday, November 2nd, 2009
Daking Audio Gear: Mic Pre IV and 3 FET II Compressors

Daking Audio Gear: Mic Pre IV and 3 FET II Compressors

I currently have three of these units in my studio right now and I have had a chance to really put them through their paces.

First, I should say that the sound quality on these units is pristine. There is very little coloration of the sound even when using heavy compression. Many compressors seem to roll off high end when they attenuate heavily, but this is not the case with the FET II. The FET II uses Jensen transformers both in and out of the unit and the pc board is extremely clean and well designed. The FET is in a socket so if it were ever to go bad, it is easy to replace.

The FET II excels at transparent compression and is easily used on bus or program material where lesser compressors really start to sound yucky. The attack times vary between 250 micro seconds to 64 milliseconds and it’s fast enough to be used effectively as a brickwall limiter if desired. The release characteristics are I think what really set the compressor apart though. You have some standard settings of .5 – 1.5 seconds, but also some really nice dual time constant releases designed to mimic some of the nicest compressors in history. The idea behind dual time constant release is this: the compressor releases a little fast at the beginning and then slows down. This effectively eliminates the “pumping and breathing” sounds associated with more abrupt release times.

I have also been able to get some really nice vocal distortion (think Flood’s production techniques) out of it by using the fastest attack and release times and a very high ratio (20:1). Then I drive a very hot signal (over +20) and get a very pretty sounding harmonic distortion very appropriate for alternative rock vocals like NIN, PJ Harvey or Smashing Pumpkins.

I recommend using only XLR cables in and out of the unit, you can use a 1/4″ input but it boosts the signal 14 dB to make up for the -10/+4 difference in operating levels between consumer and pro gear. Another odd thing is the power supply (external, but not a wall wart) uses a DB25 connector which looks pretty weird, but works perfectly well. Just make sure your intern doesn’t try to run the power supply into the DB25 input on an audio interface or multitrack….Bad intern! Bad intern!

You can link two units together to work in stereo with a 1/4″ guitar cable. The sidechaining connection uses DC summing to tell the linked unit when to compress and does not send audio. The FET III does audio summing, but it’s in stereo and is geared more towards working in stereo anyway.

All of the knobs on the unit are switches so you can set two or more compressors exactly the same way and repeat your settings later on. The knobs are really heavy and feel like you’re really working with pro gear.

All in all this is a great compressor with excellent transparent compression that doesn’t color the sounds you are working with. You can use it to chase the waveform to create harmonic distortion with the fastest attack settings to add a little crunch to vocals, bass or drums.

I can’t recommend it more highly.

Woody Giessmann of the Del Fuegos Talks about Working with Hendrik at Indecent Music

Thursday, October 1st, 2009

Recording at Indecent Music with Hendrik

Tuesday, September 15th, 2009

The following video is about my recording philosophy and the gear that I use at Indecent Music.  I record, mix, and master out of Indecent Music.  I also provide audio engineering training and private lessons so that song writers can learn to be more effective at making their own demos.

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)