Understanding Direct Boxes: PART 2


Understanding Direct Boxes: Types

In Part 1 of our Understanding Direct Boxes series, we discussed the three primary functions that a direct box performs. Today, we will look at the two main types of direct boxes and how to use them.

Active vs Passive

There are two types of direct box: Active and Passive. The passive DI works standalone, you can plugin and get to work. The active DI employs a preamplifier stage that boosts levels and requires power. Most active direct boxes receive this power from one of three sources:

  • Batteries
  • External power supply
  • Phantom power (from the connected mixer)

Selection of the appropriate DI for the job can make the difference between good results and great results. This choice offers the savvy engineer another tool to optimize the gain structure of their system.

Conventional wisdom says:

  • Active source: Passive direct box
  • Passive source: Active direct box

Running a passive single coil guitar? Grab an active DI. Slapping a modern bass with active pickups? Reach for the passive DI. Because the active direct box contains an amplifier the weaker signal inputs will be boosted before entering the stage snake.

However, many designs like the Radial Engineering J48 Stereo can blur the lines between when to grab a passive or active DiI. Active DIs can be helpful for driving longer cable runs and they provide more headroom loud instruments. Making them a smart choice for keyboard instruments or track playback from a computer or smartphone.


As you can see knowing the difference between active and passive direct boxes can help in optimizing the performance from your sound system. In addition to simply connecting an instrument they can play an important role in getting a clean signal through your sound system.

Our recommendation is to invest in at least one of each and try them everywhere. There is no harm in trying them out. This will allow you to develop your own preferences about what to use with each instrument.

Understanding Direct Boxes: PART 1


A Direct Box goes by many names:

  • DI
  • Direct box
  • Direct input
  • Direct insert
  • Direct injection
  • Direct interface

Source Types

Whatever name you choose to use, this little box performs several vital functions to achieve quality audio performance from your instruments and sound system. The direct box is most commonly used to connect unbalanced instruments like bass and electric guitars as well as electronic keyboards to a sound system. Other less common sources that can benefit from a DI are:

  • Acoustic Instruments with pickups
  • Electronic drums
  • iPods, MP3 players, and Smartphones
  • Unbalanced CD/DVD players
  • Computer audio outputs

Optimized Performance

The DI serves three primary roles in optimizing audio performance in your instruments:

  • Converts Unbalanced to Balanced
  • Impedance Matching
  • Level Matching

The direct box converts a high impedance, unbalanced instrument level signal to low impedance, balanced mic level signal.

Unbalanced to Balanced

One of the primary functions of the DI is to take the unbalanced signal from these sources and convert it to a balanced signal. This balanced signal can then be plugged into a standard microphone input on a stage snake or mixing consoles microphone preamplifier.

Balanced signal connections offer greater rejection of noise that can be introduced to the system over lengthy cables runs such as common stage snakes.

High Impedance to Low Impedance

Electrical impedance is the resistance to the flow of electricity in a circuit. These unbalanced instrument sources are high impedance signals.

High impedance signals tend to become dull, losing high frequency detail when traveling cable lengths over 15 - 20 feet. Using a short instrument cable to a DI can make an eye-opening difference to the tone of your instrument through a sound system!

Level Matching

The final transformation that the direct box performs is level matching the signal to the microphone input of your mixer.

Microphone signals are very low level signals, by contrast instrument level sources are higher in signal strength. A direct box allows you to plug in an instrument level signal into the microphone preamplifier of a mixing console.


The direct box plays an important role in providing noise free, high quality audio from instrument level sources on stage to the console at mix position.

With few exceptions, most DIs employ a transformer to accomplish their audio magic. The results are directly related to the quality of the transformer used. Well-constructed DIs can last several decades, so we suggest spending the money to get quality results for decades to come.

Circle City Audio proudly recommends DIs from:

  • Countryman Associates
  • Radial Engineering
  • Whirlwind

If you would like to purchase some new direct boxes for your system give us a call. We would be delighted to to help find the right product for your needs. 

Audio Everywhere from Listen Technologies

We regularly spend time to be aware of industry trends, allowing us to stay current on what is available for our customers. We are looking for disruptive products that offer previously unavailable features. Audio Everywhere is such a product!

With Audio Everywhere you can utilize your new or existing WiFi network to distribute audio to a free smartphone app (Android and iOS). Systems start at only $800.


For further details:

Call Us: (317) 536-2979

Audio Anywhere

Listen Technologies


Rate Changes for 2018

With the coming new year, we will be making adjustments to our current labor and training rates. We also wanted to remind our clients of certain charges and rates that are already applicable. Please take a look at the changes below by department:

Onsite Service & Training

  • Our new labor rate for onsite service and training will be $100 per hour.
  • Blocks of time can be prepaid. 10 hours can be bought for $900 - a 10% discount.
  • Charges for travel time and expenses are applied after the first hour of driving from our nearest office.
  • Telephone technical support may also be charged at the hourly rate with discretion.

Repair & Service Center

  • Repair service rates at our service center in Indianapolis are $75 per hour. Intake, and possibly repairs, can also happen at our Fort Wayne office.
  • Expedited repairs (“first in line”) carry an upcharge of $75

CCA Welcomes Martin Audio

Circle City Audio, Inc. would like to welcome Martin Audio to our growing catalog of brands. 

Sublime Sound
It goes without saying that these speakers sound remarkably good!

MLA Line Array
Martin Audio has several noteworthy products, their MLA line array products which come in a variety of sizes (MLA, MLA Compact, and MLA Mini) and provide unique control over the sound. With electronic control over the system's vertical coverage and Martin's "Hard-avoid" feature, audio can be placed exactly where the listeners are seated.  The end result is greater clarity and speech intelligibility.

CCD Point Source Speakers
The CDD and CDD-Live speakers are 2-way cabinets that employ Martin's Coaxial Differential Dispersion technology to reduce high frequency beaming while retaining all the benefits of coaxial speakers.
Translation: Smooth coverage both left to right and front to back of the venue.

One More Tool for the Toolbox
We are excited about the tools that Martin Audio brings to our toolbox. We feel these products will enhance our ability to design systems that meet or exceed our customer's expectations.


CCA Acquires LP Productions

We are happy to announce that CCA has purchased LP Productions, a well known AV company in Indianapolis, IN. 

LPP has two primary business arms: live event production and a factory authorized service center for many manufacturers. Both of these arms will be strengthened and grown as we move forward.

We will be maintaining LPP’s current facility on Lynhurst Drive in the Speedway area and our existing Indianapolis sales, technical and office personnel will be working out of that location beginning Monday, October 9th.

Thank you for your ongoing support of CCA as we enter our 23rd year of business. We are excited about our growth and are committed to continue to learn and improve in order to ensure many more years of good experiences for you.



Cincinnati Christian University 'Lights the Hill' with Circle City Audio


Circle City Audio and Cincinatti Christian University are two organizations with similar initials, and similar goals, and we have developed a partnership over the past few years.  From providing production for their annual worship conference to new lighting and projection systems in the university chapel, we have been working closely alongside CCU to provide excellent solutions for their technical needs.  

Recently we sent a crew to provide audio production for their outdoor 'Light the Hill' event, bringing all of the various gear needed to move a 7 piece band from the chapel stage, to the lawn of the 'quad'.   

The highlight of the night was the lighting of the flying lanterns that drifted majestically over the city, but underneath it all was a sound system that helped the team at CCU communicate with and inspire the students.   We are glad to have been a part of another successful event, continuing the partnership between our organizations.  

Crossroads Gets a MASSIVE Upgrade.



One of the projects CCA accomplished this week was a massive trussing and projection upgrade at the main campus of Crossroads Community Church in Goshen - https://www.mycrossroadscommunity.com

The task was to overhaul the stage ceiling space (the church folks removed a false drywall ceiling to prepare the way) with a giant grid of box truss as well as 'finish' two home-grown truss spans over the congregation. We also added long truss runs down each side of the sanctuary for flexible lighting and camera locations.

Additionally, the oddly shaped center screen that had been standing in the middle of the stage and shot with two projectors was replaced with a 16' wide HDTV format screen being illuminated by a fabulous Sony 6K laser projector yielding incredible brightness of the main/center screen even with full house and stage lighting.

Now, all three projectors are running from the Blackmagic video system we installed last year instead of the center screen having to be separately fed due to the odd resolution so now the video presentation is much more seamless and any content can go to any screen.

Lastly, we incorporated a bar system and fly points for a curtain system so the upstage side doors can be more elegantly used for stage access without people being seen coming on/off the stage. And when it is time for a baptism, the drape is simply drawn away from below the screen to reveal the sunken baptistery with easy viewing under the screen which bottoms at 7 feet high.

Many thanks to Chris Curl and other folks from CCC who helped bring the project to completion by contributing many hours of 'sweat equity'!     
Andrew Van Veld

'Creating a Moment': Incredible experiences at SHIFT National Conference

You've invited thousands of people from all over the country to join you at your bi-annual national conference, and you need the tools to inspire and engage them.  You need to create a conference full of moments, moments that tell the story of your organization, moments that will stick in the mind of your participants.  You do not  want them to just hear about your organizations work, you want them to experience it in a personal and life changing way.  You have an incredible opportunity to encourage your organization to grow, and you do not want to waste it.  

For us, it is not about the flashing lights and loud music, but rather, it is about using those tools to create an experience.  By putting together complex audio, video, and lighting systems, we gave our client the tools they needed to accomplish their conference's mission.  Our experienced technicians were on hand to help as needed, and make sure the technology was never the focus, but instead remained invisible to conference participants.  

We have the tools you need to create something spectacular.

Create a moment.  

Some of the tools we used to accomplish the goals of the Shift National Conference include gear from the following manufacturers:

Adamson Systems Design-Line arrays
Lab Gruppen-Amplification
Blackmagic Designs-Video switching and control
Chauvet-LED and Intelligent Lighting
Digico-Audio mixing consoles
Global Truss-Trussing and Rigging
Jands Vista-Lighting control
Peasoup-Atmospheric effects
RF Venue-Antenna Distribution
Shure-Wired microphones
Sennheiser-Wireless and IEM systems
Sony-Projection and Cameras

This is all gear we own and is available for rental for your next event.

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Emmanual Lutheran Church improves accessibility with Circle City Audio.

Romans 10:17 So faith comes from hearing, and hearing through the word of Christ.

If you preach a life changing message, but no one can hear it, does it have an impact?  

That’s the question that ELC and school asked itself as it began its first major renovation project in nearly 50 years.  So when ELC approached us to plan and implement the audio and video components of their historic renovation, we knew we needed to focus on one word.  


Making sure that your church is accessible is an incredibly important step to ensure that your message is coming through loud and clear.  We were able to leverage new and existing technologies to ensure that each and every member of ELC’s congregation could hear the Word.  We designed a hearing loop to serve those with hearing impairments, allowing many of them to hear the message clearly for the first time in years.  We didn’t stop there when it came to improving accessibility.  In fact, we were able to make ELC’s services accessible to those who could not be in attendance through the use of high quality video and audio recordings.  

Mission accomplished?  

Not yet, we took our focus on accessibility one step further.  

Great gear isn’t great if you can’t use it, so we also made sure to design and implement a system that has accessible control points, making the system easy to use regardless of the technical skills of the end user.  Through the use of the Allen and Heath dLive platform, we brought control into the hands of the people who needed it most, making services flow more smoothly, and reducing volunteer requirements for simple events throughout the week, including daily school chapels and smaller church services.   

The end result?  A church that can now reach outside of the four walls of its sanctuary, making the gospel accessible to those who seek it.

Projection Masking & Mapping Event

Our first 2017 event is OPEN for registration! We have three times available for your convenience. Join us in Fort Wayne, IN, February 1st at 12:00pm or 7:00pm. We’ll also be offering a session on February 2nd at 12:00pm. 

Learn how to do environmental projection with what you already have. We'll teach you the basics of what environmental projection entails, how to properly mask, and how to get started in your own venue. We'll also touch on the basic building blocks for projection mapping. Event will be 1-2 hours with plenty of time for questions about your specific space as well as hands on application.

Click the link below to register. Don’t forget to invite your friends!