Introduction: Modular Hi-Fi Speaker System (New Media Art Project)
INTRO
As a creator who is really passionate about physical acoustics and elctroacoustics, I have been greatly inspired by the works of artists/engineers like Devon Turnbull (OJAS), Mo Yasin, and Tom Sachs. All of these artists have been deeply influenced by Hi-Fi/DJ culture and have taken a dive into sound reproduction as not only a science, but as an art form. A lot of them have this very scientific understanding of sound that they have paired with a very creative and artistic mindset to create their projects.
I started college as an Audio Engineering Major and completed two years of the coursework for that degree. The coursework taken was a little bit about mixing/mastering/production, but for the greater portion it gave me a really solid understanding of basic electronic, acoustics, and some digital signal processing. When I changed out of the major, I was finding that the work in the realm of CS and more intense engineering was both harder to grasp and not as fun to think about. Despite this I was still very connected to Audio and Acoustics as a major part of my interests and I didn't want to let that go. Over the Summer after I dropped the AME Major, I worked as an Assistant Studio Engineer and did a bunch of Wall Tie Repairs, furniture assembly, and signal flow design under the instruction of a Professor and Masters student who led the renovation of the two studios. In my free time I worked on my own music and started thinking about building speakers as it had been one of the areas that made some sense to me. I really learned a lot of technical skill in that time and began thinking more as a designer than just a technician.
That same Summer I went to Devon Turnbull's Dream Hi-Fi Listening Room No. 1. There I was really inspired to try experimenting with sound and space a lot more. I also realized there is very little accessibility when it comes to experimenting with sound in the world of Hi-Fi despite the fact that it originated with a very DIY culture in the 60's and 70's. That being said I started work shopping my idea for a DIY Modular Hi-Fi System.
PROJECT ABSTRACT
I want the DIY Modular Hi-Fi System to encourage experimentation with placement/arrangement of speakers the way that old hi-fi systems used to. The current products available and oppertunities for experimentation are gatekept by location of listening rooms and money/accessiblity to equiptment that often comes prepackaged. To figure out what kind of sound you like for the space availible to you, this project offers a large woofer, a mid-size woofer, and a tweeter. Because of their seperate enclosures with independant inputs, there is a lot of control over placement, amount of sound/drivers, and crossover. I use a modular crossover with a variable frequency and the option to use 2 or 3 drivers. This provides the option to experiment and develop a preferance on how your different frequency ranges get reproduced and how powerful each section is.
Supplies
COMPONENTS
- 1x Super Tweeter Horn
- 1x 8-inch Speaker Driver
- 1x 12-inch Speaker Driver
- Several feet of Speaker Wire
- Silver solder (or any conductive electrical solder)
- 1/4 inch Female TS/TRS connector (2 to screw into enclosures and 1 to make a cable end)
- Quick release connectors
- 3x Sheets of MDF or Ash Wood (4'X8')
- Acoustic Foam/Insulation/ Dampening Materials
TOOLS
- Buzz Saw
- Rotar
- Drill - with different bits to drill holes or drill in screws
- Wood screws
- Hammer and nails
- Wrench
- Nuts, washers, screws
- Fastening mount
- Wood Glue
- Soldering Iron
- Clamps and Heavy items (not necessary, but can help when the glue is setting and with propping up walls)
- Flex Putty (not necessary but can correct for errors)
Step 1: Gathering of Electronics and Materials
I started by selecting the electronic components of the system.
For this project, I used a salvaged Sony 12-inch Woofer for the low-end (alt full-range), a new GRS 8-inch Woofer for the midrange (alt full-range), and a new Eminence APT-150 Super Tweeter (high-mids/high-end).
All of these components are matched impedance at 8 Ohm's making them easy to put into parallel. In the two charts above I have illustrated the math for putting 2 of the drivers through a crossover in parallel versus 3 of the drivers through a crossover in parallel.
Because the objective of this project is to make the set of speakers modular in the sense that you can run an amplified signal through either a 2-way or 3-way crossover out to any variation of speakers, the matched impedance creates consistency on power drawn by each speaker in each configuration.
Step 2: Designing/Building Your Enclosures
DESIGN
First, determine how much volume you want your enclosure to have.
For this project I saved a bit of time and went with some rough approximations based on Theile-Small Parameters of the woofers that found using an online calculator.
Demo: GRS 8inch Woofer
The Thiele-Small parameters of the GRS 8PR-8 8" Poly Cone Rubber Surround Woofer are:
- Fs (resonant frequency): 57 Hz
- Qts (total Q factor): 0.39
- Qes (electrical Q factor): 0.44
- Qms (mechanical Q factor): 4.7
- Vas (equivalent compliance volume): 20.2 liters
- Xmax (maximum linear excursion): 3.25 mm
- Sd (effective diaphragm area): 214.5 cm^2
- Re (DC resistance): 7.1 ohms
Using the parameters provided, we can calculate the recommended box volume for a sealed enclosure using the following formula:
Vb = (Qtc / ((2 * π * Fs)^2 * Vas))^0.5 - Vas
Assuming a desired Qtc of 0.707 (Butterworth alignment) and using the Thiele-Small parameters provided, we can calculate the recommended box volume as:
Vb = (0.707 / ((2 * π * 57)^2 * 20.2))^0.5 - 20.2
= 6.47 liters
For a sealed enclosure, we can use a rectangular box design with internal dimensions of 11.6" x 8.7" x 7.6" (width x height x depth) to achieve a box volume of approximately 6.47 liters.
After getting an aproximate volume, I looked around at some other designs and went off of Devon Turnbull's more cubic design. My sizes wound up being aproximately 16" cube and a 22" cube. This wasn't quite perfect, but it worked for the goal of the project.
I also chose to use MDF as it is a traditional speaker enclosure material that is proven highly effective.
ASSEMBLY
From there I cut out the walls from the sheets of MDF using a buzz saw and some marking chalk.
After Completing my cuts I used wood blocks and different other square shapped objects to create braces/props while I secured the pannels into place with a healthy amount of wood glue.
Step 3: Adding Wiring and Inputs
Using a drill I cut out some holes sized to fit a 1/4-inch input that I fastened into place with a washer and a nut.
After doing that I soldered on one end of my wiring to the +(tip) terminal and -(sleeve) terminal of the female 1/4-inch connector. On the other end of the cables, I soldered on two quick-release clips.
Step 4: Making Front/Back Panels
Using a router, I carved out a square for the back plates and front plates to provide access through the back of the enclosure and also so I can mount the speaker drivers inside of them.
Step 5: Mounting Drivers
I over-cut a bit with the router for the driver holes so there were some creative solutions developed.
For the 12-inch woofer, there was enough of an overlap to use a drill to carve some deeper holes and then a different drill bit to punch 4-6 securing holes in the wood. Then I fastened the woofer in place with nuts, bolts, and washers.
For the 8-inch woofer, there was no overlap so using security braces, I attached one hole to the driver with a nut, bolt, washer, and a little piece of felt for acoustic dampening and protection.
Step 6: Attaching Front and Back Panels to Enclosures
***Make sure everything is level using a power sander/belt sander***
Using another healthy amount of wood glue, secure the front and back plates onto the enclosures. If there are any openings or leaks you can use a glue or sealant like FlexSeal to close up any unwanted leaks.
This may dampen the resonance of the box, but I think for a simple correction and the first attempt at this project it worked alright.
(I would advise attaching the back pannel after your drivers are attached to inputs.)
Step 7: Connecting Inputs to the Drivers
Because we soldered on quick-release clips, all that has to be done is clipping them onto their respective positive or negative terminal and crimping to ensure they remain in place.
Step 8: Horn Cable
Solder the Yellow (or whatever positive wire you select) to the + (tip) terminal of the TS connector, then solder the black wire to the - (sleeve) terminal
Step 9: Mounting Horn and Attaching Cable
Screw in the bottom of the horn to a 6"x12" plank with some acoustical foam underneath the magnet.
Then grab some wire and attach a 1/4-inch female TS connector to one end and 2 quick-release clips to the other two ends of the speaker cable.
Then just clip and crimp the quick-release connectors to the two terminals on the driver (labeled + and -).