Sound system design
Independent Design Project
When I first got my boat, it came without a sound system so I had the opportunity of designing my own from scratch. I was excited to use apply what I learned in my electrical engineering class to design and optimize my own audio system.
I started with the speakers and decided I wanted something LOUD. I selected some 2 way coaxial speakers that are 100 Watts RMS each. To put it in perspective, the speakers that come stock in a new car are about 10 Watts RMS. When the speakers arrived, I designed and printed a speaker cutout template. I then began to cut holes in the gel coat and fiber glass with a hole saw. Then I drilled out the four mounting holes for the screws that fasten the speaker to the boat. I cut the holes for all six speakers in the boat and ran 14 AWG wire to all of them.
I started with the speakers and decided I wanted something LOUD. I selected some 2 way coaxial speakers that are 100 Watts RMS each. To put it in perspective, the speakers that come stock in a new car are about 10 Watts RMS. When the speakers arrived, I designed and printed a speaker cutout template. I then began to cut holes in the gel coat and fiber glass with a hole saw. Then I drilled out the four mounting holes for the screws that fasten the speaker to the boat. I cut the holes for all six speakers in the boat and ran 14 AWG wire to all of them.
After finishing the speaker holes, I needed to select some amplifiers to power them. I chose to power the two front speakers with a single amplifier and the 4 rear speakers with another amplifier. At this time I also had to select a subwoofer amp because I needed to design the amp rack. I designed and cut out an amp rack that would hold all three of the amps. I then drilled all the holes I would need for mounting hardware and wires. After the wood was cut out, I covered it in felt to match the boat's interior.
This amp rack has holes cut in the middle to optimize air flow so I could turn up the stereo without worrying about it overheating. I mounted the amps and then also added a fused power distribution block. I then ran speaker wire for the 6 channels and an additional 2 channels for the subwoofers. I decided to wire all the speakers into a 12 pin molex plug so I could remove the whole rack from my boat if I wanted to. I wired each amp with 4 AWG copper wire to the power distribution block. I also wired in the blue remote wires and the RCA cables. Lastly I mounted a relay on the board. This relay was for part of a plan for a future lighting project. The whole board plugs into some 0 AWG wire that connects to the boat's battery.
This amp rack has holes cut in the middle to optimize air flow so I could turn up the stereo without worrying about it overheating. I mounted the amps and then also added a fused power distribution block. I then ran speaker wire for the 6 channels and an additional 2 channels for the subwoofers. I decided to wire all the speakers into a 12 pin molex plug so I could remove the whole rack from my boat if I wanted to. I wired each amp with 4 AWG copper wire to the power distribution block. I also wired in the blue remote wires and the RCA cables. Lastly I mounted a relay on the board. This relay was for part of a plan for a future lighting project. The whole board plugs into some 0 AWG wire that connects to the boat's battery.
After I installed the amp rack, I needed to install the head unit to control the amps. I decided to mount the head unit in the glove box to keep it away from the water. I started by cutting out a piece of plastic trim to the dimensions of the head unit. I then mounted the head unit and connected it to power and the RCA cables.
After all the hardware was installed, I needed to tune the amplifier gains, high pass filters, and low pass filters. For the gains on the subwoofer amp, I played a 60 Hz tone on the head unit at about 75% of the head units volume level. I disconnected the subwoofer and plugged the oscilloscope directly into the output of the amp. I turned the gain up until I saw clipping on the oscilloscope like the images below show. I then backed down the gain until the output wave was smooth. This is how to show you are getting the maximum power from your amp without distortion. I repeated the same procedure for the two speaker amps but this time with a 1000 Hz tone.
Technical Skills learned
- Car Audio System Design
- Cable Crimping
- Low Voltage, High Current Wiring
- Fiberglass Cutting
- Gain Optimizing
- Aesthetic Design