Off the shelf electronics utilized for this Project:
- Memphis Audio MXA1MC – a little hard to find these days
- Memphis Audio MXA1MC Wired Remote (x3)
- 20′ NVX 4 Channel RCA (x2)
- 20′ NVX 2 Channel RCA
- Stetsom Bravo HQ 400.4 (x2)
- Stetsom IR 400.1
- 10 AWG Power and Ground
- 4 to 8 channel Programmable DSP
The original stereo when we purchased the boat did work alright, it was utilizing a Rockville gauge style unit attached weirdly to a pioneer 2 channel amplifier and a 4 channel Wet Sounds Amplifier. The install was not exactly desirable, but nothing was done that couldn’t be undone, and I had intended to do a complete refresh of the system.
Get to work ripping all the old stuff out and put in the new. I started by adding an “amp board” that really housed all the electronics. A second battery was installed before purchasing the boat but no battery selector switch. Priority 1 was to make sure the power and charging systems were well in order, which is covered in a different post.
I wanted to utilize micro amplifiers for this project. I have fallen in love with Class D amplifiers in all aspects of my life for their efficiency and compact size. I did some research and identified some newcomers since my last stereo work to game out of Brazil. Stetsom, they were on sale, had good specs and reviews, I gave it a shot. I got 2 4 channel amps totaling 8 channels each with 100watts RMS. At the time this would power the 4 cabin speakers and bridged the 2 tower speakers.
This would get us started on the water – I did end up with some pretty serious wine through the cabling as I had to get it working for boat rides with the family, they were all tired of waiting on me to fix it. In haste i tried to ground the RCA’s and ended up shorting out the entire system…. oops… I completely fried the “original” Rockville stereo. Now for alternates….
I ordered a stereo off aliexpress to get us through (ended up being a great stereo just no wired remotes), but then that got delayed in customs and I utilized a 3.5″ aux straight to the Amplifiers and it honestly sounded pretty good, but amazingly inconvenient. The Aliexpress stereo was good also, excellent sound quality but the lack of a wired remote made it also inconvenient, and I went back to the drawing board.
The space for the gauge stereo is small, and I wasn’t too keen on going back to a single din unit under the drivers arm, despite loving the new cupholder since blowing up the stereo. I found the stereo I wanted: the right size, the right number of RCA out, a volume KNOB, BT, eprom memory, and most importantly – Wired Remotes. It also has a decent name for warranty and support. Memphis Audio MXA1 was the choice.
Installation went fine I move all the RCAs very away from battery cables and we were back with tunes and remotes on the water! which lead to a different problem – zones. The towers we didn’t always want on, or not all at the same volume. Easy fix, RCA line output controllers; one for the tower, one for the cabin. The issue here is that I had to put them in the Spotters locker with the rest of the stereo equipment, meaning we needed to lift the seat to change the volumes. Researching this problem you will find some very expensive solutions. Being a “Maker” I decided to take this on myself and create a “Zone Controller.” I wanted it to be fit at the drivers seat but accessible to a passer by as well. I got started Designing, and ended up with a 3 zone controller with 5 zones of on/off – amplifier remote switches.
Materials for the Zone Controller:
- 12mm Latching IP65 Push Button Switches
- 20 AWG 6 core wire bundle
- Axxess RCA Level Controller
- PETG Black 3D Printing Filament
- #6 1/2″ Pan Head Stainless Screws
- DTM 6 Pin Connectors
Utilizing the latching buttons, I ran a 6 wire bundle from the stereo to the controller for Amp Remote Power, that give me control over 5 separate amplifiers individually to turn on or off. I wired the power to each of the switches and the output to an individual wire to go to each amplifier through a 6 pin DTM connector. The RCA Level Controllers mount to the top and gives control of 3 separate zones, of which i made the subwoofer it’s own zone.
Being able to control the tower speakers separate from the cabin speakers is a must. I can have someone surfing jamming out and My ears as the driver are not completely blown out. I mounted the controller on the left side of the helm, throttle control being priority number 1. This might vary for other people, but its how I chose to go about it. I did route the RCA’s up around the bow to keep them away from the power wires and prevent engine wine and also me from drilling more holes in my boat.
Wiring
The previous owner had a very unique method of wiring. The components purchased were all great and no complaints, but the installation was less than stellar. I realized this as I decided to fix the wiring of the tower speaker as they were wrapped in electrical tape and i just thought it was ugly. As i started to take it all apart, i realized that my amps were not more clever than I realized and were not self sorting for bridged mode, but rather only one channel was connected for both speakers. Despite two wires going up into the tower, there was only one connected. Well… now we get to rewire the tower speakers; 14ga tinned copper speaker wire, DT connectors at the speaker pod, and nice braided loom to keep it looking nice. I used the old speaker wire to route the new wire which made it difficult to make the holes larger. the previous holes were for 2 18ga pairs of speaker wire and now there is 2 pairs of 14ga, it was a tight fit but I made it work. Again, anything out in the open was sheathed in braided loom and with shrink wrapped ends.
This led to me rethinking the front cabin speakers, the drivers especially, the engine whine as it passes under the boat with all the power wires is quite annoying, I believe i will reroute it around the bow in the future.
