Red Box 150 Watt Subwoofer


Around the beginning of November 2009, I got the idea into my head that I should do another electronics project to keep myself occupied and to help my recovery from depression. I still haven't quite put the polish on it yet, but it sits behind my door and thumps away quite satisfactorily.
What follows is the build photo-log I made using my iPhone and the Facebook app (which sadly is now not being maintained due to the developer being sick of Apple's app store shenanigans)
Update: Did some more fiddling with the speaker ports to get the best sound, gotta put some filter capacitors on the lowpass filter's power supply which I threw together in 5 minutes.

17/03/10: After 6 months of on and off fiddling, I'm finally happy with it, still hums a bit, but it's just because of the lowpass filter I installed.

November 7th 2009:

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New toroidal transformer I'm using for my next electronics project, 25 - 0 - 25 volts output, 160VA. Cost me a good $50 but worth it when I'm finished building this active subwoofer.

November 11th 2009:

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My somewhat successful attempt at reinforcing this dodgy joint on this speaker box, for the active sub I am building, gonna use some bog to fill in the gaps, sand and paint after I'm done with the electronics. I think. If I can be bothered.

November 12th 2009:

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Here you can see the speaker box work I did yesterday (since I'm posting this at midnight) Fabricated some patches of MDF to cover the mid and tweeter ports. The mid port patch also doubles as an excellent place to mount the power transformer, since it's far away from the place I'll mount the electronics. Which also gives me more space to play with on the rear panel.
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Here's the inside of the rear panel, where all the magic stuff will be mounted. I think there will be enough space for everything I want and maybe even more. I'd like to be able to use those heat pipe heatsinks I have for this project, would be perfect.
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I know it's hard to see, but what I've done is marked out the clearance heights on the rear cover of this speaker cabinet. So that I know how much space I have to work with, because there is a 10 inch sub with a large magnet sitting not so far away from the rear cover.
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Hello new sub power plug. I love salvaging stuff, saves me so much money
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Now that is precision soldering! Just hooking up the input terminals for this active sub woofer.
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Here's a lowpass filter salvaged from a dead 1000w kicker amp. I'm gonna be using this one in my active sub box, sure it means I need to make another differential power supply, but it'll be worth it.
(This ended up being insufficient after some testing, it only works with line level signals, Instead of trying to find space for a pre-amp to put in after the low pass and rewire everything, I decided to just buy a lowpass designed for a volume controlled signal)

November 15th 2009:

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Just got the low pass filter working, I'm feeding music to it from my MacBook, and then feeding the output from the filter to my 20 watt amp and bookshelf speakers for testing. The power supply I built is working flawlessly, no hum or noise, it just works.

November 17th 2009:

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I have installed and connected every part I have so far, now I have to wait for the parts I ordered on eBay wich the stinky international shipping times at this time of the year will have no doubt delayed.

November 21st 2009:

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Amplifier rear panel finished. Now I still have to wait for these parts I bought on eBay to arrive... Stupid Christmas mail stinking up my international shipping times...

November 25th 2009:

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Finally! I got the rest of my ebay stuff today, on the left is my new stainless steel nerv watch.
On the right are the amplifier and power rectification/filtering boards for my sub project.

November 26th 2009:

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Both boards tightly secured, now on to the wiring haha!
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Main power connected, now onto transformer and signal wiring

November 29th 2009:

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Final project photo as of 29/11/09. Amp works very well, although the silvery heatsink you can see gets quite toasty, but not hot enough to burn me. Might have to install a fan and drill out a few small intake holes if it becomes a problem, but I don't think I will need to.

December 23rd 2009:

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Finally sanded and painted the red box active sub, now I can actually call it red box :)