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Written by Scott Mitchell
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Monday, 10 September 2007 |
Supplies:
· 4G iPod with a dead hard drive
· large 3.5 inch IDE drive
· 1 stylish AKAI cassette deck
· 2 Dock connectors
· Electronics for mixer circuit with output amp and headphones amp.
· Loads of hookup wire, plugs and sockets
· Power supply (pulled from an old printer)
Mod Process:
I have a couple of iPods with dead hard drives, they belong to friends of mine. I was wondering what to do with them when I came across Collin Allen's iPod Super (www.command-tab.com/2005/03/13/ipod-super/ ). Collin had connected a standard 3.5" hard drive to a 3G iPod, I was so impressed that I had to try it for myself.
 I constructed the hard drive adapter cable from the iPod's dead hard drive by removing the circuit board from the hard drive and de-soldering the connector.
 This was a lot easier than it looks, the circuit board is quite thin and by gently flexing it while applying heat from a soldering iron the board can be pealed away from the connectors pins. The next step was to solder the 1.8″ connector to a standard 3.5″ IDE cable. The pin spacing on this connector is tiny, it took quite a while to solder to all 40 pins. Once complete I covered the solder joint in hot glue to stop it from working loose.
I connected the iPod to a 120 GB hard drive, plugged the iPod into my computer, and did a software restore through iTunes. The iPod worked perfectly.
But for this to be truly useful I would need to put it in a case, I started searching for one - and found this!
An AKAI GXC-310D stereo cassette deck, sitting proud in someone's pile of garbage. This thing screams ‘iPod mixing console'.
Built like a tank, the player has timber veneer sides and a sheet of seriously thick, brushed aluminum on top. Just to the right of the tape door there's a little panel that houses the tape counter, it's exactly the right size for an iPod dock. The decisions are being made for me, one iPod Super inside, one iPod dock on top: this has to be a mixing deck. There's knobs and meters for each input, time to sort out the details...
A mixing deck needs a mixer, I got my schematics from www.all-electric.com/b&c.html and some helpful advice from Tomi Engdahl (www.epanorama.net) and Douglas Self's excellent pages on op-amp design (www.dself.dsl.pipex.com/ampins/webbop/opamp.htm )
I gutted the old cassette deck and installed switches behind the tape mechanism keys, these will be used for the click wheels five buttons (menu, play, fast-forward, rewind, centre - select).
The round buttons to the left and right of center are used to select the audio line (the left activates the internal iPod line out, the right activates the dock/aux line).
The mic inputs at the front left were replaced with volume controls for the headphones. This section mirrors the main mixing circuit allowing the user to cue tracks without disturbing the main audio output .
The power supply was pulled from an old printer, it fits neatly on the left of the unit. It has + and - 12V DC supply for the op-amp circuits and separate 12V, GND, 5V connector for the hard drive.
I pulled the click wheel from the iPod and removed the plastic face. It has a very short connecting cable, I've messed around with these cables before and they are a nightmare to work with. I'm going to leave as much of this intact as possible. The click wheel buttons are the standard surface mounted bubbles, underneath the bubble are two contacts. But you don't need to open them up to get to the contacts, two of the switch corners are connected to the internal contact, the other two are connected to the ring.
I ran wires to each of the 5 buttons and routed these to the tape transport switches.
I cut the iPod face plate in half and reused the screen surround (minus the front window) to mount the iPod screen and circuit board.
It's glued to the back of a large clear acrylic sheet which will act as the new window.
The acrylic sheet has a circular cutout for the click wheel (the battery is also glued to the back of this sheet).
The hard drive is mounted underneath the unit with the IDE adapter cable feeding through the centre hole to the iPod's circuit board on the other side.
The dock is cut from a small piece of wood and then glued in position. I lined the interior of the dock with textured plastic sheeting.
I used the same textured plastic as the dock to window out the iPod screen.
This gives an interesting feel to the click wheel interface which remains active through the plastic.
Lights in the unit were reused.
They indicate which audio line is active.
The meters are connected to the audio lines. The left meter gives the level of the internal iPod output, the right meter gives the dock/aux line level.
I added firewire and USB ports to the back of the unit. I was thinking of including a hub but in the end I decided to just hook the firewire up to the internal iPod and the USB to the dock. I reused the existing audio connectors, line in allows you to connect an external device and mix it with the main iPod.
The final units functions are as follows.
From left to right on the upper panel:
- group of 2 push switches choose which audio channel is active in the headphones
- single switch selects between AUX line inputs on the back or the iPod dock
- left volume knob controls the internal iPod volume
- meters give level reading for each line
- right volume knob controls the AUX/dock volume
- push switch on left mutes the unit output (and turns on the indicator light next to it)
- push switch on the right is a reset switch for the internal iPod (I haven't implemented this yet)
- main output level (to adjust the line level out of the unit)
From left to right on the lower panel:
- headphone jack
- headphone volume knobs for internal iPod and aux/dock volume adjustment
- left circular push button activates the main internal iPod audio line
- tape transport keys act as iPod buttons menu, rewind, select (centre button), play/pause, and fast forward
- right circular push button activates the aux/dock audio line
- far right push button for power
I'm thinking of re-labeling the buttons but I like the mystery of these miss-matched labels and most functions are fairly straight forward so for the moment it will stay like this; it's a mash-up of old and new technologies.
Mod Specs:
· iPod with large 3.5 inch hard drive
· integrated iPod dock
· inbuilt mixer and line amplifier
· secondary mixer and headphone amp
· line level meters
· cool retro case
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