I talked about the audio quality of the various iPods, and mentioned a mod for 4th and 5th Generation iPods that gives them excellent audio quality rivalling that of a $1500 CD player. Well, here is how to do the mod on a 4th gen color iPod photo – Apple model number A1099.
The 4th Gen iPods have a Wolfson WM8975 audio chip in them.
The pinout is something like this (this is a pinout of the WM8971).
ROUT1 and LOUT1 go to the headphone connector, via some capacitors etc, while ROUT2 and LOUT2 go to the dock connector (line out). There are resistors, capacitors and inductors of low quality on the signal path, but the Wolfson IC itself is a top of the range audio chip. The mod involves running a wire directly from LOUT2 and ROUT2, via some Black Gate capacitors, to the headphone jack, which will now become a high quality line out. You could run it out the dock connector instead but I decided to go out the headphone jack – it loooked easier!
You’ll need a 4th gen ipod photo and a pair of Black Gate NX Hi-Q 6.3V 22uF or 47uF capacitors – they are rare and expensive. You can find them occasionally on ebay. They are no longer made but suppliers sell them off in pairs from time to time. My pair of 47uF caps cost me $16 pounds and I had to import them from the UK! Here’s a list of alternative capsyou could try.
This is the ipod photo 4th Gen, it’s the color version of the 4th Gen ipod. :
Here’s my ipod open and Black Gates ready to go…
Step 1. Solder and heat shrink some small leads onto the black gate capacitors…
Step 1. Solder leads onto the black gate capacitors. I used wire wrap wire - strong but thin.
These are the resistors we will remove - they are tiny - about 1/4 the size of a grain of sugar. (This picture is magnified)
- Step 2. Remove the output resistors from the wolfson DAC
Step 3 - Solder one wire from each capacitor to the output of the DAC chip. (Click on image to enlarge)
Step 4. The other wire from the capacitor needs to be soldered to the headphone jack. The inductors closest to the headphone jack are removed.
Step 5 - shove it all back in and try not to break the wires! I had to remove the plastic sleeve around the dock connector to fit the capacitors in. The capacitors sit each side of the dock connector (bottom left).
Some tips:
I used a headphone lead to hold the socket while I soldered.
I used a 500W floodlight to help me see - the soldering is fine.
Actual size of resistors! I wouldn't attempt this mod unless you have had Surface Mount experience before...
