I now have on hand a Clarion/McIntosh PF-2824I and PF-4113I head units. These are fitted to higher end Subaru Legacy vehicles produced between 2005-2008. It includes MP3 and WMA support (why they didn’t support AAC instead of WMA beats me), a dual row VFD display and a more integrated look than the previous version (PF-2551I).

The PF-4113I is the Japanese version of the PF-2824I with a different tuner and a MiniDisc player. They are built around the same hardware platform (most components are the same including the PCB), however unfortunately run slightly different firmware. Unlike the previous model of McIntosh head unit in 2003-2005 Legacys, there is no easy way to convert the PF-4113I to European or American FM bands without hacking or replacing the firmware. There does appear to be a Micom firmware upgrade port on the side of the main board in the unit, however it appears that the microprocessor is of a mask ROM type and therefore cannot be flashed with new firmware.

It does use the same FM tuner module as many older McIntosh units, so if the firmware were to be sorted the necessary tuner mods are very simple.

Under the left hand seat is the EF-1259I amplifier. Unlike the old EF-1080I, this amplifier does not contain any EQ or crossover components as all this is now done in the head unit.

McIntosh Secret Key Combinations

After a bit of reading I’ve found that many Subaru head units have hidden options for changing settings. I couldn’t find much information on this unit so I spent a few moments trying various combinations to see what happens. Here’s the list I’ve discovered so far. If you discover any more please let everybody know by posting it in the comments!

To use these key combinations, switch the ignition to ACC and make sure the head unit is powered off.

Radio Location

Press the following to change the radio tuner region.

PF-2842I:
1 + AM is AUSTRALIA
2 + AM is EXPORT (North America)
5 + AM is AUS & EXP

Here are the differences between these modes:

Location	AM Range	AM Step	FM Range	FM Step
Australia	531–1620 kHz	9 kHz	87.5 – 108 MHz	100 kHz
Export	540–1610 kHz	5 kHz	87.5 – 107.9 MHz	100 kHz
Aus & Exp	Same as Australia

Note that switching locations will erase the radio presets.

PF-4113I:
5 + AM is JAPAN

Display firmware version

Press 5 + 6 + FM

Results:

PF-2824I (Japanese manufactured):
M 4.20
G34.72

PF-4113I:
M 5.60
G37.00 0.37

Disc 1 on the display lights in both cases too. If anyone has details for Chinese-manufactured versions of the radios please let me know.

Button and Display Test

5 + 6 + press RPT twice

Button test that displays the name of any button you push as well as the tuning up/ down.
Use the volume knob to toggle the display test feature which illuminates every display element and LED. When in display test you can use the tune knob to toggle a checker board pattern to more easily view display state. This will make any phosphor burn very obvious!

To exit this mode switch the ignition off.

Equaliser

In previous McIntosh models this was an analogue circuit built into the amp or head unit. It’s now all software controlled so can be changed between a number of presets or bypassed completely. This is very useful if you buy a replacement unit, so you can have it sound like the original if it needs to be replaced.

Press the following buttons and T/B:
1 + 3 + T/B WAGON CLOTH SEAT
1 + 4 + T/B SEDAN CLOTH SEAT
2 + 3 + T/B WAGON LEATHER SEAT
2 + 4 + T/B SEDAN LEATHER SEAT
2 + 5 + T/B THROUGH MODE (bypass)

I haven’t investigated the frequency response of each setting, however after a very quick listen the sedan options appear to have more bass than the wagon (quick bass boost option if you have a wagon!) and the cloth seat options appear to have a little treble boost. While it’s intended to compensate for the acoustics of the vehicle interior, purists might prefer to bypass the EQ altogether.

Loudness Control

Unlike the other settings, this must changed while the unit is powered on.

To toggle loudness, press 5 + 6 + T/B.

The default setting is on.

Other

Press 1 + 4 + CD to enter some sort of diagnostics mode. This displays the following:

H01 A1 256

Use tune to scroll through various options. As far as I can it seems to be read only. It also plays the current CD and the volume control works normally while in this mode.