I’ve had quite a few requests for more information about the McIntosh EF-1080I amplifier (often but incorrectly referred to as the EF-10801). This unit is actually made by Clarion and is supplied as stock equipment with many Subaru Legacy and Outback cars manufactured between 1998-2003.
Block Diagram and Description
The amplifier receives four balanced inputs from the head unit; front left and right, and rear left and right.
It features a built-in low pass filter (also called a crossover) for the subwoofer. This low pass filter is set to a fixed roll-off frequency and gain, although I haven’t yet worked out exactly what the frequency is.
The main channels then pass through a fixed 6-band equaliser that has been tuned to match the speakers and car interior. The front and rear equalisers are feature different configurations.
All fives stages then each go to a TDA7295 power amplifier. The main speakers are all 8 Ohms and the subwoofer is 4 Ohms.
The power supply produces +/- 26V for the power amplifier stage and +/- 15V for all of the preamp stages.
Based on the datasheet for the TDA7295 the amplifier is probably rated close to the following:
- 38W RMS per main channel
- 72W RMS into subwoofer
Wagon and Sedan
The amplifier is configured slightly different for sedans and wagons. Although they feature the same model number, they can be identified by the power connector. Amplifiers intended for a sedan have a green power connector; amplifiers for wagons have a white connector (see photos below).
Inside I’ve noticed that the subwoofer gain is reduced in the sedan version but have yet to locate any other changes.
If you have one of these amplifiers and wish to connect to it, here’s the details.
Pinouts for the input connector. The colours simply refer to the original Subaru wiring.
|1||Front Left +||Pink|
|2||Front Left –||Violet|
|3||Front Right +||Orange|
|4||Front Right –||Blue|
|5||Amp Remote Power||Red|
|7||Rear Left +||Green|
|8||Rear Left –||Grey|
|11||Rear Right +||Light Green|
|13||Rear Right –||Brown|
You can connect the amplifier to any brand of stereo; simply use the ‘+’ inputs only and connect these to the line (not speaker!) outputs of your stereo. Connect the ‘-‘ inputs of the amp to ground to prevent any induced noise on the inputs.
If you are installing your amp with a matching McIntosh head unit and do not have the official cable to connect them, you can fit the plugs to length of shielded Cat 5 (or better) cable instead, using one pair per channel. You will also need to run a separate wire for the amplifier power control.
|2||Front Right +||Violet|
|3||Front Left +||Pink|
|4||Rear Right +||Light Green|
|5||Rear Left +||Orange|
|8||Front Right –||White|
|9||Front Left –||White|
|12||Rear Right –||White|
|13||Rear Left –||White|
The power and speaker connector is a TE Connectivity (formerly AMP) Multilock 070 series 14 pin connector, part number 173852-1. This is the same type as used in Subaru head units from the early 1990s until around 2006 and it’s readily available from electronics wholesalers such as Element 14, Mouser and Digikey. The pins (part 173631-1) are sold separately to the housing so make sure you grab some of those too.
Make sure you use both ground and power pins due to the high current drawn by the amplifier.
Other Useful Info
Here’s the official service manual for this unit.
Clarion McIntosh EF-1080I-C service manual (PDF, 2.4MB)
It is very easy to change the subwoofer gain to get a bit more punch. See this post for more information.
If your amplifier is dead it could quite likely be the 25A fuse. This is a standard automotive blade fuse but is soldered onto the main PCB making it a little more work to replace.
One unit I came across appeared to be almost completely dead but was quite simple to fix. Read this post for details.
If you do decide to open your EF-1080I, make sure you take note of where every screw goes! Installing them incorrectly risks shorting the amplifier chips to the chassis of the amplifier which will permanently destroy them (the chip’s mute pin ends up internally shorted to ground).
Note the green power connector shows this unit came from a sedan. Wagon amplifiers have a white connector.
Some high resolution photos of the inside. Click for the full size version.
The subwoofer is a simple 6×9″ 4 Ohm polypropylene driver, part number 09-0291-31. In wagons it is fitted in the right wall of the boot (trunk) and in sedans it is on the left side of the rear shelf.