McIntosh subwoofer hack for more volume

Detailed descriptions of how to do things to your Liberty.

McIntosh subwoofer hack for more volume

Postby Ric » Wed Jan 23, 2013 10:08 am

This is copied from http://nzlamb.wordpress.com/2010/04/19/ ... ofer-hack/ just in case that web page disappears

nzlamb wrote:Here’s a quickie on adjusting the gain of the OEM-supplied McIntosh subwoofer in many BE and BH series (MY 1998-2003) Subaru Legacy’s. The subwoofer gain and crossover frequency is non-adjustable, at least until now. : ) If you have such a car and want to get a little more punch from the sub, read on!

The amplifier is bolted to the floor under the drivers seat and has two connectors on the end closest to the door. Disconnect and unbolt the amplifier and take it apart. Make a careful note of where each screw goes as they are not interchangeable; you can permanently damage the amp by shorting things out of you replace the screws incorrectly.

Find R519 on the underside of the PCB near the power and speaker connector. In station wagons this is rated at 10k and in sedans 4.7k, labeled as either 103 or 472 respectively. This resistor sets the negative feedback in the final stage of the subwoofer crossover.

r519_before2.jpg
r519_before2.jpg (127.16 KiB) Viewed 11938 times

Identifying R519

Replace this resistor with a higher value to increase the gain. Don’t leave it out of the circuit or it may overdrive the sub and do damage. If you short it you will mute the sub entirely.

r519_after.jpg
r519_after.jpg (129.13 KiB) Viewed 11938 times

R519 replaced

After some experimenting I feel 33k delivers quite a nice bit of punch in a station wagon, which should boost the sub by about 5.2dB. Feel free to choose any value you want between 10-100k. Be careful using high values as it becomes quite easy to inadvertently overdrive the sub.

You might want to use a potentiometer instead so you can adjust the sub gain as you please. If you do this, I suggest a 50k linear (type B) pot in series with a 10k resistor. Make sure you use shielded cable and keep the cable very short to help prevent any instability in the amp. Connect the cable shield to a suitable ground point in the amp and (ideally) a 100nF or similar capacitor between the cable shield and the pot casing to prevent possible ground loops.

Enjoy!
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Re: McIntosh subwoofer hack for more volume

Postby Ric » Wed Jan 23, 2013 10:09 am

(reserved for more info later)
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Re: McIntosh subwoofer hack for more volume

Postby PinkK » Wed Jan 23, 2013 11:08 am

Nice idea, my stereo always feels like it is lacking when I go from AUX to CD. What do you think about the amps from our models? Do you think they are the same/similar?
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Re: McIntosh subwoofer hack for more volume

Postby Viper » Wed Jan 23, 2013 5:08 pm

See viewtopic.php?f=22&t=19926 for update for Gen4.
You probably should also move it too ;p
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Re: McIntosh subwoofer hack for more volume

Postby Ric » Wed Jan 23, 2013 5:37 pm

Viper wrote:See viewtopic.php?f=22&t=19926 for update for Gen4.
You probably should also move it too ;p

Done :)
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Re: McIntosh subwoofer hack for more volume

Postby PinkK » Wed Jan 23, 2013 6:25 pm

Viper wrote:See viewtopic.php?f=22&t=19926 for update for Gen4.
You probably should also move it too ;p


Nice, thanks :)
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Re: McIntosh subwoofer hack for more volume

Postby <GB> » Wed Feb 13, 2013 10:12 pm

Sweet!! I need a little more punch out of mine!
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