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After several months of agonizing and research, I recently completed a major upgrade to the stereo in my ’98 V70 AWD. My goal was not to turn it into a thumping machine designed to break the windows of passing vehicles. Instead, I wanted a punchy, accurate, musical sounding system with lots of dynamic range. Oh… and I didn’t want to spend more than $500.
The biggest problem with the V70 stereo is its non-linear frequency response. The stock speakers are of fairly high quality, and are capable of putting out decent levels, with good detail and little distortion. But they need some help.
There is a major peak in the upper bass region, which makes the stereo sound boomy, and drowns out any real deep bass that the system can deliver. There are also a few minor variations in the midrange response that need some attention.
My theory was that the source of this problem is not so much the speakers
themselves, but the environment in which they are installed, and the acoustic properties of the car. Get rid of these problems, and you've got a great sounding stereo.
I attacked the problem by using an Audicontrol EQX 13-band stereo equalizer. I used the Volvo SC-816’s pre-amp output to feed the equalizer, and then fed the equalizer to a JBL 50 watt x 4 channel amplifier, mounted in the cargo area. I mounted the EQX inside the glove box. I had to make a cable that ran from the SC-816’s pre-amp output 6-pin DIN socket to two RCA plugs that feed the equalizer.
The Audicontrol EQX is really the perfect device for the Volvo for two important reasons. First, it has a pre-amp level booster in it, which serves to boost the relatively weak pre-amp output level that comes out from the Volvo head unit. This is important, because aftermarket power amps need to see a high signal level to avoid noise problems. Also the EQX has six of its 13 control channels dedicated to the bass region below 250hz. This is very helpful, because this is the area where the V70’s stereo has the worst problems.
Adding the EQ required the use of an outboard power amplifier to drive the speakers. I used a JBL GTQ-360 4x50 watt amplifier. Any decent 4-channel amp will do, but it must be able to drive a 2-ohm load. I mounted the amp on the left wall of the rear cargo area. I ran the speaker wires back to the dash board area, and spliced them into the wiring harness that used to feed the speakers from the SC-816.
I've only had the new system in for a few weeks, and I'm still fine tuning
the equalizer to get the perfect EQ curve. I'm getting pretty close. The
system sounds really smooth, accurate and punchy. Here are the EQ settings I used to get the system sounding great:
31.5 Hz 0
45 hz +9db
63 hz +6db
90 hz -6db
125hz -7db
180 hz -5db
250 hz 0
500 hz -1db
1 khz -2db
2 khz -2db
4 khz -1db
8 khz -2db
16 khz +1db
It’s important to turn the EQX’s output levels up to maximum, to avoid picking up electrical noise from the car.
It’s easy to cause more harm than good with an equalizer. I used the EQ to remove the big boomy upper bass peak between 90 and 180 hz, and boost the deep bass frequencies at 45 and 63 hz. A subwoofer would probably help here, but with these settings the bass is remarkably strong and clean. Sometimes I have to check the cargo area in my rear-view mirror to make sure there isn't a drummer playing back there! The system now sounds better than most home stereos!
So did I make my $500 goal? You bet. I got the equalizer and amp from an E-Bay auction for about $350, and the rest covered installation costs.
--Phil Mastman
1998 V70 AWD (with kick-ass stereo)
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