July 31st, 1998
By: Robert Leidy

Choosing the right amplifier proved to be the most difficult part of this upgrade. Initially I choose a pair of amplifiers from Phoenix Gold new line of amps that were all chrome. The salesman showed me how Phoenix Gold's QX4150 4 channel amp and the QX2100 2 channel amp could be mounted together and joined using this cosmetic piece to make them look like one big amp. We took the amps out and laid them in the trunk to see if they would fit. Sure enough they fit just perfectly, almost the entire width of the trunk. The band of all chrome across the back of the trunk looked really good too so I decided these amps were going to be the ones.

The Phoenix Gold amplifiers sounded really good, however they started overheating and shutting down after only 30 minutes of hard use. The stereo shop that installed the amplifiers diagnosed the fault to be the amplifiers and suggested trying a different brand.

The salesman suggested a more expensive Rockford Fosgate 360.6 six channel amp with the promise that it would not only run cooler but it would also sound better. This single unit six channel amplifier delivered 30 watts per channel so the overall output was lower however the salesman promised it would run cooler.

After the new amplifier was installed I found that the bass sound had improved (probably due to the rockford bass EQ feature) but the Boston Pros were not as clear and couldn't get nearly as loud before distorting. It still sounded pretty good, but not as good as with the previous pair of Phoenix Gold amplifiers. The lower power of this amp didn't sit well with me especially considering the additional cost and poorer sound quality, but I had resigned myself to accept it as long as this one didn't overheat.

However after putting the Rockford Fosgate amplifier through a road test this amplifier overheated as well. After talking with Rockford Fosgate's customer service they suggested that something was wrong with the installation. I returned to stereo shop to question the installer but they didn't find anything wrong with the installation, and suggested I choose another amplifier. Since I wasn't happy with the sound quality with the Rockford Fosgate anyway I started looking for another replacement.

At this point I was getting very frustrated and confused. Alan's a/d/s/ show car was running nearly twice the power with his a/d/s/ P840 amplifier that I was with the Rockford Fosgate. And he was telling me his amps were cool enough to rest your hand on. I really wanted to just give up and retreat back to the stock stereo, but even this option had additional costs. In the end I decided to stop listening to advice from the shop that was installing the equipment. I did my own research and decided to try the same a/d/s/ P840 amplifier that Alan was using in the a/d/s/ showcar. This amplifier has 8 separate channels rated at 40 watts per channel. The amplifier also had full crossover control over each channel. With this much power and flexibility the new amplifier required a lot of thought and planning on how everything would be set up. I ended up setting the new amplifier up in the following configuration.

• Channel 1&2 bridged: Source should be the front, left channel with the high pass crossover set at the lowest point of 45Hz. This signal would deliver 120 watts from 45Hz to 20kHz to the driver side (left) boston pro series 6.4 component speaker set via the boston crossover.
• Channel 3&4 bridged: Source should be the front, right channel with the high pass crossover set at the lowest point of 45Hz. This signal would deliver 120 watts from 45Hz to 20kHz to the passenger side (right) boston pro series 6.4 component speaker set via the boston crossover.
• Channel 5: Source should be the rear left channel with the band pass crossover set to drive the range between 80Hz and 100Hz. This signal would deliver 40 watts from 80Hz to 100Hz to the front facing driver in the BMW subwoofer.
• Channel 6: Source should be the rear right channel with the band pass crossover set to drive the range between 80Hz and 100Hz. This signal would deliver 40 watts from 80Hz to 100Hz to the rear facing driver in the BMW subwoofer.
• Channel 7: Source should be the rear left channel with the low pass crossover set to drive the range below 100Hz. This signal would deliver 40 watts from 20Hz to 100Hz to the driver's side (left) alpine bass shaker.
• Channel 8: Source should be the rear right channel with the low pass crossover set to drive the range below 100Hz. This signal would deliver 40 watts from 20Hz to 100Hz to the passenger's side (right) alpine bass shaker.

Fighting Amplifier Heat