Hi folks, I just tried "upgrading" the stereo in my wife's car a 2001 A4 1.8TQ with the non-Bose "Symphony" head unit. I installed one speaker on the rear deck (oh what a pain it was to get back there) and wanted to see the difference between the stock speaker and the new Alpine SPS-17C2 6-1/2"/6-3/4" 2-way. Guess what? THE STOCK SPEAKER SOUNDED BETTER! Can anyone explain to me why this is so? I am thinking that the stock head unit does not have enough power to properly drive the Alpines. Specs for the Alpine are:

2-way car speakers for 6-1/2" and 6-3/4" locations (pair)
aluminum-coated woofer cone with air-injected rubber surround
1" pivoting silk dome tweeter
power range: 2-50 watts RMS (250 watts peak power)
frequency response: 35-30,000 Hz
sensitivity: 92 dB

People tell me that you want the head unit RMS powerto be at least 70% of the speaker power. So in this case, 70% of 50 Watts = 35 Watts. The stock head unit must have at least 35 Watts per channel. I would have thought that the stock head unit would at least have 35 Watts. Does anyone know exactly what the specs for the stock head unit is?

Do you guys think that I need a new amplifier to fully take advantage of the speaker?

Thanks in advance guys...

 

Would be interested in this info as well. I just got a 2001 A4 Quattrowith the Symphony stereo and thought about upgrading the speakers as well.

 

I'd been searching the forums for a while until I realized my car still has all the original manuals, one of which is the Operating Instructions for Sound System Symphony. Attaching the page with the specs. It contains info for the A4, A4 Avant, A6, A6 Avant, and A8, both the standard and Bose options.
Also, I measured the impedance of the speaker from my front passenger door with a multimeter. I got a reading of 2.6 ohms. Since this quick multimeter reading is usually 15% less than the nominal impedance, I would say it's a 3 ohm impedance for the stock speaker.

 

Would be interested in this info as well.