Good upgrade from stock speakers, when used with a stock (or low-powered aftermarket) Head Unit

Cannot handle anywhere near their rated power (claimed up to 40 WPC RMS, I would say max of about 10 WPC RMS) Tweeters drop out above about 8kHz Harshness / brightness at crossover frequencies (i.e., about 5kHz to 8kHz) Woofers drop out below about 125Hz Woofers have some resonation issues Woofers sound fuzzy / distorted at elevated volume levels

I purchased these (along with a set of SPS-170A's for the rear) as an upgrade to my stock factory speakers. They were originally hooked up to a Kenwood KDC-MPV619, then to an Alpine CDA-9813 I bought as an upgrade to the Kenwood. The SPS coaxials were a huge improvement over the factory speakers. The factory speakers would distort badly at ANY volume level, and had no high end response at all. On the CDA-9813, the SPS speakers sound really good at low volume, then get a little fuzzy at about one-third volume, then somewhat indistinct at about half volume, and finally distort at about two thirds volume. The SPS have better-than-stock high end response; however, the stock door locations combined with the lack of swivel on the tweeter causes the very high frequencies (say >8kHz) to aim at your ankles, and thus drop out greatly (to the tune of about minus 12-15 dB versus a white noise baseline of 90 dB...definitely very noticeable). This lack of directability on the tweeters also gives a less-than-impressive soundstage. The woofers are also certainly better than stock, but not all that impressive. Their stamped steel cages are not very stiff, and this causes some issues like flabbiness below about 250Hz and a sharp drop out below about 125Hz. Also, these speakers had some problems with frame resonation at about 500 Hz. Finally, these speakers have a 6dB/octave high pass to protect the tweeter (a single capacitor in-line with tweeter), but no low-pass on the woofer. This causes some significant reinforcement in the frequency range of about 5kHz to 8kHz (to the tune of about plus 9-12 dB versus a white noise baseline of 90 dB...definitely very noticeable). When combined with the STEEP dropoff above 8kHz mentioned earlier, this makes these speakers sound VERY harsh whenever reproducing frequencies in this 5-8kHz range. In short, these speakers are a good upgrade over factory speakers, and indeed I believe this is how they are marketed. Although rated to be able to handle up to 40 WPC RMS, it appears to me that they are better suited to handle power up to about 10 WPC RMS (typical stock or low-powered aftermarket head unit), and not more. Do not expect these speakers to make you happy if you have any appreciable power in your system. At full retail (around $70-$80), and for the intended purpose of stock replacement, I call these an average product at a fair price. I am in the process of installing an external amp and replacing the SPS 570A's with SPR 57LS components. I will review these when the job is done.