JBL Audio System Information...pretty impressive!

This was posted by SPL on GreenHybrid Camry forum. The Camry and Prius share the same amplifier with slightly different use of speaker specs. For me, i have found that the best sound in my Prius is with near zero settings on all 3 adjustments (bass, mid, treble) with ASL OFF. Recently, i have found that ASL boosts the bass and treble quite a bit...adding unnatural sound to the music. This info should help clarify some misunderstanding about how car audio should sound and how low the JBL system can go.

Anyway, here is the info (on 2 separate posts, the 2nd one explaining the 1st post to another member):

Both the NAV and the non-NAV versions of 2007 Camrys with JBL audio systems use the same digital signal processor/amplifier unit under the front passenger's seat, and 8 loudspeakers (2 mid/tweeters + woofers in the front, and 2 tweeters + mid/woofers in the rear). Placing the front mid/tweeters right next to the windshield not only prevents people and clothing from absorbing the treble (as occurs with door-mounted tweeters), but also prevents the windshield reflection from degrading the high-frequency response. The woofers go down to around 30 Hz, and can handle a reasonable volume before they overload at this low frequency. The system is pretty neutral in its frequency response with the tone controls set at '0'. The 8 amplifiers (one for each driver) are rated at 55 watts each (= 440 W total, but I don't know whether this is with all channels driven simultaneously). The bass tone control operates in a band around a center frequency of 50 Hz; the midrange tone control operates in a band around a center frequency of 800 Hz; and the treble tone control operates in a band around a center frequency of 14 kHz. Since their frequency ranges are largely non-overlapping, raising all three tone controls will result in a decidedly "swayback"-shaped frequency response. AM, FM, and CD allow independent tone-control settings.

Stan
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High-frequency sound bouncing off the windshield can interfere with the direct sound from the tweeter to your ears, because its path-length to your ears is longer than that of the direct sound. This causes "comb-filter" notches in the frequency response. The best solution to this problem is to place the tweeters as close to the reflecting surface (the windshield) as possible, so that the delay of the reflected sound is as short as possible. Toyota have done this.

The three tone controls each affects the frequency response only over a limited part of the frequency band. The bass tone control's adjustments center around 50 Hz (which is a pretty low frequency — so it only affect the low bass); the midrange tone control's adjustments center around 800 Hz (this is a mid-band pitch — the voice range will be affected by this control); and the treble tone control's adjustments center around 14 kHz (this is such a high frequency that only the high treble is affected). Since these three frequencies are so far apart, if you raise all three controls you get a frequency response that is: boosted at low bass frequencies, and then returns to flat again; boosted again at midrange frequencies and returns to flat again at low treble frequencies; and is boosted again at high treble frequencies. These three "mountain peaks" are what I was referring to as a "swayback" frequency response. It will sound decidedly "colored" and not "neutral," but that's what tone controls are there for I suppose. At least, with the tone controls set to "flat" ('0') the system's sound is pretty uncolored and accurate. Many car audio systems aren't acoustically "flat" at any setting. Of the three controls, the midrange control will "color" the sound most — check this out on voices or on acoustic musical instruments whose sound you know well, and you'll quickly see what I mean.

Stan

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