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"The speakers just need to be efficient and clean. Most of the JBL/Harman sound comes from the cabin eq tuning and DSP. Even the greatest speakers can sound like garbage with bad source and eq."
There are a few million vehicles on the road where I've had a significant hand in designing one or more of the speaker drivers. So a few comments:
1. Efficiency has no direct impact on final sound quality except with respect to EQ inaccuracies to cover production shifts in Fs, due to an overly high Qts.
2. "Clean" is just another term for mostly low distortion, and ideally for good temporal response. The latter is tricky: the perfect driver with a true delta function for its IR, can, in the cabin/system, where acoustical "ping-pong" predominates, create a net IR at the listening position that looks as hashy as a field of weeds.
3. All automotive sound, it could be said, is strongly influenced by EQ, independent of OEM.
4. "Even the greatest speakers can sound like garbage with bad source and eq." True. But conversely, the worst speakers will never sound good, even if the source and EQ are great.
Most OEM car systems (Toyota included) come closer to the latter category than the former. It's cheaper to put high quality into the electronics that count, than into the loudspeaker drivers. The drivers have significant non-linearities that cost real money to fix. However, electronics in the A chain and today's ubiquitous class-D for the B chain, are highly linear, "for free."
Soundstaging is a discussion unto itself. It's generally true that more drivers, up to a point of diminishing returns, can give better and more consistent soundstaging for all cabin occupants, than can fewer.
Stryder 911, good to hear your crisis was averted. So, rubber meets the road, how does it sound?
I don't like the excessive use of acronyms, and here I catch myself doing just that. To save time hunting all over the web for those who may be interested:
EQ = equalization: a processing of the speaker's input signal, to create a target acoustic frequency response transfer function under a particular measurement regimen.
DSP = digital signal processing. The other kind is obviously analog.
Fs = free-air resonance. Here, Fb is really the more pertinent term since the driver is mounted in some kind of baffle or enclosure. But Fs is far more widely recognized than Fb, hence my use of it. Fs or Fb can change depending on a myriad of factors.
Qts = total quality factor in free-air. Quality factor is proportional to the energy stored per cycle, to the energy dissipated per cycle. As above, Qtc is the in-baffle equivalent.
IR = Impulse response. Only perfectly linear devices possess a unique one, and loudspeakers are far from linear, so the IR for a speaker is not unique but signal-dependent. The ideal, perfect IR conforms to a (Dirac) delta function: it has infinite amplitude, infinitesimal width, and an integral of one. The FT (Fourier transform) of a delta function has constant amplitude over frequency.
Class-D (amplification): the use of pulse-width or pulse-density modulation of a digital input signal, to yield, in the power output, through the loudspeaker driver, an analog acoustic output signal. Class-D has been prevalent since the 1970's in automotive vehicles.
A-chain: typically less than 5v, and very low power, signal processing. B-chain: high power.
OEM: original equipment manufacturer.
Last edited by mapirc; 02-19-2017 at 03:42 PM.