Car Stereo head unit power is VERY deceiving! Head units all have HUGE power ratings on the Boxes or right on the front of the units! The highest head unit power I have ever actually tested was 20 watts (at a half way decent THD)… So even if the head unit says 40Watts or 50 watts per channel on it don’t EVER expect for it to REALLY BE more than 19! Just cant happen!

REAL amplifiers use LARGE power supplies in them with transformers to STEP UP the voltage So that large amounts of power can be made! Head units just don’t have room in them For transformers or large power supplies!!!! So NEVER expect more than 19watts per Speaker out of head units! Some of the more reputable head units might LIE on the boxes but If you read the small print in the spec sheets in the owners manual they might admit to the 19watt figure!


Ex.
Clarion CZ500

CEA 2006 Power Ratings

19W × 4RMS [4?@14.4V ?1% THD+N]

S/N: 80dB (Ref:1W into 4?)
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Alpine CDA 9887

CEA-2006 Power Rating: 18W x 4

Max Power Output: 50W x 4
---------------------
Clarion DXZ785USB

CEA 2006 Power Rating: 18W × 4RMS [4?@14.4V ?1% THD+N]

S/N 87dB (Ref:1W into 4?)
----------------------
Pioneer DEH-P7200HD

CEA-2006 Power Rating: 14 W RMS × 4 Channels (4 W and ? 1 % THD+N)
S/N ratio: 91 dBA (reference: 1 W into 4 W)
-------------------------
Dual XDMA7715

CEA-2006 Power Rating: 17 Watts RMS x 4 channels at 4 ohms and < 1% THD+N
S/N ratio: 80dBA (reference: 1 watt into 4 ohms)
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AS you can see no matter what they deck says as far as max power ie 50x4, 60x4, in reality you will not get more then 19Wrms x 4 at 14.4V. So unless your charging system will maintain 14.4V you may not even see close to the 19Wrms.


As far as selecting speakers based on head unit specs, you want to choose speakers with high s/n ratio (sensitivity) 90dB+ which means they will get loud with very little power.

Some Companies with speakers that have a s/n of 90dB+- these speakers will sound great (loud and clear) off of just head unit power. This is just a brief list.

Re Audio
Bravox Audio
Audiopipe
Focal
Seas Lotus
DLS


Let me know your thoughts!!