Two car speakers sit on a shelf at about the same money. One prints 88 decibels on the box and the other prints 92. The one printing 88 is the louder of the two on the power your car actually supplies, and neither company has done anything wrong.

In this video I read the sensitivity figure off four manufacturers' own
specification pages, find that two of them measure it one way and two
measure it another, convert all four onto the same single watt, and watch the order change. The speaker that looks four decibels behind on the shelf finishes three tenths of a decibel ahead.

Then the same sum goes to the amplifier already in your dashboard, where a chip whose own box says fifty watts a channel publishes nineteen watts clean in its own table on page eight.

CHAPTERS

0:00 The two speakers on the shelf
0:44 The one line of arithmetic
1:26 The amplifier already in your dashboard
4:39 Fifty watts on the box, nineteen in the table
5:59 What a watt is actually worth
6:43 The loudness ladder, one watt to fifty
8:07 What the last seven watts cost
9:50 The figure on the speaker box
11:23 Two standards, and why the order is wrong
12:55 The proof, from a maker that publishes both
13:37 The four, reordered on one watt
15:24 What the money says
16:04 The number nobody publishes
17:43 The four limits
19:16 The three steps

EVERY FIGURE IN THIS FILM, READ 5 OCTOBER 2026

AS PRINTED ON THE BOX
Rockford Fosgate Punch P1650 — 88 dB at 1W/1m — 4 ohm — 55 W RMS — $109.99
JBL Stage3 627 — 92 dB at 2.83V/1m — 3 ohm — 45 W RMS — $89.95
Infinity Reference 6532ex — 93 dB at 2.83V/1m — 3 ohm — 55 W RMS — $79.99
Hertz DCX 165.3 — 93 dB at 1W/1m — 4 ohm — 60 W RMS — $129.99

THE SAME FOUR, CONVERTED ONTO ONE WATT
JBL Stage3 627 — 87.7 dB
Rockford Fosgate Punch P1650 — 88.0 dB
Infinity Reference 6532ex — 88.7 dB
Hertz DCX 165.3 — 93.0 dB

Three of those four land inside one decibel of each other. Only the Hertz is genuinely clear, by 4.3 decibels, and buying that lead with power instead would take 2.69 times the watts.

WHY THE TWO CONDITIONS ARE NOT THE SAME
2.83 volts is one watt into 8 ohms. Into a 4 ohm speaker it is 2 watts, which is 3.02 decibels. Into a 3 ohm speaker it is 2.67 watts, which is 4.26 decibels. Rockford publishes the same speaker both ways, at 88 dB on one watt and 91 dB at 2.83 volts, and 88 plus 3.02 is 91.02. The conversion is confirmed on their own product, by the same people, on the same page.

THE AMPLIFIER ALREADY IN THE DASH
STMicroelectronics TDA7850, datasheet title: 4 x 50 W MOSFET quad bridge power amplifier. Table 4, page 8, at 13.2 volts and 1 per cent distortion: 19 watts typical, 16 watts minimum. Fifty against nineteen is 2.63 times, which is 4.2 decibels.

Sensitivity figures and power figures come from each manufacturer's own published page or datasheet, read on 5 October 2026. Prices are street prices from three different retailers on one day, and prices move, so check before you buy. Nothing here was measured on a bench and no listening test was done.

Both measurement standards are legitimate and both are printed openly.


Which speakers are you running, and does the box say 1W or 2.83V next to the decibel figure? Put it in the comments. Plenty of boxes say neither.

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