94 » Performance auto & Sound

t te SR e p o R t

reviewKTP-445U AmplifierALPINE ELECTRONICS

M

Words and MeasureMents by Garry sprinGGay

aybe your audio system suits you pretty well, but lacks the clean power you need to really enjoy your music. Perhaps you also don’t want a big, current-hungry amplifier that robs precious cargo space and empties your bank account. If that describes you, there is a solution.

the “Head unit Power Pack” by alpine is a four-channel amplifier add-on for use with virtually any aftermarket radio or oem system. Best of all, it’s small enough to mount behind the dash near your radio! rated at 45 watts per channel at either two or four ohms, the power pack gives your system a nice power boost, and it sells for only $149.95 in the u.S. or $179.95 in canada.

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FeaturesThe KTP-445U is a basic rectangular amp

measuring 7.5 inches long, 2.5 inches wide and 1.5 inches high. The small size and slender shape allow it to be hidden almost anywhere — so you don’t lose cargo space — and it’s light enough you can mount it on any flat surface using hook and loop fasteners. A 15-amp mini ATC fuse resides on one end; gain controls are on the other end. Pre-amp inputs are also included for typical balanced high level and RCA connections. The low level inputs are handy for using the amplifier in applications that don’t have a traditional source unit (motorcycles and ATVs) where you would use an MP3 player as your source. There is also a switched 12-volt output wire to control additional amplifiers and the

teCHNICaL Data

ManufacturersRated Power

Actual Measured Power@ 1.0% THD+N

@ 14.4 V Battery

Actual Measured Power@ 1.0% THD+N @ 12.6 V Battery

45 x 4 @ 4 Ω 48 x 4 @ 4 Ω 37 x 4 @ 4 Ω45 x 4 @ 2 Ω 45 x 4 @ 2 Ω 38 x 4 @ 2 Ω

The following power measurements have been obtained using industry standard methods. (1 kHZ @ 1.0% THD+N - Battery voltages shown +/- 0.2 V)

tHe KtP-445u addS notIceaBle Power to your

SyStem comPared to a tyPIcal Head unIt, ANd SOuNdS gOOd

dOINg IT.”

Alpine KTP-445U Head Unit amp v5.indd 1 12/20/2012 3:10:06 PM

amp is bridgeable for two- and three-channel configurations. Thoughtfully, the harnesses are long enough for a variety of mounting locations without needing to add wire.

The KTP-445U is equipped with built-in crossovers to select the front and rear channels. Available crossover frequencies are 60, 80 and 120 Hz, but the default settings for front and rear channels is 'off.' A rubber plug at the bottom of the amplifier covers the selec-tor switches for the frequency filters, two- or four-channel in-put, and either high level or RCA inputs. The amplifier is a class D design for high efficiency operation, but it is designed to drive either two- or four-ohm loads — making it compatible with virtually any OEM or after-market speaker system.

ListeningThe KTP-445U adds notice-

able power to your system

compared to a typical head unit, and sounds good doing it. The little amp adds virtually no additional character and does exactly what a good amp should — faithful reproduction of the recording with adequate power. The amp has no audible noise floor and draws very little current.

PeRFORMAnCe / BenCH MeAsUReMents

On the test bench, the KTP-445U performs like a typical Alpine amplifier. As suspected,

96 » Performance auto & Sound

ALPINE ELECTRONICS KTP-445U AmplifierReview

Signal to Noise Ratio referenced to 2 V output (CEA-2006A) (1 watt @ 4 ohms) -89.2 dBA

Signal to Noise Ratio referenced to full 4 ohm output -106.0 dBA Distortion at rated power 0.6% CEA-2006A rated 4 ohm power (minimum power per ch. developed over the entire audio bandwidth) 47 watts/ch.

Maximum Efficiency at full 2 ohm power per ch. 82.8% Idle Current (warm) 0.5 A Maximum Current @ full power 2 ohms per ch. 16.2 A Frequency Response (-3 dB) 10 Hz – 46 kHz Stereo Separation (Crosstalk) -76.7 dB @ 5 kHz

teCHniCAL DAtAThe following power measurements have been obtained using industry standard methods. (1 kHZ @ 1.0% THD+N - Battery voltages shown +/- 0.2 V)

While many of uS have been brainWaShed With the “amPS are big and go in the trunk” ideology, ThE ALPINE KTP-445U mAKES US REThINK ThIS.”

« Power output connector and 15-amp mini ATC fuse shown here

«Sound control settings

«Input connector and gainadjustments

Alpine KTP-445U Head Unit amp v4.indd 2 12/19/2012 5:53:31 PM

ConClusion

While many of us have been brainwashed with the “amps are big and go in the trunk” ideology, the Alpine KTP-445U makes us rethink this. Sure, you aren’t going to win any SPL contests with it, but the high efficiency design, ultra compact size and startlingly good sound might make it the perfect am-plifier for you. pas

For additional photos, visit pasmag.com/AlpineKTP445U

ALPINE ELECTRONICS KTP-445U AmplifierReview

the frequency response is ex-ceptionally flat and the signal-to-noise ratio is excellent. The input sensitivity has plenty of adjustment range to handle virtually any input source. Even after hours of fairly high vol-umes, the amp is barely warm.

Cogent Audio Labs 4 OHM POWER vs THD+N 1kHz 12.6V Batt

ALPINE KTP-445U 2nd Approval 4 OHM POWER vs THD+N 1kHz - 12.6V Batt

0.001

10

0.002

0.005

0.01

0.02

0.05

0.1

0.2

0.5

1

2

5

%

600m 2001 2 5 10 20 50 100W

4 OHM Power vs. THD+N

Cogent Audio Labs MAX FLAT - FREQUENCY RESPONSE

ALPINE KTP-445U MAX FLAT - FREQUENCY RESPONSE Ref - 2.0Vrms

-5

+3

-4.75

-4.5

-4.25

-4

-3.75

-3.5

-3.25

-3

-2.75

-2.5

-2.25

-2

-1.75

-1.5

-1.25

-1

-0.75

-0.5

-0.25

+0

+0.25

+0.5

+0.75

+1

+1.25

+1.5

+1.75

+2

+2.25

+2.5

+2.75

dBr

10 50k20 50 100 200 500 1k 2k 5k 10k 20kHz

Max Flat-Frequency Response

The freqUency resPonse is excePTionAlly flAT ANd ThE SIgNAL-TO-NOISE RATIO IS ExCELLENT.”

Cogent Audio Labs CROSSOVER RANGE - FREQUENCY RESPONSE

ALPINE KTP-445U 2nd Approval Sample CROSSOVER RANGE -- FREQUENCY RESPONSE Ref - 2.0Vrms 4 ohm load

-50

+6

-48

-46

-44

-42

-40

-38

-36

-34

-32

-30

-28

-26

-24

-22

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

-0

+2

+4

dBr

10 30k20 50 100 200 500 1k 2k 5k 10k 20kHz

Crossover Range-Frequency Response

Alpine KTP-445U Head Unit amp v4.indd 3 12/19/2012 5:53:52 PM