4x40W amplifier manual

4x40W amplifier manual
4x40W amplifier V2
page: 1
Manual 4 x 40W amplifier
Version 2
Technical data:
Supply voltage:
9.6-18V (4S LiPo recommended)
Output power:
4 x 40W at 2 Ohm, THD=10%, 14,4 V
Recommended speaker impedance: 4 Ohm
ca. 55 x 50 x 35mm
about. 40g, incl. heatsink
Allgemeine Hinweise:
• The amplifier is intended to be used at one to four 4 Ohm speakers. Speaker Nr. 3 + 4
must be connected by solder connections at the bottom of the PCB.
• The amplifier MUST be mounted in airplanes somewhere in the airstream for proper
cooling. It can get VERY hot at full volume (>100°C) without cooling. Make sure the
propeller is running during bench tests !
• Connect all speakers with the same polarity to the amplifier
• Not used outputs must be isolated
• Watch to power supply polarity
Otherwise the amplifier can be damaged!
Electrical connections:
Audio input
(Top to bottom):
Bn: Ground
Rd: Audio In „Low“
Or: Audio In „High“
LED „Max. Volume“
Bottom solder junctions: LS3+ LS3- LS4- LS4+
Power connections
(top to bottom):
Vl: Speaker 2 Bl: Speaker. 2 +
Gn: Speaker. 1 Ye: Speaker. 1 +
Or AND Rd: Battery +
Bn AND Bk: Battery Important:
Or and Rd must be
connected together at
Battery +
Bn and Bk must be
connected together at
Battery Bottom:
Solder connections for
speaker 3 (LS3) and
speaker 4 (LS4)
4x40W amplifier V2
page: 2
Volume setting
According to the ordered speakers, the amplifier is delivered with the volume set at a
safe max. level for the speakers. It should not be changed much.
Details for setting the max. volume:
The volume can be increased until the “max. volume Led” flashes permanently.
Short flashes are not critical.
At this point, the max. achievable output power, providable by the amplifier is achieved.
This is depending (beside other parameters) on the temperature. It is recommended
checking the setting after 5min of operation.
Don't forget running the propeller during bench tests for cooling!
Of course the connected speakers must be able handling this output power!
The following formula is used for calculating the supply current, drawn by the amplifier
at the recommended volume.
Measure the supply current by a common multimeter and increase the volume until the
calculated current is reached. If the “max. volume Led” starts flashing before, the max.
volume is also reached and the volume must not increased more.
Max. current[A] = ( Speaker power [W] * 0,8) / Supply voltage [V])
Faktor 0,8:
Safety factor
Speaker power: Sum of sinus power of ALL connected speakers
Supply voltage: Battery voltage
No warranty on damaged speakers !
4x40W amplifier V2
page: 3
Recommended speakers for airplanes (Brand: Visaton)
Dimension [mm]
Total weight[g]
2x R10S / 4 Ohm
2x SPH-30 / 4 Ohm
(Brand: Monacor)
Smaller foam planes
4x K50 / 8 Ohm (jew. 2 parallel) 50x50x20
2x BF-45 / 4Ohm
Examples of speaker installations:
1x SPH-30
4x K50
Amplifier with additional heat sink
Installation videos
Technical changes reserved
Not suitable for children under
14 years
Benedini Modellbauelektronik
Müllergasse 15, 52159 Roetgen (Germany)
Web: www.benedini.de
Mail: Thomas@Benedini.de
~ volume [dBA]
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