Car amplifier

[sniper007]

Hi!

I'm curious how car amplifier produce 1kW or more power with 12V single power supply? I know that op-amp(transistors) have max voltage output limited with power supply. Maybe car amp first lift up voltage ?


Tnx for reply's,


Sniper

 

[Nigel Goodwin]

Hi!

I'm curious how car amplifier produce 1kW or more power with 12V single power supply? I know that op-amp(transistors) have max voltage output limited with power supply. Maybe car amp first lift up voltage ?

They use an inverter to produce a higher HT rail for the amplifier - the power outputs are usually EXTREMELY exaggerated though - a 1KW amplifier is probably 100W per channel RMS, or less.

 

[Analog]

They use an inverter to produce a higher HT rail for the amplifier - the power outputs are usually EXTREMELY exaggerated though - a 1KW amplifier is probably 100W per channel RMS, or less.

yep. about 2/3 of the device is inverter and not amplifier hardware.

 

[Willbe]

I'm curious how car amplifier produce 1kW or more power with 12V single power supply?

In addition to high Vcc, they also use a bridge circuit.
Low speaker impedance helps.

 

[sniper007]

yep. about 2/3 of the device is inverter and not amplifier hardware.

hmm, if i understand corectly inverter is used to produce -12V or what ? What do you mean not amplifier hardware?

 

[audioguru]

The manufactures lie about car amplifier and speaker power.
When they say 1000W it is really 1000 Whats which is only 15 Watts to 200 Watts.
When they say PEAK or MAXIMUM then the real power number is simply doubled.
Music power is also a lie. Peak Music Power Output (PMPO) is two or three lies all together.

Good car amplifiers and speakers are rated in continuous RMS Watts with a spec's load impedance at a spec'd low distortion and a spec'd frequency range.
A bridged amplifier with a positive 35V and a negative 35V supply will produce 1000 Watts RMS into a 4 ohm speaker at a low distortion from 20Hz to 20kHz.

Most aftermarket car radios are marked 200W (200 Whats). They have 4 channels that are 14 Watts RMS each into 4 ohms at a low distortion from 50Hz to 15kHz.

 

[sniper007]

Thanks audioguru for replay, but I'm still curious how get +/-35V which you have mantion ?

 

[Analog]

hmm, if i understand corectly inverter is used to produce -12V or what ? What do you mean not amplifier hardware?

The inverter takes +12V and creates +/- whatever voltage needed for the amplifier, like +/-35V etc.

 

[picbits]

They have a built in switch mode power supply if you want something to google/wikipedia to get the higher voltages.

 

[audioguru]

Rod Elliot has a power supply for a 350W car amp on his website. It is too complicated to post its schematic here.

 

[Nigel Goodwin]

In addition to high Vcc, they also use a bridge circuit.

Most don't, because it's adding lot's of extra complexity for no advantage - the SMPSU can be designed to output any supply rails you want, and bridging is not needed. Often though an amplifier will give the option to bridge two of the amplifier channels to give a higher power one for a sub-woofer.