audio amplifiers

[karthikeid]

hi

i have a doubt that an 20W amplifier can be used to 60W speakers ??? if not post a circuit for 2x60W audio amplifier....

 

[Hero999]

A 20W amplifier can be used to power 60W speakers providing they have an equal or higher impedance than the speakers the amplifier is designed to drive. For example a 4Ω 20W amplifier can drive 8Ω 60W speakers but it can't drive 2Ω speakers.

 

[audioguru2]

Feeding the speaker 30W instead of 60W will result in a small loss of volume.
You probably will not notice the very small difference in volume between 30W and 20W.

Your hearing's response to loudness is logarithmic:
1) 6W sounds half as loud as 60W.
2) 600W sounds twice as loud as 60W.

You never play music at full power all the time. The average amount of power is about 1/10th the maximum.

 

[karthikeid]

so can i use an 20W amplifier to an 60W 4 ohms speaker.....

 

[Hero999]

Yes.

 

[karthikeid]

hi
here is an datasheet of an ic from ti, can u help me to put a volume controller to this circuit and what is meant by 4step gain control, multiple class d devices, shut down and mute control.... ???
what should be the input voltage and current?

http://focus.ti.com/docs/prod/folders/print/tpa3100d2.html#samples

 

[Hero999]

Assume four step gain control refers to the gain select pins which can select gains of 20, 26, 32 or 36dB.

A volume control can be added to this circuit using a potentiometer as with any other audio amplifier.

 

[audioguru2]

The TPA3100d2 has many tiny pins that would be very difficult to solder.
Adding a heatsink would also be very difficult.

The sales sheet is wrong. It says that the output per channel is 20W into 8 ohms with a 12V supply but the datasheet shows only 7.5W to 10W per channel.
It produces 10W per channel (2 channels) at a horrible-sounding 10% distortion when its supply is 12V and its speakers are 8 ohms. It produces only 7.5W per channel at 1% distortion.

It produces 20W per channel (2 channels) at a horrible-sounding 10% distortion when its supply is 12V and its speakers are 4 ohms. It produces 15W per channel at 1% distortion.
But with 4 ohm speakers it gets very hot because is is so small.

 

[karthikeid]

anyone have the circuit 60watts stereo 2channel amplifier circuit ???

 

[audioguru2]

anyone have the circuit 60watts stereo 2channel amplifier circuit ???

Rod Elliot has many good amplifiers and other audio projects on his site:
http://www.sound.westhost.com/projects.htm

 

[karthikeid]

i have added a circuit it is used for a 8ohms speaker what should i do for 4ohms load?

 

[audioguru2]

A 60W amplifier that drives an 8 ohm speaker might be able to drive a 4 ohm speaker with 60W if its supply voltage is reduced to 0.707 times.

 

[karthikeid]

sorry here is the circuit will this works fine...

View attachment 40743

 

[Hero999]

It looks like it should work.

Have you looked at the datasheet for the LM3876/86?

 

[audioguru2]

The LM3886 will try to provide 94W RMS to a 4 ohm speaker when it has a 35V dual-polarity supply which will cause it to over-heat. It is spec'd with a 28V dual-polarity supply which allows 60W into 4 ohms.
It is an excellent amplifier.

 

[karthikeid]

what must be the input current for this amplifier??
2amps is ok??

 

[audioguru2]

what must be the input current for this amplifier??
2amps is ok??

You must say what is your speaker's impedance and how much output power you want.

The LM3886 can produce 68W into 4 ohms with a plus and minus 28V supply. It dissipates about 42W so its total power is 110W and the current in the 56V supply is 2A.

The LM3886 can produce 50W into 8 ohms with a plus and minus 35V supply. It dissipates about 
30W so its total power is 80W and the current in the 70V supply is 1.14A. 

 

[aston]

Audioguru have right Rod Elit have many good amplifiers on hes site but there
is one big lies to.
He say that two or three amplifiers are A-Class but is not A then is AB.

 

[audioguru2]

Audioguru have right Rod Elit have many good amplifiers on hes site but there
is one big lies to.
He say that two or three amplifiers are A-Class but is not A then is AB.

Most of the amplifiers on Rod Elliot's site use class-AB and a few use class-A.
The class-A amplifiers waste a lot of power making heat.