Headphone amp

audioPT · 20th September 2004, 11:20 AM

hi!

Does this topology will work well?
I've draw the basic schematic...

Regards,

Pedro Martins

Jennice · 20th September 2004, 11:45 AM

Why so many op-amp's in stead of a single buffer-chip with sufficient output power?

I suppose you consider the first op-amp (on the left side of the schematic) to act as a driver since it is connected differently than the rest? No need to use a "driver", if the input impedence is as high as a typical op-amp (don't know your particular chip).

Remember, headphones use fairly little power, so a lot of circuits should be able to do the trick.

Have you tried to simulate a circuit, which is basically a class-A buffer stage (voltage follower)? It seems to me that you're making life more complicated than it needs to be.

Jennice

cunningham · 20th September 2004, 09:08 PM

The input impeadence to an op-amp is very high. The output impeadence is much lower. The only reason to use op-amps in this fasion is to put RC filters in between them to make an active filter network. You are attempting to lower the output impeadence of the op-amp circuit by parralelling the devices. There is a much easier way to amplify current. It is called an emitter follower circuit. (or source follower if you use a FET). Use one op-amp to drive the emitter follower stage which will drive the speaker or headphone.

Upupa Epops · 20th September 2004, 10:17 PM

Why to do that " old way " ? Look at sites of peranders - there you will see modern headphone amps, buy one, build it and you will have not problems

.

20th September 2004, 11:20 AM	#1
audioPT diyAudio Member Join Date: Aug 2002 Location: Right here	Headphone amp hi! Does this topology will work well? I've draw the basic schematic... Regards, Pedro Martins

20th September 2004, 11:45 AM	#2
Jennice diyAudio Member Join Date: Jun 2003 Location: Planet Earth	Why so many op-amp's in stead of a single buffer-chip with sufficient output power? I suppose you consider the first op-amp (on the left side of the schematic) to act as a driver since it is connected differently than the rest? No need to use a "driver", if the input impedence is as high as a typical op-amp (don't know your particular chip). Remember, headphones use fairly little power, so a lot of circuits should be able to do the trick. Have you tried to simulate a circuit, which is basically a class-A buffer stage (voltage follower)? It seems to me that you're making life more complicated than it needs to be. Jennice __________________ I get paid to break stuff. My g/f gets paid to play with children. Life is good.

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20th September 2004, 09:08 PM	#3
cunningham diyAudio Member Join Date: Jun 2004 Location: Knoxville	The input impeadence to an op-amp is very high. The output impeadence is much lower. The only reason to use op-amps in this fasion is to put RC filters in between them to make an active filter network. You are attempting to lower the output impeadence of the op-amp circuit by parralelling the devices. There is a much easier way to amplify current. It is called an emitter follower circuit. (or source follower if you use a FET). Use one op-amp to drive the emitter follower stage which will drive the speaker or headphone.

20th September 2004, 10:17 PM	#4
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	Why to do that " old way " ? Look at sites of peranders - there you will see modern headphone amps, buy one, build it and you will have not problems .

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