Headphone question

[Wynand]

I recently accuired an old Elektor Magazine from 1983. In it is a design of a 160mW Class-A discrete headphone amplifier.

I want to build it, but is it worthwhile to build a discrete amplifier (with way more components) or can I use a LM833, which I’ve bought already, and get the same quality sound?

I have no problem building either, but will have to design a PCB if using the LM833.

If the op-amp variation is better, is there a good PCB layout around?

 

[jan.didden]

Which is the impedance of the headphone you want to drive? That is an important piece of data in deciding on the amp.

Jan Didden

 

[Wynand]

I've got a pair of 8-ohm headphones.

 

[jan.didden]

Well, in that case, an opamp is out. You need something that can drive what is in effect a speaker load, albeit not to such high levels. Any info on sensitivity? How many volts or milliwats does this require for max sound level?

Jan Didden

PS Are you sure? I thought most headphones are 32 or above ohms?

 

[Wynand]

The headphones are an old pair of kenwoods from almost 25 years ago. It was my dad's. They play beautifully.

I did measure them with a VOM but I'll just make sure tonight at home.

I dont know the specs for the headphones and the Elektor magazine is at home also.

If I read your answer correctly. Is op-amps ok to use SQ wise when you use higher impedance headphones (+32Ohms ?) ?

 

[jan.didden]

The headphones are an old pair of kenwoods from almost 25 years ago. It was my dad's. They play beautifully.

I did measure them with a VOM but I'll just make sure tonight at home.

I dont know the specs for the headphones and the Elektor magazine is at home also.

If I read your answer correctly. Is op-amps ok to use SQ wise when you use higher impedance headphones (+32Ohms ?) ?

There are opamps that can drive 32 ohms, but ususally they cannot. Hi-speed opamps used for ADSL are generally very good for this low impedances, and they have low distortion as well.

There is also a special headphone chip available that CAN do it. Search the forum, there is quite a lot of traffic on it. I think Per-Anders has a design on it.

Jan Didden

 

[Wynand]

Thank you very much.

 

[jan.didden]

Thank you very much.

http://home.swipnet.se/~w-50719/

 

[Wynand]

Thank you very much. I think I'm gonna build the Elektor amplifier.

Reasons are
1) I'll be my first Class-A amplifier
2) It already designed by people who know
3) I've got most parts
4) It can drive 8 Ohms
5) It should be a good reference Amplifier for future Op-anp designs.

Thanks for your help.

I must be off now.

Bye.

 

[jan.didden]

Have fun!