[sdiy] Headphone amps using op-amps

[bbob]

http://www.paia.com/proddetail.asp?prod=9605K  looks like it might be relevant?

On Wed, Dec 12, 2012 at 4:23 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
>
> On 12 Dec 2012, at 18:36, Veronica Merryfield wrote:
>
>>
>> On 2012-12-12, at 9:52 AM, Tom Wiltshire <tom at electricdruid.net> wrote:
>>
>>> If I'm driving a pair of cheap headphones from a standard op-amp (I've got a TL072, a MC1458 or a LF353 available - you don't get much more 'bog standard' than that lot) is there anything special I need to do?
>>
>> I use NJM4556AD - it can provide 70mA to the output. I try to rig it as a follower stage only although one can use some gain, in which case I add some roll off. I add a resistor in series with the load just to protect it from shorts etc. Working fine in 1000s of units out there.
>
> Ok, that sounds reasonable. So I could add a '4556 wired as a voltage follower to the output of the amp I've got presently and buffer it. How much resistance do you use, Veronica? Would a couple of hundred ohms do it, or do I need more?
> Finally, what about the levels? How much juice can I use before the headphones start to overdrive?
>
> JPs schematic is similar inasmuch as it buffers the op-amp output (with a push-pull stage) and adds resistance in series.
>
> Thanks,
> Tom
>
>
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