gar2520 as a headphone amp?

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ChrioN

Well-known member
Joined
Aug 31, 2005
Messages
1,235
Location
Gothenburg, Earth
I got me some new headphones today, and I want to build an amp for them.

Some specs on the cans:
62 ohms impedance
200 mW max
105 dB/mW sensitivity

The gar2520 opamp can drive 75 ohms minimum

so maybe this is a better circuit to use them in:

http://gilmore2.chem.northwestern.edu/images4/aph_47b.gif

any thoughts?
 
No need for complex schemes. The gar2520 (or most any 2520-style DOA) by itself can supply enough power to kill your hearing on all but the most inefficient headphones.

That 75R rating is not an absolute minimum; it's a minimum for full-drive at max dissipation. You do not ever run headphones that hot, or it's brain through the nose time.

For various reasons you'd want a build-out resistor between the op-amp (be it discrete or not) and the headphone jack. PRR has written an essay over on Headwise suggesting an optimum of 29R (see the article for full context); I'll be so bold to say that any value between 10R and 100R that you happen to have lying on your desk will do for an initial test and will likely be Just Fine for all but the most demanding situations.

JDB.
[searching here for headphone with author PRR brings up more gems that you might be interested in]
 
> 200 mW max
> 105 dB/mW sensitivity


128dB SPL ? ? ?

What JDB said. If you need that much SPL, your hearing is ruined.

20mW should be more than ample.

In 62 ohms that's just over 1V RMS. Indeed these are intended to get really f-ing LOUD on 3V-battery Walkmen/iPods.

Why do you need an amp? To make your iPod louder? To use at home? In the studio?

The APH47 will work, at the minimum +/-4.5V voltage the OPA2131 will work at.
 

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