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What's the deal with Broskie's iPod buddy?

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leadbelly

leadbelly

Member
Joined 2002
I don't understand the reasoning behind Broskie's "normal" Aikido low-Z headphone amp:

aikido_low_impedance_headphone_amplifier.png


and his "iPod buddy" version:

ipod_aikido_low_impedance_headphone_amplifier.png


The latter version features higher gain in the front stage and a feedback loop in order to implement it. Why would you need higher gain when iPod's and MP3 players can already drive headphones directly?
 
moamps

moamps

diyAudio Member
Joined 2002
moxtone.com
leadbelly said:
The latter version features higher gain in the front stage and a feedback loop in order to implement it. Why would you need higher gain when iPod's and MP3 players can already drive headphones directly?
Click to expand...

Hi:

The use of higher open loop gain and NFB will result in smaller output impedance than in a non-NFB design, which is important when small-impedance phones need to be driven. Also, in this case, the application of NFB lowers the headphone amplifier gain to an acceptable value.

Regards,
Milan
 
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