This opamp is discussed mostly as a part of Gilmore amplifiers' servo loop, but it can be used by itself as the main part of a headphone amplifier.
I assembled a difference amplifier with gain of 30 and input impedance of 1 kOhm. "+" input is grounded, so the difference amplifier now works as an inverting amplifier. Two 9V batteries are used for bipolar power supply. No capacitors are involved. (thanks to low offset voltage of OP27 it doesn't even click when headphones are inserted)
The gain turned out a bit more than actually needed for my Zen V to drive a pair of AKG K240 Monitor. The volume is uncomfortable at about 20 and the amplifier begins to clip at 22 (checked with an oscilloscope), when the maximum volume is 25, so I'm going to cut the gain to 10 or probably 15 (the other solution is to double supply voltage, but I don't want to hear my ears clipping
).
The sound is definitely pleasing. Warm and fat (like your mum
. Not much detail, but no harshness. Soloing instruments prevail.
In future I'm thinking on trying a pair of AD797's in my headamp. It's bigger supply curent isn't going to be much trouble with 9V batteries, but inceased headroom and generally superior sound quality are among desireable options.
I assembled a difference amplifier with gain of 30 and input impedance of 1 kOhm. "+" input is grounded, so the difference amplifier now works as an inverting amplifier. Two 9V batteries are used for bipolar power supply. No capacitors are involved. (thanks to low offset voltage of OP27 it doesn't even click when headphones are inserted)
The gain turned out a bit more than actually needed for my Zen V to drive a pair of AKG K240 Monitor. The volume is uncomfortable at about 20 and the amplifier begins to clip at 22 (checked with an oscilloscope), when the maximum volume is 25, so I'm going to cut the gain to 10 or probably 15 (the other solution is to double supply voltage, but I don't want to hear my ears clipping
).The sound is definitely pleasing. Warm and fat (like your mum
. Not much detail, but no harshness. Soloing instruments prevail.In future I'm thinking on trying a pair of AD797's in my headamp. It's bigger supply curent isn't going to be much trouble with 9V batteries, but inceased headroom and generally superior sound quality are among desireable options.
