Desktop Cmoy with NJM4556 Buffers

[amendiola]

Dear All:

I have built a Desktop Cmoy amplifier using an OPA2134.

I want to know whether I can add two NJM4556 in parallel at the output of each OPA2134.

I want to apply the NJM4556 buffers that the O2 project uses.

Do I have to use the high pass filter formed by C13 and R12 on the O2 schematic?

Regards.
Alfredo Mendiola Loyola
Lima, Peru

 

[jcx]

its a good idea to keep them if you have a volume pot in that same location - bjt input op amps draw a bias current which may annoy the potentiometer wiper contact - can become noisy

if the output buffers are driven directly from the preceding op amp output then its not strictly necessary

 

[amendiola]

its a good idea to keep them if you have a volume pot in that same location - bjt input op amps draw a bias current which may annoy the potentiometer wiper contact - can become noisy

if the output buffers are driven directly from the preceding op amp output then its not strictly necessary

Is it possible that the output of one amplifier be greather than the other amplifier due to differences on the feedback gain (Both amplifiers from the same NJM4556 Chip)?

Is the Unity Gain of each amplifier in the NJM4556 the same?

Regards.
Alfredo Mendiola Loyola

 

[sgrossklass]

Unity gain is unity gain, but input offset may be slightly different, hence the 1 ohm combining resistors in the O2. As this value already seems to increase average current consumption a bit, you could up that to maybe 3.3 ohms or so. Still plenty low enough for anything that isn't a super picky multi-driver BA IEM, including any full-sized headphone.