Samuel Groner
Well-known member
Hi
Just successfully finished a slightly simplified version on breadboard: [removed]
My design criterions were:
* good audio performance
* low noise, OSI around 1k ohm (for 1:2 mic input transformers)
* class A output into 600 ohm up to clipping
* stable at noise gains of 2 or lower
* offset preferably below 20 mV
* reasonably high CMRR and PSRR
* running on +/- 18 V
* input- and output-protected
* easy to squeeze into a 2520 footprint
* easy to build (no matching and selecting)
* cheap and easy to source parts
Q1/Q2 could be replaced with 2N4403s if you don't mind higher input bias current and a tad more noise.
As shown, this opamp could rival the noise performance of the 990! Output swing is close to 34 Vpp.
Detailed report and Gerber files to come (you might need to give me a few month though, as I have to write my master thesis first...).
[Edit latest documentation: SGA-SOA-1_documentation.pdf. And pictures: SGA-SOA-1.html.]
Samuel
Just successfully finished a slightly simplified version on breadboard: [removed]
My design criterions were:
* good audio performance
* low noise, OSI around 1k ohm (for 1:2 mic input transformers)
* class A output into 600 ohm up to clipping
* stable at noise gains of 2 or lower
* offset preferably below 20 mV
* reasonably high CMRR and PSRR
* running on +/- 18 V
* input- and output-protected
* easy to squeeze into a 2520 footprint
* easy to build (no matching and selecting)
* cheap and easy to source parts
Q1/Q2 could be replaced with 2N4403s if you don't mind higher input bias current and a tad more noise.
As shown, this opamp could rival the noise performance of the 990! Output swing is close to 34 Vpp.
Detailed report and Gerber files to come (you might need to give me a few month though, as I have to write my master thesis first...).
[Edit latest documentation: SGA-SOA-1_documentation.pdf. And pictures: SGA-SOA-1.html.]
Samuel