Sam Groner’s op amp distortion study

Former Analog Devices great Walt Jung was nice enough to tip me off about Sam Groner’s website about audio applications. The site hosts a huge 313-page 24-megabyte pdf on operational amplifier distortion. It has an audio focus, so there are mostly high supply voltage parts in study, see below for the list as of this date. On page 301 Sam draws some conclusions, noting how loading effects the distortion numbers (a lot) as well as how power supply voltage effects distortion (not much but these are higher-voltage parts). There is also an appendix on page 303 about op amp topologies. This is also with an audio low-frequency emphasis. He does not discuss current feedback amplifiers. It is more about single, double and triple-stage designs and the tradeoffs involved.

Another page on his website has a whole bunch of op amps made from discrete parts. Lets see those IC designers try to put a 47uH inductor across the collectors of the input differential pair like Sam did in his SGA-HVA-1 high-voltage discrete operational amplifier. Sam also has a section about resistors, capacitors, transformers and a lot of other discrete parts.

Well, sorry, I was going to copy the amplifier part numbers here so you could see what parts Sam tested, be he locked the pdf for copying and I don’t have the time to take a screenshot and do an ocr. [UPDATE: Sam unlocked the pdf and sent the chip part numbers, I will copy below, Thanks SAM!] I will tell my amplifier pals about the study and the sight and get some feedback.

Analog Devices AD797

Analog Devices AD823

Analog Devices AD825

Analog Devices AD826

Analog Devices AD829

Analog Devices AD845

Analog Devices DY2000

Analog Devices OP275

Analog Devices OP467

Analog Devices OP471

Audio-gd OPA-Earth

Audio-gd OPA-Moon

Forsell Technologies JFET-993

Linear Technology LT1007

Linear Technology LT1057

Linear Technology LT1115

Linear Technology LT1124

Linear Technology LT1122

Linear Technology LT1128

Linear Technology LT1213

Linear Technology LT1215

Linear Technology LT1220

Linear Technology LT1358

Linear Technology LT1363

Linear Technology LT1469

Linear Technology LT1630

Linear Technology LT1632

National Semiconductor LF356

National Semiconductor LM833

National Semiconductor LM837

National Semiconductor LME49860

SGA-HVA-1

SGA-LNA-1

SGA-SOA-1

SGA-SOA-2

Signetics NE5532

Scott Liebers SL-2520 Blue Dot

Scott Liebers SL-2520 Red Dot

Sound Skulptor SK25

Sound Skulptor SK99A

Sound Skulptor SK99B

Texas Instruments MC33078

Texas Instruments NE5532

Texas Instruments NE5534

Texas Instruments OPA551

Texas Instruments OPA627

Texas Instruments OPA2132

Texas Instruments OPA2604

Texas Instruments RC4580

Texas Instruments TL071

Texas Instruments TL4581