discrete operational amplifiers

we have developed several fully discrete operational amplifier flavors in the 2520/990 footprint, some original and some adaptations or inspired on legacy iconic designs

OpAmp comparison table

Name
Description
Design Remarks
Sound
Transistors
Operating Voltage
M2
original design inspired by Melcor 1731 output stage
cascode amplification stage with quasi-complementary output
clean, warm, solid
11
±12V to ±24V
flick
original inspired by Flickinger 290-3 mic pre cards
differential amplification followed by all NPN output
open top with rich harmonics
6
±15V to ±24V
ADOA
our take on the most famous American discrete op amp
differential amplification with complementary output
edgy highs and punchy mids
8
±12V to ±20V
JDOA
adaptation of Jensen 918
darlington amplification stage with complementary output
nice low end and openess
9
±15V to ±24V
NDOA
adaptation of highly configurable German design
common emitter amplification stage with complementary out
thick warm sound
12
±2.5 to ±22V
QDOA
adaptation of a classic American op amp used in southern California large format consoles
novel gain stage with complementary out
gentlemanly sound
10
±14 to ±28V
M2_edited_edited.png

M2

clean

warm

solid

A_edited.png

ADOA

edgy highs

punchy mids

N_edited.png

NDOA

thick

warm

sound

F_edited_edited.png

flick

open top

rich harmonics

J_edited.png

JDOA

nice low end

openess

QDOA

gentlemanly

sound