Discrete Opamps / Purple Audio, LLC

Purple Audio LLC A Professional Audio Equipment Manufacturing Company. Home of the MC77 Limiter and Biz mic preamp. Gear resources for repair, PDF schematic library - Altec, Ampex, Gates, Pultec, Telefunken, UREI.

Discrete Opamps & Daugtherboards None of our daughterboards are potted, you should never have to trash one of these. In all of our design that uses these opamps we use a footprint that allows a DIP-8 IC opamp to take the place of our opamps or followers. This is for ease of service as well as for experimentation.
The KDJ 3 Class A input opamp Standard Pinout		Supply Current 8ma Supply Voltage Range +/-12v – +/-25v Single piece price $45
The KDJ 4 Class A input stage Class AB output stage Standard Pinout		Supply Current 16ma Supply Voltage Range +/-12v – +/-25v Single piece price $65
All Purple products that use our Discrete Opamps will also accept DIP8 IC opamps
The RLA 2 Dual Class A Emitter Follower		Supply Current 2 x 10ma Supply Voltage Range +/-12v – +/-25v Single piece price $45
SMT Dual LED Driver		Supply Current 16ma Supply Voltage Range +/-12v – +/-18v Single piece price $30
SMT Single LED Driver		Supply Current 12ma Supply Voltage Range +/-12v – +/-18v Single piece price $25

Originally the Purple discrete opamps were designed as building blocks for the highly customizable Super 8 console. This gave us some leeway in designing the footprint, and so for the original output opamp we made it as big as we wanted. The result was the KDJ 2, which had a larger footprint and different pinout from standard dicrete opamps. As we started to work on 500 module format projects, the larger size of the output opamp became a problem. Eventually we were able to find suitable output transistors that were in a tall, flat package rather than the stubby round cans we had been using. The new transistors were also actually faster. We did a new PCB layout for the opamp and realized that with the new transistors, we could use the same PCB, stuffed with different components to make either the input or output opamp, now called the KDJ 3 and KDJ 4. With everything packed a bit tighter, we felt better after adding some heatsinks. To further highlight the difference between the old and new designs, the new KDJ 3/4 PCBs are black where all the KDJ 1 & 2 PCBs were green. For reference, the KDJ 1 and KDJ 2 are shown below, though there are precious few of them "in the wild" and they are no longer available to order.

The KDJ 1 – DISCONTINUED Replaced by the KDJ 3 Standard Footprint
The KDJ 2 – DISCONTINUED Replaced by the KDJ 4 Unique Footprint