Purple Audio
 
   PRODUCT    PRESS    DISTRIBUTION    ABOUT    FAQ    LINKS   
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
 

 

We gave out about 30 of these at the PotluckCon June of 2008,

The first batch had power via hardwire only.

 

We gave out about 50 of the second batch (shown) at AES 2008 in San Francisco,

this version has power via hardwire or 5 Pin XLR.

EG = Earth Ground

AG = Audio Ground

-----------------------------

We have used a couple of these with Elpac

Wall warts, these don't have 48 but they work OK

for testing and utility boxes. I have a couple of Cans headphone amps on these

and a -10 -> +4 stereo bump box.