CLA-2A Version 2 Register Login      
CLA-2A Version 2

Around 1999 I went through an awful lot of trouble to redesign the CLA-2A, to make it easier to manufacture. The original design was somewhat modular, with the audio and control amps on one circuit board, the power supply on another and the meter circuitry on a third board. Although this layout resulted in an excellent sounding unit, the three boards had a considerable amount of point-to-point wiring between them which added significantly to the amount of labor necessary to build a unit. I began the arduous process of laying out a single board that included all of the circuitry and interconnects previously located on and between the three boards. One of the biggest challenges was to make sure the sound quality was not affected by the proximity to the signal and control amps of unregulated DC and unrectified AC currents on the same PC board. To accomplish this I had to lay the board out by hand, as the autoroute functionality built into Protel was obviously not built with tube audio circuits in mind. I autorouted a board just to see what it would do and it was hilarious. No human - even a noob - would ever lay out a board that way.

Dubbed the "V2", this version also included the updates that were tested on the "Frank" prototype, including the circuitry to switch between two different sets of photocells (allowing for 3 different compression curves) and unbalanced inputs and outputs (which I ended up eliminating anyway because nobody ever used them.) I used Protel software to lay out this board and it's been so long since I've used Protel I don't remember how to use it, so this design is probably going to die on the vine. I might put an image of the board up here at some point just for conversation's sake but don't hold your breath since I'll have to dig out and install my 10 year old version of Protel to read the files.