I've put the Spice model online for the π implementation of the 6DJ8 tube crossover. You'll need OrCad's version "PSpice" to run this model, and you'll need to install the libraries contained in the distribution file. It's a pretty big distribution, to tell the truth, but it has the advantage of allowing you to work directly with the schematic. OrCad was originally written for PCB layout, so you can layout a circuit board and have fiberglass made with it too.First, download "PSpice" and install it, and then download the 6DJ8 crossover model. Inside the crossover distribution file, you'll find another archive called "Tubemods.zip" which must be installed and configured before the model will work.
Active implementation of π compensated crossover using 6DJ8 tube
First, second and third order networks can be formed by configuring the circuit to use one, two or three poles. Components R15/R16 and C10 are similar to R1/R2 and C1 on the π passive crossover networks. This is the HF compensation section of the circuit, and values may be modified for different amounts of compensation. You'll also notice the addition of resistor R17 in the LF circuit, which damps the filter and improves response. All other component designations follow those used by Steve Bench in his crossover circuit.
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