Simulating the LX-521 ASP

February 12th, 2013

To help me learn about and consider the design trade-offs of the Linkwitz LX-521 ASP (the active filter based crossover) I have spend a bit of time creating a spice simulation in LtSpice4. This a considerable amount of time to create as there are a lot of parts in the design. I have also obtained models of the LM4562, the LME49990 and a few other op-amps just for fun. After removing my typos and running the simulation I have been able to re-create the response of the ASP as provided in the construction plans provided by Seigfried Linkwitz.

The circuit board is designed for thru-hole size components and as such the LME49990 op-amp, which is an SO8 surface mount package, will not fit but adapters can be built. The LME49990 is a newer design than the previous parts OPA2134 and LM4562 parts and at least published data shows lower noise and distortion for the LME49990.

Of course, all of this is a prelude to building the ASP and actually measuring the various stages and determining the optimum design. It just may be that there is little to be gained by changes or supposed improvements, but I intend to actually measure and listen to the thing and find out.

Copyright © 2013 David L. Bytheway

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