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Original Message

The CX-7e does not use op-amps

Posted by Charles Hansen on February 7, 2009 at 14:35:33:
From a 2003 interview (linked below):

We are now using ICs (integrated circuits) in some of our less
expensive products designed by Dr. Barrie Gilbert, one of the
"godfathers" of analog circuit design. Now, itâ€™s very important to
differentiate between the terms "integrated circuit" and "op
amp" (operational amplifier). Weâ€™re using integrated circuits,
which simply means that there are many transistors created at
once on a single piece of silicon. An op amp, on the other
hand, uses negative feedback as its fundamental operating
principle. You cannot use an op amp in a zero-feedback circuit.
The topology of the IC we use in the less expensive products is
very similar to the topology of our discrete circuits. We've fig-
ured out how to implement these monolithic ICs with zero feed-
back. By using two of them together, and modifying their char-
acteristics, we can get within spitting distance of the perform-
ance of our discrete circuits at a much lower cost. The critical
advantage here is that the monolithic design of the IC means
that all of the transistors are matched extremely closely. In con-
trast, with our discrete circuits we have to spend a lot of time
measuring, sorting, and matching transistors, which translates
to a more expensive final product. By using an IC in a way that
hasnâ€™t been done before, weâ€™re able to achieve a real break-
through in performance at a real-world price point. It's great to
make an all-out assault on the state of the art, when the only
limit is your imagination. But the real challenge is to bring those
lessons back to the real world where more people can enjoy
the fruits of our labors.

We are very happy with the analog section of the CX-7e MP. We are not planning to make any changes to it.