Jeff Fritz: Coda has been producing amplifiers and preamplifiers for . . .
Doug Dale: We started as Continuum in 1985 and made a small run of MC cartridge head amplifiers. Then we hibernated for a couple of years and began Coda with a limited line of preamps and amps. We operated comfortably from 1989 until 2003. We relocated at that time, forced by the purchase of the industrial park in which the original facility was located. We relocated again in 2007 and have worked to improve our product flow and continued to improve the designs.
JF: Class-A amplifiers sound so good because?
DD: A perfect design should be totally neutral, but nothing is perfect. If a spectral analysis is done of a class-A circuit the distortion that is produced has harmonics that are more related to the original signal than those that are present in a non-class-A design. This is a characteristic that is shared with tube amplifiers and may be the reason that class-A amps are often referred to as tube-like. When they do clip or distort they do so in a less "offensive" manner than a typical class-AB amp.
JF: Are Coda amplifiers of today better than the Thresholds of yesteryear?
DD: We certainly think so. Electronically our designs are quite different, being non-Stasis. The Threshold amps were quite good at the time, however. As a group we all preferred class-A circuits to the Stasis topology. In regard to objective measurements, there is no comparison. The class-A circuits implemented by Coda are dramatically better.
JF: What do you first think of when I say "class D"?
DD: Too much processing for my taste. Also, there are usually noise issues. They all seem to have a "harsh" character. Class-A and -AB just seem more appropriate for producing an analog signal with power.
JF: The new Coda Model 15.0 and Model 33.0 are special because?
DD: They use devices (transistors) that were not available until a couple of years ago. They have allowed for a degree of bias control that was not available in the past. This is something that is critical in class-A designs and, along with some changes in the voltage gain stage, helped us produce a phenomenal-sounding amp.
JF: Why have solid-state amplifiers improved so much over the last 15-20 years?
DD: As always, designers have worked to advance circuit topologies, but the biggest differences have come from the availability of improved components as with the 15.0 and 33.0.
JF: Are there any design elements that typify the Coda approach to high-end electronics?
DD: We tend to build amps that have a lot of margin in their performance. This gives us very good reliability. Of course, there is class A. Also, we typically use minimal or no global feedback to improve IM and phase response.
JF: Why gold-plated circuit boards?
DD: Actually, in the beginning they just looked good. Of course they do not discolor over time and have low contact resistance. Now they are necessary to meet the EU non-lead requirements.
JF: How important are measurements in the design process?
DD: They are essential. Objective measurements provide the only neutral way of evaluating a design. Subjective comparisons are made once a design is completed, and both play an important role in the final result.
JF: One word that describes the sound of Coda products is . . .
DD: Accurate. The products are also fast, high bandwidth, powerful, but the thing we strive for most is accuracy.
JF: What do you want folks to know about Coda that they might not have any clue about?
DD: We try to be very user-friendly. We are a small company and have remained so by choice. This decision has allowed us to ride out some difficult economic cycles while other companies have expanded and disappeared. The side benefit is that owners can often have product tailored to specific applications with minimal effort. This is particularly true in the US, where we sell direct to the end user. When someone requests information on a product, it is not being filtered through a dealer, who is unlikely to have as complete or accurate knowledge as the manufacturer.