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Amplifier design / Bob Carver's thoughts

Here's an interesting article i ran across. For those that are interested in how devices work and the decisions that engineers make when designing a product, try taking a look at this article. It is an older interview with Bob Carver and gives background on the how's / why's of the Sunfire designs and why he chose the design attributes that he did. Obviously, the specific decisions made when designing any product are a matter of subjective preferences and some may not agree with Carver's personal designs / take on things. Having said that, the info provided here may help some of you that are less technically inclined understand how an amp works and what the various trade-offs are. Good reading, even if you don't like "Sideshow Bob". Sean
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Design attributes of the Sunfire amplifier
sean
arthursmuck
447 posts
 
I just added a Sunfire Sig 2ch for my N802's and am amazed at what it brings out in these speakers...a new Sunfire convert!
shubertmaniac
350 posts
 
Sean: I still have my Phase Linear 400 from 1971, still runs. Not much current for speakers less than 4 ohms, but works fine with anything else. I ran the PL 400 about 2 months ago with the Radians, a little lean on the high end, the bass response was surprising good, the midrange a little soft, a little gritty, edgy, but really not half bad either, though tiring after a hour or two.
sean OP
6,231 posts
 
The older Phase amps were very simple circuits, but due to poor implimentation and quality control, sounded worse than they should have. If one removed the current limiting circuit and matched the output transistors on these amps, you would get rid of a lot of the "grunge" and smearing that passes for treble response in these amps. It is this "grungy grit" that causes fatigue and makes everything sound harsh and veiled.

On top of all of that, these amps didn't overload very gracefully, partially due to the lack of matching in the output stages and the lack of power supply reserve. Once they started to clip, they went into hardcore saturation and smearing. Not only were the transistors being pushed, the power supply had given all that it had and was also trying to recover. Given the lack of power supply reserve to begin with, this happened more frequently than one might think. As such, many of the sonic problems with these amps under load was directly due to all of the voltage sag taking place during heavy demands. As such, increasing filter capacitance can make a VERY big difference with these amps, but the problem is, there just isn't much room to do this in these chassis. Kind of a "Catch 22" situation.

There are ways around this if one is resourceful, and these amps can be purchased quite cheaply. Quite honestly though, i can think of better candidates to work with if looking for powerful amps at or near the same price levels. As a spare amp "just in case" or something to provide "oomph" on the bottom end of an HT system, they don't work too bad though. I wouldn't want to run one in stock form powering the mains of a two channel rig though. As Shubertmaniac commented, they rank relatively high in the "sonic fatigue" department. Sean
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