Spatial Audio Raven Preamp

The anecdote is true, not fictional. I was there and saw it happen.

Not surprisingly, the preamp and power amp were all solid-state and were stupendously expensive, in the $100,000 range. As we old-timers know, price does not guarantee quality in our business, unfortunately.

DC servo failure is not rare in the high-end solid-state world. It should be, but isn’t. When it happens, the results are very expensive, not to mention the cost of down time.

Looking back, my guess is poor solder technique somewhere in the preamp, or maybe a regulator in the plus or minus supply gave up, yanking the preamp output to 15V or more. Or a DC servo went nuts. Results were the same, a destroyed power amp and loudspeaker. The only unusual thing was a designer (me) seeing the failure in real time, in a domestic setting. You usually see this kind of drama on a test bench, not in the context of an ultra-deluxe system in a home.

Should it have been better designed? Of course! But how is the consumer to know? They assume [higher price = better product].

That’s the real difference between pro gear and audiophile equipment. The pro stuff is reliable, because it has to be.

That’s the real difference between pro gear and audiophile equipment. The pro stuff is reliable, because it has to be.

@lynn_olson If you're going to stay in business for the long haul producing high end audio products they have to be reliable too. I can't imagine how anyone thought that a solid state amp without the ability to protect itself from something like this was a good idea. At the very least if the amp smoked it should have blown a fuse...

Oh it blew a fuse all right. After the output section was completely destroyed, and a massive DC pulse killed the woofer. This was European oligarch-class audio gear from a well-known manufacturer.

The manufacturer is still around, twenty years later. The buyers are expected to suck it up and not complain, I guess.

The joke amongst designers of transistor gear is transistors do a great job protecting the fuses (because transistors fail in milliseconds, while fuses can take a half second or longer). Transistors fail much faster than any human response time, whether on a bench or across the listening room. And a good, solid DC pulse will destroy any woofer ... audiophile-grade woofers can only take 1 watt (or less) of DC on the voice coil. Professional 15" woofers with 4" voice coils can take a little more DC, but certainly not 200 watts.

Sheesh. If our stuff had been damaging speakers we'd not have been in business very long. Odd how a solid state manufacturer could get away with that!

Happens all the time in the small-production-run solid-state world. Oversights in manufacturing like no heat-conducting paste between transistors and heat sinks, for example. Or a wave solder machine not properly set up for EU-required leadfree solder, so the solder joints on a circuit board start going bad after a while.

There’s some pretty sketchy tube stuff too ... I remember seeing bulky, heavy electrolytic capacitors "attached" to the chassis with RTV silicone goo ... and no bolts, clamps, or other hardware! From a highly reviewed European manufacturer that is still in business twenty years later. Or a well-known American manufacturer that omitted, or forgot, the required 10~100 uF decoupling/stabilization capacitors for the multiple 3-pin voltage regulators, so they sang happily in the 10 MHz range. Easily visible on an RF spectrum analyzer, but not easily seen on a scope.