lynn_olson
Responses from lynn_olson
| 300b lovers If you’ve been curious the kind of things two designers discuss with other, the previous posts give a simplified example. Sonics, different circuits and what they sound like, and reliability. It's also an example why collaborations between designe... | |
| 300b lovers One variant we did not try was a center-tapped inductor to load the 6SN7 plates, and direct coupling between the input and driver tubes. That requires a high B+ voltage for the driver, but that’s no problem when the input + driver have their own p... | |
| 300b lovers It may strike some readers as weird that Don and I are taking a minimalist approach to a PP amplifier, more like a SET than a typical PP. The signal path is simple: Optional SE/Balanced input transformer -> Balanced 6SN7 -> Interstage #1 -&... | |
| 300b lovers That’s a subtle aspect of feedback theory that is often overlooked. The summing node must be distortionless, and also free of overshoot or slewing artifacts. Applying input signal to a grid, and feedback to the cathode, impresses tube distortion (... | |
| Spatial Audio Raven Preamp 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 so... | |
| 300b lovers Ralph, you’re the acknowledged OTL expert. How does an OTL amp work without feedback? I’d like to know. The last I checked, tubes designed for series regulator use like the 6080, 6AS7, or the Russian 6C33C have a Zout on the cathode side somewhere... | |
| Spatial Audio Raven Preamp 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 l... | |
| 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... | |
| 300b lovers To recap, there are different challenges associated with low and mid-frequency distortion vs high frequency distortion. HF distortion is very often caused by nonlinear current delivery into a capacitance, and stray capacitance is everywhere in aud... | |
| 300b lovers Something both transistor and tube amps share are performance limitations set by current available to drive a capacitance. In a transistor amp, that will be the dominant pole capacitor associated with the second voltage-gain stage. The current ava... | |
| 300b lovers Interesting SET that harks back to the original Western Electric 91A, which also used feedback to get the desired performance. I have mixed feelings about cathode follower drive: the output impedance of the CF is low (probably 100 ohms or so), bu... | |
| Spatial Audio Raven Preamp The most dangerous of all are DC-coupled preamps and power amps. If the DC servo system in a preamp fails, the failure can propagate all the way to the loudspeaker. I saw this happen when I was visiting the home of a reviewer. It took out one chan... | |
| Spatial Audio Raven Preamp Another small note: conventional tube preamps can be dangerous for transistor amps unless they have an automatic muting relay with a timer circuit. A conventional tube preamp with cathode follower output typically has the output node (the cathode)... | |
| Spatial Audio Raven Preamp Don and I are pleased that Raven owners have an equal choice between RCA-input power amps and XLR-input power amps. The Raven treats both the same, so the sonic choice is on an equal footing. Classic vacuum tube amps almost always have RCA inputs... | |
| Spatial Audio Raven Preamp Although Don and I optimized the Raven and Blackbird to deliver their best performance with each other, we went to considerable trouble to make sure they add sonic value to other systems, too. For the Raven, this means optimal performance when mat... |