lynn_olson
Responses from lynn_olson
| 300b lovers The 845 is not happy at 500 volts. It is a (low-power) transmitter tube, and is designed to work from 800 volts (minimum) to well over 1000 volts. Once you go over 500 volts, construction, and the parts required, are a whole different world. It r... | |
| 300b lovers Which I guess leaves the question why does the input stage have the topology it does. The quick-and-easy approach would be a Mullard-style long-tailed pair or differential stage, or maybe borrow from Williamson or Dynaco and direct couple a half-6... | |
| 300b lovers The 300B ... all of them ... quite happily accept at least 20 volts of positive grid drive. This is not secondhand info gleaned off the Internet, I’ve seen it for myself on a Tektronix scope screen back in the Nineties. I was frankly surprised, be... | |
| 300b lovers You want a technical presentation, here’s my talk at the 2004 European Triode Festival: 2004 ETF Presentation As for the lengthy previous post, I am not sure about the impact of dynamic variations in output impedance. One way to measure the impa... | |
| 300b lovers By the way, my own little hypothesis about output impedance of SET amps varying over the signal cycle could be completely wrong. Transformers do store energy, which is why the primary easily swings well above B+ voltage. So the transformer itself ... | |
| 300b lovers What’s fun about knowing Don and Thom is they have different ideas that bounce off each other. Way back when, Thom had some pretty gruesome-sounding amplifiers, and in my usual blunt and ham-fisted way, I said as much. I may be the son of a diplom... | |
| 300b lovers I usually hang out at DIYaudio, and am the originator of the notorious "Beyond the Ariel" thread in the "Multi-way" speaker forum. Gary Dahl, my neighbor when I lived in Silverdale, Washington State, finally retired the thread when he built his ow... | |
| 300b lovers Weirdly enough, both Thom Mackris and Don Sachs came up with the 6V6 driver within hours of each other. Thom was hacking around with his SET 300B amp and swapped in the 6V6 driver and was jumping up and down about it, and Don calls the same day. O... | |
| 300b lovers Last but not certainly not least, my collaboration Don Sachs, which began with phone conversations and many, many emails after I bought Don’s preamp. Naturally, my preamp had to be different, with a balance control ... the dual-mono Khozmo volume ... | |
| 300b lovers I am extremely pleased the Amity, Raven, and Karna designs are having their public debut. The only people who have heard them before were very adventurous DIY builders, but now, thanks to Don and the team at Spatial Audio, we are moving steadily t... | |
| 300b lovers Fortunately, Don and I know where the "bad actors" are, and it’s no secret. Caps. Specifically, film caps. They’re the parts that need the 10 to 50 hour run-in. I do not like this ... it suggests the plastic film is undergoing a very slow chemical... | |
| 300b lovers One of the really fun things about designing an amplifier from scratch (not from 1950’s schematics) is you can hear for yourself when you make a change. Reviewers can only treat these things as "black boxes", and customers can only work at the mar... | |
| 300b lovers As mentioned above, the Mark I Karna used a quartet of 45 tubes, but new production is limited at this time, with future availability an open question. Five years from now? Maybe, maybe not. Ten years? Maybe, maybe not. I can only go by popularity... | |
| 300b lovers Pindac brings up a good point. Designing a good amplifier is a lot of work, and there’s just as much work getting a product market-ready. The input and output tubes were obvious choices, based on subjective sonics, low distortion, and continuing a... | |
| 300b lovers RC coupling, although fast and compatible with overall loop feedback (highly desirable in pentode amplifiers), throws away about 1/3 of the potential swing (through voltage divider action) and also creates a steeper load-line, which increases dist... |