lynn_olson
Responses from lynn_olson
| 300b lovers What separates the Euro super tubes is massively higher electron emission. For example, what separates the EML 320B XLS from the EML 300B XLS is 50% greater heater current, with correspondingly higher emission. But even the EML 300B XLS, although ... | |
| 300b lovers The operating points are conventional, well within standard 300B specs, with the plate at about 75% of max rating (which typically gives maximum life). But if you really want to slam the amplifier, well, you can. There’s nothing stopping you. The ... | |
| 300b lovers Considering that each Blackbird B+ regulator can crank out 500 mA peaks, and 400 mA steady-state, there’s plenty of current the super tubes can use. The only thing limiting the Blackbird is peak emission from the 300B filaments ... nothing else. ... | |
| 300b lovers Yes, I would not mind a matched quad of Elrog 300B's with their thoriated-tungsten filaments. That would be something quite wonderful. The Mark I Karna's thrived on a matched quad of Emission Labs 320B-XLS, but that was also a serious investment. ... | |
| 300b lovers I met Thomas Meyer at the 2004 European Triode Festival (I was the invited keynote speaker). He’s a lot of fun, and super knowledgeable about tube history. He, too, is a transformer enthusiast, particularly with modern transformers. I’m super hap... | |
| 300b lovers Don did a marvelous job here. It’s actually quite functional, with a clean and direct front-to-back signal path, and with all wires in the balanced circuit equal length (yes, he went to that much trouble). You can infer that from the top plate. T... | |
| 300b lovers This is very close to the production version. It is simpler and more straightforward to build than the shoebox format shown at the PAF show ... more spacious, more direct layout, and the power supplies are confined to their own section of the amp,... | |
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| 300b lovers My first experience of a 300B amplifier was back when I was writing reviews for Positive Feedback magazine back in 1993. It had grown from a 4-page mimeographed club magazine for the Oregon Triode Society to a fat 100-page periodical with cartoons... | |
| 300b lovers Let’s talk technical about DHT filament power supplies. My friend John Atwood built a low-RF filament supply a few years back (100 kHz or so), but he made the discovery that the filament inductance of DHT tubes was all over the place, making it di... | |
| 300b lovers Although I don’t enjoy "tuning", it is an unpleasant necessity for speakers and power amps. For reasons that are not clear, various brands of metallized polypropylene capacitors sound quite different from each other, and there is little correlatio... | |
| 300b lovers I should mention SE tuning is not the same as balanced-amp tuning. The dominant coloration with SE are the tubes themselves, and it requires artful selection to avoid heavy additive coloration. The fad for 2-stage SET amps makes this worse, since ... | |
| 300b lovers Areas for improvement: The 5U4G rectifier is not ideal. I’d use HEXFREDs, high-voltage Schottky rectifiers (Don’s choice), or damper diodes for the 300B plate supply. Any of the three will have more dynamics and more vivid tone colors. The improve... | |
| 300b lovers I should note my description of feedback circuits is a grossly oversimplified, non-mathematical overview of a complex subject. For the curious, read about how op-amps are stabilized, and the concepts of loop gain, excess gain, dominant-pole compen... | |
| 300b lovers By way of comparison, neither the Raven nor the Blackbird use any form of feedback, either local (around the tube) or global (around the entire amplifier). The incoming audio signal only flows forward, with no secondary paths around the circuit. F... |