jazman Posted March 18, 2005 Share Posted March 18, 2005 ---------------- On 3/18/2005 6:13:16 AM Erik Mandaville wrote: Greg: Mike said (was it mike or Edmond!?) "Sovtek and KR can take a little more voltage and current than the old NOS tubes. If the amp/amps are biased with KR and Sovtek tubes, they may run the NOS harder." This is absolutely right. I seemed to find something similar to your experience with the RCAs in the Horus and Moondogs. With the GZ37 and 5AR4 rectifiers, the Moondogs in my amp exceeded the max. plate voltage (taken between cathode and plate)by about 75 VDC. While this would be a complete non-issue for the KRs, and in fact would be to their advantage, the max plate voltage given for the RCA manual for this type of tube is 250. The stock Moondogs, per the specs given on the schematic, exceed that figure by about 55 volts. I'm not saying that this is a problem in your amps or with your tubes (since there better and less good examples of every kind of tube in existence), but it's one of the reasons I started using 5Y3 rectifier in both the Moondog and Horus amps. This brought the voltage down a bit, and was thus a little more gentle on our antique RCA 2A3s. I just felt better about it. Erik ---------------- Erik, I had been using the GZ37 for the first 2 years, and the GZ34 over the last 2. I probably run my Moondogs for longer periods of time than most. I also have periods of extended "on" time, which translates to days without turning them off. I have also run them for periods of weeks without turning them off. In four years, I have not burned out even 1 pair of RCA blackplates. I did have one tube develop a hum, though it still reads good. I understand your worry, but have not found it warranted with the RCA. They have proved themselves to be very durable. Klipsch out. Quote Link to comment Share on other sites More sharing options...
jazman Posted March 18, 2005 Share Posted March 18, 2005 ---------------- On 3/18/2005 1:26:58 PM Colin wrote: read the posts, enjoyed them too, just truying to be a little devil, and movies absolutely do count... ---------------- No attack intended. BTW Colin, Has your pub considered publishing a list of all "current" 2A3 manufacturers, as well as listening tests? What are you using for 2A3s? Klipsch out. Quote Link to comment Share on other sites More sharing options...
Colin Posted March 18, 2005 Share Posted March 18, 2005 I asked tube stores and manufactorers for 2A3s for a tube shoot-out, but no responses, I have the Bottlehead'd Valve Arts... Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted March 19, 2005 Share Posted March 19, 2005 "Thanks for the information. Good to know. But lets see if I remember my college statistics. It takes 30 observations to mathematically correlate 1 independent variable to a dependant variable, or something like that. So if we have 4 reviewers, 4 tubes, 1 low and 1 high voltage setting, all the same components and loudspeakers (a BIG assumption) and listen to the same 4 songs (different types, same medium) of music and same 2 movies (different types) tracks, at 3 to 10 minutes long, then we are talking about 48 tests for about 144 minutes (call it 3 hours, with cooling and swapping) per reviewer, or 12 hours total. Makes even measurably objective reviews like the venerable Stereophile magazine seem ludicrously arbitrary, doesnt it? How many of us have the same tubes, can set voltage, share the same components, agree on the same media and perform the same test? ---------------- Colin: I also took statistics in college; however, I'm not sure that I want to apply 'T' tests and 'R' tests to my interest in vacuum tube amplification. Over many years of using a number of both vintage and current production 2A3s, I have also gleaned enough experience during that time to be able to hear and appreciate their differences. There are in fact differences. The point I think we are trying to make is that there is probably no single variation of 2A3 species that is, in very much of a subjective sense of the word, the 'best' in all 2A3-based designs. I think rather that what is of interest, here, is the convenient fact that there are many types and brands of 2A3s available for the kind of experimentation that can lead toward 'personal best' and 'favorite' versions. It's something that may not happen over night, and what we have been discussing is the result of truly years of listening to different types, brands, and vintages of the same tube. Like coupling capacitors between stages of a circuit, different tube types can be used to help provide or certain desired 'voice' or 'flavor' to an amplifier. I have listened to so many different variations on the single-ended 2A3 amplifier theme, that I know for certain that, TO ME, a given tube will not sound the same in each of those designs. So, with experience, one can begin to have or develop a sort of intuition that can be of great help in selecting an output tube. Even then it's not so simple, since there can be variations within a given species of tube. (please forgive the Darwinian tone, here, but it is helpful to me in this explanation). So, it takes a considerable amount of time and patience and careful listening to arrive at what might, for a time, be thought of as the 'best' application to the design. And yet, this doesn't even account for the human equation and variability in all of this; and this is where we might apply your reference to statistics. It is where we could look for a correlation between our mood, our level of fatigue, our musical preference, etc. on a given day and the type of output tube that best fits those human factors and elements. Today I feel like a nice merlot, but remember yesterday something a little less robust (though still red)seemed easier -- such as a pinot noir or syrah. (doesn't the little devil seem out of place!?)Forget that, I'd rather go with something like a nice or, maybe this evening, enjoying music and my family, something along the lines of a warm Edmund: I'm sure you are right. I have always been so inclined to 'go by the book' with this stuff. One thing I did want to address in my Moondogs when using the GZ37, was that the input to filter cap is more than twice the max value listed for that rectifier. That can be hard on the tube. I think Kelly even lost one of his rectifiers this way. It's a case where there are other ways of bringing up the B+ after the rectifier, such as using a more correctly sized input cap, and reducing or even doing away with the dropping resistor between filter stages. With the GZ34/5AR4 type, 10uf is nothing at all, and would be fine. Also, if you leave amps on for long periods, it would be really easy to install a standby switch that would allow the filaments to glow without applying high voltages to the plates. More work, and as you've said you haven't had any problems. Erik Quote Link to comment Share on other sites More sharing options...
3dzapper Posted March 19, 2005 Share Posted March 19, 2005 Very interesting thread guys, thanks. Have any of you used Sylvania engraved base 2A3s? Rick Quote Link to comment Share on other sites More sharing options...
Colin Posted November 21, 2011 Share Posted November 21, 2011 thinking about doing a review, need to get some tubes to try, any suggestions for the best value? Quote Link to comment Share on other sites More sharing options...
Guest " " Posted November 21, 2011 Share Posted November 21, 2011 i was surprised how unbusy this landscape was...thought there would be more...so you're breaking new ground http://www.google.com/search?q=2a3+review&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a Quote Link to comment Share on other sites More sharing options...
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