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| Romy the Cat's
personal site dedicated to advanced audio and evolved music reproduction
techniques
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This thread has been pretty interesting overall. I've read most of it and would at least like to provide some feedback on the technical side of designing with the 45 and 2A3 DHTs... at least from my personal experience. A few years back I decid...
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This thread has been pretty interesting overall. I've read most of it and would at least like to provide some feedback on the technical side of designing with the 45 and 2A3 DHTs... at least from my personal experience. A few years back I decid...
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[quote user="floobydust"]The 2A3 can be almost as quiet, but ONLY in the dual-section paralleled types. I adopted a split balance technique. It only works with cathode bias due to the topology but it is effective. You also need a good quality filamen...
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Having listened for a while with the tubes, I have come to some conclusions. The three tubes I have seriously listened to are: Kron, Sophia, and Emission Labs. All the tubes are much better than any other modern 2A3 tubes I have tried. I felt my in...
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First, Adrian, Thanks for your feedback on the newer designed 2A3 tubes... very interesting. I've looked at all 3 of these brands before but have not as of yet purchased any (I have a large collection of 45 and 2A3 of various NOS US brands...
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Just some additional thoughts on the new generation of 2A3 tubes. The only ones I would seriously consider are the Kron Enterprises, the Sophia Electric, and the Emission Labs tubes. If I did not hear these side by side over an extended period of ti...
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You will be happy to hear I have got the new 2A3 tubes. I have spent the evening listening to them all. Some very interesting results! I will be posting soon...
Adrian...
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[quote user="Romy the Cat"]BTW, I run today the Chinese 2A3 and they were much better then Sovtek tube, much-much better, in fact I was very surprise how bad the Sovtek were.[/quote]Having received a bunch of tubes, I have spent some time liste...
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[quote user="drdna"]
Having received a bunch of tubes, I have spent some time listening….[/quote]
Yes, it looks like the Sovtek 2A3 are remarkably bad, even I with my stinky Tannoy was able to get it. Regarding the rest of your comments I ha...
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Romy and drnda,
When you speak of the "Chinese 2A3" which one do you mean? Romy, if you have the Shuguang 2A3C then I understand why you find it better than the Sovtek, no argument there! drdna, the Shuguang is a little more extended on top than t...
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[quote user="Romy the Cat"]I was thinking about this: how come that driving 6C33C (in fact driving anything one can imagine) the 6E5P was very fine but driving 2A3 it was dull like hell. I opened the amp and tested all – everything was perfect but th...
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I totally am a believer that the construction of a tube determines how it will sound. This makes perfect sense when you consider the tube is relies on the changing flux of electrons in a vacuum. It is easier at least for me to visualize this as a ph...
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[quote user="floobydust"]I do agree that the internal structure makes a big difference... but, if the tube specs properly and has adequate immunity to mechanical induced interference, then you should not be able to discern any major difference in sou...
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I am not sure what rectifier the 2A3 SET uses. Mine uses the GZ37. The best regarded is usually the Mullard NOS. I have used that for years.
Recently I was on the kick of listening to the vibration of tubes and I came across a dirt cheap tube fr...
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Okay so I got the NOS Sylvania "Spring Top" dual filament 2A3 tubes and have been listening to them for a while, now I am ready to make a report on the tube.
The tube is well built and structurally sound. Tapping gives a very small "tabla" sound ...
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[quote user="Romy the Cat"][quote user="drdna"]However, there is no comparison to the expensive tubes from Kron, Sophia, and Emission Labs. These are all in a separate category. These produce a very different sound. It is like this: on the old black ...
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First of all, this not an attack on NOS tubes and it is all meant to be just sort of fun and educational. I happened to have all these 2A3 tubes side by side for comparison, so why not? I also have done the same thing with other tube types like 6SN...
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Adrian, Romy, et al, Okay, I don't take any of it as an attack... so none of that bothers me.... I'm fine with it... again, it's a view on what you heard based on your test scenario, nothing more and I certainly welcome the review. Now tha...
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[quote user="floobydust"]Running the higher B+ voltage (350 volts) with a 1K cathode bias resistor and the 2.5K load results in higher distortion than the text-book operating point, which is B+ of 300 volts and a 750 ohm cathode biasing resistor and ...
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[quote user="floobydust"]If you do some modeling you're running about 15.5 watts of dissipation on the plate and pushing over 4.5 watts output. Running the higher B+ voltage (350 volts) with a 1K cathode bias resistor and the 2.5K load results in hig...
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Adrian, Romy, (Dima), First, I most certainly agree that the textbook operating point for the 2A3 is not optimal and can be improved on, hence my own design from a few years ago. If you are sticking with a 2.5K load, you will simply not ge...
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[quote user="floobydust"][The Moondog amplifier has] a higher B+ voltage (350 volts) with a 1K cathode bias resistor and the 2.5K load.[/quote]
[quote user="Romy the Cat"]...the most proper operation of this tube will be at 275V on plate and 4.1K ...
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I do not remember details already but Dima and I had the same discussion a few weeks back. After all his research he was very much disagree with textbook use of 2A3. He felt that max power and the most proper operation of this tube will be at 275...
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KM:
It will be a little project to modify the amplifier, but it may be educational. To optimize the Moondog circuit for the NOS 2A3 tubes, so they will give their best, I plan to buy a new OPT with primary impedance around 3.5-4K. Will that be s...
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[quote user="drdna"] How about using the 6C33C for the low midrange-woofer, the 2A3 for the upper midrange, and the 45 for the tweeter? I suspect if each circuit can be optimized, that they can do their best within each frequency range. [/quote] Hm…....
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[quote user="drdna"] It will be a little project to modify the amplifier, but it may be educational. To optimize the Moondog circuit for the NOS 2A3 tubes, so they will give their best, I plan to buy a new OPT with primary impedance around 3.5-4K. [/...
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[quote user="floobydust"]As Romy pointed out, having high gain is not the same as power. If you're only barely cracking the volume control on your amplifier or preamplifier then it should be obvious that you have more gain than you need. If you're p...
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Adrian, Fair enough... it's not about power or gain in your case, just making it sound as clean as possible. Well, if you go back to my earlier post on findings, I list the basic operating values. Just to recap them here:Plate supply ...
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[quote user="floobydust"]Plate supply = 350 voltsOPT Primary impedance - 3.5K
Cathode bias resistor = 866 ohm
Cathode bypass capacitor = 50uF
Grid resistor to ground = 249
You need to select a new OPT.... I would suggest the H-20-3.5U.[/quote]I b...
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Romy, I did some models using a 400V supply and a 6K OPT load. It's easy to get 4 watts output in this configuration, but using a 2K cathode resistor results in higher distortion and a weak transfer curve. Plate dissipation is around 11 wa...
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