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| Romy the Cat's
personal site dedicated to advanced audio and evolved music reproduction
techniques
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Hello Romy,What brand of 0A2 do you use in your phonostage?I used RCA, but after 1.5 years of work it began to spark when phonostage is switched on.I tried Siemens, Mazda and now Sylvania 0A2.Siemens has "disco sound", without mids, just metallic hig...
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Would anybody recognize who manufactured those 0A2 regulators?
Since I use them quite aggressively, I picked at MIT's fleamarket a few dozens of them dirt-cheap. The tube looked suspensions. Then marked as Amperex, Made in England and National Elect...
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You're welcome, Romy.I have still not found the original Russian "number" for those ones, but if ever I will, I'll forward you the info.For what purpose are you using them at 22mA ?...
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Hi Jack ,Thank you for your very educational info ! It looks like you are right , and your tubes are rebranded SG13P .... Maybe a big stock of those tubes were exported , and you know them better than we do :-)And another question . You wrote :...
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[quote user="Jack 14"]Hi, these ones are Russian military stock: see that no mica elements have been used in their construction, like the US Bendix Red Bank tubes (used in US ICBMs of the '50's-'60's). Old Soviet ICBM spare stock ?[/quote]It's v...
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My preamp also uses those 0A2 and I have a bunch of "made in USA" ones that look right the same than those "National", using the same orange color for the brand letters, but they're supposed to be RCA. They all failed in a quite short time in deliver...
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Jack, thank you very much, it was very informative. As I understand all 150V regulators use violet-glowing gas. In my case those tubes cares 22mA and it looks like (so far) they do hold stable voltage with no noise.
Once again, thanks,Romy the Cat...
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[quote user="N-set"]
Other changes to come:
- looking for Amperex 0A2 with mesh plates
- will rewire MM input in silver with silver WBT RCA's - it now welcomes my top cart, Decca London Reference with silver AQ Leopard ph...
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National is the brand name of Richardson Electronics http://www.rell.com/They buy and have bought tubes from factories all over the world and rebranded them 'National'When I worked for a UK based tube amp manufacturer some 10 years ...
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Hi, these ones are Russian military stock: see that no mica elements have been used in their construction, like the US Bendix Red Bank tubes (used in US ICBMs of the '50's-'60's). Old Soviet ICBM spare stock ?I happen to have a lot of ...
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Hi Dirma,Unless you can prove me something else: the ones I have (0C2s and 0B2s) are printed "Made in USSR" very clearly.I doubt that Canadian General Electric, or Sylvania, put this lettering on the tubes to conceal another ...
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[quote user="Romy the Cat"]3) There is an army of the 150V 7-pins gas tubes: 0A2, SG1P, STV150/30, StR150/30, 150C1, G150m 150C2, 150C4, CV10664, CV1832, CV2903, CV8161, HD51, M8223, QS1207, GD150/4K, QS1210, SR56. I did not try the larger octal 150V...
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My preamp also uses those 0A2 and I have a bunch of "made in USA" ones that look right the same than those "National", using the same orange color for the brand letters, but they're supposed to be RCA. They all failed in a quite short time in deliver...
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Hello Romy,What brand of 0A2 do you use in your phonostage?I used RCA, but after 1.5 years of work it began to spark when phonostage is switched on.I tried Siemens, Mazda and now Sylvania 0A2.Siemens has "disco sound", without mids, just metallic hig...
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[quote user="Romy the Cat"]Did anyone ever see the ready to do tube sockets adapaters that would let to pit the large gas tubes ingot the small sockets? Melquiades use 7-pin small 0A2 tubes but I would like to try the 0D3. They are the same 150V tube...
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Thanks for the extensive reply. I wish I knew exactly the use the preamp is doing of them and if they could be safely replaced by those alternatives you mention. I believe they're regulators within the power supply. The problem with them is not burni...
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Romy, Sure, the tone could be a bit more special ie: delicate and colorful (sorry for lack of the right word). Thats why I have come back to these pages to read and hopefully understand a bit more and find the right incentive to tinker further. I hav...
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I do not remember what I sent to you, since I sent you for measurement perpose then it might be the impulse version of the tube. In the image below are vertical tubes from left to right:
0A26E5P-E (smaller)6E6P-DR (larger)6E5P (the largest)0A2
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Hi Romy,What a busy year just gone! Finding enough time to just sit down and get the DSET's going has been impossible, but I have time now and have started the process.At the moment I am introducing some high voltage to the first amplifier chassis, ...
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[quote user="guy sergeant"]When I worked for a UK based tube amp manufacturer some 10 years ago we had a couple of pre-amps using OA2's in shunt regulator circuits. These (physically shorter than standard) OA2's came from Richardson and did work very...
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Post #205:
B+
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by
N-set
on
2012-02-10
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IIRC, 6k was when you feed both channels through it, but given the currents maybe it does not matter. The target was 270V on B+ and I got it with two 12k as I wanted to separate the channels after the 0A2, just like you say. Cheers,nset...
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Thanks for the answers. The R23 was my personal interest, not the builder's. As you cleverly noted he knows very well what happens into the circuit, but it's my ignorance who needed to know. Sorry if I annoyed you ;-)I think we'll leave VR1 reachable...
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I remember when I built Melquiades I detected that quietly of wire that feeds the grid of output stage with bias, quality of soldering or any other minute detail on this wire was very auditable. I also detected that the proximity of this wire t...
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Romy,Thank you.I think I should to give some break-in time to Sylvania 0a2.50 hours is enough? Previously I used in my EAR the next set of tubes ECC83: 1-Amperex (red print), 2-Amperex (red print), 3-Sylvania 7025 (yellow print).When I built "End of ...
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[quote user="N-set"]
Other changes to come:
- looking for Amperex 0A2 with mesh plates
- will rewire MM input in silver with silver WBT RCA's - it now welcomes my top cart, Decca London Reference with silver AQ Leopard ph...
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Hi Paul,My question was of cause about my phonostage based on EAR834p and "End Of Live" modification with air capacitors and LCLC + 0A2 power supply.A couple weeks before I increase the second stage ECC83 cathode capacitor value to 43400uF (Kaisei no...
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[quote user="AlexBerger"]Hello Romy,
What brand of 0A2 do you use in your phonostage?I used RCA, but after 1.5 years of work it began to spark when phonostage is switched on.I tried Siemens, Mazda and now Sylvania 0A2.Siemens has "disco sound"...
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[quote user="AlexBerger"]I think I should to give some break-in time to Sylvania 0a2.50 hours is enough? Previously I used in my EAR the next set of tubes ECC83: 1-Amperex (red print), 2-Amperex (red print), 3-Sylvania 7025 (yellow print).When I ...
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Who know how they die, at least I was not able to figure it out. The literature suggest that when gas regulator at the end of their life they stop regulate or maintain regulation but increase noise. I was not able to detect it.
I have many gas regu...
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I calculated the whole circuit and it looks each channel draw a total of about 3mA (could be even somewhat less). The second and third stage works like a whole and it´s very curious because I have seen this design before only in guitar amps in order ...
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