| guy sergeant wrote:
|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 well being both quiet and reliable. However those we used had silver coloured pins and were 'new' production, I believe from China. The compact glass envelope and printing looks similar though.
Thanks, Guy. Most likely it’s it, since they are the smallest OA2 among all.
| Antonio J. wrote:
|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 de stabilized voltage they should. I guess they might be chinese.
Do you know where to get reliable 0A2? They also last little here.
Hm, you keep burring the OA2? Are you sure that your preamp is designed properly and that it does not care excessive power and excessive start up voltage? A good 0A2 is very reliable: I remember that it was able to care 250mA over 2 days and was able to start up with 100uF across it – both absolutely barbaric and ridiculous modes.
Anyhow, There are plenty OA2 around and probably the best place to buy them form hum radio shops. The http://www.radiodaze.com/ has quite a large stock and there you might pay one extra buck per tube and to choose the specific manufacturer brand (do not be drooling – I have suck out from there all “kinky” brands). However, since you are far form NY then get some of your local tubes. The Europeanians produced many 150V regulators that are direct substitute of OA2: SG1P, STV150-30, 150C2, CV1832, QS1207, GD150M. If you wish to replace it with “larger” VR150 and go for the 0C2 then you might fine another half-dozen models. Anyhow, I will not comment how all-different tube and different breads sound, as I'm sure that Melquiades and your preamp use them differently. The Milq do not really use them as the regulators but as the decouplers....
Romy the Cat
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche