Chris Albertson wrote: > On Thu, May 21, 2009 at 5:00 PM, Joerg <joerg...@analogconsultants.com> wrote: >> Chris Albertson wrote: >> >> [...] >> >>> I'm thinking about tube amps that had an output impedance of about 1M >>> ohm that used transformers to drive 8 ohm speakers. About a 100,000 >>> to 1 ratio. >>> >> 1M? What kind of tube was that? I think the highest I had was about 5K. >> At 5000 volts on the plates ... > > OK off by "just one decimal point". My point still is that tube amps > have to deal with a huge impedance mis-match and they handle it with a > transformer. Then you ask "what transformers can handle a load that > is well under 1 ohm. So I thought about arc welders. >
Point-contact welders may also be an option. > While on the subject, I'm wanting to build a tube amp. But my goal is > not to re-create an old design. Mostly for entertainment and > education I want to design and build the transformers too. Anyone > have any leads or links to places to buy the parts? I know you can > buy frames and the metal plates used to stack a transformer core but > where?. I'd start by building something small and easy, like a low > power 12V power supply but the goal is to learn the art of high power > transformer building > Hammond makes tube-stage transformers, even quite large ones. But those cost a pretty penny and I couldn't bring myself to chop up some of those beauties to stack the cores. Paralleling, yes. You might want to ask in a hardcore audio-freak group. As for tubes I found that HV-driver tubes for color TVs were the best deal. But this was decades ago, today you'd have to take a look at which current production tubes are available and at what cost. Sovtek, Svetlana and so on. The biggest tube amp I ever built was with two of these and you almost had to call the utility before turning it on: http://www.pll.gr/qb5-1750.pdf -- Regards, Joerg http://www.analogconsultants.com/ _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user