[JN] tube heating

Joseph Levy tourists04 at nycap.rr.com
Sun Jun 30 10:13:24 CDT 2013

On Thu, 20 Jun 2013 Coolhandluc <coolhandluc at optusnet.com.au> wrote:

> Speaking of toob heating, I'm very shortly to commence building an 
> interesting variation on a theme, an OTL amp using 300B's designed by 
> Bruce Rozenblit...
> With his 25 Hz filament current limited supply, he measures a 1mV spike at 25 Hz and 3mV at 50 Hz with virtually no other noise measurable in the audible spectrum, which is a pretty darned impressive result !

Have you actually taken delivery of the kit? A few months ago, Bruce 
Rozenblit said that the 25Hz filament supply was going to be offered as 
a separate kit, but changed his mind, claiming that it would only give 
his competition an advantage. Given the relatively low cost for the two 
mono amps and separate supply, this sounds goofy. I'm just curious to 
know what's in the heater part of the kit and if it's something you 
could put together with off-the-shelf parts.


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