Technical Articles on Tube Amps

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Theory — Here is a good place to start to learn some of the characteristics of vacuum tube circuits.

Practice — Here are a collection of circuits and other implementations of V.T. circuit theory.

Wire Table — Just what it sounds like… a wire table!

Building Your Own Tube Amp — Over the years this has proven to be an immensely popular article. Not that I can take any credit for it, though.. Ralph Power is the man you want to thank!

Vacuum Tubes — I scanned in the first few hundred pages of this incredible book by Spangenberg.

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3 Comments

1. Richard Christie, February 6, 2009:

   Thank you for Spangelberg! I really appreciate that, is there any chance you might add the index pages? Please email me is you do,

   Reply

   Richard Christie Reply:
   February 6th, 2009 at 11:26 pm

   dang, made a typo in previous comment, “IF you do”, not “is you do”.

   Reply

2. Mike Anon, November 17, 2010:

   Thanks for your effort making Spangenberg available – a great resource!
   Please add the Index pages if you get an opportunity.

   Reply

3. Bob Ready, April 30, 2012:

   Hi Ken , the BAGA is looking awesome as ever. I hope your keeping one hand in your pocket when you tweak it! Ouch! I’m coming to you with a question about ecc808 heaters on dc. The 808 spec sheet wants 6vac across the heaters grounded in the center but I dont want to induce AC anywhere near my first gain stages. I’ve got the chassis all cut and roughed in ready to wire it up. I’ll go AC on the heaters for now but well enough must never be left alone and eventually I want dc on these heaters. I’ve got some ideas in my head for rectifying the 5 or 6 v windings and dropping down the dc with diodes .7 – .7 to a fat filter cap till it gets to 3 vdc then put +3vdc on pins 4 and 5 grounding pin 6 …. am I on the right track? The tube and the heater is actually very cool and easy to use with ac but I’m confused how to make it work on dc. Please email me when you have a minute.

   Reply

   Ken Reply:
   May 18th, 2012 at 9:00 am

   @Bob Ready: you COULD do it that way, but you’d be wasting a lot of power as heat dropping down that voltage. a better solution is to use the entire heater circuit (which expects 6.3vacrms). use schottky diodes (which have a lower forward voltage drop, and no reverse carrier current, making them “quieter”) to rectify your 6.3vac into something like 8.4vdc no load. that will drop down as you connect the heaters and draw some current. heaters are good for +/- 10% on voltage. you may have to tweak things by adding low value resistors to bring your unregulated heater supply into that range. it’s easier/better to drop down a higher voltage/lower current rail than a lower voltage/higher current rail (hence sticking with the 6v heater supply).

   Reply