Home  |  High-End Audio Reviews  Audiophile Shows  Partner Mags  Hi-Fi / Music News

High-End High-Performance Audiophile Review Magazine & Hi-Fi Audio Equipment Reviews
Audiophile Equipment Review Magazine High-End Audio

  High-Performance Audio Reviews
  Music News, Show Reports, And More!

  29 Years Of Service To Music Lovers

 

Enjoy the Music.com Review Magazine

Sound Practices Magazine Online!

Sound Practices Magazine Online!

 

The Rejuvenation Process
How to get the longest life out of your power triodes.
Article By Heiner Jakobi
From Sound Practices Issue 8, Winter 1994/1995

 

Sound Practices Issue 8, Winter 1994/1995

 

  Since there is a shortage of high quality power triodes just like in the 1940s although, touch wood, for different reasons -- it is necessary for the tube amp user to consider some old recipes which were common in the 1940s and earlier on. This one was passed on to me by an old tube lover from Germany.

I will use as an example the European type AD-1. This tube is considered by some to be one of the best output triodes ever built and it has become very rare.

The AD-1 was invented by Philips in Holland and built there under Philips and Valvo and by Tungsram and Telefunken in Germany. Later, Tesla made a copy which was not on par with the Western European production. A professional version with different basing called the Ed was produced by Valvo under contract for Siemens for use in telecommunication systems. Also, RFT from East Germany built a tubular version, later replaced by the even more powerful, indirectly heated Ec.

A regenerated tube does not look like a new tube. The shiny getter deposit will still look "burnt" or "bleached" like it was - but the tube will perform for its full life one more time, usually another 2000 hours. If regenerated yet another time, it might last another
50%!

 

AD-1 data
Filament 4V/0.95A
Plate voltage 250V/60 rnA
Negative grid voltage - 45V
That's all you need to know!

 

We start with the heating process: Instead of 4 volts we use about 7 volts and overheat our triode for about 10 minutes! Then go down to 5 volts on the filament and add plate voltage. Apply so much that the plate starts to glow red. That's right! Most important is a milliampere meter to read how much current the triode is drawing. With an AD-l, the max current is around 250 mA and this occurs around 600 V on the plate.

When new tubes are produced, a small amount of barium compound is vaporized inside the sealed tube in order to bind gases and impurities inside the glass. What we are doing is using getter material that wasn't used during the initial production process. Up to 60% of the barium is left over from the first process and we can use this potential now to rejuvenate the tube! As you heat the tube, you will see the barium glowing green, evaporating, and doing its proper job all over again.

The critical thing in this process is that you keep your eyes on the meter. After about ten minutes (and this time will vary), the current drops. You must switch off IMMEDIATELY!!! One second too late and the tube is dead! Forever. You have not lost anything since you couldn't use it anyway. I leave all you tube lovers to experiment with this idea and to use your common sense about which settings are correct for each triode.

 

Some Guidelines:
1) Heat the filament for about 10 minutes with around 40-50% more than the rated value.

2) Drop down to around 20% overrated filament voltage, then,

3) Add plate voltage until your milliamp meter does not rise,
i.e. max current, and the plate shall glow red!!!

4) Keep your eyes on the meter until current falls and immediately switch off!

 

In the old days there were special tube rejuvenators on the market, but nowadays you will have to build it yourself!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     

Premium Audio Review Magazine
High-End Audiophile Equipment Reviews

 

Equipment Review Archives
Turntables, Cartridges, Etc
Digital Source
Do It Yourself (DIY)
Preamplifiers
Amplifiers
Cables, Wires, Etc
Loudspeakers/ Monitors
Headphones, IEMs, Tweaks, Etc
Superior Audio Gear Reviews


Show Reports
Capital Audiofest 2024
Toronto Audiofest 2024
UK Audio Show 2024
Pacific Audio Fest 2024
HIGH END Munich 2024
AXPONA 2024 Show Report
Montreal Audiofest 2024 Report

Southwest Audio Fest 2024
Florida Intl. Audio Expo 2024
...More Show Reports

 

Videos
Our Featured Videos


Industry & Music News

High-End Audio & Music News

 

Partner Print Magazines
audioXpress
hi-fi+ Magazine
Sound Practices
VALVE Magazine

 

For The Press & Industry
About Us
Press Releases
Official Site Graphics

 

   

 

Home  |  High-End Audio Reviews  |  Audiophile Show Reports  Hi-Fi / Music News  About Us  |  Contact Us

 

 

All contents copyright©  1995 - 2024  Enjoy the Music.com®
May not be copied or reproduced without permission.  All rights reserved.