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Bros, I have a GE422A rectifier tube that sparks when I power up my WA33 amp. even though it sparks, there are no weird sounds and no abnormal behaviour once the amp warms up and I start playing music as usual.    

 

in the interests of self-preservation, I followed Woo Audio's advice to stop using the GE422A.    I have since removed the tube and I have put back in the stock rectifier tube that came with the WA33 - no sparks, no weird sounds and no abnormal behaviour with the stock tube.    

 

I'm looking for access to a tube tester to find out more about what is happening to the GE422A to cause it to behave like that. if anybody knows of a shop or person where I can test my tube out using their equipment, I would appreciate the contact very much.    

 

thank you 🙂

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Arcing on turn-on can be caused by many things including a weak tube, excessive capacitance in your power supply circuit, or switching on your amp on while the rectifier tube is still hot.

 

A tube tester would be able to check the health of the rectifier itself, but I wouldn't use it in the Woo anymore.

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I've got an AVO CT160 tube tester. Could do a check. But would not recommend putting it back.

As an indication either a wrong tube for that kind of load output. Or power supply capacitance is to high.

You could check GE422A rectifier tube specification on basic maximum   Milliamperes delivery. Versus your amplifier requirement in Milliamperes . 

Edited by jtsamarinda
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If you are near the Ubi area I have an eTracer that can test your tube for you.  Let me know if I can help.

 

I also concur with the other posters comments re use of this rectifier tube given your description of what is happening with it. For what its worth the 422A looks like it has specs (1800V PIV and 300mA (cap input) to 350mA (choke input)) that "might" be able to handle the WA-33, but that s somewhat dependent on the current they are running through the 6C45P's and 2A3's.  6C45P's can be run anywhere from 20mA to 40mA each to sound their best (IMHO :-D) and the 2A3's in the 50mA range so anywhere from 280mA ( close to the wind but doable) to 360mA (probably a non starter).

 

Woo does not indicate whether the WA33 power supply is choke or capacitor input.  The 422A has a maximum 10uF if capacitor input power supply, so as per @watchdog  this might be the issue and unfortunately, if so, may have damaged the tube.  The 5U4G can handle 40uF or so as a cap input filter.

 

It is worth also bearing in mind that the maximum current through the 5U4G ( regardless of whether it is cap or choke input power supply based on NOS data sheets) is actually LOWER than the 422A.  So by using the 5U4G as standard that implies that Woo is operating the tubes in the amp well below their typical operating points and I might suggest that their claim of 10W per channel output is even more heroic than even what might be expected form PP 2A3's at the more traditional operating points indicated above.

 

Hope this helps and good luck!

 

cheers,

Bill

 

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