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Title: Changing a rectifier tube question... Post by: mcinku on November 13, 2007, 09:19:35 AM It's my Champ again :P
...as I moded it to take a 6L6 tube I was thinking, what would happen if I swap the stock 5Y3 rectifier tube with something bigger like 5U4 for example. Would that be a stupid idea? I sure don't want to blow up my Champ. ;) Title: Re: Changing a rectifier tube question... Post by: ChrisL on November 15, 2007, 06:16:40 AM I'm no expert but it just depends on the amp and it's components. There is a lot of speculation on the subject. The 5Y3 will drop more voltage than a 5U4 so you are going to have a higher B+ so you will probably have to adjust your bias resistor value. Also, a 5U4 has a higher capacitance value so your power cathode cap should be doubled.
The most important spec to check is how much draw your PT can safely handle. A 5U4 requires a full amp more than your standard 5Y3. Also, consider a 5V4....similar "less sag" characteristics as a 5U4 without the extra amp of current draw. I hope you don't have a sovtek 5Y3 in there now. :o Title: Re: Changing a rectifier tube question... Post by: mcinku on November 15, 2007, 06:20:17 PM I'm no expert but it just depends on the amp and it's components. There is a lot of speculation on the subject. The 5Y3 will drop more voltage than a 5U4 so you are going to have a higher B+ so you will probably have to adjust your bias resistor value. Also, a 5U4 has a higher capacitance value so your power cathode cap should be doubled. The most important spec to check is how much draw your PT can safely handle. A 5U4 requires a full amp more than your standard 5Y3. Also, consider a 5V4....similar "less sag" characteristics as a 5U4 without the extra amp of current draw. I hope you don't have a sovtek 5Y3 in there now. :o Thanks for your input. I actually replaced the sovtek 5Y3 with some Russian NOS 5Y3. This sovtek rectifier was making some noise I didn't like. BTW what is wrong with the sovtek 5Y3? Title: Re: Changing a rectifier tube question... Post by: ChrisL on November 16, 2007, 12:17:42 PM The Sovteks don't have the same characteristic 60 volt drop @ 125 mA DC as a typical 5Y3 so by specs they aren't a 5Y3. Watch your B+. Their designs are very different as well and I think Sovteks decision to call it a 5Y3 was a "sneaky" thing to do...lol
Title: Re: Changing a rectifier tube question... Post by: Alpedra on November 29, 2007, 05:36:41 PM And thats why I have a 5Y3WGTA JAN/Philips NOS on my 5E3 ;)
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