Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fossilshark on June 27, 2017, 02:35:27 pm

Title: 5u4 into 50w amp
Post by: fossilshark on June 27, 2017, 02:35:27 pm
Can i put a 5u4 rectifier in my 50w amp? Its basically a modded jcm800 but b+ is a little high (504v off the rectifier) and was wondering if switching out the ss rectifier for a tube one would help. Does anyone have a schematic to do this? Also my power transformer has the CT for a tube rectifier as it was taken out of a tube audio system that had a tube rectifier.
Title: Re: 5u4 into 50w amp
Post by: pompeiisneaks on June 27, 2017, 02:44:51 pm
That's not yet enough information to answer for sure. 

1. your transformer has a 5v Tap?  Sounds like yes, but what is the maximum current on that tap?  Is it enough for a 5U4?
2. Does the existing first stage capacitor exceed the first RC node allowed for a 5U4?  If not you'd need to swap that out too.  (Edit this appears to be 40uF in the datasheet from the old days for 5u4GB)
edit: 3: does your amp have room to drill out a hole for a rectifier socket?
That's all I can think of off hand.

~Phil
Title: Re: 5u4 into 50w amp
Post by: sluckey on June 27, 2017, 03:32:56 pm
EL34 amps are very happy with 500V.
Title: Re: 5u4 into 50w amp
Post by: fossilshark on June 28, 2017, 01:39:54 pm
That is a good point, i beleive i have a 50uf for the first filter cap and i would have to drill the hole for the tube socket. Ill just leave it SS for now, thanks