First guitar amp build power supply question.

OrganicBud · 10th August 2009, 05:42 AM

Well, I've got the transformers. Hammond 374BX for power and 1650NA for the output. 4H choke. Its going to be running two EL34s. NOw, I will readily admit that this amp is based off of a Super Reverb AA1069. But barely. The taps for the B+ coming off the power xfrmr are 375 volts, and the original Fender filter caps for the power stage are two 70mfds, but I want more punch, and I was going to bump them up to 200 to 220mfd. Its going to have SS rectification as well. The OT is rated for 60 watts.

Bumping up the filter caps to 200-220mfd each would be safe, right?

Akita · 10th August 2009, 07:58 AM

I would use 100uf --> 4H --> 440uf for a CLC filter with SS rectification.

Geek · 10th August 2009, 08:23 AM

You don't need a lot of cap with a PP amp, because the rail noise is cancelled out in both the PI and output circuit. It's the divider down the line that needs the smooth power.

I've never used more than 47uF --> 5H --> 47uF to the power tubes and all has been well. But since you're using SS, Akita's advice looks nice

Oh... do use fast recovery types - it makes a difference.

Cheers!

10th August 2009, 05:42 AM	#1
OrganicBud diyAudio Member Join Date: Feb 2009	First guitar amp build power supply question. Well, I've got the transformers. Hammond 374BX for power and 1650NA for the output. 4H choke. Its going to be running two EL34s. NOw, I will readily admit that this amp is based off of a Super Reverb AA1069. But barely. The taps for the B+ coming off the power xfrmr are 375 volts, and the original Fender filter caps for the power stage are two 70mfds, but I want more punch, and I was going to bump them up to 200 to 220mfd. Its going to have SS rectification as well. The OT is rated for 60 watts. Bumping up the filter caps to 200-220mfd each would be safe, right?

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10th August 2009, 07:58 AM	#2
Akita diyAudio Member Join Date: Dec 2006 Location: Kuala Lumpur	I would use 100uf --> 4H --> 440uf for a CLC filter with SS rectification.

10th August 2009, 08:23 AM	#3
Geek diyAudio Member Join Date: Sep 2004	You don't need a lot of cap with a PP amp, because the rail noise is cancelled out in both the PI and output circuit. It's the divider down the line that needs the smooth power. I've never used more than 47uF --> 5H --> 47uF to the power tubes and all has been well. But since you're using SS, Akita's advice looks nice Oh... do use fast recovery types - it makes a difference. Cheers!