Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dude on August 06, 2010, 10:29:53 am

Title: filter caps in series
Post by: dude on August 06, 2010, 10:29:53 am

Can I use "1 watt", 220K balancing resisters in the first stage?

I'm using two 350V, 70uf's in series for 600w, 35uf.

I only have one 2 watt, 220k and several 1 watts. I only need to use the series hook-up on the first and second stage filtering.

I'd use the 2 watt on the first stage (B+ around 500v) and the 1 watt on the second stage around 480v.

Or I could use a 500v single cap on the second stage running at 480v,

For that second stage which is better?

thanks, Al   

Title: Re: filter caps in series
Post by: jjasilli on August 06, 2010, 11:38:10 am

The balancing resistors are optional, though a very good idea.  So, you could order some proper resistors, finsh your build and install them later.  Or: first stage: (2W) in series with (4X 1W's in series-parallel);  Second stage 500V cap.   

Title: Re: filter caps in series
Post by: Merlin on August 07, 2010, 04:51:11 am

Even the full 350V across a single 220k resistor is only 0.55W, so you can use any of those resistors.

Title: Re: filter caps in series
Post by: dude on August 07, 2010, 09:22:49 am

I used the 1 watt 220K bleeder's, balancing resistors and biased the 6550's. The highest voltage at the choke is 515v.

If 350v is 0.55watts, I'm I little lower then the max.

Are the one watts OK? And if they go I don't think they would harm anything...?

Or should I replace them with 2 watts

thanks, Al

Title: Re: filter caps in series
Post by: Merlin on August 08, 2010, 10:30:09 am

Quote from: dude on August 07, 2010, 09:22:49 am

I used the 1 watt 220K bleeder's, balancing resistors and biased the 6550's. The highest voltage at the choke is 515v.

Half of 515V is 258V. Across a 220k resistor that's 0.3W. I'll let you figure out if 1W resistors are ok.