Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Bub on April 02, 2011, 09:23:11 am

Title: 6L6gc bias question
Post by: Bub on April 02, 2011, 09:23:11 am

Hi Gent's

I have a 5F6A fixed bias, 390V on the plates and RCA 6L6gc black plates. Do I set bias for 23w mpd or 30w mpd?. Right now I have them set for 35mA

Thanks for any help

Rob

Title: Re: 6L6gc bias question
Post by: Searing on April 02, 2011, 09:38:52 am

I believe 23w is your max.  Don't go that high.  17-20w will sound nice.  They say 70% max works well, as a rule of thumb.

Title: Re: 6L6gc bias question
Post by: HotBluePlates on April 02, 2011, 12:54:23 pm

RCA 6L6GC can dissipate 30w. If we decide that 70% is a good place to start, try 30w * .7 = 21w/390v = 53.8mA (!).

As Searing says, you don't have to go that high.

Title: Re: 6L6gc bias question
Post by: Bub on April 02, 2011, 06:21:38 pm

Thank you Gentlemen.

Rob

Title: Re: 6L6gc bias question
Post by: jeff on April 02, 2011, 07:32:15 pm

 I just went through this to and felt like this for a while(see picture). I have mine set at 35 mA and it sounds great, altho my B+ is 410V. Once I stopped trying to find the"one true, perfect, golden number" I can finally sit back, play, and enjoy it.

Title: Re: 6L6gc bias question
Post by: firemedic on April 02, 2011, 09:16:22 pm

I'll 2nd that emotion.

Title: Re: 6L6gc bias question
Post by: Bub on April 03, 2011, 08:37:22 am

Yup, I know the feeling. At 35mA my amp sounds amazing but I've never had them higher than 40mA so now I know my range I can play a little more. I love the orange glow just not the red.

Thanks again

Rob