Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: steveo7868 on December 01, 2020, 07:11:07 pm

Title: Transformers for 4x6v6 and 4xel84 builds
Post by: steveo7868 on December 01, 2020, 07:11:07 pm

I have always wanted to try a 4x6v6 build I was going to try this Edcor power

XPWR007
Power transformer for a 120V, 60Hz. or 240V, 50/60Hz. line to 550V (275-0-275) at 200mA center tapped, 6.3V at 6A and 5V at 3A.

I think a 50W marshall transformer should work or even a 4k bandmaster type rated at 40W should work
I really think the Iron for  a Vox AC30 is overkill, I have built a 4xel84 amp with a hammomd 270-FX
and a 4k bandmaster type with decent results

but I  thought this edcor was cool with the extra current
I plan to use cathode bias

Is there a good value for the 4x6v6 amps? like pair of 250 5W or ?
or is it better to go fixed bias?

thanks

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: vampwizzard on December 01, 2020, 07:38:02 pm

this is a good tool for planning your current needs: https://thesubjectmatter.com/calcptcurrent.html (https://thesubjectmatter.com/calcptcurrent.html)

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: AmberB on December 01, 2020, 08:16:14 pm

As for the output transformer, you can use the same push-pull OT for 2 6L6s on 4 6V6s.  The impedance works out about the same, and the transformer will definitely handle the power of  4 6V6s if it will handle a pair of 6L6s.

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: bmccowan on December 02, 2020, 10:30:54 am

Interestingly enough I have transformers from both Baldwin 4xEL84 amp; and Hammond 4x6V6 amps. My plan is to use that iron in 2x6L6 amps. I'm not foreseeing a problem with that. Close enough for rock & roll!

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: steveo7868 on December 02, 2020, 12:28:49 pm

I guess I just wonder why a Vox Ac30 replacement  transformer has 270MA of current and a 100W Marshall has about 290ma am I missing something?

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: PRR on December 02, 2020, 02:32:46 pm

Quote from: steveo7868 on December 02, 2020, 12:28:49 pm

I guess I just wonder why a Vox Ac30 replacement  transformer has 270MA of current and a 100W Marshall has about 290ma am I missing something?

Different voltages? (P=V*I)

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: SILVERGUN on December 02, 2020, 03:04:41 pm

Quote from: steveo7868 on December 02, 2020, 12:28:49 pm

I guess I just wonder why a Vox Ac30 replacement  transformer has 270MA of current and a 100W Marshall has about 290ma am I missing something?

Which 100W Marshall PT has 290mA?

Title: Re: Transformers for 4x6v6 and 4xel84 builds
Post by: steveo7868 on December 02, 2020, 06:38:33 pm

classictone 40-18024 has the 290 ma

Sorry guys I am going to chill out I should not post
I get these ideas half baked and think I need to post

I am going to build my amp eventually  and see how it goes