Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Joeriz on April 09, 2017, 06:28:40 pm

Title: Question on Hoffman Deluxe Reverb build
Post by: Joeriz on April 09, 2017, 06:28:40 pm

Hello,

I am currently building a Hoffman Deluxe Reverb. In the instructions I received with the board from the Airtight Garage it says that one should either ground the green/yellow 6.3v center tap coming from the power transformer or use the 100 ohm resistors on the board...but not both. My question is: is there an advantage to one approach vs. the other?

Thanks,
Joe

Title: Re: Question on Hoffman Deluxe Reverb build
Post by: sluckey on April 09, 2017, 07:24:03 pm

Flip a coin.

Title: Re: Question on Hoffman Deluxe Reverb build
Post by: Joeriz on April 09, 2017, 09:13:51 pm

I can do that.

Thanks!

Title: Re: Question on Hoffman Deluxe Reverb build
Post by: Joel on April 09, 2017, 09:51:38 pm

As I undertand it, the 100 ohm resistors simulate a centre tap.  Useful when the 6.3Vac winding is not of the centre tap variety. 

Title: Re: Question on Hoffman Deluxe Reverb build
Post by: pompeiisneaks on April 10, 2017, 04:32:20 pm

Yeah as stated, the 100 ohms simulate a center tap, so you're wasting a few cents using them if you have a center tap.  On the other hand, if you want to go for almost 0 heater noise (so long as other things are done right) you can use a hum balance pot,  The center tapped transformer should be pretty perfectly balanced, BUT that doesn't mean it 100% is.  The hum balance pot allows dialing the hum to near 0.

~Phil

Title: Re: Question on Hoffman Deluxe Reverb build
Post by: Tone Junkie on April 10, 2017, 07:11:41 pm

+1 for humdinger.
Bill