Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: JustMike on January 05, 2019, 09:56:17 am

Title: DIY 2204 B+ Voltage Question
Post by: JustMike on January 05, 2019, 09:56:17 am
 I built a 2204 clone (50w Marshall) using a Classic Tone 40-18023 Power transformer. It has a 690v center tapped secondary which is higher than what is called for on the schematic. It works fine, but I'd like to know if it can be made to sound better if the voltage were a little lower. My reference is the Ceriatone layout which shows 650v center tapped.
 Exactly how does the B+ voltage affect the sound?
Thanks


Title: Re: DIY 2204 B+ Voltage Question
Post by: sluckey on January 05, 2019, 12:33:41 pm
Let's look at that another way... Your PT puts out 345-0-345 and the Ceriatone layout shows 325-0-325.

I'd be surprised if you hear any difference between the two voltages.
Title: Re: DIY 2204 B+ Voltage Question
Post by: tubenit on January 05, 2019, 03:51:39 pm
IF you wired it for a tube rectifier like a GZ34, then you could also use a 5V4 or Hoffman's solid state plug in rectifier and have three voltage ranges to use to see what you liked best?

With respect, Tubenit

solid state 1.4 x 345
GZ34        1.3 x 345
5V4           1.2 x 345

Title: Re: DIY 2204 B+ Voltage Question
Post by: jjasilli on January 05, 2019, 05:53:39 pm
You can use a variac to drop 40 plate volts. If you like it, you  can make it permanent with a power resistor in the B+ line; maybe reverse zener; and/or a bucking tranny.


You may need to re-bias.  B+ & bias voltage can be made switchable together.  Another option is VVR or similar.
Title: Re: DIY 2204 B+ Voltage Question
Post by: DummyLoad on January 06, 2019, 02:29:47 pm
You can use a variac to drop 40 plate volts. If you like it, you  can make it permanent with a power resistor in the B+ line; maybe reverse zener; and/or a bucking tranny.


You may need to re-bias.  B+ & bias voltage can be made switchable together.  Another option is VVR or similar.


marshall 100W super-lead runs with 530V to EL34 plates - it sounds really nice. laney 60 runs 600V+ to the plates of EL34s and also sounds nice. - if anything, i'd be in the opinion that your amp may sound better with a higher B+.



--pete