Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Leevi on March 11, 2011, 01:27:27 pm

Title: VVR for 50W amp
Post by: Leevi on March 11, 2011, 01:27:27 pm

I would like to find a simple schematic for a VVR to be used
in a 50W fixed bias amp. I'm not looking for ready a kit but a circuit I could implement with point-to-point techniques.
/Leevi

Title: Re: VVR for 50W amp
Post by: kagliostro on March 11, 2011, 01:42:19 pm

Hi Leevi

have you read this

http://www.el34world.com/Forum/index.php?topic=6899.msg100221#msg100221

http://www.el34world.com/Forum/index.php?topic=8424.0

Kagliostro

Title: Re: VVR for 50W amp
Post by: Leevi on March 11, 2011, 02:53:38 pm

Yes, I have looked at them. The first thread is for cathode biased 18W amp which is not my case.
The second one is handling 100W fixed bias amp which might interest me but I didn't find any
verified schematic. I would like see a circuit that has been tested e.g. by some member in this forum.
/Leevi

Title: Re: VVR for 50W amp
Post by: mcrracer on March 11, 2011, 10:33:51 pm

Dana has a VVR for cathode biased and one for fixed bias. He is not giving away the fixed bias unit schematics and I don't blame him. He put the work, in he should be paid for it. It's only $50 I believe.

Title: Re: VVR for 50W amp
Post by: LooseChange on March 12, 2011, 06:22:26 am

London Power will sell you thier version. It is just another regulator that runs in proportion with the scaling of the B+.

Title: Re: VVR for 50W amp
Post by: GuitarPilot65 on March 12, 2011, 08:47:42 am

Please forgive me; I'm still a novice.  What's VVR? 

Title: Re: VVR for 50W amp
Post by: kagliostro on March 12, 2011, 10:42:42 am

VVR

Variable Voltage Regulator

usually used to lower B+ to final tubes and Phase Inverter (is also possible to lower the preamp section, but this didn't seem to be very appreciated, also if you can this way achieve some sounds as if you use a variac, without lowering the filament voltages)

that is done as to reach at lower levels some sounds you can have from the amp only at full power

this is in few words, someone more expert can explain you in detail

Kagliostro