Lowering B+ in PS - Page 4

h00hbt · 14th February 2011, 04:37 AM

Quote:

Originally Posted by Sheldon

BTW are you measuring the unloaded power supply, or with the complete amp?

Sheldon

im measuring loaded.....

Cheers

Sheldon · 14th February 2011, 05:14 AM

Here's a screen grab from PSUD. I don't know the inductor resistance, so just a guess there. I put in 370V at a rated 150mA for the transformer (it would be double that for your actual transformer, because you are running two channels.) I set it up as a full wave rectifier, to reflect the impedence of the rectifier. It will be slightly different for a bridge, but it will get you close. Voltage is taken at the first Current tap.

richwalters · 14th February 2011, 10:47 AM

If you have Morgan Jones Valve amps 4th ed, page 360 HT rectifier..shows a 317 job, I don't like using this chip or elevated B+ but the idea of configurating a HV power mosfet for 2nd post regulation (as cap multiplier)to drop the excess may be an idea. Obviously SS gate protection has to be engineered into any arrangement.
There are SS methods of regulating the neg return, but that creates more complications and may not be justifyable.

richy

h00hbt · 14th February 2011, 05:30 PM

Hi all

Great news! I have succeeded lowering the B+. I changed the 2 first 47uf/500V caps to 2 10uf/630V Polys. Now I have 465V/445V/335V so im smack on what I wanted. Listening to the amp now and it sounds great. I hope I finally can put the building part of this project behind me now and start to enjoy the amp for music.

Thank you all for your input and help and I promise I will be back with more tricky questions for my next project.

Cheers

h00hbt · 14th February 2011, 05:34 PM

Quote:

Originally Posted by Sheldon

Here's a screen grab from PSUD. I don't know the inductor resistance, so just a guess there. I put in 370V at a rated 150mA for the transformer (it would be double that for your actual transformer, because you are running two channels.) I set it up as a full wave rectifier, to reflect the impedence of the rectifier. It will be slightly different for a bridge, but it will get you close. Voltage is taken at the first Current tap.

Thanks Sheldon, you where right and your PSUD simulations where spot on, se my latest post.

Take care......

Rod Coleman · 14th February 2011, 06:07 PM

I bet it sounds improved, too, if you found some good quality MKPs to put in there, in place of those Electrolytics.

Sheldon · 14th February 2011, 06:16 PM

Nice looking project. Enjoy.

Sheldon

h00hbt · 14th February 2011, 06:32 PM

Quote:

Originally Posted by Rod Coleman

I bet it sounds improved, too, if you found some good quality MKPs to put in there, in place of those Electrolytics.

Yes I believe it does. Im thinkung that I maybe will change the double 47uf cap for a pair of 47uf Polys. Tricky thing is what to do with the 500uf.....

Anyway, I will give myself a rest for the time beeing.

Cheers

Sheldon · 14th February 2011, 08:11 PM

Quote:

Originally Posted by h00hbt

Tricky thing is what to do with the 500uf.....

Might I suggest PSUD?

h00hbt · 14th February 2011, 08:12 PM

Quote:

Originally Posted by Sheldon

Might I suggest PSUD?

:-)

14th February 2011, 05:30 PM	#34
h00hbt diyAudio Member Join Date: Jun 2007	Hi all Great news! I have succeeded lowering the B+. I changed the 2 first 47uf/500V caps to 2 10uf/630V Polys. Now I have 465V/445V/335V so im smack on what I wanted. Listening to the amp now and it sounds great. I hope I finally can put the building part of this project behind me now and start to enjoy the amp for music. Thank you all for your input and help and I promise I will be back with more tricky questions for my next project. Cheers __________________ /H

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14th February 2011, 10:47 AM	#33
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	If you have Morgan Jones Valve amps 4th ed, page 360 HT rectifier..shows a 317 job, I don't like using this chip or elevated B+ but the idea of configurating a HV power mosfet for 2nd post regulation (as cap multiplier)to drop the excess may be an idea. Obviously SS gate protection has to be engineered into any arrangement. There are SS methods of regulating the neg return, but that creates more complications and may not be justifyable. richy

14th February 2011, 06:07 PM	#36
Rod Coleman работник diyAudio Member Join Date: Jul 2004 Location: Warwickshire UK	I bet it sounds improved, too, if you found some good quality MKPs to put in there, in place of those Electrolytics.

14th February 2011, 06:16 PM	#37
Sheldon diyAudio Member Join Date: Dec 2003 Location: San Diego	Nice looking project. Enjoy. Sheldon