Lowering B+ in PS - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 13th February 2011, 09:28 AM   #1
diyAudio Member
 
h00hbt's Avatar
 
Join Date: Jun 2007
Default Lowering B+ in PS

Hi all

What would be the best way to lower the B+ in the PS. I have an excessive 30-40V overall. Im pushing 520V into first caps rated max 500V.

Click the image to open in full size.


Cheers
__________________
/H
  Reply With Quote
Old 13th February 2011, 10:58 AM   #2
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
If you can get a GZ37, these will drop at least 20V more than a GZ34. Watch out for extra heater current though!

A better way is to configure the PS to quasi- choke input. Remove the electrolytics at C1 [cap after rectifier] and replace with MKP [stacked] polypropylene. Panasonic box type for preference. Use PSUDii to find the value of the MKP: 1uF to 5uF are good starting points.

Cheap motor run MKPs sound horrible IME. Stacked MKP are cheap and 630V rated, and sound fine.
  Reply With Quote
Old 13th February 2011, 11:08 AM   #3
diyAudio Member
 
h00hbt's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by Rod Coleman View Post
A better way is to configure the PS to quasi- choke input. Remove the electrolytics at C1 [cap after rectifier] and replace with MKP [stacked] polypropylene. Panasonic box type for preference. Use PSUDii to find the value of the MKP: 1uF to 5uF are good starting points.
Hi Rod

Yes, I have been reading up and this might be the way to do it. Pity I don´t know how to use the PSUDII or I would have.....

Thanks
__________________
/H
  Reply With Quote
Old 13th February 2011, 11:10 AM   #4
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
What's your Load Current?
  Reply With Quote
Old 13th February 2011, 11:19 AM   #5
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Try using a buck winding on the primary- a 12.6V filament transformer will work. That will be the most efficient way to do it rather than burn up heat in a higher rectifier drop or series resistors. It will also drop the heater voltages, but not by much- if you drop 30V out of 520, your 5V heater will drop to about 4.7V. That could work in your favor as well.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 13th February 2011, 12:02 PM   #6
diyAudio Member
 
h00hbt's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by Rod Coleman View Post
What's your Load Current?
Rod

I have 390VAC, 0,5A, 18 OHM

Cheers
__________________
/H
  Reply With Quote
Old 13th February 2011, 12:05 PM   #7
diyAudio Member
 
h00hbt's Avatar
 
Join Date: Jun 2007
This maybe a stupid question but why wouldn´t a 600V 30uf cap and resistor after the rectifier and keep whats already there in the PS work?


Cheers
__________________
/H
  Reply With Quote
Old 13th February 2011, 12:14 PM   #8
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
It work work fine.
You can make 33uF or so by using 100uF/400V electrolytic (Panasonic HA or HB or TSUP, Nichicon KX). Use three in series like you have two in series now, with 220K 1W resitor across each one, to keep the voltage balanced in each one.

Or you could use a quality MKP of 30uF/630V. I use and enjoy the AMPOHM [LCR] MKP series

AMPOHM WOUND PRODUCTS|FP-CA-10-AU|CAPACITOR, AUDIO, 10UF, 630VDC | Farnell United Kingdom
  Reply With Quote
Old 13th February 2011, 12:19 PM   #9
работник
diyAudio Member
 
Rod Coleman's Avatar
 
Join Date: Jul 2004
Location: Warwickshire UK
O, and the second capacitor, if that is seeing more than 500V, would need to be made from 1000uF/400V x2, and 150K 3W across each. That may be found to be somewhat expensive, though, in which case, reducing C1 to a 10uF 630V MKP may be a better solution.
  Reply With Quote
Old 13th February 2011, 12:22 PM   #10
diyAudio Member
 
h00hbt's Avatar
 
Join Date: Jun 2007
Quote:
Originally Posted by Rod Coleman View Post
It work work fine.
You can make 33uF or so by using 100uF/400V electrolytic (Panasonic HA or HB or TSUP, Nichicon KX). Use three in series like you have two in series now, with 220K 1W resitor across each one, to keep the voltage balanced in each one.

Or you could use a quality MKP of 30uF/630V. I use and enjoy the AMPOHM [LCR] MKP series

AMPOHM WOUND PRODUCTS|FP-CA-10-AU|CAPACITOR, AUDIO, 10UF, 630VDC | Farnell United Kingdom
Rod

Oh shoot, I thought I had 30uf but checking now they are 50uf/600V. So I guess these won´t work?

Click the image to open in full size.

I was thinking of something like this. 1st cap 50uf/600V and then a resistor.

Click the image to open in full size.

Cheers
__________________
/H

Last edited by h00hbt; 13th February 2011 at 12:37 PM.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lowering B+ voltage blue lander Tubelab 41 31st May 2013 07:20 PM
PC for a source. Help lowering PS noise. HaLo6 Digital Line Level 22 12th February 2009 02:58 AM
lowering Qts MCPete Multi-Way 4 31st December 2008 11:09 PM
Lowering HT waner Tubes / Valves 7 29th May 2006 10:31 AM
lowering the voltage Lowjacker Power Supplies 7 11th March 2006 09:11 AM


New To Site? Need Help?

All times are GMT. The time now is 05:15 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2