GAS VR Tubes on B+ - 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 1st April 2006, 06:30 PM   #1
diyAudio Member
 
Join Date: Apr 2006
Location: Toronto
Default GAS VR Tubes on B+

I have all the parts pretty much to build an RH84 as pictured here (see link) except a low enough value power transformer. So I was thinking to lower the B+ by designing in VR tubes on the B+. This brings down the voltage and provides some regulation. However, one seldom sees VR regulation in amp designs, any bad things sonically etc happen with doing this?

EL84 SE advice'n'schematics needed
  Reply With Quote
Old 1st April 2006, 10:09 PM   #2
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
just look at current range of any VR tube...
I doubt that you'll find any capable do feed even just one channel of even flea power amp......

most VR tubes are good to max 30mA
that's good for load current of some 20mA max......
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa... by Mighty ZM
  Reply With Quote
Old 2nd April 2006, 01:01 AM   #3
diyAudio Member
 
Miles Prower's Avatar
 
Join Date: May 2005
Location: USA
Blog Entries: 7
Default Re: GAS VR Tubes on B+

Quote:
Originally posted by skip_scratch
I have all the parts pretty much to build an RH84 as pictured here (see link) except a low enough value power transformer. So I was thinking to lower the B+ by designing in VR tubes on the B+.
How much extra voltage do you have? It just might be better to use the VR tubes in an electronic voltage regulator.

Quote:
This brings down the voltage and provides some regulation. However, one seldom sees VR regulation in amp designs...
They were too cheap "in the day" to use them. You don't see them too often because we basically inherited all those circuits from the 1950s.

Quote:
any bad things sonically etc happen with doing this?
No. In fact, the noise that VR tubes produce is a good deal "softer" than what zeners (or any other reverse current across a PN junction) produce. Use them right, and this is not a problem.
__________________
There are no foxes in atheistholes
www.dolphin-hsl.com
  Reply With Quote
Old 2nd April 2006, 09:15 AM   #4
lndm is offline lndm  Australia
diyAudio Member
 
Join Date: Mar 2006
Location: nsw
Quote:
Originally posted by choky
just look at current range of any VR tube...
I doubt that you'll find any capable do feed even just one channel of even flea power amp......

most VR tubes are good to max 30mA
that's good for load current of some 20mA max......
I assume the VR will be used as a shunt regulator, with a series resistance and the VR in parallel with the load. In this case the VR needs only to pass a current such that it can vary up and down by the current delta (total swing) of the load. A class A stage (or stages) draw a more or less constant current and are a good candidate here, even though they need regulation less than Class AB.

For class AB, I agree with Miles about the active regulator as a good way to use the VR.

PS, you could use your raw supply for your output and the VR in shunt form to power your earlier stages.
  Reply With Quote
Old 2nd April 2006, 06:30 PM   #5
diyAudio Member
 
Join Date: Apr 2004
Location: Monroe Township, NJ
Skip,

Have you considered a pseudo choke I/P filter? If the 1st cap. in CLC filter is held under 1 muF., behavior is primarily choke I/P. Experiment with the value of the 1st cap. to get exactly the rail voltage you need.
__________________
Eli D.
  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
Tube Noob! need help with tubes lots of tubes therapy_fan Tubes / Valves 15 29th January 2009 10:01 PM
WTT: Various tubes for 6CA4/EZ81 rectifier tubes GordonW Swap Meet 4 27th August 2008 01:37 AM
Tubes! Geek Swap Meet 4 16th May 2008 07:20 PM
CV428 tubes (Loktal 807) tubes FS mobyd Swap Meet 3 2nd January 2008 12:26 PM
many new tubes and tubes meter for sale elviukai Swap Meet 4 30th October 2003 10:22 AM


New To Site? Need Help?

All times are GMT. The time now is 03:42 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