blue glow, how? - 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 10th March 2010, 10:46 PM   #1
newtube is offline newtube  United Kingdom
diyAudio Member
 
Join Date: Mar 2009
Default blue glow, how?

What makes a tube glow blue guys?
is there a particular kind of tube that glows more than others?

Reason i ask is my tubelab sse has chinese 6l6gc tubes that glow with a little blue just after startup but fades after a few seconds but some images i see on here are just divine!

Its purely an asthetic thing but it would be nice to see the blue all the time
  Reply With Quote
Old 10th March 2010, 11:02 PM   #2
diyAudio Member
 
Join Date: Apr 2003
Location: Southern Tier NY
My EH kt88 have a nice blue glow on the glass.
Where is the blue glow coming from. Some is asthetic andother times can be spectacular (when it fries)
__________________
Living Life Doing the Waltz in 4/4 meter.
  Reply With Quote
Old 10th March 2010, 11:03 PM   #3
tomchr is online now tomchr  United States
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Greater Seattle Area
Unless you're talking about mercury vapor rectifiers -
Click the image to open in full size.
or voltage regulator tubes -
Click the image to open in full size.
the blue glow you refer to is caused by electrons that are accelerated past the tube structure and hits the glass envelope, where it excites impurities in the glass.

I'm running with a small sweep tube power amp using a 6LU8 tube. One is a Westinghouse brand and does not exhibit the blue glow. The other is an RCA branded tube and this one does glow blue around the pentode section. Increasing the anode voltage increases the amount of blue light emission as the electrons flowing in the tube are accelerated to higher velocities due to the higher anode voltage. This causes more of them to leave the tube structure and hit the glass... The higher anode voltage is not a desirable operating point from a distortion stand point, though.

I'm guessing the reason your tubes glow blue on start-up and then fade is because it takes a while for the bias voltage to stabilize.

If you really, really want blue light, you could pull the tacky, el-cheapo Chinese eBay amp trick and add a blue LED below the tube socket... Or you could buy a bunch of 6L6'es of different brands and see if you can find any that glow blue in your amp.

~Tom
  Reply With Quote
Old 10th March 2010, 11:04 PM   #4
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
I know that some Russian 6P3S tubes have a glass that glows blue when bombarded by electrons.

Click the image to open in full size.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 10th March 2010, 11:36 PM   #5
TheGimp is offline TheGimp  United States
diyAudio Member
 
TheGimp's Avatar
 
Join Date: Aug 2009
Location: Johnson City, TN
6P1P is notorious for blue glow along the screen rods inside the tube.

Then there is the occasional blue glow that is not good:

Click the image to open in full size.
  Reply With Quote
Old 11th March 2010, 02:16 AM   #6
diyAudio Member
 
Join Date: Nov 2007
The 5B/254M produces a nice glow around the glass. See here:
CV428 or 5B254M useful?

Just for fun I hooked one up on the bench this morning and even at 200v/35mA plate it produced a faint blue ring around the glass extending about 3/4" up from the base of the plate structure.

Gary
  Reply With Quote
Old 11th March 2010, 02:39 AM   #7
diyAudio Member
 
tubelab.com's Avatar
 
Join Date: Jul 2005
Location: West Virginia panhandle
Quote:
My EH kt88 have a nice blue glow on the glass.
Mine did when I got them, but now 2 years later they still rock, but don't glow much.
__________________
Too much power is almost enough! Turn it up till it explodes - then back up just a little.
  Reply With Quote
Old 11th March 2010, 03:20 AM   #8
diyAudio Member
 
SpreadSpectrum's Avatar
 
Join Date: Nov 2007
EH 7591s
Attached Images
File Type: jpg 7591glow_web.JPG (55.5 KB, 665 views)
  Reply With Quote
Old 11th March 2010, 06:50 PM   #9
newtube is offline newtube  United Kingdom
diyAudio Member
 
Join Date: Mar 2009
Thats the stuff i mean spreadspectrum! its beautiful, i want mine to do that
  Reply With Quote
Old 11th March 2010, 06:57 PM   #10
rknize is offline rknize  United States
diyAudio Member
 
rknize's Avatar
 
Join Date: Feb 2009
Location: Chicagoland
Send a message via AIM to rknize Send a message via Yahoo to rknize
SED KT88s have a very pleasant blue glow on the glass. Not as apparent in the pic, but strong in person:

Click the image to open in full size.

Their EL34s also glow, especially near the screens.
  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
blue glow on one channel wicked1 Tubes / Valves 10 29th April 2008 02:20 AM
Blue glow confused :( bobhayes Tubes / Valves 50 20th January 2007 06:00 PM
New WE 300b's blue glow TubeHound Tubes / Valves 26 31st March 2003 02:22 PM
Blue Tubes the glow jleaman Tubes / Valves 34 6th August 2002 12:07 PM


New To Site? Need Help?

All times are GMT. The time now is 02:38 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