EZ81 rectifier noise - 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 20th December 2006, 07:27 PM   #1
Stixx is offline Stixx  Germany
I am
diyAudio Member
 
Stixx's Avatar
 
Join Date: Sep 2003
Location: Southern Germany
Default EZ81 rectifier noise

I tried to search, but over 200 results came up, many of them being large threads, so please forgive me for not reading thru all of them...

I am about to finish my second amp (Morgan-Jones headphone amplifier with 3x 6922) after successfully building and de-humming my first one (c3g-headphone amp, see thread somewhere here).
I changed the psu slightly by adding a hybrid tube rectifier with two UF4006 to form the centertap (trans hasn't got one...) and a EZ81.
Now the amp is up and running for testing, voltages are in the ballpark, but upon warming up there is a strange noise coming from the rectifier....hard to describe...it's a tiny somehow mechanical noise but clearly audible (with no headphones over my ears!).
Also I' ve got some 120 Hz hum with headphones on...

Any suggestions?

Thanks in advance,
Oliver
Attached Images
File Type: jpg mj_07.jpg (79.4 KB, 702 views)
  Reply With Quote
Old 20th December 2006, 08:00 PM   #2
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
Have another rectifier tube to try? Try also switching around the 6922's, just to rule that out.

Picture of the grounding arrangement?

Sheldon
  Reply With Quote
Old 20th December 2006, 08:44 PM   #3
diyAudio Member
 
dsavitsk's Avatar
 
Join Date: Jan 2005
Location: Hartford
I have experienced this too while the tubes warm up -- if it is the same thing, it sounds like current and or heat rushing trough the tube causing banging and clanging and a sort of rushing noise. It has happened to me with 2 different EZ81's, but it goes away after things are warm. I just ignore it and it eventually (~30 seconds) goes away.
  Reply With Quote
Old 20th December 2006, 09:36 PM   #4
diyAudio Member
 
Join Date: Nov 2005
Location: maryland
I have an Eico HF81 with two EZ 81. One or both did this during warm up after I replaced the first two electrolytics in the PS ( I went from 30uf to 40 uf) They only did it during warm up and after about three days they no longer did it at all.
Steve
__________________
steve
  Reply With Quote
Old 20th December 2006, 09:40 PM   #5
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Hi Stixx,
I assume you are in Germany so that would be 100Hz buzz.

Also PLEASE cover the terminals on your power transformer. I used similar ones whilst living in Belgium (teenage years long ago) and zapped myself more than once. (And they were usually covered - don't use electrical tape for this except as a temporary thing.) Accidents happen easily!

Clanking and banging of the envelope is not unusual with the EZ81, as doug indicates it should go away once the tube has warmed up.

Safety OT story:
Doing a repair on a Studer Revox G36 as a kid (17 or so) in the 1970's I somehow got a couple of fingers across the power switch. 220V will definitely cause a strong involuntary contraction if the connection is good enough. (It was) I watched my right arm fly into my face with fascinated horror as the muscles contracted. At the same exact moment the sound effects from "the six million dollar man" (tv show) filled my head as my arm moved in what seemed like slow motion... It was all over in less than a second, amazing how long that second was - and it really, really hurt. Left a bruise on my forehead, and burn marks on a couple of my fingers. I was very lucky. My younger brother who witnessed the whole thing thought it was hysterically funny, particularly after I mentioned the accompanying sound effects..

Edit: additional thoughts

__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 20th December 2006, 09:43 PM   #6
diyAudio Member
 
sorenj07's Avatar
 
Join Date: May 2006
My 6P14P amp makes a sound like ice cracking for a few seconds as the tubes warm up, and for a few seconds after turning it off. Everything works fine though so I don't mind too much.
  Reply With Quote
Old 20th December 2006, 10:01 PM   #7
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
Hey Sorenj07,
I didn't realize you were in the Boston area. PM me sometime through the board.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 20th December 2006, 10:19 PM   #8
Sheldon is offline Sheldon  United States
diyAudio Member
 
Join Date: Dec 2003
Location: San Diego
Quote:
Originally posted by kevinkr
My younger brother who witnessed the whole thing thought it was hysterically funny
As it turned out well, he was right. Thin line between tragedy and comedy.

Sheldon
  Reply With Quote
Old 20th December 2006, 10:29 PM   #9
diyAudio Member
 
valveitude's Avatar
 
Join Date: Apr 2005
Location: Naches,WA
Quote:
As it turned out well, he was right.
Or "The essence of comedy is other peoples misfortune"

-Casey
__________________
Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.
  Reply With Quote
Old 20th December 2006, 11:56 PM   #10
diyAudio Member
 
aletheian's Avatar
 
Join Date: Apr 2004
Location: Philly
I have a few circuits with 6CA4/EZ81 and they all do that... both old manufacture and new JJ's.
__________________
Heghlu'meH QaQ jajvam!
  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
WTT: Various tubes for 6CA4/EZ81 rectifier tubes GordonW Swap Meet 4 27th August 2008 12:37 AM
Rectifier diode noise in CCS and biasing wleediy Solid State 2 24th January 2008 11:01 AM
Rectifier switching / choke ringing noise zigzagflux Tubes / Valves 13 12th October 2007 04:18 PM
WTB: 6ca4/EZ81 Rectifier Tubes mrdon Swap Meet 2 10th January 2006 01:28 AM
EZ81 tube rectifier kephaudio Tubes / Valves 13 29th March 2005 12:44 AM


New To Site? Need Help?

All times are GMT. The time now is 10:27 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