Loud buzz and hum from one monoblock!!! - 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 12th June 2006, 12:27 AM   #1
victor1 is offline victor1  Canada
diyAudio Member
 
Join Date: May 2005
Location: Toronto
Default Loud buzz and hum from one monoblock!!!

I have a problem with one my monoblock (Chinese Mingda-Mc845-C) . As I turned them on today I heard a very loud hum and buzz from my speaker. I disconnected the source ,swapped tubes from a good one and turned it on again. The same very loud hum and buzz. I checked the output signal from the amp. At the very beginning it was 10V then it decreased to 3V. What can it be? All tubes are ok.
  Reply With Quote
Old 12th June 2006, 01:31 AM   #2
Jeb-D. is offline Jeb-D.  United States
diyAudio Member
 
Jeb-D.'s Avatar
 
Join Date: Nov 2005
Location: SoCal
If it's a 60 or 120 cycle hum, it's most likely caused by a grounding issue(such as a ground loop) or ripple in the power supply. Also make sure it's not located right by something that may cause interference like a TV.
  Reply With Quote
Old 12th June 2006, 01:35 AM   #3
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
You may have had a diode failure in your power supply too. Are they tube rectifiers or SS?
  Reply With Quote
Old 12th June 2006, 06:54 AM   #4
victor1 is offline victor1  Canada
diyAudio Member
 
Join Date: May 2005
Location: Toronto
I can't be ground hoom because I use cheater-plugs.
The amps have solid state rectifiers.
  Reply With Quote
Old 12th June 2006, 02:53 PM   #5
poobah is offline poobah  United States
diyAudio Member
 
poobah's Avatar
 
Join Date: Nov 2005
Just a guess... but maybe you popped a rectifier...

Does it make any music at all?

  Reply With Quote
Old 12th June 2006, 05:32 PM   #6
Jeb-D. is offline Jeb-D.  United States
diyAudio Member
 
Jeb-D.'s Avatar
 
Join Date: Nov 2005
Location: SoCal
Yeah, you'll just have to check the rectifier, supply caps and inductor(may not have one but most SET amps do). And if it's fixed bias check the DC supply to the grid, to make sure thats clean as well. Check each stage because they may have different power supplies. If you have to replace the rectifier I suggest HEXFRED diodes, they have a soft recovery, wich will reduce any spikes in the supply if there are any.
  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
LM3886 Very Loud Buzz colindj69 Chip Amps 3 2nd September 2008 07:26 AM
Melos triode and computer as source: BUZZ BUZZ BUZZ zigo3 Tubes / Valves 4 28th November 2007 02:11 AM
buzz noise from loud speakers vibeline Multi-Way 9 7th January 2007 06:19 PM
Car audio amp, LOUD buzz. what is wrong? silentblackhat Chip Amps 2 12th April 2006 05:49 AM
a 71A monoblock Joel Tubes / Valves 30 30th December 2002 09:19 PM


New To Site? Need Help?

All times are GMT. The time now is 08:22 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