First ECL82 amp probs. - 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 2nd January 2007, 02:42 PM   #1
the_rod is offline the_rod  Italy
diyAudio Member
 
Join Date: Jan 2007
Default First ECL82 amp probs.

Hello All,
I'm quite a tube noob and I'm making my first amp, based on this schematic:
schematic

I only modified the power supply to add an insulation transformer. After a bit of experimenting I got the amp working - well, almost. When the volume pot is at max, the amp works well and I get a great sound, and when it is at min I don't get no noise at all (how it sould be...) the problem is in between: if I move the pot from the max or min position I get a loud siren-like sound! Does anyone have any pointers on what I may have done wrong?
thanks a lot,

Rodolfo
  Reply With Quote
Old 2nd January 2007, 03:14 PM   #2
diyAudio Member
 
the_manta's Avatar
 
Join Date: Nov 2006
Location: Munich, Bavaria
Hi !
You probably built an oszillator due to wiring capacities. When you build with combined Tubes like XCL82 and especially XCL86 you have to be careful and you must use a deliberate layout. Only use short wires ans never put to wires from different sections in parralel for longer distances. I used ECL86 for my first tube experience, but luckily it worked fine, but I know the problems you have. The best beginner tube amp still ECC83 + EL84...

Hope this helps

Simon
  Reply With Quote
Old 2nd January 2007, 03:21 PM   #3
Sherman is offline Sherman  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Chicago area
The first thing I would try is putting a 220 ohm resistor at the grid of the triode. A 1/4 watt resistor should be fine there.

Remove the wire connected to the grid (Pin 1 in your schematic). Solder one lead of the resistor directly to the pin on the tube socket then connect the other resistor lead to the wire you cut.

Also, I would recommend using shielded wire from the input to the volume control and from the volume control to the grid (or the new resistor you just installed).
__________________
--Sherman
  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
Ecl82 alexandar888 Tubes / Valves 15 10th May 2009 07:39 AM
TT grounding probs. DragonMaster Analogue Source 7 11th November 2005 03:18 PM


New To Site? Need Help?

All times are GMT. The time now is 06:16 PM.


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