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Left channel buzz please help!
Left channel buzz please help!
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Old 25th May 2020, 03:02 PM   #1
Andyj42 is offline Andyj42
diyAudio Member
Join Date: May 2020
Default Left channel buzz please help!

Hello everyone.

Long time lurker, first time poster.

I've spent the last six weeks chasing demons inside this amplifier and I'm running out of ideas. I'm a bit of a newbie when it comes to...well anything amplifier related really so I'd love any advice.

I purchased a G&W T2.6F a number of years ago which worked wonderfully for about 6 months. It then developed a strange flickering noise in the left channel which has since persisted. I haven't used it in a number of years due to this, however I've recently pulled it out of storage to use with the Audeze LCD2.

Its an excellent pairing and adds a lot of life to otherwise clinical planars so I'd like to save it if at all possible. My other amp is an audio gd which sounds excellent but is a little too 'reference'.

The noise can best be described as an intermittent static like flickering noise, but only in the left channel. Sometimes its there from the second I turn on the amp, at other times it appears after a few minutes of use. I can adjust the left channel trimpot low enough to a point where I don't hear the buzzing, however the music sounds terrible. Since beginning, I've:

- Isolated to left channel for the headphone out only. The line out does not seem to have this problem but it looks like the line out does not pass through the tubes. I've also used different sources.

- Switched tubes around as well as inputs. Left channel only.

- Changed thermal paste on heatsink connections.

- Resoldered and cleaned the alps pot.

- Removed solder and resoldered almost every joint on the board.

- Checked caps and resistors with a multimeter. Everything is within spec.

- Insulated the back of the board from the plate it is attached to just in case a joint was accidentally touching the plate.

- Changed the 50k trimpots to new ones.

Next up, I was thinking of soldering the tubes directly to the board with some extension wires in case the tube sockets are the issue.

I've included a photo below. Would appreciate any and all advice!
Attached Images
File Type: jpg 20200525_233029.jpg (1.00 MB, 68 views)
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Old 25th May 2020, 07:31 PM   #2
duncan2 is offline duncan2  United Kingdom
diyAudio Member
Join Date: Mar 2013
Location: Scotland.
Flicker noise can be found in various components but usually its a resistor fault .
The problem is its found quicker using an oscilloscope .

Looking at your picture shows your resistors are not low noise metal film but older generation types .
places to try -
1- the input resistors .
2- resistors that have some heat to them under load .
3- grid resistors .

Next any interstage coupling capacitors .
Have you got a circuit diagram ?
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Old 25th May 2020, 08:03 PM   #3
rayma is online now rayma  United States
diyAudio Member
Join Date: Apr 2011
Bad solder joints are possible, look carefully. Try freeze spray (not on tubes).
Don't solder the tubes. This is not going to fix it, but could ruin the tubes.
Do clean the tube pins and tube sockets, and other connectors/switches.

Last edited by rayma; 25th May 2020 at 08:15 PM.
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Old 26th May 2020, 12:23 PM   #4
Andyj42 is offline Andyj42
diyAudio Member
Join Date: May 2020
Thanks for the help!

Replaced most of the front end resistors today. Couldn't find everything I needed at the local, but the noise has almost disappeared now. Just a tiny hint left which I believe will disappear once I replace all of them.

I did suspect the left channel heatsink was badly connected as the heatsink on that side was significantly cooler than the right. Maybe a bunch of damaged resistors contributed to the problem.

Thanks again!
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