Spider Valve MKII 112 High Pitched Hiss Noise Issue

[BlueLanternFlash]

I have three spider valve mkii 112 combo amps and each of them are exhibiting a high pitched sound around 3khz-3.5khz when the amp is on.  For the most part it is in the background, but at various times it can get higher in the mix where it can be a distractor or even painful.

 

The tubes have been switched out and verified as the correct tubes and re-biased and the noise still persists.   I switched cables, guitars, used a power conditioner, but the sounds still persists.   I believe the sound may be somehow connected to the master volume.  When I use the amp live I can hear the sound.  However, when I use the amp and use the direct output feature (via studio or performance mode), the high pitched noise no longer persists.

 

Has anyone else experienced this issue or have any potential fixes?

 

Thank you.

[psarkissian]

Microphonics from tube starting to fail. When was the last time the tubes were changed?

 

Can also be intermittency in the circuit hardware. Oh and, stay away from florescent lights.

 

Being a 10 year old product, it should be checked and serviced by an authorized service center

that knows the insides of this product. Shock hazard is too great to be doing this yourself.

I still get a zapping every now and then,... it hurts.

 

 

[BlueLanternFlash]

Thank you for the response.   I stay away from florescent lights when possible. 

 

I just bought one of the amps used, but the other two had tubes changed within the past few months. 

 

I do not change the tubes myself, I  use a service center that is nearby and they did do an investigation and could not find the cause of the high pitched noise.  I will try getting the tubes changed again and if that fixes the problem, I will update the thread. 

 

Thank you for your time,

Jordan

[psarkissian]

1) Is it a Line 6 authorized service center?

 

2) Power tubes should be 5881WXT matched set (no JJ's, Mesas, Groove Tubes, Tung-Sol, or others),

and properly bias to specs, for good characteristic curve response and linear transfer function. Otherwise,

too much distortion too soon. And that means shorter tube life.

 

3) Pre-amp tubes should be 12AX7 B, China or 12AX7EH.

 

These amps are unforgiving of modifications. Authorized service centers know to reach out to us to

confirm what they already will know. Makes the job go quicker.

[BlueLanternFlash]

Yes it is an authorized line 6 service center.  They are listed on the site as such. 

 

for 2 and 3 understood.  When I get the amps taken in next I will provide your instructions and verify that the bias is set correctly. 

 

Thank you,

Jordan

[Markfothebeast]

I had a similar issue on a bass amp. It was a solder joint to a pot. The heat of the tubes below like to melt solder on combo amps that are poorly vented.