Jon Kasper
New Member
Hi all,
So the project of bring my Fisher 400 back to being able to perform to its full potential continues!
Would really appreciate your help with diagnosing some undesirable noise coming from my speakers when using the Fisher 400 as both phono stage as well as amp for my turntable.
I'm having some trouble with a hum (equally from both left and right speaker) & slight crackle (only from right speaker) when phono-stereo input is selected. Details as follows:
- Have my TT (Rega Planar 3) connected directly to phono-low input on the Fisher.
- Fisher 400 directly to Klipsch Cornwall II speakers.
- When phono-stereo is selected, a distinct hum can be detected once the volume knob reaches 50%.
- Further, when I turn the Fisher 400 on, it takes approx. 10 seconds for the hum to to begin.
- no such noise when phono-mono selected as input, and same when aux is selected.
- Also, slight crackle coming from right speaker, even when control knobs aren't being moved.
Here's a video:
Here's an audio click of noise coming from right speaker (volume knob turned to 75%):
https://drive.google.com/open?id=1b47U9LT2vzTSOJLA1a2NEdYWMqRZOGQE
Here's an audio clip of noise coming from left speaker(volume knob turned to 75%):
https://drive.google.com/open?id=1hiOUDfV_h8fcy5NkUPmCtqJ2Mxb7itPk
Any ideas where to start guys? Could it be the tubes? My tech has told me my output tubes are a bit weak and need to be replaced soon. The rest of the tubes were supposed to be ok. Output tubes in use are original "The Fisher", phono tubes are Toshiba (toyko shibaura electric), the tone control driver tubes are Sylvania and “ASB USA”, the phase inverters/driver tubes are "made in usa for PILOT radio".
Any help is greatly appreciated!
So the project of bring my Fisher 400 back to being able to perform to its full potential continues!
Would really appreciate your help with diagnosing some undesirable noise coming from my speakers when using the Fisher 400 as both phono stage as well as amp for my turntable.
I'm having some trouble with a hum (equally from both left and right speaker) & slight crackle (only from right speaker) when phono-stereo input is selected. Details as follows:
- Have my TT (Rega Planar 3) connected directly to phono-low input on the Fisher.
- Fisher 400 directly to Klipsch Cornwall II speakers.
- When phono-stereo is selected, a distinct hum can be detected once the volume knob reaches 50%.
- Further, when I turn the Fisher 400 on, it takes approx. 10 seconds for the hum to to begin.
- no such noise when phono-mono selected as input, and same when aux is selected.
- Also, slight crackle coming from right speaker, even when control knobs aren't being moved.
Here's a video:
Here's an audio click of noise coming from right speaker (volume knob turned to 75%):
https://drive.google.com/open?id=1b47U9LT2vzTSOJLA1a2NEdYWMqRZOGQE
Here's an audio clip of noise coming from left speaker(volume knob turned to 75%):
https://drive.google.com/open?id=1hiOUDfV_h8fcy5NkUPmCtqJ2Mxb7itPk
Any ideas where to start guys? Could it be the tubes? My tech has told me my output tubes are a bit weak and need to be replaced soon. The rest of the tubes were supposed to be ok. Output tubes in use are original "The Fisher", phono tubes are Toshiba (toyko shibaura electric), the tone control driver tubes are Sylvania and “ASB USA”, the phase inverters/driver tubes are "made in usa for PILOT radio".
Any help is greatly appreciated!