Query failed: connection to localhost:9312 failed (errno=111, msg=Connection refused). Amp advice please - Bad Cat mains hum - Amps Discussions on The Fretboard
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UNPLANNED DOWNTIME: 12th Oct 23:45

Amp advice please - Bad Cat mains hum

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StefBStefB Frets: 2139
in Amps
All,

I recently acquired a Bad Cat USA Player Series Cub 40R head, which is a terrific sounding amp.

After only 30 or so minutes of light use at home however it has developed a really loud mains hum that just will not go away.  It doesn't do it on standby, only when flicked to fully on, and if happens whether a guitar is plugged in or not.

Before I take it to a local amp technician does anyone have any obvious suggestions what it might be, please?  These are not cheap amps, it shouldn't be doing this, and I'm not happy at the thought of having to spend money on it already.

The sound quality is still in tact but the hum is obtrusive and very annoying.

I have already tried the following:-
  • Plugged it in in different rooms around the house
  • Different IEC lead
  • Different speaker cable
  • Different cabs and different impedances (the amp is switchable between 4, 8 & 16 ohms
Thanks ever so much in anticipation of any suggestions.  I'll be out for most of the day today so please don't think I'm being rude if I don't participate in the thread again until later on in the day.
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Comments

  • ICBMICBM Frets: 69426
    Probably a power valve failing, if it’s not affected by the control settings.

    Valves can do this at any age unfortunately. Bad Cat amps also run them very hot, which doesn’t help.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • StefBStefB Frets: 2139
    edited September 2023
    Turns out it was just a power amp valve, thanks as ever for the advice @ICBM ;;

    I borrowed a pair from a Laney to confirm the diagnosis. 

    Interestingly the Electro Harmonix EL34EH valves that were in the Bad Cat are noticeably slimmer than EL34STRs. I need to order a new pair for the amp now, so is there any real difference between the two or will standard EL34s suffice?
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  • ICBMICBM Frets: 69426
    EH EL34s do have narrower bottles.

    They sound good but are among the less reliable, in my experience. Any standard EL34 will do the job.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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