Valve amp sounds like its got a Pog on every note, especially the higher notes

jakeollyjakeolly Frets: 114
hi everybody 
i hope my explanation is understandable!. Actually checked that i hadnt got an pog / higher octave setting switched on on my multi - effect at last nights rehearsal. Almost like a 12 string effect, but not nice!. The unit was in bypass. 
 my normally beautiful pure noted hot rod deluxe sounded like its notes had got an octave note above them, not loud, but annoying. 
i changed the valves about 6 months ago. Only a few gigs and weekly playing since 

i am going to try the valves but any tips on whether this a particularly characteristic type of defect would be greatly appreciated . Ive searched on this site but cant find anything similar ?
Its not wolftones from pickups , i tried other guitars. 

Looking forward to any help 
thanks 

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Comments

  • ICBMICBM Frets: 71956
    Could be a failed power valve or phase inverter, if the maximum volume is also now a lot less - you won’t notice it at low volume but it will run out of headroom quickly.

    Have a look at the power valves and see if they’re glowing properly blue - easiest to see as you switch from standby to fully on.

    If one isn’t, remove the other one and test the amp - if it’s now silent, the valve still in it may be dead.

    The problem is that this fault can be caused by a blown resistor as well - either a power valve screen resistor or a phase inverter plate resistor.

    Or it may be something else entirely...

    "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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  • DJH83004DJH83004 Frets: 196
    I have also known failed power supply caps cause a similar problem in HRDs particularly the last one in the chain feeding the preamp section.
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  • jakeollyjakeolly Frets: 114
    Thanks chaps. Will try the valves. Havent noticed headroom issue. iirc I have  heard of thescreen  resistor burn out thing on these mk 1 hot rods. I checked them about a year ago and they were original and ok. Maybe needs a full service . Thanks
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  • DJH83004DJH83004 Frets: 196
    If you don't get anywhere with the valves and you can't find anywhere local to take it to, more than happy to have a look, my workshop is in North Notts.
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  • jpfampsjpfamps Frets: 2723

    As above it's likely to be either valves or caps.

    I've seen plenty of these amps with defective caps.

    https://jpfamps.com/fender-hot-rod-deluxe-guitar-amp-repair-new-filter-caps/
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  • jakeollyjakeolly Frets: 114
    Thanks guys. I took it to andy at oldamps in sheffield who tightened up some tubes, swapped a couple that were too close to the rear baffle , replaced a few missing circuit board screws and checked bias and goodness knows what else. Turns out it was just generally loose and its a bit of a lesson about things like valve amps needing some tlc regularly . Whatever he did the pog has gone and we are back to lovely sweet hot rod cleans. Thanks so much for your help everybody. Really grateful 
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