Stub Mandrel Posted April 16, 2023 Share Posted April 16, 2023 In the last half hour my Joyo Bantamp (50W hybrid) has started making farty/crackly noises if I dig in on the E string. I have volume low and gain modest. It seems to be very biased towards low frequencies. It doesn't sound like distortion as much as a really noisy volume control and appears to be independent of gain and master volume settings. I can turn up loud and play gently without the nasty noise. Turn it really quiet and dig in, and it crackles and snaps. It's a hybrid amp, and my worry is that something 'mechanical' has gone awry in the 12ax7preamp stage. Is this possible? Quote Link to comment Share on other sites More sharing options...
Bunion Posted April 16, 2023 Share Posted April 16, 2023 Could be the tube on its way out, do you have a spare? Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 16, 2023 Author Share Posted April 16, 2023 32 minutes ago, Bunion said: Could be the tube on its way out, do you have a spare? I have 12ax7 tubes in two other amps, so I OUGHT to have a spare. Don't want to cannibalise, so I've just ordered one. See if it sorts it in a few days. Quote Link to comment Share on other sites More sharing options...
Dan Dare Posted April 17, 2023 Share Posted April 17, 2023 (edited) 12 hours ago, Stub Mandrel said: I can turn up loud and play gently without the nasty noise. Turn it really quiet and dig in, and it crackles and snaps. If this is the case, might you be overdriving the tube preamp stage, causing it to behave like an overdriven guitar amp? The difference between playing gently and digging in, in terms of the signal you are sending to the amp, is pretty large. There isn't a lot of headroom to play with with 50w, either. 12AX7s are not all the same. If you have a higher gain version, it will increase the likelihood of overdriving. I swapped the 12AX7 in one of my heads for a lower gain version because it got dirty too quickly, with only a small increase in gain. A lower gain version gave a more gradual transition into overdrive. Watford Valves were helpful in helping me choose a suitable tube. Edited April 17, 2023 by Dan Dare 1 Quote Link to comment Share on other sites More sharing options...
Paul S Posted April 17, 2023 Share Posted April 17, 2023 I've always had a similar horrible noise. Class D, hybrid, tube amp - always the same horrible noise. Swapped to FRFR and a pedal, yup, same horrible noise. It's just my playing 5 Quote Link to comment Share on other sites More sharing options...
Waddo Soqable Posted April 17, 2023 Share Posted April 17, 2023 35 minutes ago, Paul S said: I've always had a similar horrible noise. Class D, hybrid, tube amp - always the same horrible noise. Swapped to FRFR and a pedal, yup, same horrible noise. It's just my playing Nah, It's them 'orrible lil' basses with mudbucker PUs you like so much.... 😁 Quote Link to comment Share on other sites More sharing options...
Bunion Posted April 17, 2023 Share Posted April 17, 2023 7 hours ago, Dan Dare said: 12AX7s are not all the same. If you have a higher gain version, it will increase the likelihood of overdriving. I swapped the 12AX7 in one of my heads for a lower gain version because it got dirty too quickly, with only a small increase in gain. A lower gain version gave a more gradual transition into overdrive. Try changing the 12AX7 for a 12AT7 they put out less gain so give you more clean headroom I have one in slot 1 of my Handbox WB 100 2 Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 17, 2023 Author Share Posted April 17, 2023 It seems better today... might be an intermittent issue, see what happens after the valve has run hot for a few hours, like yesterday. Quote Link to comment Share on other sites More sharing options...
Bunion Posted April 17, 2023 Share Posted April 17, 2023 Have you tried just reseating the valve? Sometimes just a bit of a wiggle or pull the plug and push back in can clear corrosion 1 Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 17, 2023 Author Share Posted April 17, 2023 Good point, if it starts again I'll try that. My brother's new valve amp had a rectifier tube that was 'buzzing' mechanically but it turned out to be an internal fault. Quote Link to comment Share on other sites More sharing options...
Lozz196 Posted April 17, 2023 Share Posted April 17, 2023 55 minutes ago, Bunion said: Have you tried just reseating the valve? Sometimes just a bit of a wiggle or pull the plug and push back in can clear corrosion Good call, I had a similar issue in a hybrid amp a few years back and reseating the valve sorted it. Quote Link to comment Share on other sites More sharing options...
Stub Mandrel Posted April 17, 2023 Author Share Posted April 17, 2023 Seems OK this evening... hmm. Quote Link to comment Share on other sites More sharing options...
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