Dankology Posted September 26 Share Posted September 26 I picked up a c20 year old AC30 last week but when I crank it up it cuts out and emits a continuous hum. Has anyone any inklings before I lug it to a tech? Could it be a simple as a duff/loose valve? Quote Link to comment Share on other sites More sharing options...
Burns-bass Posted September 26 Share Posted September 26 10 minutes ago, Dankology said: I picked up a c20 year old AC30 last week but when I crank it up it cuts out and emits a continuous hum. Has anyone any inklings before I lug it to a tech? Could it be a simple as a duff/loose valve? Likely to be the valves but an amp that old should be looked over by a tech and serviced to avoid any issues. Might need a re-bias etc. Valves aren't cheap and it's never a good idea to mess around with electrical devices unless know what you're doing. 1 Quote Link to comment Share on other sites More sharing options...
Dankology Posted September 26 Author Share Posted September 26 5 minutes ago, Burns-bass said: Likely to be the valves but an amp that old should be looked over by a tech and serviced to avoid any issues. Might need a re-bias etc. Valves aren't cheap and it's never a good idea to mess around with electrical devices unless know what you're doing. Absolutely! I've no desire to go digging in there myself - just hoping someone was going to suggest it was a nice cheap fix... Quote Link to comment Share on other sites More sharing options...
Dad3353 Posted September 26 Share Posted September 26 16 minutes ago, Dankology said: I picked up a c20 year old AC30 last week but when I crank it up it cuts out and emits a continuous hum. Has anyone any inklings before I lug it to a tech? Could it be a simple as a duff/loose valve? You'll have to take it to a qualified, reputable tech, I'm afraid. I have several valve amps; they are, in general, very reliable for home use, but they do age badly, some more than others. Your Vox has a valve diode rectifier; it may well be that which is failing/has failed, which would cause the hum (the amp must be shut down straight away once it starts doing that...). There are also several electrolytic capacitors in there, which dry out over the years, whether used or not, and need inspecting, and often enough changing. The EL84 valves in there are not the most robust, being quite heavily loaded to get the thirty watts, so may be tired. In short, find a Good Technicien and get it thoroughly checked out. On no account try to open it up and poke around in there yourself; there are very high voltages that can take your fingers off or kill you dead. Get it seen to, and enjoy it for years to come afterwards. Hope this helps. 1 Quote Link to comment Share on other sites More sharing options...
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