Vox AC30 Top Boost Channel

servventer

Hi,

I have an AC30CC2 which started acting up a bit. The Top Boost channel has almost no output at any volume even with both the channel and master volumes turned up. The Normal channel is however 100% fine

My question is, is this just normal valve wear? Previously when it was time to replace valves all the channels were low on output. So my thinking is that it is not the rectifier tube as that would affect all channels. Maybe V2 Pre amp? Or am I way off the mark here?

Unfortunately I don't have a "good set" of valves lying around to test my theory so before I order some I'd like to at least get an idea.

Regards,
Serv

Gearhead

Doubt it's the valve, but might be the socket. Either way, swap V1and V2 and see what changes. You mention 'previously when it was time to replace valves', who said it was the rectifier tube? The GZ43 should last at least a decade imho, so it's hard to imagine this was actually the trouble at the time.

guitarboy2828

If it's anything like my AC30, it's the toggle switch, cheap little thing. Mine was doing exactly the same thing. Wriggle that thing till you get a good sound, if it works, either replace the switch or get some switch cleaner to help it out.

servventer

thanx for the reply gearhead.

I changed the V2 pre amp tube and it seems to have done the trick. I will see how it goes, if it is the sockets then I will have to send the amp in for TLC.

The amp previously had symptoms where the volume would drop/cut playing harder chords. I scoured the interwebs and found this very nice website:

http://www.ac30-guide.com/?page_id=789 and under Maintenance:
"
The rectifier tube only needs to be changed if you feel the amp is not keeping its tone when playing hard chords. The volume may lowers when playing hard chords. This can be because the tubes are not getting enough voltage from the rectifier when stressed. Another indicator is a blown amp fuse."

Wasn't a blown fuse so replaced the rectifier and voila. Decided then to sommer replace all the stock tubes.

Paul E,

Which toggle switch are you referring to? On the Top Boost there is only the Custom vs Standard one.

regards