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Studio 4 valve, power reduction [message #19073] Sat, 10 August 2013 05:18   jorisg Messages: 17 Registered: January 2013 Location: Netherlands Junior Member Hi guys, I want to limited the power of my Studio 4 valve somewhat since I mainly use it at home, I know I read somewhere that pulling two valves of the four will reduce the output by half.... but can somebody help me and tell me which 2 valves I should pull? Many thanks! Report message to a moderator

Re: Studio 4 valve, power reduction [message #19075 is a reply to message #19073] Sat, 10 August 2013 08:02   jorisg Messages: 17 Registered: January 2013 Location: Netherlands Junior Member Found it! In the 100W version of this amp, the push-pull pairing of the valves is staggered. If the sockets are numbered 1-2-3-4 from left to right, 1 is paired with 3 and 2 is paired with 4. The low input is on 1&3 and the high input is on 2&4. If you want to try running it on 2 tubes, I would suggest sockets 1&3 (though I'm not entirely sure how well it will be matched with the output transformer). I considered doing this when I built mine (to get a little more adjustment on the master volume), but I opted to build it with all 4, because that was the way it was engineered with the factory transformer. When my cathode resistors burned up, it was basically running on 1&3 (resistors on 2&4 burned open). It sounded OK. I didn't know there was anything wrong until, took it apart to fix the solder joints on the ch2 pot. That's when I found little chunks of carbon in the bottom under the socket PCB. If you're not overly concerned with output matching, it will run this way. Report message to a moderator

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