Members onelife Posted August 9, 2016 Members Share Posted August 9, 2016 When your power tubes go bad, is it both of them or just one? If it is just one that goes bad, have you been able to identify which socket it was in at the time? Link to comment Share on other sites More sharing options...
Members bluesmann Posted August 9, 2016 Members Share Posted August 9, 2016 Check out the Allen amps, it might be a good option in that price range. I've been thinking about one of his 4 10" cabs. Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 9, 2016 Author Members Share Posted August 9, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members WRGKMC Posted August 10, 2016 Members Share Posted August 10, 2016 Its highly unlikely you'll ever find any real NOS, especially for the popular ones musicians use. All you will find is someone's used tubes stuck back in an old box. There is no way to tell how many hours are on a used tube and the chances of finding some New USA tubes stashed for the past 30 years is about as rare as winning the lottery. There are counterfeits made to look like the real thing. They relabel the tube which is very easy to do and even counterfeit the boxes too. Link to comment Share on other sites More sharing options...
Members Out of the Past Posted August 10, 2016 Members Share Posted August 10, 2016 try loctite on the screws...ive got a vibrochampXD with a Hammond USA 6v6 tube (I think its a mullard, hammond always used the best parts)Ive tried the Tungsol RI in my tweed deluxe-nice tubes if not high-fi sounding to me edit: if youre blowing power tubes the map isnt biased properly you dont need NOS, its just nice to know how many hours are on them (zero for NOS)any old USA, British, Russian made tube is going to last longer than new ones. Ive got a 6v6 from a 1960s organ in my amp thats been there since 2008. who knows how long it was in the organ? who cares? Link to comment Share on other sites More sharing options...
Members mrbrown49 Posted August 10, 2016 Members Share Posted August 10, 2016 I bias the tubes to run at about 33.5mV total instead of the usual 40mV. You do mean mA, correct? Link to comment Share on other sites More sharing options...
Members WRGKMC Posted August 10, 2016 Members Share Posted August 10, 2016 He's having tubes go bas shortly after installing them. Buying a tube with mileage on it may give him the noise as soon as he installs it. Link to comment Share on other sites More sharing options...
Members WRGKMC Posted August 10, 2016 Members Share Posted August 10, 2016 There's a reason the tubes are going bad. The fastest things to eat up tubes is incorrect bias, vibration and improper load.You need to take that thing to a tech who knows what he's doing and can fix that thing. Throwing tubes at it isn't getting the job done. Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members onelife Posted August 10, 2016 Members Share Posted August 10, 2016 Some amplifiers have a 1 Ohm resistor connected from the cathode to ground. Measuring the Voltage drop across the resistor will give a direct reading of the current flowing through the tube. For example, a reading of 40 mV will indicate a current flow of 40 mA. Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members onelife Posted August 10, 2016 Members Share Posted August 10, 2016 How are you taking the measurement? Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members onelife Posted August 10, 2016 Members Share Posted August 10, 2016 ^^^^ In that case, the Voltage reading will be a direct indication of the current flowing through the tubes. If you are reading 33.5 mV at the test point then, unless the 1 Ohm resistor is faulty, you will be getting 33.5 mA of current flow. Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members mrbrown49 Posted August 10, 2016 Members Share Posted August 10, 2016 How would I know if my 1ohm resistor is faulty? Is 33.5mA a cold bias or hot bias? Would running the tubes at 33.5mA instead of 40mA cause them to wear out quicker? The only way to really test it is to remove it from the circuit and then measure the resistance with a meter. If you don't disconnect it the rest of the circuit can influence the reading. Commonly resistors get damaged when they are over heated. They will either burn up entirely, or get damaged to the point where their resistance changes but still "function" in a circuit. Did you remember to hook the speaker back up when the amp was removed from the chassis. Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members onelife Posted August 10, 2016 Members Share Posted August 10, 2016 How would I know if my 1ohm resistor is faulty? Is 33.5mA a cold bias or hot bias? Would running the tubes at 33.5mA instead of 40mA cause them to wear out quicker? I doubt that the resistor is faulty although it is not unheard of. Based on the schematic, you should be able to get a reasonably accurate measurement with an Ohmmeter. Remove the power tubes and place the Ohmmeter leads on each end of the resistor and note the reading. Reverse the leads and measure again while noting the reading. If the readings are different, use the larger one to determine if the 1 Ohm resistor is actually 1 Ohm. Because the resistance is so small, it's a good idea to touch the two meter leads together to see what zero Ohms looks like on your meter. The schematic suggests setting the bias to 40 mA which is where I would set it. 33.5 mA is less current so it would be considered cold bias and would not cause the tubes to wear out quicker. You may find this interesting... https://www.tubedepot.com/pages/bias-point Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 10, 2016 Author Members Share Posted August 10, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 11, 2016 Author Members Share Posted August 11, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members Grant Harding Posted August 11, 2016 Members Share Posted August 11, 2016 I'd take the amp back and tell them it's chewing through tubes. They should be responsible for making it right. Link to comment Share on other sites More sharing options...
Members jjang1993 Posted August 11, 2016 Author Members Share Posted August 11, 2016 Deleted for privacy and safety reasons Link to comment Share on other sites More sharing options...
Members onelife Posted August 11, 2016 Members Share Posted August 11, 2016 I agree that the very thing that makes tube amps great is also their weakness. I have a couple of modelling amplifiers that I find work really well. One is a Yamaha DG80-112 and the other is a Fender Mustang IV. I'm finding that tube amps, with their associated issues, are not that appealing to me now that modellers are getting so much better. The Yamaha DG80 is the best amplifier that I have ever had. It replaced a Fender Twin Reverb that I used as a regular gigging amp for over fifteen years. I don't have much experience with the Super Champ XD but I'm thinking a Fender Mustang III might do it for you and they are relatively inexpensive. Link to comment Share on other sites More sharing options...
Members Grant Harding Posted August 11, 2016 Members Share Posted August 11, 2016 I'm not suggesting a different model - just a replacement with one that doesn't eat tubes. I understand if it's not under warrantee, but if it is I'd use it. Link to comment Share on other sites More sharing options...
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