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New member Username: Macisgr8Jacksonville, FL USA Post Number: 10 Registered: Dec-05 | I recently purchased a small tube amp on ebay direct from Hong Kong. If you want to look it up, see ebay item #5842529464. Anyway, it sounds great on the low end but looses a bit on the high end. But that's fine. My question is: the four power tubes get to be about 350 degrees F. The two smaller ones are around 160F. This is just sitting idle, I have not measured the temp after playing music yet. The person responding says in his reply to me "this is no problem of tubb so hot...since EL84s are power tubes, it is provided the power for the speaker. the temperature is normal." I never had a tube amp before so I am asking you guys who have the experience. |
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Gold Member Username: John_aLondonU.K. Post Number: 3849 Registered: Dec-03 | I do not known the exact temperatures, but it sounds normal to me. It is the way valves work. Valves/tubes are much like light bulbs. There is a filament in each one, glowing hot, radiating heat. |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7105 Registered: May-04 | Tubes run hot. Solid state should not run at the same tempereratures unless the circuit is biased into a class A operation. The bias applied to a tube will also affect its operating temperature. The lower heat and reduced weight of solid state amplifiers are much of the reason the technology caught on; it certainly wasn't the sound of early transistors which made people buy them. As John states, you have a glowing filament inside the tube envelope just fractions of an inch from the glass. There is going to be heat in this situation. Depending on the bias voltage/current applied to the tube, the amount of heat will change to some degree. If the filaments are glowing evenly and none display a cherry red filament, the temperatures are probably normal for your amplifier. If your amplifier has adjustable bias, you can lower the temperature by lowering the bias. You will, in doing this, also be affecting the operation of the amplifier. |
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Bronze Member Username: Macisgr8Jacksonville, FL USA Post Number: 11 Registered: Dec-05 | The 4 power tubes glow a bright orange at the filament at the top of the metal assembly inside the tube. Looking closely at the filament, the glowing area on each tube appears slightly different. The tubes all have chinese(probably) writing on them. I read that the chinese made tubes are not as good as russian made ones. I guess the model of the power tubes is EL84/6P14. The spec's say the input/driver tube is a 6N3 and that this is a 15 watt x 2 Class A Push-Pull circuit design. I don't know if it has adj. BIAS and I wouldn't know what to do with it if it did. But I do intend to learn about this new hobby. Does any of the spec's tell you anything about this amp that I should know? Where do you find a cross-reference for tube model numbers/type? Thanks for your help! |
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Gold Member Username: Jan_b_vigneDallas, TX Post Number: 7112 Registered: May-04 | http://www.worldtubeaudio.com/ You can put "vacuum tube cross reference" into a search engine or you can go to several tube dealers and buy a RCA tube reference guide book. There are various publishers of the tube cross reference guides; the RCA is the best known. The information you've given doesn't tell us anything that you shouldn't already know by looking. Browse through the links I recently gave Bill Collins on this thread; https://www.ecoustics.com/electronics/forum/home-audio/111344.html |