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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: 12BH7A in ARC SP-8- very hot! posted by Bambi B on August 12, 2005 at 06:12:43:
The 12at7 and 12bh7 or any of the 12 novar series are not necessarily "power supply" or interchangeable tubes. The at7 is a medium mu tube of much higher gain than the bh7 which is a low mu current gain tube. They are different animals and you can't freely interchange these tubes because they have the same filament voltage. Of course some "gitar picker" would try anything to get "the right sound". They have different plate and cathode demands. A capable engineer designed the ARC very well and you need to take a chill pill and use the correct tube in the correct sockets and stop worrying. Make sure the tubes are tested as Ok but you don't have to worry if they were made by gnomes from the black forest or what kind of stamp is on the bottom or what shape of getter it has, or if it flahes which is common to all series string 12 volt tubes (two 6 volt tubes in series and one is acting as a current limiter) or whether they were blessed by a rabbi and a bishop or the Punjab of Jabbapoe. Very few calamities can beset any of the Audio Research components. Certainly not like a solid state amp that can self destruct. Read VALVE AMPLIFIERS by Morgan Jones. Ray Hughes
"Polarities are seldom aware of their polarness." Prospero
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Follow Ups
- You need to do a lot of reading...... - grhughes 11:13:38 08/12/05 (2)
- Sorry, Perhaps I wasn't clear, plus some Shakespeare! - Bambi B 11:43:31 08/12/05 (1)
- Re: Sorry, Perhaps I wasn't clear, plus some Shakespeare! - grhughes 12:01:57 08/12/05 (0)
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