Cornwalled Posted June 8, 2002 Share Posted June 8, 2002 Hello, I have a vintage tube amp, that I've been fooling around with, trying to get it working so I can use it with my Cornwalls. It's from an old radio console of the 60's. It's a stereo power amp, not an integrated, with 2 EL-84's per channel, one 12AX7 (total) and one 5R4 rectifier. The problem I am having is it makes this loud hummmmm all the time. It's a 60 cycle ground hum, and it's really loud. There is also some crackling from time to time. It does play sound, which is a good sign I guess, but the hum is so loud you can't really hear the music much at all. All the tubes do light up. Anybody have any ideas what could be causing this? I changed several caps underneath- about 6 I believe, observing their values, and replacing with identical caps. But they haven't helped at all. Could it be the large filter cap on top? If so, I would be dumbfounded when it came to replacing it, because it is actually numerous caps inside there- all of different values. The values are all written on the side of the can though. Any one with any ideas here? I'd really like to get this thing going again, and caps and resistors are cheap so I figure it's worth the effort if it'll work for me. I used to use it with my AR3a's- those speakers are inneficient enough that the hum was much more subtle- still there, but tolerable. However, on the Klipsch's (and a pair of JBL D208 midrange cones I tested first) the hum is unbearable- since these are much more efficient. Thanks, Jon ------------------ markvi82@hotmail.com 1981 Cornwall I's Yamaha DSP-A1000 integrated amp Acoustic Research AR3A's for Pro-Logic rears (Music only setup) Marantz CD Player Pioneer turntable with Audio Technica cartridge Quote Link to comment Share on other sites More sharing options...
NOSValves Posted June 8, 2002 Share Posted June 8, 2002 You can order a custom can cap for about $25 from Virba World just jot down the values and give them a call. Good luck Craig ------------------ HH Scott 299 Amp HH Scott LT-110B Tuner HH Scott P-87 Turn Table JVC JL-F50 Turn Table Sony CDP-CA7ES CD Drive 1985 Walnut Heresey I W/Layne Audio Woofers KSW-15 Subs>c> Quote Link to comment Share on other sites More sharing options...
hetmann Posted June 8, 2002 Share Posted June 8, 2002 Sounds to me like you have an open ground. Make sure your power cord has a third prong and that the unit is properly grounded. ------------------ Klipschorns and Moondogs Quote Link to comment Share on other sites More sharing options...
kenratboy Posted June 9, 2002 Share Posted June 9, 2002 I dream of a tube amp someday ------------------ Receiver: Sony STR-DE675 CD player: Sony CDP-CX300 Turntable: Technics SL-J3 with Audio-Technica TR485U Speakers: JBL HLS-610 Subwoofer: JBL 4648A-8 Sub amp: Parts Express 180 watt Center/surrounds: Teac 3-way bookshelfs Yes, it sucks, but better to come. KLIPSCH soon! My computer is better than my stereo! Quote Link to comment Share on other sites More sharing options...
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