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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: Heathkit aa-32 and aj-63 posted by mark.korda@verizon.net on February 2, 2002 at 14:22:56:
Check under-chassis for 4 electrolitics, one flanking each 6GW8/ECL86 tube. If they are copper-colored, plastic-encased, maybe go ahead and replace these (with 46uF/35volt ones from Radio Shack for cheap and quick). If they are brown paper encased (with rolled over ends) like the 2 larger voltage-doubler ones over by power supply, and show no signs of leakage, corrosion at terminals, or pimpling at reddish end they may still be OK. I replaced all of these on mine simply because of age, but couldn't tell a difference afterwards. The brown clay-pot looking coupling caps (Mylar) had a bulged appearance to start with, and unless they show signs of sweating (like shiney wax) or a pimple, they will be OK. The Hum Null adjustment on back is simply set for lowest background hum with Bass advanced, Treble reduced, and Volume at an appropriate level (higher as you fine-tune the setting). I have to use the phono input (no need to connect a Turntable for this) on mine (it's the noisiest input) and stick my head in the speaker; it's that quiet. What slight residual hum is left occurs in the right channel and could possibly be eliminated with copper shielding or different orientation of the output transformer, but I haven't bothered. This is a real sleeper amp and although the triode/pentode output tubes limit tube-rolling, it is rather inexpensive to re-tube if neccessary or desired. I'm still using the original Mullards. BTW, the AJ-13 was the matching Stereo tuner; I'm using a Heathkit AJ-14 solid-state FM tuner and Heathkit/Electro-voice AS-16 8" sealed bookshelf speakers alternately with DIY speakers, and a Miracord 50H turntable/Shure V15/III cartridge.
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Follow Ups
- Re: Heathkit aa-32 caps and Hum adjustment - Ron Oehlert 10:20:34 02/03/02 (0)
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