Problems with EICO HF-12 amp. - Page 3

ivegotmono · 19th January 2006, 01:45 AM

Hi,
When I got my first HF-12 about a year ago, my Power tranny vibrated like crazy and it had a loud hum. After about a month of part time usage it stopped completely. I would guess the can cap has to reform and did since both problems went away. You should be fine going up on the values of the can cap and many reccomend this. Keep the under chassis cap located under the chassis ( the first one after the rectifier at 40 or 50uf max though since these amps have a small rectifier tube. I increased the coupling caps and it sounded much worse so I wen't back to .1uf orange drops and it's great now. I increased the 50uf 25v cap at the output tubes to 100uf 150 volt and it sounds more open and the instruments playing are more distinct. I doubt that more than 100uf would be any better.
Steve

ivegotmono · 19th January 2006, 11:27 AM

By the way, so you have the old 12au7 (tube in v2) or more common 12ax7 model??
Steve

DragonMaster · 19th January 2006, 03:18 PM

Both don't have any 12AU7s. No, I don't have the early versions.

Ok I could try what you've done.

19th January 2006, 01:45 AM	#21
ivegotmono diyAudio Member Join Date: Nov 2005 Location: maryland	Hi, When I got my first HF-12 about a year ago, my Power tranny vibrated like crazy and it had a loud hum. After about a month of part time usage it stopped completely. I would guess the can cap has to reform and did since both problems went away. You should be fine going up on the values of the can cap and many reccomend this. Keep the under chassis cap located under the chassis ( the first one after the rectifier at 40 or 50uf max though since these amps have a small rectifier tube. I increased the coupling caps and it sounded much worse so I wen't back to .1uf orange drops and it's great now. I increased the 50uf 25v cap at the output tubes to 100uf 150 volt and it sounds more open and the instruments playing are more distinct. I doubt that more than 100uf would be any better. Steve __________________ steve

19th January 2006, 11:27 AM	#22
ivegotmono diyAudio Member Join Date: Nov 2005 Location: maryland	By the way, so you have the old 12au7 (tube in v2) or more common 12ax7 model?? Steve __________________ steve

19th January 2006, 03:18 PM	#23
DragonMaster diyAudio Member Join Date: Dec 2003 Location: Montreal	Both don't have any 12AU7s. No, I don't have the early versions. Ok I could try what you've done. __________________ Antoine http://dmsaudio.ca/

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