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Title: Strange noise on certain notes Post by: narapo on January 10, 2008, 09:17:23 PM Hi, I have completed my 20W Lead and Bass ; it works on first power on, the lead channel has a great clean and a marvelous cranked sound. I have only a slight problem on the bass channel only when cranked, I hear a crackling noise only on low E notes (6th string empty, or 5th string on 7th fret) but not on any other note. The noise is encountered on any of the two jack inputs, but the volume is lower on the bottom jack (as usual). It must be some kind of resonnance ? but I don't know where to look for. I have checked the values and the solder joints. Any other idea ?
Title: Re: Strange noise on certain notes Post by: ChrisL on January 11, 2008, 12:14:11 AM I know you inspected the solder joints but did you re-flow them? Sounds like a bad tube to me. Swap v1 and v2 valves. If no change sub in other pre's, first v1 and test, then v2 and test. Post back.
Title: Re: Strange noise on certain notes Post by: narapo on January 11, 2008, 08:52:50 AM Thanks, I will try that tomorrow
Title: Re: Strange noise on certain notes Post by: narapo on January 14, 2008, 08:24:15 AM Sorry, I less time this weekend to make tests ; the tube swapping doesn't change anything, I tried the head on another cab, with the head not resting upon the cab (for any mechanical vibration issues), with the same noise coming from the bass channel only on low E notes. Must be definitively on the preamp boad, maybe a bad component. Will check later and post back.
Title: Re: Strange noise on certain notes Post by: narapo on January 24, 2008, 09:53:09 AM You never check enough .... Chris, you were right on
it was after all a dry solder joint on the capacitor between the tone pot and the volume pot on the bass channel ; after resolder, the strange noise is gone ;D Title: Re: Strange noise on certain notes Post by: ChrisL on January 24, 2008, 11:48:05 PM Very Cool. Glad you found the offender. I'm chasing an oscilation in a build right now. No doubt it is something simple that I've overlooked....
Title: Re: Strange noise on certain notes Post by: narapo on January 25, 2008, 03:21:33 PM the guts of the completed amp :
(http://i30.servimg.com/u/f30/09/02/28/99/dscn2314.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2315.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2317.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2410.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2411.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2412.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2414.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2413.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2416.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2415.jpg) (http://i30.servimg.com/u/f30/09/02/28/99/dscn2417.jpg) Title: Re: Strange noise on certain notes Post by: ChrisL on January 26, 2008, 12:02:26 AM Good job, great pics. One bit of "constuctive" criticism...if you don't mind... Watch your lead dress particularly in the power section. You have a lot of runs that can be significantly shortened. Even the build Nik has pics of on his website of the 20watt is a little "loose" IMHO. Just something to think about for your next build. Cheers, enjoy.
ChrisL Title: Re: Strange noise on certain notes Post by: sixstringsteve on March 10, 2008, 04:12:42 PM I want to hear some sound clips of that bad boy. That's the next amp I've been thinking about, but I"m not sure if I can handle a solid state rectifier. Maybe I'll mod it for a tube rectifier (but then I'd need a different PT).
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