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In Reply to: Dynaco question, popping noise, can cap,PAS resistors posted by airtime on July 28, 2002 at 05:44:23:
Intermittent noises can require lots of patience to run down. To eliminate the preamp from the suspect list, unhook it and use shorting plugs on the inputs to the ST70, then, I guess read a book for awhile in the same room to listen for crackles.The noise you describe can be caused by an old carbon comp resistor which has developed voids. Sometimes you can get these to act out by hitting them with freeze spray.
I just replaced my can cap with one from AES, 40x20x20x20 @ 525V. It mounts just like the original, but is shorter. At the same time, I replaced the two voltage dropping resistors attached at the cap with 1% metal oxides. I did this just because I felt like giving the old can a rest after over fourty years. The audible results were nothing spectacular, but the extra 10uFD in the first section gives it just a hint more authority. The cap cost about $32 on sale. Sale runs til the end of the month.
An EH GZ-34 would be my current first choice for a replacement rectifier, if you need one. I don't have a feel for the life-span yet, but I haven't had the infant-mortality problems with these that have been commonplace with Chinese and Russian rectifiers the past few years.
Cheers!
Jim
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Follow Ups
- Re: Dynaco question, popping noise, can cap,PAS resistors - Jim Carlon 13:00:05 07/28/02 (0)