conducted noise

64.12.116.16

Posted on November 1, 2009 at 14:57:21

PakProtector
Audiophile

Posts: 9953
Joined: May 14, 2002

hey-Hey!!!,
I built a balanced output linestage running a pair of 12B4's in a LTP circuit. It gave me a low level ringing noise that was not dependant on the volume control. I tried some re-work on the layout, and even rigged a set of triode-ed EL86's to get rid ov the noise. The EL86's were less microphonic than the 12B4 but it still sang to me...

While messing with it again I ran my ear close by the chassis and heard the same sort of noise issuing forth. Nothing wrong with anything but noise conduction issues. I am going to split the plate and put some damping under the amplifier section next, shich should do away with it.

It is driving my AC22B active cross-over, and it deals with the 10k per phase input impedance well. It has a 480V B+, 20k plate loads and runs almost 20 mA/tube idle current. It is very dynamic and clean, well worth the effort so far. Never had to do this for a linestage before, and its power Irons don't seem to be any more stressed out than the previous ones. Always something new...:)
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

Philip Glass

diamondsouled

17:47:09 11/01/09

Philip Glass, posted on November 1, 2009 at 17:47:09
diamondsouled Audiophile Posts: 609 Location: The Great White North Joined: May 2, 2007	;^). Lar

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conducted noise

64.12.116.16