by erichayes » Wed Nov 15, 2006 9:02 pm
Hi All,
As I have mentioned more than once here and on other threads, the 5AR4--any 5AR4--is being pushed to its absolute limits in a Stereo 70. If you look at the ST70's contemporaries, you'll see that almost without exception, they either have solid state rectification, or more than one rectifier tube. In trying to keep costs down, Hafler decided that a single rectifier, undersized transformer and dense topography were worth the downside of premature tube (and, unbeknownst to him at the time, filter cap) failure.
The best thing you can do for any ST-70 is put a whisper fan on it to get rid of the heat that accumulates. Your tubes, transformers and capacitors will thank you for it.
Eric in the Jefferson State