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After two hours of listening music, when I check the temperature of the PA774, I can read 108F. Is it too hot for the power transformer? Do you have the same thing ?

By the way, the sound is very good!


Tigrine
http://picasaweb.google.ca/TigrineAudio/GetSetGo#5408263298948244610

The power transformer on the Dynaco Mark III has been reported to reach temperatures of 170 deg F.

Your PA774 is barely loafing along at that temp. It is perfectly normal, and you have nothing to worry about.

Thanks for the information!

As compared with the operating temperature iof a PA774 in an ST35 (especially the original Dynaco units) your 108 degrees F is just barely warm. In the GSG it is running about 60% of its full VA capability.

In the confines under the cage of a Dynaco ST35, the power trannie gets very hot, painful to the touch kind of hot.

/ed B

Speaking of Dynaco PT's, good grief, I wonder which gets hotter in my ST-70.... the PA-060 or the EL34's?

Cheers!

Geek wrote:Speaking of Dynaco PT's, good grief, I wonder which gets hotter in my ST-70.... the PA-060 or the EL34's?

Cheers!

The PA-060 in my ST-70 gets hotter than the EL-34's!

The PA774 in my GSG gets hot, but it is still touchable.

I prefer using rectifier tubes, but I do have a Weber Copper Cap for each amp. When using the Copper Cap the transformers run much cooler.

With no rectifier filament to light up, you're saving between 7.5 and 10 to 15 VA, so the trannie would run a bit less hot, and probably deliver a shosh higher B+ voltage in the bargain.

/ed B