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Re: For that sake of academics

Posted by Tre' (P) on March 1, 2007 at 15:24:23

In Reply to: Re: For that sake of academics posted by rdf on March 1, 2007 at 11:58:10:

Those are just numbers from the push pull tube cad. 300Bs loaded with about 6.6K. Cathode biased with 430VDC at the plates. And yes, that is assuming complete balance so that there is no even ordered harmonic distortions. Doesn't happen in real life.

My only point was to show that running low current in output tubes is usually not a good thing.

Please understand when Jeff says "Run em 5/8ths of Maufacturer's spec" he means 5/8 of manufacturer's suggested operating point. Not 5/8 of max.

In this post
http://www.audioasylum.com/forums/tubediy/messages/117656.html

Jeff says "Of Maufacturer's $ugge$ted operating point$, and NOT max points at all."

That's just crazy. A 300b with only 37.5ma of current. There will be very little power and very high distortion.

I don't think Jeff really understands audio electronics. He just talks like he does. And speaks as if in decrees from above.

"you must have low DCR in your power supply or your system is Lo-Fi"

"All output tubes sound better if they are run at 5/8 of suggested operating point"

"The value of a grid stop resistor is critical to .01 ohm"

The thing is, people seem to listen to him. I'll never understand why.

Tre'

P.S. Those numbers for the 300b are impressive. But take some time to look at the plate curves for the 300B. It's a very linear tube. The 2a3 is better and the 45 even better. The 45 is near perfect. Loaded right you will get almost no distortion from a 45. It's the lowest distortion amplifying device ever made. I wish I has some really good horn speakers. I don't so I use 300b's to get some power going.

.
Have Fun and Enjoy the Music
"Still Working the Problem"

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