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previous: Richie GW; I knew when you had time you'd ... -- 2/20/1999 8:00 PM View Thread

Re: How to measure Output Wattage

2/22/1999 1:02 PM
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Re: How to measure Output Wattage
Richie:  
 
Speedracer posted before I got to your question about using the scope. What he said is correct. The 5% point of THD is about where your eye can just detect a slight change in the sine wave curvature. So if you were looking for output level @ say 2% distortion, your eye can't tell when you've reached that point. Lucky for us 5% is a usable reference point for guitar amps.  
 
6973 tubes are very similar to 6BQ5, but have beam forming plates instead of a screen grid. I'd venture to say the plate & cathode structures are the identical parts. Anyway, they are rather expensive because they are a good tube but no onger made. If you look at the curves & power vs. distortion specs for both tubes, you'll see how much more linear the 6973 type is. They're actually better in a hifi amp than 6BQ5. Last commecial use for 6973 was replacement in juke boxes. They used these bottles for some years just prior to switching over to SS power amps.