Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: shooter on May 09, 2019, 07:00:29 pm
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with 400 plate, 50mA Ip, the "happy" load ~ 8k
you plug in the wrong speaker and now the load is ~ 2k
Does the tube only get cranky under AC conditions, or do I need to "worry" about the DC conditions also :dontknow:
thanks as always
dave
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As long as the tube is biased to idle safely it doesn't matter what size load is connected as long as you don't put a signal in. Heck, you don't even need speakers if the amp is just gonna idle.
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thanks, that's what one of the voices in my head was saying, the other was pretty noisy though :icon_biggrin:
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From PRR in Dude's thread;
electrolytic caps won't blow-up in 11 seconds
There is NO "inrush" if the caps charge at power up with NO load ?
If I got that one correct, when load IS applied to full charged caps does the "supply" just "produce" the current as voltage sags, NO "inrush"?
(I think this 1 day Sunshine in 8 is messing with me:)
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With everybody ! :icon_biggrin:
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From PRR in Dude's thread;
electrolytic caps won't blow-up in 11 seconds
So, no inrush with standby on...?
al
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There is NO "inrush" if the caps charge at power up with NO load ?
The very action of the caps charging will result in an inrush current. Even if nothing is connected to the caps (other than the PT and recto).
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The very action of the caps charging will result in an inrush current
thanks, for some reason I couldn't get there, I seen it as "voltage potential" only, without a current element like static charge, all the electrons to one side, wait for R :think1:
I did find a good PDF by TI on PS design for dealing with inrush
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Are we confusing Volts and Amps?
Consider a Stand Pipe. A variant "water tower".
(https://www.paxwater.com/hs-fs/hubfs/Old_Town_standpipes_5-1-09.jpg?width=275&height=315&name=Old_Town_standpipes_5-1-09.jpg)
You build it dry. Then you connect pressurized water supply. The pumps run all day to fill it until the water height equals the supplied pressure. Then you draw water off and the water height drops a little.
In an amplifier often the rectifier comes to life faster than the main load. The 5V4 hots-up and a gush of current flows to the stand-pipe (capacitor). With a saggy rectifier, for a few seconds the voltage may rise much higher than normal. Then your 6V6es hot-up and suck current. The capacitor voltage drops some.
With tubes, in the 3 to 10 seconds after start-up, the voltage may rise significantly higher than the running voltage you picked your caps on. But 460V on a 450V cap for just these few seconds at start-up won't blow a cap. Yes it would be wise to pick a higher-spec cap, but often we just let it take the hit and some amps run decades with over-volt at start-up.
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:laugh: I confuse a lot of things :icon_biggrin:
the voltage may rise much higher than normal. Then your 6V6es hot-up and suck current
I was pondering without LOAD, ie, standby. I need to read more about caps. My brains assumption was the caps electrons just get sucked to one side until the voltage potential can't move anymore and there they wait til a load happens by, then current happens