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>> The purpose of this video is to dispel some myths about discharging a tube amplifier.

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I am using a vendor blues junior here as an example,

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but it applies to any other tube amplifier.

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As you can see, I've got a volt meter,

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hooked up to the main power supply filter capacitor,

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and it's measuring four volts right now,

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which is just a chemical residue in the electrolytic capacitor,

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it doesn't really mean anything,

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it's just a byproduct,

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not at all important.

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I'm going to turn the amplifier on and then turn it off quickly.

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Now, you see that it's going down and went up to

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about 330 volts and it slowly going down 266,

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265 and it's discharging slowly just leaking

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through various components inside the amp and

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natural leaked down that you get with electrolytic capacitors,

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but that's more than enough voltage to knock you on your tail,

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so you don't want to mess around with that.

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Now, one way to discharge a cold amplifier like this is with

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a simple jumper wire with a 10,000 ohm resistor 10K resistor held in one clip.

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If I touch that, actually anywhere around here,

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it'll take the voltage down rather quickly, 8460, 2216, 1812,

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anywhere in the power supply will take it down.

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Now we're down to two, one volt.

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So, that's a very safe and easy way to discharge any amplifier.

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The 10K resistor only prevents sparking,

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I could touch it directly but I would get an arc,

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the 10K resistor slows down the discharge and makes it easy.

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Now, let's do the same thing again,

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we'll bring the amp up to full operating voltage,

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which is in this case,

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we see 347 volts, 348,

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and as the two tubes warm up,

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you'll see that the amp will actually drop in

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voltage because the tubes will start conducting.

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Now it's down to 333, 334, 330.

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So this is a normal voltage that you would see in a blues

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junior with normal operating conditions.

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Now, you can play through the amp, it's live.

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Now, if we just turn it off,

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remember we turned it off before when the amp was cold and nothing happened.

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Now, I'm going to turn it off and watch how quickly the voltage goes down, 50, 42,

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26, 16, faster than it did through the 10K resistor,

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three volts, two volts.

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Why? Because it's conducting through the ELAD force primarily and the other tubes,

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but these guys are always using a lot of current all the time.

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So, simply turning off a warm amplifier is all you have to do to discharge it.

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So, now we can strum it,

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nothing is coming through the amp,

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and this is ice cold,

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I can touch it with confidence,

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know that I'm not going to get knocked on my tail or anything like that.

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So, what about the old myth of having to strum the guitar while you're discharging?

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Let's take a look at that, we'll bring it back up to operating voltage again.

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So, we're stable at around 334 volts,

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and we have a normal sound,

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and now we'll strum while we're discharging,

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the powerful E chord there,

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and you notice that it discharged in exactly the same way as it did when we didn't strum.

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There is no reason to actually strum the guitar,

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that's just one of those internet myths that gets perpetuated.

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The only thing that the strumming does is

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confirm that all of the current is gone from the tubes,

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but it can be deceptive,

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if you had turned the amplifier on and off quickly and these were cold tubes,

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it would hold a charge and it wouldn't play when you strummed it.

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So, the safest thing to do is always to bring the amp up to full operating temperature,

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so you can play through it and simply turn it off,

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that will always discharge it all the way down.

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Don't put it in standby,

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don't do anything else with it,

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and you can play if you want to confirm,

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as the sound fades out,

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you know that it's being discharged and that's all there is to it.