Speaker Crackle After Power Down

[plexi50]

What causes a speaker to crackle a little after the amp is shut completely off?

[jhadhar65]

Prolly that middle dude from your Rice Crispies.  I hate those guys!  Real trouble makers they are.

 :)

[supro66]

Prolly that middle dude from your Rice Crispies.  I hate those guys!  Real trouble makers they are.

 :)

YEP OFFICER THATS HIM IN THE MIDDLE

AND I THOUGHT YOU PEOPLE WERE PROFESSIONALS

MY TUBE AMP SITE
http://www.geocities.com/insp/SUPRO6420.html

[plexi50]

That was it! Now how did that get in there?

[tubesornothing]

he he

I ws thinking a few things about this, but it depends upon the design of the amp and what you mean by "crackle"

When I shut off some of my amps, without shutting off standby, any signal degrades and distortion takes over and it sounds a mess as it slowly discharges the caps.  Basically the headroom on the tubes is being reduced causing distortion.

When I shut off standby first, then shut off the power, sometimes there is a noise.  This is a little more interesting to me, because B+ has been turned off, so where is the power coming from that powers the speakers?

Is this more of what you are wondering about?  Or is it really the cereal?

[plexi50]

When I shut off standby first, then shut off the power, sometimes there is a noise.  This is a little more interesting to me, because B+ has been turned off, so where is the power coming from that powers the speakers?

Is this more of what you are wondering about? 

Yes thats it exactly. After i shut the standby off and let it sit there is no noise

But after i shut the power switch off then about 5 seconds later i hear this crackling through the speaker as the voltage bleeds down

May be the cure is just to put in some bleeder resistors that will drain the voltage before reaching the speaker / Then maybe not

Im going to take another look at the schematic / It just hit me! There is no choke in this amp

Could that be a factor / Choke vs: Resistor in possable voltage spike?

Could a choke at shut down act as a VDC storage buffer/filter in effect bleeding VDC itself?

This is only the second amp i have heard doing this that is quiet noticable / Not a great selling feature if you know what i mean....

[JimH]

Hey guys,

I wanted to bump this thread since I'm having a similar issue, except it's not crackle as much as actual guitar signal!

Is this anything I should worry about?

My amp is a 2204 clone type that I just built. It works great. I don't think there are bleeder resistors. Would that solve this issue? I should put one in anyway, so Where is the best place to install one?

Any info appreciated,

JimH

[Geezer]

I usually install a 220k/3W bleeder across the 1st filter cap.

Look at this schem, just to the right of the standby switch>>> http://www.el34world.com/Forum/index.php?action=dlattach;topic=6176.0;attach=10812

[plexi50]

WOW! I must be getting Alltimers. I dont remember posting this thread. Febuary wasnt that long ago!
Too many Ampegs i think / Bleeder resistors will be used on my next adventure / Thanks all!

[JimH]

Man! A month since I bumped this and I'm finally getting to this. Thanks, I'm going to try this tonight.

[Rich]

I'm getting this crackling on my DR clone.  One of my tubes started making noise and in the course of tracking it down I noticed this crackling - arcing type sound after killing the power switch (standby still on).

With the power off it has to be the caps draining feeding this noise to the speakers.  I do have a choke and this speaker noise is a new experience.

Anyone have another explanation?

[JimH]

Ok. I just added a 220K 3W resistor at the first cap to ground. No change though. Fully powered on, switch to Standby and all is quiet, power off and the input signal comes through quiet, and fades.

Could it be that 220K is to high a value, so the voltage doesn't leak down quickly enough?

I'm not overly concerned about it, but I would like to get this amp "right", if anyone has any other ideas.