What causes amp on/off to pop loudly?

**CarolM** · 03-14-2012, 09:33 AM

I found this used rogue amp with 10 in, reverb, nice tweed cab...enjpying the hell out of it, only it pops so loudly when turned on or off. no other noises.

is there something that can be done to attenuate the sound? it doesn't make any difference whether the volume is all the way down or not. It really snaps when turning it off.

**Insufferable_Rhythm** · 03-14-2012, 09:55 AM

Could the noise be more accurately described as a "thump"?

The cause may be that one side of the amplifier's (presumably) bipolar power supply is rising/falling before the other, causing DC offset at its output -- something like connecting a battery across the speaker's terminals. This is actually very common in solid-state amplifiers, even the more expensive ones. Some include circuitry to delay the connection of the speaker until the amplifier has stabilized.

The intensity of the thump may be significantly lessened by replacing the amplifier's main filter capacitors.

**mr. beaumont** · 03-14-2012, 09:58 AM

Some amps just do that--it's not necessarily bad.

**SOR** · 03-14-2012, 11:17 AM

I find it usually happens when an amplifier is turned off, it's usually harmless unless it's really loud. By the way it doesn't always happen on the turn on/ turn off cycle, try putting a Deluxe Reverb into standby while it on, our pets tear out of the room!

**CarolM** · 03-14-2012, 11:20 AM

Originally Posted by Insufferable_Rhythm

Could the noise be more accurately described as a "thump"?

...

The intensity of the thump may be significantly lessened by replacing the amplifier's main filter capacitors.

Not really a thump, no. But I'll check again later.

I just want to make sure it's not hurting anything...like when you plug a cord in when it's hot and it arcs and pits the metal, that sort of thing.

**ruiner54** · 03-14-2012, 12:04 PM

I am was wondering the same thing about my polytone. If I turn it off gently the thump is significantly less loud

**mr. beaumont** · 03-14-2012, 12:12 PM

Polytones are notorious thumpers.

Henriksen's too. They got so many questions about it they put in in their website FAQ at one time, I believe...they assured the owners that it's harmless...considering my henriksen has been turned on and off a few thousand times over the past 3 years, I tend to agree with them.

**Retroman1969** · 03-14-2012, 01:12 PM

If it's more of a crack (sound of plugging cord in guitar jack hot) than a thump, I'd say static electricity? Loose ground to the switch or power supply?
Just guessing, but that's what it sounds like to me. I've had amps with that issue before but never did anything about it. Never seemed to cause a problem, even though it was a bit unnerving turning it on and off.

**lpdeluxe** · 03-14-2012, 01:30 PM

I've had several amps that did this, including my DRRI, which makes a noise whether or not it has been switched to standby, and I had a solid state Ampeg B100R that I loved that did the same thing. Others of the same model did not.

I don't know what causes it, but none of my amplifiers have ever suffered damage from it.

**Bluedawg** · 03-14-2012, 03:48 PM

I've always called it transistor pop ...

It is normal for most solid state amps and the occasional tube amp with some solid state components.

**lpdeluxe** · 03-14-2012, 06:54 PM

I've had several all-tube amps over the years that popped like that, so I'm certain it's not confined to solid-state components. In fact, the DRRI is all-tube, unless you want to call the circuit board "solid-state."

**CarolM** · 03-14-2012, 09:51 PM

Originally Posted by Retroman1969

If it's more of a crack (sound of plugging cord in guitar jack hot) than a thump, I'd say static electricity? Loose ground to the switch or power supply?
.

Yeah it does have kind of a staticky sound, like it has something to do with the carpet??

I'll check out the wiring...thanks.

**Bluedawg** · 03-14-2012, 11:24 PM

Originally Posted by lpdeluxe

I've had several all-tube amps over the years that popped like that, so I'm certain it's not confined to solid-state components. In fact, the DRRI is all-tube, unless you want to call the circuit board "solid-state."

There may be solid state components on the DRRI ...

whatever ... I'm sure that some tube amps pop ..

But it has been my experience that solid state amps almost always pop ... while tube amps rarely do

Not that I'm an amp expert ...

Nuff Said · 03-15-2012, 05:29 AM

I've built a few tube amps in my time, when turning them from standby to on, I got a popping sound when I used a solid state rectifier (diodes) instead of a tube rectifier. I thought it was due to the surge of current from the capacitors through the rectifier to the output. I never got a popping noise when I used a Tube rectifier, maybe a solid state rectifier is instant current and the Tube rectifier slows (smoothed) the current flow.

The rectifier just converts the current from AC to DC, because tubes use a DC power supply.

Just my thoughts.
Nuff

**CarolM** · 03-15-2012, 11:20 AM

It kinda hurts my ears.

It's open-back and I saw only a red and white wires to the PS from the speaker. Shouldn't there be a ground wire?

Nuff Said · 03-15-2012, 11:29 AM

Originally Posted by CarolM

It kinda hurts my ears.

It's open-back and I saw only a red and white wires to the PS from the speaker. Shouldn't there be a ground wire?

Do you mean the Output transformer?

Be very careful, 550 DC voltage goes to the Tubes in a Tube amp!

Nuff

**HighSpeedSpoon** · 03-15-2012, 01:34 PM

Originally Posted by CarolM

It kinda hurts my ears.

It's open-back and I saw only a red and white wires to the PS from the speaker. Shouldn't there be a ground wire?

To reinforce Nuff Said's remarks: Look if you must, but don't touch. You can get a bad shock even from an unplugged amp.

That said, your speaker will be attached to the relatively low voltage secondary coil of an output transformer, and part of the circuit is very likely grounded already. Even if it isn't, that won't cause the pop. OTOH, if you mess around with the amp and touch an unshielded primary lead, you can get a serious or fatal shock. You can also damage your amp if you ground the ungrounded side of the secondary coil, or otherwise short it out.

**CarolM** · 03-15-2012, 03:24 PM

Originally Posted by HighSpeedSpoon

To reinforce Nuff Said's remarks: Look if you must, but don't touch. You can get a bad shock even from an unplugged amp.

That said, your speaker will be attached to the relatively low voltage secondary coil of an output transformer, and part of the circuit is very likely grounded already. Even if it isn't, that won't cause the pop. OTOH, if you mess around with the amp and touch an unshielded primary lead, you can get a serious or fatal shock. You can also damage your amp if you ground the ungrounded side of the secondary coil, or otherwise short it out.

OK, I'll let it be...

**bborzell** · 03-15-2012, 03:34 PM

My Polytone 101B has always thumped when I turn it off. Only, in my case, the thump comes several seconds after throwing the switch. Sometimes, I shut it down and go to do something else and suddenly I hear "thump" and have to look around to see if the cat just knocked something over.

I'm sure the cat is getting tired of unwarranted looks from me.

My guess is that, if the thump were a problem, it would have manifested itself shortly after I first started hearing it 35+ years ago. Same amp, different cat.

**tubeswell** · 03-16-2012, 01:42 AM

The thump at std-by on is usually the filter caps experiencing the inrush current surge at switch on. If it bothers you you can mod the std-by switch by putting a 180k 1W resistor across it (to make it a 'soft-start' switch instead of a standby switch).

**Insufferable_Rhythm** · 03-16-2012, 10:31 AM

"Too many cooks spoil the broth."

Do you see any tubes, CarolM?

**CarolM** · 03-17-2012, 05:30 PM

Originally Posted by Insufferable_Rhythm

"Too many cooks spoil the broth."

Do you see any tubes, CarolM?

No, it's just a cheap solid state Rogue amp probably 10 yrs old. I can't even find any info on it anywhere.

But it works.

**mincheol.seo** · 10-10-2021, 02:41 AM

Hi all,

A long time lurker and rarely post any here. So I feel sorry that my new thread is only a question and not contributing much.
But I am really unsure about my amp, a Polytone Baby-Brute, and whether what it does is normal or not.

Here is a video clip:

Polytone Baby-Brute speaker pop noise - YouTube

As you see, my amp does a loud thump (or pop) when it turns on and when turns off, it immediately makes a pop noise then continues with a weird cycle hum for a sec before it cuts off from power. And of course, a thump from a speaker follows right after.
Do Polytone amps normally do this or is it just mine? And if it just mine, is there a fix for this? Would it damage the speaker or circuit?

Best,
Min

**Franz 1997** · 10-10-2021, 03:43 AM

Yes, Polytones and some other old solid state amps do that, including very early model Hendriksen amps. There is a fix ( a high specification stress- rated capacitor across the switch) but it's not strictly necessary. The noise is annoying, but not dangerous.