Change load while amp is on?

madmatt · #1 03-01-2011, 11:08 PM

I have seen people do this so many times.
The amp is on and people are plugging speakers in and unplugging them.
Do you guys think this is safe for the amp?
I would normally turn the amp off if I am changing loads.

And I am only talking about solid state amps. I know you do not want to do this on a tube amp.

JimmyM · #2 03-01-2011, 11:11 PM

have i done it and been fine? yes. but i can't see any good coming from it when turning your amp on and off is easy.

**lowfreqgeek** · #3 03-01-2011, 11:53 PM

Depends on the kind of power section. Some bridged amps DO NOT handle direct shorts well and may blow as a direct short is made if a 1/4" cable is used. Speakon cables are designed to not ever short, so there's less to worry about.

Otherwise, it's really not an issue as long as there is no power being put to the cabinets - no music being played. The voltage is essentially at 0V, or very close to when no signal is present. When you hot-plug a speaker, you're really not doing anything to rapidly change the current through the speaker, or the voltage across, so it should be fine. If the music is playing, that might create problems - especially if you're using a 1/4" plug and it shorts the contacts together as it's inserted into the jack.

I have been known to plug/unplug different cabs when testing an amp, or testing different cabs through a particular amp. I just turn the volume down to limit the chance of the amp trying to push any power through a direct short.

Adam Bomb · #4 03-01-2011, 11:57 PM

I fried the 1/4 inch jacks of a beloved 210 this way. It's got a Speakon too but still. Not a myth.

--Bomb

jelwood · #5 03-02-2011, 02:20 AM

I do this with my GK all the time, however I know GK's have full short protection and are safe into no load. I also always make sure the mute is engaged. No pops, nothing fried, ever.

billfitzmaurice · #6 03-02-2011, 06:21 AM

Quote:

Originally Posted by Adam Bomb

I fried the 1/4 inch jacks of a beloved 210 this way. It's got a Speakon too but still. Not a myth.

--Bomb

+1. The possibility of toasting the amp in this way is a good reason not to use 1/4" connectors. Even if you just blow a fuse how many of you carry spare fuses to every gig?

beans-on-toast · #7 03-02-2011, 07:46 AM

Turn the amp off before changing speaker loads, unplugging the power outlet, or flicking triode/pentode or half power switches. Turn the volume down before plugging in your instrument. Anything that can send an impulse out to the speakers is a bad thing.

You mentioned that you know that you shouldn't do this with a tube amp. Some tube amps have speaker outputs that short or switch in a load resistor when the speaker plug is removed. You shouldn't tempt fate by testing these safety features.

impactwrench · #8 03-02-2011, 09:34 AM

Quote:

Originally Posted by jelwood

I do this with my GK all the time, however I know GK's have full short protection and are safe into no load. I also always make sure the mute is engaged. No pops, nothing fried, ever.

this is good to know, but I will still keep cutting power on my GK heads whenever I switch cabs. My Guitard Player fried his mesa head one time by turning it on without pluggin in the cab, so I make a point to always connect my speaker cable before my power cable whenever Im setting up. I also disconnect the power before removing the speaker cable at take down.

Good to know that speakons can prevent this...maybe I will go that route now.

Electricblue · #9 03-02-2011, 09:44 AM

Jacks are fine, if you are connecting and disconnecting them while the amp is on, thats your fault, not the plug's.

tdub0199 · #10 03-02-2011, 09:51 AM

My understanding is this: SS amps = OK - Tube Amps = NOT OK......... I may be wrong.... I wouldn't do it either way SS or Tube.... The on/off button is there for a reason....

KramerBassFan · #11 03-02-2011, 10:04 AM

Is it really so hard to flip ONE switch?

The on/off in the case of a SS amp, and the standby on a tube amp....

I mean, if it was a lengthy three hour fifty seven step procedure... then OK... but all it takes is flipping one switch, then plugging some bits around, then flipping the switch back...

billfitzmaurice · #12 03-02-2011, 10:05 AM

Quote:

Originally Posted by Electricblue

Jacks are fine

No, they aren't, because 1/4" jacks are prone to drummers and other assorted idiots tripping over cords and pulling them out. And they can be easily mistaken for effects sends/receives and line outs, allowing same to be plugged into a speaker out with disastrous results. 40 years ago the PA/recording industry woke up, smelled the coffee, and changed across the board from 1/4" to XLR connectors for microphones and peripherals, in part to prevent that scenario. The electric instrument industry remained soundly asleep.

christw · #13 03-02-2011, 10:07 AM

Quote:

Originally Posted by KramerBassFan

Is it really so hard to flip ONE switch?

The on/off in the case of a SS amp, and the standby on a tube amp....

I mean, if it was a lengthy three hour fifty seven step procedure... then OK... but all it takes is flipping one switch, then plugging some bits around, then flipping the switch back...

But... but... I have to wait a couple of seconds for my amps to totally shut down. Seriously!? That's time I could be saving by just plugging and unplugging as needed. I'm sure my amps will be fine.

The above was a joke brought to you by my poor sense of sarcasm.

chokeslam512 · #14 03-02-2011, 10:07 AM

Quote:

Originally Posted by KramerBassFan

Is it really so hard to flip ONE switch?

The on/off in the case of a SS amp, and the standby on a tube amp....

I mean, if it was a lengthy three hour fifty seven step procedure... then OK... but all it takes is flipping one switch, then plugging some bits around, then flipping the switch back...

This. I'm surprised this is even an issue.

Electricblue · #15 03-02-2011, 10:19 AM

Quote:

Originally Posted by billfitzmaurice

No, they aren't, because 1/4" jacks are prone to drummers and other assorted idiots tripping over cords and pulling them out. And they can be easily mistaken for effects sends/receives and line outs, allowing same to be plugged into a speaker out with disastrous results. 40 years ago the PA/recording industry woke up, smelled the coffee, and changed across the board from 1/4" to XLR connectors for microphones and peripherals, in part to prevent that scenario. The electric instrument industry remained soundly asleep.

I thread mine through the handle of the cab.

Look at what you are doing

If all the connectors in the world were speakon, this would still happen. Its not a design fault in the jack's part

christw · #16 03-02-2011, 10:27 AM

Quote:

Originally Posted by Electricblue

I thread mine through the handle of the cab.

Look at what you are doing

If all the connectors in the world were speakon, this would still happen. Its not a design fault in the jack's part

His point is that if all power cables were speakon which lock and are distinctly not instrument cables, it wouldn't be an issue.

Electricblue · #17 03-02-2011, 10:29 AM

Quote:

Originally Posted by christw

His point is that if all power cables were speakon which lock and are distinctly not instrument cables, it wouldn't be an issue.

I see where you are both coming from. But jacks as a product are perfectly up to the job. Get locking jack sockets.

Each to their own i suppose

Passinwind · #18 03-02-2011, 10:31 AM

Quote:

Originally Posted by Electricblue

If all the connectors in the world were speakon, this would still happen. Its not a design fault in the jack's part

The tip of a 1/4" plug can readily short to ground on insertion or removal.That very clearly is a design fault, and one that is germane to the original post.

billfitzmaurice · #19 03-02-2011, 10:31 AM

Quote:

Originally Posted by Electricblue

Its not a design fault in the jack's part[/color]

It is not a design fault in the intended use for the 1/4" phone jack, which is with telephone switchboards. The fact that it will short on insertion and removal is very much a design fault where speakers are concerned, a job that it never should have been used for. That only happened because the notoriously cheap Leo Fender decided to use them, instead of a more appropriate connector, because he already had 1/4" jacks on hand and it saved him a few bucks.

Electricblue · #20 03-02-2011, 10:34 AM

Quote:

Originally Posted by billfitzmaurice

It is not a design fault in the intended use for the 1/4" phone jack, which is with telephone switchboards. The fact that it will short on insertion and removal is very much a design fault where speakers are concerned, a job that it never should have been used for. That only happened because the notoriously cheap Leo Fender decided to use them, instead of a more appropriate connector, because he already had 1/4" jacks on hand and it saved him a few bucks.

Dont insert and remove your plugs when its switched on in the first place. Thats your fault for doing that.