Changing Speaker\Cab (Load) On The Fly: Good, Bad or Ugly?

[MrKite89]

Is it safe to disconnect the amp from the speaker\cab\load and quickly connect it to another?

I have a problem with the bypass switch on one of my attenuators, so, after cleaning it, I decided to test it with my 65 DRRi: since it wasn't working properly, I just unplugged the speaker cable from the amp and connected my other attenuator.

The amp was ON, standby switch turned ON. Guitar unplugged and volumes\EQ on "0". No signal (except for the very low hiss\noise floor).

It stayed unloaded for 5-10 seconds.

Do you commonly do this for testing or is it bad for the tubes\OT?

 

[xtian]

Because I'm an amp tech, and can fix my own mistakes, I play fast and loose with my own amps. As long as there is no signal, unplugging speaker for short periods is fine. You can't damage the OT or tubes without a signal.

HOWEVER! As has been pointed out here, some tube amps can be unstable without a load connected, and can start oscillating, putting the OT in danger.

 

[Daves' not here!]

I'd use the standby switch then switch loads...
Quality amp/OT probably OK on occasions with Vol at 0

SS amp, never... Too risky

 

[Eugene Wallace]

roll vol down on amp and there will be no problems.

 

[xtian]

SS amp, never... Too risky

What? Why? SS amps do fine with no load.

 

[pdf64]

Provided the amp has a global feedback loop, and all presence, trem and volume controls turned down, then it should be fine.

 

[MrKite89]

roll vol down on amp and there will be no problems.

Preamp or Master volume? My amp doesn't have a Master, so a little bit of signal (hiss) reaches the output stage.

 

[MrKite89]

Many thanks guys, seems like my amp works\sounds fine: later I will test it with a Mullard CV4024 in the PI which arrived today...

I will definetely use the standby switch next time, but if it sounds OK then it's OK, right?

 

[Eugene Wallace]

they're not digital devices. it takes a bit more than the energy from a hiss to kill one of these amps.
Just your volume is fine.
Master vol, Normal un-master volume any of them is ok.
People in the tube amp world love scare-mongering with two things, setting negative bias and speaker mis-match and jack issues.
With simple rules like roll your amp volume down before changing speaker plugs ( using standby supposedly poisons cathodes right?...more scaremongering) you never have any problems.
I have a simple procedure that I follow at home which is sort of related to this.
When I turn an amp off I roll down the volume every time.
And when I turn an amp on and cant hear anything, it's not the volume I check, it's the speaker cable first , then the volume.