Is it safe to add/subtract cabs while the amp is on?
- Thread starter OlinMusic
- Start date
ericmeyer4
New member
Re: Is it safe to add/subtract cabs while the amp is on?
I personally wouldnt do it.
I personally wouldnt do it.
muttonchopsrule
New member
Re: Is it safe to add/subtract cabs while the amp is on?
in theory it sounds OK since there would be a load on the amplifier the whole time. however, i wouldn't do it without powering the amp down. i've seen power tubes fry on the spot from impedence mismatches, granted they were all pretty extreme mismatches. but it's better to be safe than sorry with that kind of stuff, especially if it's a nice amp.
in theory it sounds OK since there would be a load on the amplifier the whole time. however, i wouldn't do it without powering the amp down. i've seen power tubes fry on the spot from impedence mismatches, granted they were all pretty extreme mismatches. but it's better to be safe than sorry with that kind of stuff, especially if it's a nice amp.
wixedmords
New member
Re: Is it safe to add/subtract cabs while the amp is on?
The impendance will change with the addition/subtraction of cabs.
Just shut it down, change the impendance, and power up.
The impendance will change with the addition/subtraction of cabs.
Just shut it down, change the impendance, and power up.
Stevo
Tonus Maximus Pacificas
Re: Is it safe to add/subtract cabs while the amp is on?
Me neither - not with a tube amp.
The Golden Boy
Fleecy Sweaterologist
Re: Is it safe to add/subtract cabs while the amp is on?
EXACTLY!!!
Although it's an incomplete analogy, would you take your car, in Drive, at 55mph at 2000 RPM and drop it into 'L' like that? It's kinda the same thing. Or maybe pulling the parking brake while cruising at 55...
EXACTLY!!!
Although it's an incomplete analogy, would you take your car, in Drive, at 55mph at 2000 RPM and drop it into 'L' like that? It's kinda the same thing. Or maybe pulling the parking brake while cruising at 55...
Last edited:
That90'sGuy
DyzaBoyzologist
Re: Is it safe to add/subtract cabs while the amp is on?
+1. Just can't say it any better
The question is "why would you ever want to try it?" It takes two seconds to power down the amp and do it safely, why even risk it?
+1. Just can't say it any better
The question is "why would you ever want to try it?" It takes two seconds to power down the amp and do it safely, why even risk it?
shredaholic
New member
Re: Is it safe to add/subtract cabs while the amp is on?
Obviously no, because the impedance changes when you add more cabs like wixedmords said. Therefore when you change the impedance switch, you break the connection between the OT and all the speakers. Therefore you have to turn standby off, plug in the extra cab, change the impedance switch, and then turn it back on. It shouldn't really be a big deal, having to flick a switch up and down isn't gonna cost you any time.
Obviously no, because the impedance changes when you add more cabs like wixedmords said. Therefore when you change the impedance switch, you break the connection between the OT and all the speakers. Therefore you have to turn standby off, plug in the extra cab, change the impedance switch, and then turn it back on. It shouldn't really be a big deal, having to flick a switch up and down isn't gonna cost you any time.
Re: Is it safe to add/subtract cabs while the amp is on?
Wait, I get what is being said. Does it CHANGE the impedance if you are already running 8 ohms into 16 ohms.
The amp is putting out 8 ohms already, no?
Does impedance change if you are already running the output/impredance low?
Wait, I get what is being said. Does it CHANGE the impedance if you are already running 8 ohms into 16 ohms.
The amp is putting out 8 ohms already, no?
Does impedance change if you are already running the output/impredance low?
Gearjoneser
Gear Ho
Re: Is it safe to add/subtract cabs while the amp is on?
I think if you use the standby, in between changes, you won't hurt the amp.
The thing is....you only want to do this quickly to test cabs, but don't keep them mismatched for long. Transformers die when they're accumulating heat from a mismatch, so doing it as a quick experiment shouldn't kill anything.
I think if you use the standby, in between changes, you won't hurt the amp.
The thing is....you only want to do this quickly to test cabs, but don't keep them mismatched for long. Transformers die when they're accumulating heat from a mismatch, so doing it as a quick experiment shouldn't kill anything.
devastone
Well-known member
Re: Is it safe to add/subtract cabs while the amp is on?
Exactly right, when the amp is on standby, the heaters are all that's on, the high voltage to the power tubes is off so it won't hurt the amp.
If needed, you can also change the impedance selector while in standby to match the new load.
Exactly right, when the amp is on standby, the heaters are all that's on, the high voltage to the power tubes is off so it won't hurt the amp.
If needed, you can also change the impedance selector while in standby to match the new load.
Metalman_666
Well-known member
Re: Is it safe to add/subtract cabs while the amp is on?
So it's obviously not ok to switch cabs while the amp is ON and the standby is off (meaning the amp is generating sound I'm assuming?), but is it ok if you keep the amp on but only turn the standby to ON?
So it's obviously not ok to switch cabs while the amp is ON and the standby is off (meaning the amp is generating sound I'm assuming?), but is it ok if you keep the amp on but only turn the standby to ON?
muttonchopsrule
New member
Re: Is it safe to add/subtract cabs while the amp is on?
not exactly...an amp doesn't put out impedence, it puts out power. impedence is simply the resistance to electrical flow, which is inherent in any electrical circuit. for example, a 16 ohm speaker in a circuit puts more resistance on the flow of electricity than an 8 ohm or 4 ohm speaker does. the reason amplifiers have different (or switchable) outputs for different impedences is so that it knows how much resistance to expect from the speakers, that way excess heat won't build up in the output transformer.
the only time the impedence changes is when you switch to a cabinet that has a different impedence rating, or when you add or subtract cabinets or speakers that are already there. if you have a 16 ohm cabinet running out of the 8 ohm output, the impedence is still 16 ohms, the amp is just expecting to see 8 ohms.
not exactly...an amp doesn't put out impedence, it puts out power. impedence is simply the resistance to electrical flow, which is inherent in any electrical circuit. for example, a 16 ohm speaker in a circuit puts more resistance on the flow of electricity than an 8 ohm or 4 ohm speaker does. the reason amplifiers have different (or switchable) outputs for different impedences is so that it knows how much resistance to expect from the speakers, that way excess heat won't build up in the output transformer.
the only time the impedence changes is when you switch to a cabinet that has a different impedence rating, or when you add or subtract cabinets or speakers that are already there. if you have a 16 ohm cabinet running out of the 8 ohm output, the impedence is still 16 ohms, the amp is just expecting to see 8 ohms.
