how long does it to take for a amp to fry if on with no speaker?

andrenighthound · March 28th, 2008, 04:16 PM

i had one of my amps on for about 5 seconds accidently without a speaker plugged into it. The amp still sounds fine. Did I possibly hurt the amp? If so, what part of the amp would get affected the most? Also, how long does it take to generally fry an amp by having it on with a speaker attached to it?

thanks.

Billm · March 28th, 2008, 04:43 PM

If your amp has a shorting jack, there's no problem. Tube amps would rather have a shorted output than an open circuit.

If the speaker connection was open, with no load, damage could happen with just a couple of big chords. You would get flyback voltages from the output transformer, which can cause the OT to arc and burn internally. You might also see arcing in the tubes.

Most newer Fender amps have flyback suppression diodes in the output to prevent or minimize damage.

Joe M · March 28th, 2008, 07:02 PM

Hey Billm, welcome to the forum. I'm assuming you're the same Billm that's on "another" forum who has tremendous insight and helpful tips on amps. Glad to have you and your knowledge on this site.

Larry F · March 28th, 2008, 08:21 PM

Can you explain the principle behind this? If there is is no guitar plugged in, how long can the amp be on without causing damage? Seconds, minutes?

surfoverb · March 28th, 2008, 09:22 PM

6 seconds.

andrenighthound · March 29th, 2008, 04:03 AM

i used the amp tonight for a 3 hour gig and it sounding fine...can i assume my amp did not get damaged?

Scott S · March 29th, 2008, 04:45 AM

I think so. Might have to test it a couple more times to be absolutely sure.

EMan · March 29th, 2008, 12:00 PM

Hey Bill, glad to see you here!

If the amp still works fine, then you didn't hurt it.

klasaine · March 29th, 2008, 12:10 PM

I'm "pretty sure" that if you're not actually putting a signal into the amp, ie; playing through it, you won't hurt it.
That may not be true for a true class A amp cranked up to 10 without a load though.

March 28th, 2008, 04:16 PM	#1 (permalink)
andrenighthound Tele-Meister Join Date: Dec 2007 Location: Bronx NY Age: 33 Posts: 236	how long does it to take for a amp to fry if on with no speaker? i had one of my amps on for about 5 seconds accidently without a speaker plugged into it. The amp still sounds fine. Did I possibly hurt the amp? If so, what part of the amp would get affected the most? Also, how long does it take to generally fry an amp by having it on with a speaker attached to it? thanks. __________________ "Blues in a doggy bag, is what I got to eat!" www.andreandthenighthounds.com

March 28th, 2008, 08:21 PM	#4 (permalink)
Larry F Friend of Leo's Join Date: Nov 2006 Location: Iowa City, IA Age: 56 Posts: 2,665	Can you explain the principle behind this? If there is is no guitar plugged in, how long can the amp be on without causing damage? Seconds, minutes? __________________ larry

March 28th, 2008, 04:43 PM	#2 (permalink)
Billm Tele-Holic Join Date: Mar 2008 Location: New Jersey Age: 62 Posts: 575 1 Photos	If your amp has a shorting jack, there's no problem. Tube amps would rather have a shorted output than an open circuit. If the speaker connection was open, with no load, damage could happen with just a couple of big chords. You would get flyback voltages from the output transformer, which can cause the OT to arc and burn internally. You might also see arcing in the tubes. Most newer Fender amps have flyback suppression diodes in the output to prevent or minimize damage.

March 28th, 2008, 07:02 PM	#3 (permalink)
Joe M Moderator Tele-Afflicted Join Date: Mar 2003 Location: Michigan Posts: 1,277	Hey Billm, welcome to the forum. I'm assuming you're the same Billm that's on "another" forum who has tremendous insight and helpful tips on amps. Glad to have you and your knowledge on this site.

March 28th, 2008, 09:22 PM	#5 (permalink)
surfoverb Tele-Afflicted Join Date: Jul 2007 Location: Virginia Posts: 1,889	6 seconds.

March 29th, 2008, 04:03 AM	#6 (permalink)
andrenighthound Tele-Meister Join Date: Dec 2007 Location: Bronx NY Age: 33 Posts: 236	i used the amp tonight for a 3 hour gig and it sounding fine...can i assume my amp did not get damaged?

March 29th, 2008, 04:45 AM	#7 (permalink)
Scott S Tele-Afflicted Join Date: Dec 2005 Location: SW CR IA US NA PE Age: 28 Posts: 1,922	I think so. Might have to test it a couple more times to be absolutely sure.

March 29th, 2008, 12:00 PM	#8 (permalink)
EMan Tele-Holic Join Date: Apr 2003 Location: Dallas, Texas Posts: 939	Hey Bill, glad to see you here! If the amp still works fine, then you didn't hurt it.

March 29th, 2008, 12:10 PM	#9 (permalink)
klasaine Tele-Afflicted Join Date: Nov 2006 Location: los angeles, ca Age: 46 Posts: 1,572 12 Photos	I'm "pretty sure" that if you're not actually putting a signal into the amp, ie; playing through it, you won't hurt it. That may not be true for a true class A amp cranked up to 10 without a load though.