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Author Topic: Guitar Amp powering off?  (Read 8503 times)

Mike Sokol

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Guitar Amp powering off?
« on: March 10, 2014, 07:59:55 am »

You're gonna love this. When one of my seminar students tried to get the guitar player at his church to turn down the volume on stage, here's the response he got.

Well, there's a "sweet spot" on the amp, you see.  He CAN'T turn down the
amp because then it doesn't sound right.  It HAS to be at THIS volume for it
to sound right.  In fact, it'll TURN OFF due to low signal level if he turns
it any lower.  (So he says.)  Now what do I say to him?  Just food for
thought for your next sound board class. 


I've heard a lot of excuses for playing a guitar amp too loud on stage, but never that the amp would "TURN OFF" if it was played too softly. Who knew??? :o
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Jerome Malsack

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Re: Guitar Amp powering off?
« Reply #1 on: March 10, 2014, 09:31:38 am »

Because some of the battery powered units might have a battery saver option and turn off for no activity.  ???   

Playing loud on stage is a symptom of him wanting to get feedback from the amp??  If he wants to have the guitar and amp to get into a feedback for the song than he will need to have a volume level and proximity of the guitar to the amp to get the feedback.  Does he need to do this from across the stage ??   I hope not. 
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TJ (Tom) Cornish

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Re: Guitar Amp powering off?
« Reply #2 on: March 10, 2014, 10:22:53 am »

  In fact, it'll TURN OFF due to low signal level if he turns
it any lower.
He clearly "understands" how under-powering damages loudspeakers.  ::)
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Mike Sokol

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Re: Guitar Amp powering off?
« Reply #3 on: March 10, 2014, 11:08:54 am »

He clearly "understands" how under-powering damages loudspeakers.  ::)

Seriously, some powered speakers (such as Mackie) have an auto power-off button that turns off the internal amplifier after several minutes of inactivity. Had a customer once call me for a service call that his speakers were turning off randomly. Of course, as soon as you send some music to them they come back on.

I'm pretty sure this guitar player has an old-school tube amp which he needs to distort for tonal qualities, and if the speaker is loud and close enough to his guitar then he'll get extra sustain and feedback. I just think it's funny he told the soundguy that his amp would "Turn Off" if played too softly.   
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John Roberts {JR}

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Re: Guitar Amp powering off?
« Reply #4 on: March 10, 2014, 11:29:45 am »

Not to perpetuate any new myths, but there could be an oxidized switch or jack metal-on-metal contact, where the voltage from playing the amp louder punches through a thin oxide layer and conducts again. Generally after it punches through you can turn down the volume again, but it "could" happen that after sitting for some time (like a week), the amp needs to be turned up at first to pass audio.

JR
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Mike Sokol

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Re: Guitar Amp powering off?
« Reply #5 on: March 10, 2014, 11:57:22 am »

Not to perpetuate any new myths, but there could be an oxidized switch or jack metal-on-metal contact, where the voltage from playing the amp louder punches through a thin oxide layer and conducts again. Generally after it punches through you can turn down the volume again, but it "could" happen that after sitting for some time (like a week), the amp needs to be turned up at first to pass audio.

JR

I have seen that exact scenario more than a few times, especially on older mixing consoles with ribbon connectors between the channels. I had something like that happen on a missile guidance system back in 1979 with predictably bad results. But if I tell you about it I'll probably have to kill you...  ::)

On a different tangent, I was doing a gig at a big church yesterday where they claimed that earlier in the morning a "power surge" caused their media computer and digital mixer to shut down and need to be restarted. They wondered why their SurgeX conditioner would let this "surge" through, but I told them it was more likely an AC power drop-out or brown-out and that a UPS was also needed. They somehow thought a SurgeX would protect them for ALL power conditions, including power outages and low-voltage conditions. Just one more thing their sound system installer left out of the mix. I would NEVER run a modern digital mixing board without a good UPS providing the AC power.   
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TJ (Tom) Cornish

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Re: Guitar Amp powering off?
« Reply #6 on: March 10, 2014, 12:07:17 pm »

Seriously, some powered speakers (such as Mackie) have an auto power-off button that turns off the internal amplifier after several minutes of inactivity. Had a customer once call me for a service call that his speakers were turning off randomly. Of course, as soon as you send some music to them they come back on.
I will bet any amount of money you like that this is not the scenario.  I am familiar with gated devices, and avoided buying the JBL PRX500 series boxes for this reason among others, but have never heard of a guitar amp with this function.  Even if this did exist, it would certainly open at a level far lower than "face melting."

Either the guitarist is full of it (likely scenario), his equipment is damaged, or he is incompetent - he is using some kind of gate effect, but has his final level knob cranked, etc. 
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John Roberts {JR}

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Re: Guitar Amp powering off?
« Reply #7 on: March 10, 2014, 12:15:23 pm »

I have seen that exact scenario more than a few times, especially on older mixing consoles with ribbon connectors between the channels. I had something like that happen on a missile guidance system back in 1979 with predictably bad results. But if I tell you about it I'll probably have to kill you...  ::)


The more likely culprit in consoles (in my experience) are the switch contacts bypassing insert jacks. These switch contacts over time can get dirty/oxidized and cause intermittent and level dependent signal drop outputs.

The same phenomenon can happen from cold solder joints, where the solder doesn't wet the connection and the physical metal to metal connection oxidizes and degrades. Faulty ribbon cables, where the gas-tight insulation displacement contact is not actually gas tight can cause similar symptoms, but there are a few bazillion good ribbon cables out there, and even more good solder joints.

JR
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Mike Sokol

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Re: Guitar Amp powering off?
« Reply #8 on: March 10, 2014, 12:19:34 pm »

I will bet any amount of money you like that this is not the scenario. 

I am positive your are correct. It's not a gate or auto-shutdown feature on the amp. It's an emotional shutdown of some type, for sure.  ;D
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TJ (Tom) Cornish

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Re: Guitar Amp powering off?
« Reply #9 on: March 10, 2014, 12:21:22 pm »

I am positive your are correct. It's not a gate or auto-shutdown feature on the amp. It's an emotional shutdown of some type, for sure.  ;D
:D
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Re: Guitar Amp powering off?
« Reply #9 on: March 10, 2014, 12:21:22 pm »


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