Can I run my Tube amp without tubes?

  • Thread starter Thread starter cephus
  • Start date Start date
cephus

cephus

Slow Children Playing
My son pulled all the tubes out of my peavey classic 20 and turned it on. It may have been on for a couple hours. It's not like I can do anyting about it, but anyone care to venture a guess as to what may have been damaged?
 
If there would have been some mischief with the speaker (like disconnecting it or shorting the leads together), that could've done some damage.
 
cephus said:
My son pulled all the tubes out of my peavey classic 20 and turned it on. It may have been on for a couple hours. It's not like I can do anyting about it, but anyone care to venture a guess as to what may have been damaged?
Click to expand...

It's probably OK, but what possessed him to do that?
 
18-month old kid. Not supposed to be in the bedroom but the door was left open. It would have been awful if he turned it on and grabbed one. I love that amp, but the tubes have accidentally been removed a bunch of times. Usually when you pull the power cord out of the back. May have to invest in one of those tube guards I saw on ebay.

It is a great living room amp and I've gotten it to sound pretty big recording. 20 watts just isn't enough clean power to play with a band. Peaveys have a pretty terrible fuzz when the pregain is too high. I turn the master up and try and get it as loud as I can but still be clean. Then it has good sustain, but you can still play a minor chord and hear all the voices.

I am making a closed back 12" external cabinet for it to see if that will buy any ground when scrimaging with the band.
 
cephus said:
I am making a closed back 12" external cabinet for it to see if that will buy any ground when scrimaging with the band.
Click to expand...

It will IF connecting the external cab does not disable the internal speaker....

Not sure if it will bring it up to "band scrimmage" levels, but I've experimented with a 1x12 and a 2x10 and it seems to almost double the apparent volume of the guitar.....
 
ericlingus said:
why did your son do that?
Click to expand...

They just do shit like that. I'm lucky I found all the tubes. I got him a marine band hohner for christmas and he lost it in like 3 minutes. He liked the little box better anyway.

I bought the 6 year old a uke when he was 3. He cut the strings off it so it'd be easier to put stuff inside of it.
 
soundchaser59 said:
It will IF connecting the external cab does not disable the internal speaker....

Not sure if it will bring it up to "band scrimmage" levels, but I've experimented with a 1x12 and a 2x10 and it seems to almost double the apparent volume of the guitar.....
Click to expand...

I think it did. I had a 210 cab for it a long time ago, but it still wasn't good enough for live. I was thinking of making the cabinet big enough to put the chasis in, too. if it works out. With the tubes outside of the closed back cabinet, of course.

If it doesn't shut it off by way of the jack, will it hurt it to disconnect the internal 10"? Will that put the whole 15-20 watts through the 12"?
 
cephus said:
They just do shit like that. I'm lucky I found all the tubes. I got him a marine band hohner for christmas and he lost it in like 3 minutes. He liked the little box better anyway.

I bought the 6 year old a uke when he was 3. He cut the strings off it so it'd be easier to put stuff inside of it.
Click to expand...

I gave my daughter a pair of bongos when she was 4. She cut the heads off and used the drums as a washer & dryer for her dolls.
 
I have an old silverface Bassman that I was swapping out the tubes on one time, and for whatever reason, I managed to forget to put in the power tubes. It made a loud humming noise when I turned it on. When I put the tubes back in it worked just fine (and still does today, four years later). I think your amp will be fine.
 
Yeah, it shouldn't hurt anything. In fact, it's a good test for a shorted power tube...If your amp suddenly keeps popping the main fuse, pull the power tubes to see if it still blows. If it stops, it's got a bad tube, if not then it's an internal problem. Tube amps are real tolerant when it comes to stuff like this. When you unplug your speaker(from the jack) the plug is usually designed to short. It's better for it to short than have no resistance. Kind of like a car in neutral with the gas floored.
 
When the power diode tube was pulled, all power to the amp stopped. Even if it has a bridge rectifier, w/o any laod, theere will be no power generated to da any damage - the input is what causes the amp to <GO>, otherwise it is like a bike on a hill, waiting to roll down...As for the speakers, it is the resistive laod presented to the amp that determines what power comes out of it; that is, if 2- 8ohm speakers are connected in parallel, it will look like 4 ohms, If 2 - 4ohm spkrs are connected, it will look like 2 ohms. When the load resistance goes down, the pwoer goes up until the signal (sound) coming out of the amp is as large as the power supply voltage, and then it begins to distort. Less load = more power, limited by the internal pwoer supply. That is why, and I don't recomend this - Eddie Van Halen used to use a variac transformer to boost the 115VAC wall pwoer to 150, and get more sounds. I SAY AGAIN, I DONT' RECOMEND ANYONE DOING THAT ! HE HAD PLENTY OF MONEY TO BUY NEW STUFF WHEN HE SCREWED UP - DO YOU ? That is today's lesson amp electronics. I hope it helps !
Cape Chris
'70 Les, Gold Top
 
Been there with Classic 20 too

Cephus, I have the exact same Classic 20 and the same power cord situation knocked my 2 power tubes loose a few months back. I was freekin' out about it also but after reinstalling the power tubes it worked just fine. You should be okay, as long as the speaker load is not removed the tube amp should not have fried anything. And I love that little amp too, goes from squeeky clean-well the headroom isn't really great-to outright overdrive with a tweek of the volume and master knobs. :)
 
999 times outta a thousand it wont hurt a thing. In fact this is part of the normal initial start-up sequence when you build an all tube amp from scratch.
 
goldtopchas said:
When you unplug your speaker(from the jack) the plug is usually designed to short. It's better for it to short than have no resistance. Kind of like a car in neutral with the gas floored.
Click to expand...

Can you point me to a schematic that shows that? A short is a no resistance condition; an open circuit (no speakers) is "infininite" resistance. Although running an amp into an open is bad for the output tubes and tranny, I'm pretty sure that a short is much worse.
 
ahh kids.....I remember a couple of years ago I had a brand new guild acoustic(can't remember the model #) that I payed $1200.00 for....just had it out of it's case for ten minutes...my kid walks into the room and throws his toy screwdriver at it and put a big ass ding in it.....he's lucky to still be alive.
 
Ahhh yes...memories! About 20 years ago my daughter took a small block of cheese and pushed it through the strings of my new 12 string into the sound hole thinking it was a vego-matic or something :)
My ex-wife always told me that my playing was cheezy
 
goldtopchas said:
When you unplug your speaker(from the jack) the plug is usually designed to short. It's better for it to short than have no resistance. Kind of like a car in neutral with the gas floored.
Click to expand...
No, this isn't right. A short is like your car in nuetral with the gas floored.
 
The amp will be fine.
My main concern would be in the future to prevent your boy from doing it again.

Glass tubes can break (and cut of course). He could also give himself a severe shock if he turned the amp on and stuck his finger or metal object in a socket.
 
You must log in or register to reply here.
Back
Top