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Has Anyone Here Thought Of The Possible Fire Potential Of Tube Amplifiers?

CoogarXR said:
DISCLAIMER- I'm not that lousy of a tech to have stuff catch fire...
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Careful with the blanket statements. The tech working on that amp at the time was Dennis Had, founder of Cary Audio, and it was a Citation V. The windings inside one of the transformers shorted starting some of the tar on fire. We happened to be right there as it happened, pulled the plug, put it out and repaired it easily enough (if you're Dennis Had that is). But even the highest quality piece of gear is subject to the degradations of time and environment and I think that's the take home lesson...
 
I had a G.F. from Moscow who told me that her apartment there had almost burned to the ground from a faulty-design TV. Stella said that the problem with those TVs was well-known.
 
Those projection sets had a habit of leaking the CRT coolant on to the PC board. Initially that is fine if you know about it and clean it off. However, if not it becomes corrosive and conductive when voltage is applied over a period of time. If this happens to a part of the PC board that handles any power, it is an extreme fire hazard. So much so that manufacturers started incorporating a gutter in the design so any leaking coolant would run out of the cabinet or into a reservoir. If the coolant got into the signal circuits it wold screw it up as well, but rarely become any sort of danger.

In older TVs, the high voltage cage was not just there for EMI and Xray shielding, the flybacks in those old jobs would catch fire when they failed. Some were designed so that they would not work without the shield in place, and it was made quite hard to defeat. (RCA i.e. CTC25 chassis))
 
I never leave my tube amps unattended, even more so now that my grandson is about to become mobile!
Regards,
Jim
 
Hiya,

Its amazing anyone over the age of 40 is alive with all these fire hazards in homes during our youth.

Frannie
 
The only electronics i have seen a fire in were solidstate with paper circuit boards , and they had fuses in them
 
I set a "flameproof" resistor on fire in an amp I was rebuilding some time back. Still not sure how I did that.
 
Sam Cogley said:
I set a "flameproof" resistor on fire in an amp I was rebuilding some time back. Still not sure how I did that.
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When the sun expands and engulfs the Earth a Billion or so years from now we will finally know that not everything is as "Flameproof" as we think.

Frannie
 
I suppose you could wire a GFCI electrical outlet into the AC box you use for your tube gear. In any catastrophic failure situation that you weren't present to deal with it would shut the AC down. Otherwise you just have to remember to always shut things off.
 
I've got one of these on my tube equipment ...

41XDsihA10L.jpg

Not gonna set the amp on fire to see if it works though ... <G>

** PS ... that's there to prevent "hot starts" if the power blips. Now that's something that WILL kill an amp. This adapter will trip where a standard GFCI breaker won't, and requires a manual restart, protecting your delicate tubes from excess current if the caps didn't have time to discharge properly. Best $20 insurance policy you can buy! :thumbsup:
 
When I first started messing with Tube amps I insisted that, whenever I was going to "fire a tube amp up", my wife had to have her shoes on, her car keys located and that she was aware of what I was doing. I told her that if the lights should dim or if she should smell an acrid smoke, to check on me

I had a BIG fire extinguisher on hand and controlled the amp from a remote on/off switch with eye protection
True story
Since then I have backed off a little
 
sKiZo said:
I've got one of these on my tube equipment ...

41XDsihA10L.jpg

Not gonna set the amp on fire to see if it works though ... <G>

** PS ... that's there to prevent "hot starts" if the power blips. Now that's something that WILL kill an amp. This adapter will trip where a standard GFCI breaker won't, and requires a manual restart, protecting your delicate tubes from excess current if the caps didn't have time to discharge properly. Best $20 insurance policy you can buy! :thumbsup:
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I could not agree more. I saw a McIntosh MC240 arcing 1 power tube, and blowing the internal fuse (no damage to the amp itself, thank god) when the power tripped and came back within the same second.
What is that thing you have in the picture? Thanks.
 
That's a TRC 90033 Shockshield

It's designed for the construction trade to prevent runaway saws and such. Forget the GFCI thing here ... what we're interested in with tube equipment is the manual reset. Once the power trips, it stays off till you push the button. Handles 15 amps, so if you've got more than one tuber, just gang em up.

I go one step further and plug that into a DIY bucker that cuts my usual 123vac wall current back to a more comfortable 116vac or thereabouts.

bucking-transformer.jpg


That also makes the amp run cooler, and bonus ... sound better.
 
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Just get one of those Christmas light extension cords. They have two fuses in the plug - one for the hot and one for the neutral so this will add a measure of safety without having to modify your amp.

True, plug in strips have breakers but so many of those have caused fires in-and-of themselves. So make sure you don't buy one that has been recalled.

In actuality, for personnel protection, A GFCI protected extension cord can both prevent a fire and save someone from being electrocuted. A fuse or a breaker trips at too high a current to save a life. A GFCI cord or even a GFCI receptacle can save a life. A GFCI electronically compares the hot and neutral current which always should be equal and opposite polarity. If there is any imbalance in these currents, the device will trip and disconnet the load.

An imbalance can be caused by a human touching a grounded metal wall plate (or screw) and touching the hot amp chassis. This is why they ars used on many things like window air conditioners and any circuit running outdoors, bathroom and kitchen receptacles, etc.

I am sometimes cautious about touching anything metal when touching metal parts of plugged in tube gear.

And what about the other components plugged into your tube amp via AC cords OR RCA patch cords? Everything now gets energized in a bad way.
 
Sound better ? Really? Run cooler that's for sure.

Thanks for the info. I need to build myself one of those but the box holding the xformer and such is the hard part to chose from.
 
Yes ... sound better ...

My Latino is a Dynaco clone with current day iron, but the original design was happiest at around 115vac. It can handle 120vac easily, but 123vac is pushing it.

And yes ... it can sound ... choked ... for want of a better word, when the power supply runs hot. Maybe subjective, but pretty obvious to my ears ... your results may vary.

The bucker is the result of me being a packrat and never throwing anything out. The transformer is an old Hammond mounted up to an equally old metal power strip. Those are nice as they already have a breaker, switch, and pilot light built in. Just cut out a couple outlets to make room for the transformer and wired it in.

bucker-wiring.jpg


I did have to tear it apart to flip the outlet around so the Shockshield would fit ... no biggie ...
 
The thing with a GFCI unit is that they are only effective in certain situations. They are not useful for over-current conditions. They will only trip if there is an imbalance of current between the hot and the neutral line. If something leaks to chassis, it will pop. The transformer can dead short and be boiling tar out of it and the GFCI won't do anything to help you.

A lot of tube gear can't really deal with a GFCI anyway, especially if there is a ground connection in the mix. Its those line to chassis caps. If you ground the chassis, there can be an imbalance in current between the hot and neutral conductors and it will pop the GFCI unit. The outlet in my bedroom that my Sherwood is connected to happens to be on the wrong side of the bathroom GFCI. It trips every now and then, and I'm pretty sure its because of that. It never trips if the Sherwood is unplugged, or if its not connected to any external source. My phono preamp happens to use a grounded cord.
 
... and once again ... ignore the GFCI feature on this and similar adapters when used with tube equipment! It's the "non-latching" breaker trip that requires a manual reset when the power blips that's important in this application. That's saved my bacon a few times here. When the house flashes for whatever reason, none of the house breakers trip, but I know my amps are safe when hiding behind the ShockShield.
 
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