[tonyptony]

Specifically my Telefunken ECC801S? I had a something happen today and I'm worried.

Verizon came by to install FIOS (yay!). My FetValve Ultra is on the bottom shelf of the rack the TV is on, so that it can be close to my speakers. There is one shelf above the amp, about 8" from the top surface of the amp. That's where the FIOS STB was placed.

At one point the installer wanted to check the back of the STB. He tried to pull the whole shelf out, but this shelf is not on runners. It's resting on four pins that are set into holes along the sidewalls. I'm sure you've either seen or owned racks like this. Well, he pulled it out too far and the back end of the rack pivoted down and hit the top of the Ultra  , pretty much on the top back edge of the heatsink structure. So the amp had more of a rotating smack along the back than the whole shelf dropping down on it.

I immediately pictured in my head the insides of the tubes breaking like light bulbs. Holding my breath I turned the amp on and it sounded the same as it always does. No weird sounds, no extra tube noise. But is it possible that some damage could have been done to the tubes? I did check them later on my B&K 707 and they read okay for shorts and emissions. So I go back to the beginning - how tough are tubes like this?

After I checked the amp I told the installer very nicely that if something had happened to the tubes Verizon would have to cough up about $250 for a replacement pair. Needless to say he was a bit surprised.

[avahifi]

Tubes are pretty tough.  If the equipment was turned off when the accident happened and the jar was not enough to actually knock the tubes out of their sockets, then I would not be worried.

If the tubes were on and hot when it happened, then the structural strength of the inner elements is less and some deformation and performance loss might happen.  Your tube tester should have verified that however.  If the tubes are still quiet, low microphonic, and the amp sounds as good as ever, likely there was no damage.

Regards,

Frank Van Alstine

[parker16]

Tubes apparently are sturdier than they appear. WWII aircraft used tube-type radios. If you have ever seen a film of a Corsair or Hellcat fighter landing on a carrier deck, you know that it could be a pretty hard landing. From my own experience, car radios before 1963 were nearly all tubed. We drove on a lot of rough unpaved roads in those days, but the radios seemed to play on and on.

[tonyptony]

Thanks Frank and parker. I figured they must be rugged. The Russians were still using tubes in their jet fighters at least through the 60s - I think maybe even the early 70s. Fortunately the amp was off at the time so I guess (I hope) I'm okay.

[weirdo]

I remember a story about a russian fighter plane that landed somewhere friendly and the pilot defected. ( maybe early 80's during the cold war ). Anyway, we dissected the plane and some of the avionics in this thing had vacuum tubes in it and the intelligence community was in a tailspin trying to rule out or verify their actual use. Turns out, they actually used them. I imagine they were hard wired but still......

[Freo-1]

I remember a story about a russian fighter plane that landed somewhere friendly and the pilot defected. ( maybe early 80's during the cold war ). Anyway, we dissected the plane and some of the avionics in this thing had vacuum tubes in it and the intelligence community was in a tailspin trying to rule out or verify their actual use. Turns out, they actually used them. I imagine they were hard wired but still......

Yep..The story is as follows:

The advantage of using electronic valves (vacuum tubes) for the MIG fighters was that tubes were impervious to Electro Magnetic Pulse (EMP), which will wipe out solid state devices.  The EMP effect will occur during a detonation of a Nuclear weapon.