Amp Falls From Height of Six Feet and Survives (sort of)!

[Zippy]

The truth about the spill that the amp took is not nearly as interesting...

Hmmm, you're right. I'd work on that story.

Please let us know what you find to get it working again.

G'luck!

[vibratoking]

AJD - you're a better man than I. I would have never confessed to that. It would have stayed between my and the priest. I'm surprised you were able to balance it on the bed long enough to remove your hand and get back to vacuuming. Sorry, I am just running that scenario through my mind's eye. Totally razzing here.

[AJD]

I would have never confessed to that. It would have stayed between my and the priest.

Ha! I don't know if I am better. In fact, I would argue just the opposite. I figure that confessing here on the world wide web is my way of atoning for my carelessness and hopefully the resulting embarrassment will make me think twice the next time I have to mop and need to move the amp. Definitely have to work on my story though. That one is about as lame as they come.
Anyhow, the amp is fixed now. Sounds great. You all want to know what the problem was? Well, so do I but I really have no idea. Last night I opened the amp to start checking my grounds, voltages,etc.... I figured I would fire it up first to listen to the ghosting problem just to have a reference point (You are correct Plexitone, ghosting is what I was hearing). Well, when I powered it up it played just fine. WTF? After the fall I twice replaced all of the tubes with known good ones but the problem remained. I walked away from the amp, leaving in a set of known good tubes, and then five days later I fired it up and it sounded fine. I have not yet tried the tubes that were in the amp when it fell, but I will do that tonight. Any guesses as to what might have happened? I checked all grounds, joints, etc... and everything looks (and reads) just fine. I am stumped. I don't do drugs, so I know that it was not my imagination.

[selloutrr]

solder point.

this time the solder make a joint and didn't go cold.

I'd hit them all just to be safe.

[Dingleberry]

Not every amp survives from that drop...
Hi, I'm Tommy Dingleberry and I'm a ampaholic.
Here is my story.

My friend brought me his amp last week and told me that their band's roadie had kind of screwed up and his Vibrolux had took a leap from back of their tour bus to the ground...
Well it turned out that the output transformer had fallen out from it's place and smashed one power tube.
The funny part was that the mounting brackets, that were completely wrecked had gone broken actually some time ago in the past, who knows when. It probably would had survived that drop if the OT mounting brackets had been ok.
The guy who had "repaired" it before, had "fixed it" just trying to solder it to it's place and while it was missing another "dog ear", it was clearly to be seen that he had tried to solder the other side of the OT straight to the chassis... IMHO solder joints are not probably the best way to mount an OT to the chassis and cold solder joints are even worse. Wonder how it lasted this far.

I had to tear the OT's original mounting bracket thingy apart and fabricate "custom" mounting brackets using the parts what I had on hand.
I had one day time before his next show and it was sunday...
Found some steel from my "special treasures collection" (i.e. junk metal pile as my girlfriend likes to put it) and with some basic tools (wise, hammer, cordless drill, and some metal files) and LOTS of elbow grease I managed to ge the amp going.
Went trough the amp and everything else seemed to be ok.
Installed new power tubes, biased the amp and voila!
Enjoy the pics.

-T

[M Fowler]

Tommy,

You did a good job getting that tranny back in use

Mark

[crbowman]

When I was a teenager I had an Ampeg V4 stack.
Damn thing got knocked over at a gig and the amp landed face first, flat on the stage. Busted the baffle on the top speaker cab, and snapped off two of the 7027's center posts. Reseated the tubes, plugged into the bottom cab and finished the gig with no further probs. I think it hurt the stage more than my amp.........wait, I'm SURE it hurt the stage more than my amp.

[AJD]

Well gentleman, I have found the source of the problem. The amp itself is 100% fine. The source of the ghosting sound is............a ceiling fan. Yep. I was playing the amp this evening and it sounded great. I turned on the ceiling fan in the room and what do you know? The ghosting sound was back. Turned the fan switch off and the amp was back to normal.
I am surprised that a ceiling fan could have that affect on the amp, but there it is. Oftentimes when I turn on a nearby light switch (especially fluorescents ) the amp will buzz a bit if I am playing a single coil guitar, but the fan is a new one on me.

[xtian]

Well gentleman, I have found the source of the problem. The amp itself is 100% fine. The source of the ghosting sound is............a ceiling fan. Yep. I was playing the amp this evening and it sounded great. I turned on the ceiling fan in the room and what do you know? The ghosting sound was back. Turned the fan switch off and the amp was back to normal.
I am surprised that a ceiling fan could have that affect on the amp, but there it is. Oftentimes when I turn on a nearby light switch (especially fluorescents ) the amp will buzz a bit if I am playing a single coil guitar, but the fan is a new one on me.

I know that from experience. There's a ceiling fan in my office. Makes a nice Leslie out of the whole room.

[AJD]

Oh good. I am not alone I see. Do you know the exact cause? Does the fan put out some weird oscillating EMF that the amp picks up on?

[plexitone]

You're probably just hearing the acoustical effects of the air "flutter". Play high single notes on an acoustic or even an unplugged electric under a fast ceiling fan and it can sound out of tune or have a "warbling" sound.

[selloutrr]

your amp loads the room with volume (sound Pressure) compressing the room and fan blade cuts the air... causing the flutter.

[AJD]

Wow! No kidding? Learn something everyday. Thanks!

[AJD]

Is the reason that the effect is most present on higher notes due to their shorter wavelength as compared to lower notes?

[plexitone]

Is the reason that the effect is most present on higher notes due to their shorter wavelength as compared to lower notes?

Exactly. Same reason you hear high frequencies fade in and out at an outdoor concert on a windy day.