RecPit

Aspen Pittman, founder of Groove Tubes and all around interesting audio guy and entertaining party animal was killed in a traffic accident a couple days ago.

I first met Aspen when I was working at Don Wehr's back in the mid '80s with my friend Joey Swails and it turned into a very memorable evening, including a dinner at Fisherman's Wharf followed by a long session of smoking pot and discussing VF-14 tubes and other audio subjects at the residence of the other soundman at the club I was working at.

The last time was about 10 years ago at the last AES conference where he was entertaining a crowd of audio engineers with a bar trick involving a length of 1/2" copper pipe and a round silvery 1/2" sphere which took an inordinately long time to make it through the vertically held tube. I'm rather proud thjat, of the whole crowd, I was the only person who could explain what was going on and why it took so long to get through the tube. I was also quite surprised that nobody else got it.

Aspen was a great guy, life of the party, and a boundless well of information on the subjects of tubes and audio in general.

Gone too soon.

There will never be another like him.

RIP, Aspen, fare thee well.

Sorry to hear that.

As for the silvery sphere, it probably went through faster than you think but you guys were one toke over the line.

nobby wrote: ↑August 15th, 2019, 7:20 am Sorry to hear that.

As for the silvery sphere, it probably went through faster than you think but you guys were one toke over the line.

Nope. Definitely slooow.

There's a sound scientific principle in play here, something absolutely basic to the science of electricity.

If you can't figure it out soon, I'll give you a hint that's probably a dead giveaway.

It's also a cool trick that you can use to mystify your friends.

Jesse DeCarlo figured it out almost immediately on another forum.

Fight the power! I mean, uh, resistance?

upstairs wrote: ↑August 18th, 2019, 4:24 am Fight the power! I mean, uh, resistance?

More inductive thinking!

John Eppstein wrote: ↑August 17th, 2019, 7:32 pm

nobby wrote: ↑August 15th, 2019, 7:20 am Sorry to hear that.

As for the silvery sphere, it probably went through faster than you think but you guys were one toke over the line.

Nope. Definitely slooow.

There's a sound scientific principle in play here, something absolutely basic to the science of electricity.

If you can't figure it out soon, I'll give you a hint that's probably a dead giveaway.

It's hard to figure out from such a vague description. We don't know the composition of the "silvery ball", what its exact circumference is and the exact inside diameter of the pipe, whether the pipe is sealed at the bottom, etc.

nobby wrote: ↑August 20th, 2019, 6:55 am

John Eppstein wrote: ↑August 17th, 2019, 7:32 pm

nobby wrote: ↑August 15th, 2019, 7:20 am Sorry to hear that.

As for the silvery sphere, it probably went through faster than you think but you guys were one toke over the line.

Nope. Definitely slooow.

There's a sound scientific principle in play here, something absolutely basic to the science of electricity.

If you can't figure it out soon, I'll give you a hint that's probably a dead giveaway.

It's hard to figure out from such a vague description. We don't know the composition of the "silvery ball", what its exact circumference is and the exact inside diameter of the pipe, whether the pipe is sealed at the bottom, etc.

OK, the pipe is standard copper water pipe of the sort that is slightly oversize so it can be used to splice regular copper water pipe. That would make it slightly larger than 1/2" inside diameter. It's available at any plumbing supply outlet. The splicing tubing is used to ensure that there is no real friction with the ball, which is 1/2' outside diameter. The pipe can be anywhere from a foot to 18" long, any longer and it starts getting a bit large to carry around in a briefcase or shoulder bag. Also, I don't think they sell the splicing tubing in longer lengths.

The ball appears to be a 1/2" ball bearing. It is solid metal. It's a bit heavy but not inordinately so. What the exact properties of this metal might be I'm going to withhold a bit longer to keep the fun going. That should be a hint right there.

It‘s made from neodymium.

keks wrote: ↑August 21st, 2019, 6:17 pm It‘s made from neodymium.

BINGO! (Neodymium alloy, actually....)

So how does the trick work?

John Eppstein wrote: ↑August 20th, 2019, 9:48 pm OK, the pipe is standard copper water pipe of the sort that is slightly oversize so it can be used to splice regular copper water pipe.

I'm pretty sure there's no such thing. There is a coupling you can use to join pipes by soldering, and there are compression fittings for joining pipes without solder.
Ever done any plumbing around the house?

Still betting on the weed

John Eppstein wrote: ↑August 21st, 2019, 9:15 pm

keks wrote: ↑August 21st, 2019, 6:17 pm It‘s made from neodymium.

BINGO! (Neodymium alloy, actually....)

So how does the trick work?

The magnet and the tube create what's known as a "eddy current". This creates a force against the magnet causing it to drop slowly.

But you didn't say anything about a magnet.

The way to do it without magnetism would be to seal a 1/2" inside diameter pipe at the bottom, then drop a ball bearing (a silvery sphere) with an outside diameter of .499" in the top.

nobby wrote: ↑August 22nd, 2019, 12:07 am

John Eppstein wrote: ↑August 20th, 2019, 9:48 pm OK, the pipe is standard copper water pipe of the sort that is slightly oversize so it can be used to splice regular copper water pipe.

I'm pretty sure there's no such thing. There is a coupling you can use to join pipes by soldering, and there are compression fittings for joining pipes without solder.
Ever done any plumbing around the house?

Still betting on the weed

Sorry, my friend, but you are obviously NOT a plumber. I, unfortunately, am, having done fairly major plumbing projects on a number of nightclubs and restaurants over the years (and whose owners were too damn cheap to pay a union guy.) Not my favorite job, but it's basically the same thing as doing electricity except what's flowing is bigger and less likely to kill you if you get careless.

Hoe do you think one splices two pieces of already installed copper that have been cut in half* together, or how one repairs a split in a 1/2" copper water line?

The coupling you refer to won't work if you're dealing with a break in a line that is in place, as the coupling has a detented ring that prevents it from sliding all the way onto a line that's fixed in place. If you're patching lines that are already installed you need something that can be slid all the way on, then the two ends are lined up and the splice is slid halfway back (since you cant pull the two sides far enough apart to get the usual coupling on if they're fixed in place. The same slightly oversize pipe is used when you have a longitudinal split in the line, which is why it's available in lengths over a foot.

Seriously, you should know by now not to argue with me over really basic tech stuff.

But anyway, now that the material of the ball has been identified, can you tell us what the principle involved causes the passage of the ball through the pipe to be significantly slower than expected?


* - for example when some idiot hits an installed line when he's cutting into a wall with a Sawzall...

nobby wrote: ↑August 22nd, 2019, 2:29 am

John Eppstein wrote: ↑August 21st, 2019, 9:15 pm

keks wrote: ↑August 21st, 2019, 6:17 pm It‘s made from neodymium.

BINGO! (Neodymium alloy, actually....)

So how does the trick work?

The magnet and the tube create what's known as a "eddy current". This creates a force against the magnet causing it to drop slowly.

But you didn't say anything about a magnet.

The way to do it without magnetism would be to seal a 1/2" inside diameter pipe at the bottom, then drop a ball bearing (a silvery sphere) with an outside diameter of .499" in the top.

GOT IT! Except that you don't seal the pipe at the bottom (or the ball couldn't fall all the way through.

When the ball passes through the pipe the moving magnetic field induces a current in the conductor (pipe), which in turn creates a magnetic field of its own but of opposite polarity to the field of the ball. This slows the passage of the ball through the pipe by at least a couple of seconds.

When I went to duplicate the trick I was able to locate 1/2" Neo sphere magnets at an online surplus outlet. Finding the tubing was a lot easier - I just went to Fox Hardware in downtown SF, but any plumbing supply store or (very) well stocked hardware store should have it.

No, I didn't say anything about a magnet initially. Aspen didn't either. That would give away the trick.

What got me at the time was that out of a whole crowd of audio engineers around the AES booth where Aspen was holding court, I was the only one who was able to identify the principle involved and to state that the ball must be a magnet. And there were a number of guys much older, well known, and ostensibly more knowledgeable that myself who didn't get it.

John Eppstein wrote: ↑August 20th, 2019, 9:48 pm OK, the pipe is standard copper water pipe of the sort that is slightly oversize so it can be used to splice regular copper water pipe.

You seem to be describing a "sweat repair coupling" or "repair sleeve"

That would make it slightly larger than 1/2" inside diameter.

Slightly larger than the outside diameter of the 1/2" copper pipe, I think you mean.

Anyway, I'll bear that in mind if I get a leak. Where I live, pipes can freeze and occasionally burst in the really cold weather. They have repair sleeves with compression fittings at both ends, which is probably a more popular way to make the repair now. Sometimes it's hard to get the pipe away from the wooden frame of the house, so using a butane torch to solder pipes could be tricky. I had to be careful to avoid starting a fire with an electric heat gun last year while thawing out a frozen pipe.

In your case, you can join pipes together without solder or compression fittings by Bogarting the joint

nobby wrote: ↑August 22nd, 2019, 2:53 pm

John Eppstein wrote: ↑August 20th, 2019, 9:48 pm OK, the pipe is standard copper water pipe of the sort that is slightly oversize so it can be used to splice regular copper water pipe.

You seem to be describing a "sweat repair coupling" or "repair sleeve"

That would make it slightly larger than 1/2" inside diameter.

Slightly larger than the outside diameter of the 1/2" copper pipe, I think you mean.

Anyway, I'll bear that in mind if I get a leak. Where I live, pipes can freeze and occasionally burst in the really cold weather. They have repair sleeves with compression fittings at both ends, which is probably a more popular way to make the repair now. Sometimes it's hard to get the pipe away from the wooden frame of the house, so using a butane torch to solder pipes could be tricky. I had to be careful to avoid starting a fire with an electric heat gun last year while thawing out a frozen pipe.

In your case, you can join pipes together without solder or compression fittings by Bogarting the joint

They make flexible torch shields with (IIRC, it's been awhile) a layer of thick aluminum foil (or something similar) bonded to a layer of some sort of fireproof material to be used to protect wooden structures when torch soldering in situ. And the torch is either propane or MAPP gas (a type of processed acetylene) - butane doesn't get hot enough or burn clean enough. Might be OK for thawing pipes though. Having a turtbo-torch helps on difficult soldering jobs.

Actually, "in my case" I've pretty much given up smoking pot in an effort to preserve what semblance of a singing voice I have left. These days I pretty much just do edibles after dinner.