How to Play the Bass With Marbles

Stringed instruments make noise from the vibrations of tuned strings, using acoustic or electronic means to amplify those vibrations to the point where they’re loud enough to hear. The strings are triggered in a variety of ways – piano strings are hit with hammers, guitar strings are plucked, while violin strings are bowed. Meanwhile, [Martin] from the band [Wintergatan] is using marbles to play a bass guitar.

[Martin] starts out with a basic setup. The bass guitar is placed on the workbench, while a piece of wood is taped to a tripod. The wood has a hole drilled through it, and marbles are dropped through the aperture in an attempt to get them to land on the string. Plastic containers are used to easily alter the angle the bass guitar sits at, relative to the bench, while an acrylic guide sits around the string to try to guide the marbles in the desired direction. These guides are important to make sure the marbles hit the top of the string, and bounce cleanly in the desired direction afterwards.

The initial setup is too inconsistent, so [Martin] places a notch in the wood and builds a lever system to hold the marbles and then release them in a controlled manner. [Martin] then checks that the system works by analysing footage of the marble drop with slow motion video.

The video covers the CAD design of an eight-slot guide so the four strings of the bass can be played more rapidly than in their previous build. Two guides per string allow each string to play two notes in quick succession without having to worry about marble collisions from playing too quickly.

It’s a great build, and we’ve seen [Wintergatan]’s work before – namely, the incredible build that was the original Marble Machine.

Thanks to [Tim Trzepacz] for the tip!

Dumpster Dive Speaker Results In Tube Amplifier

[Michael Wiebusch] found the leftovers of a wrecked vintage tube radio in a pile of electronics junk. Unfortunately, he could not recover any vacuum tubes in it. And to his dismay, it didn’t even have the output transformer, which he figured would have been useful in a guitar amplifier project. The output transformer is not easy to come by nowadays, so he was hoping to at least score that item for his future build. All he could dig out from his dumpster find was a pair of speakers and he ended up building nice Output-Transformer-Less Tube Guitar Amplifier around them.

Valve output stages are generally high-impedance which means they cannot be directly interfaced to low impedance speakers. An impedance matching output transformer is thus used to interface the two. Back in the day when valves were still the mainstay of audio electronics, many cheap amplifier designs would skimp on the output transformer to save cost, and instead use high impedance speakers connected directly to the amplifier output.

[Michael] found a nice reference design of an OTL amplifier for a 620 ohm single speaker. He decided to use the same design but because these speakers were about 300 ohm each, he would have to wire his two speakers in series. At this point, he decided to make his build useful as a proper guitar amplifier by adding a preamplifier stage replicated from another design that he came across. A regular halogen lamp 12V transformer takes care of the heater power supply for all the tubes, and a second, smaller 12V transformer is wired backwards to provide the 300V needed for the plate supply.

The final result is pretty satisfactory, considering that it all started with just a pair of junked speakers. Check out the result in the video after the break.

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Two Guitars, Two Amps, And Three Pole Dual Throw

[Alexbergsland] plays electric guitar. More accurately, he plays two electric guitars, through two amps. Not wanting to plug and unplug guitars from amps and amps from guitars, he designed an AB/XY pedal to select between two different guitars or two different amps with the press of a button.

The usual way of sending a guitar signal to one amp or another is with an A/B pedal that takes one input and switches the output to one jack or another. Similarly, to switch between two inputs, a guitarist would use an A/B pedal. For [Alex]’ application, that’s two pedals that usually sell for $50, and would consequently take up far too much room on a pedalboard. This problem can be solved with a pair of 3PDT footswitches that sell for about $4 each. Add in a few jacks, LEDs, and a nice aluminum enclosure, and [Alex] has something very cool on his hands.

The circuit for this switcher is fairly simple, so long as you can wrap your head around how these footswitches are wired internally. The only other special addition to this build are a trio of LEDs to indicate which output is selected and if both inputs are on. These LEDs are powered by a 9V adapter embedded in the pedalboard, but they’re not really necessary for complete operation of this input and output switcher. The LEDs in this project can be omitted, making this a completely passive pedal to direct signals around guitars and amps.

Fail More: The Story of [CNLohr]’s Clear Keytar

[CNLohr] is kinda famous round these parts; due to some very impressive and successful hacks. However, for his 20k subscriber video, he had a bit to say about failure.

Of course glass circuit boards are cool. Linux Minecraft things are also cool. Hacks on the ESP8266 that are impressive enough people thought they were an April Fool’s joke are, admittedly, very cool. (Though, we have to confess, posting on April 1 may have added to the confusion.)  For a guy who puts out so many successes you’d think he’d talk about the next ones planned; hyping up his growing subscriber base in order to reel in those sweet sweet Internet dollars.

Instead he shows us a spectacular failure. We do mean spectacular. It’s got beautiful intricate copper on glass key pads. He came up with clever ways to do the lighting. The circuit is nicely soldered and the acrylic case looks like a glowing crystal. It just never went anywhere and never worked. He got lots of people involved and completely failed to deliver.

However, in the end it was the failure that taught him what he needed to know. He’s since perfected the techniques and skills he lacked when he started this project a time ago. We’ve all had experiences like this, and enjoyed hearing about his. What failure taught you the most?

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MIDI Guitar Pedals

Ever since Jimi Hendrix brought guitar distortion to the forefront of rock and roll, pedals to control the distortion have been a standard piece of equipment for almost every guitarist. Now, there are individual analog pedals for each effect or even digital pedals that have banks of effects programmed in. Distortion is just one of many effects, and if you’ve built your own set of pedals for each of these, you might end up with something like [Brian]: a modular guitar pedal rack.

ae0fmjxTaking inspiration from modular synthesizers, [Brian] built a rack out of wood to house the pedal modules. The rack uses 16U rack rails as a standard, with 3U Eurorack brackets. It looks like there’s space for 16 custom-built effects pedals to fit into the rack, and [Brian] can switch them out at will with a foot switch. Everything is tied together with MIDI and is programmed in Helix. The end result looks very polished, and helped [Brian] eliminate his rat’s nest of cables that was lying around before he built his effects rack.

MIDI is an extremely useful protocol for musicians and, despite being around since the ’80s, doesn’t show any signs of slowing down. If you want to get into it yourself, there are all kinds of ways that you can explore the studio space, even if you play an instrument that doesn’t typically use MIDI.

Touchless MIDI: The Secret’s In the Mitten

MIDI is a great tool for virtually any musician. Unless you’re a keyboard player, though, it might be hard to use it live. [Evan] recently came up with a great solution for all of the wistful guitar players out there who have been dreaming of having a MIDI interface as useful as their pianist brethren, though. He created a touchless MIDI controller that interfaces directly with a guitar.

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Rocking An Acoustic Guitar By Making It Electric

Brothers [Armand] and [Victor] took their acoustic guitar to the next level, making their own pickups to turn it into an electric guitar. The result is that awesome electric guitar sound.

The pickups are homemade magnetic pickups. Each string has a steel bolt behind it with three ceramic magnets on each bolt. A coil is also wrapped around all the pickups. That coil is what’s connected to the wires going to the amplifier. When a string vibrates, it changes the magnetic field in the pickup which induces a current in the coil and that is then sent on to the amplifier to be altered as desired and turned back into sound. Of course that meant the guys had to replace their nylon strings for steel ones.

With just the volume amplified the sound isn’t very different but when the amplifier’s gain is turned up and the volume turned down the sound is undoubtedly electric. As you can hear in the video below, Johnny B. Goode, Paint it Black and Satisfaction take their acoustic guitar’s sound to a whole new level.

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