Last night at the… begins with A.

Spent yesterday afternoon rehearsing a little piece with the looper, and mainly voice, but it didn’t really work so I went to the theatre in Point Chevalier for the Ten Acre Block performance, as part of something gleefully called “Original Orifice” (which, by default makes me think that a performance in future could be called Anemic Artifice…not this one but just as a name for something that explores the artiness so inherent in art performance) knowing, pretty much, I wouldn’t be performing a solo.

So I get there and find a place to set up and it’s near a power point so alls good but by the time I set up, as I start from the outside and work in so the power cords are always last, the power point I wanted is gone and the nearest available is a lighting circuit which kinda irked my but I’m never one to cause a fuss so I plugged into that. Then my pedal power supply won’t work and keeps knida dimming out the pedals. So I end up taking out the pedals, which means I definitely can’t do a solo (no looper) and fire everything and it works good… so I power down and wait for the show…

Show starts and my power disappears… The lighting circuit was dimmed. So the hint I got with the pedal power supply coming in and out should’ve had me abandoning the lighting circuit. Seems the circuit of the dimmer was working in conjunction with the switch mode supply for my pedals and creating a low frequency tremolo. All the other amps and supplies worked because they’re all transformers at 50Hz but the switch mode supplies use high frequencies to get a DC current…blah, blah, blah.

So problems with switch mode supplies means you’re on a lighting circuit with a dimmer. Anyways nights of failure aren’t a worry, success and failure being flip sides of the coin that overall means learning, and if anything the smile on ones face during success can be a big wall for learning to get over… so maybe lots of failure is good… actually its really good, mistakes are the spice for the basic ingredients of success!

So heres a pretty little circuit that allows one to hear very low frequencies. Very low magnetic waves transformed into audio frequency.
and it comes from this page
The 160mH choke can be the primary from a Jcar 1k/8 ohm output transformer just like they mention the radio shack 1k/8. As for the other mentions of chokes on the input and as a high pass filter after the 160mH choke, at 100-150mH to get rid of 50Hz hum from power lines, your on your own as they are quite difficult to get hold of as straight chokes but the 1k/8 ohm might work in those places as well.

The 2N3819 fet is used in boss pedals as the switches to bypass and can be gotten from RS but I’d think just about any audio frequency fet would do. Likewise the transitor on the end could be a BC547. The antenna is a bit of a mystery but I suppose it’s just an ordinary telescopic type at three mtrs but maybe a three mtr length of wire would do as it’s the length that counts.

Now go out into the world and listen to the ripples of remorse in the magnetosphere!

3 Replies to “Last night at the… begins with A.”

  1. Sounds like an interesting set up – was everyone supposed to be playing
    (or have the potential to play) at once or something?

    Is the switch mode supply for a Boss pedal? Is that what they usually are?

  2. Yup. The old theatre has these big sculptures set out around and about the floor space which have flourescent tubes in them as part of the sculpture and they were on a lighting mixer set with automatic dimming, tremolo effects, so we were patching into these. This though, wasn’t apparent until the lights went down for our show… and didn’t happen during a rehearsal on Thursday… most people in the perf were on seaparate audio only lines so they were good. Just me and one other guy were patched into a lighting circuit… the trials of unprofessional proffessionalism.

    I can only surmise that the Boss supply is switchmode simply because all the other stuff was powered by garden variety transformers and it is somewhat likely that the system they’d use to fade lights would be a type of switchmode thing and then having another switchmode down the line from it would create the types of effect I came accross. Just conjecture though but it seems the likely scenario.

    I’m not sure that all Boss supplies are switchmode but I think mine is. The LED’s on the pedals weren’t bright and were kinda fading in and out on a low frequency… maybe a rise even two seconds so it’d be some weird interelationship of phase that could happen with high frequency hash on the top of supplies at 50Hz effecting the high frquency switching that switchmodes use.

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