USB to 9V 'Pedal' Cable

Histories of Electronic Music often  concentrate on hardware, in an 'insider' code: TR-808, DX7, MPC, D-50, RC-505, EIV, etc., or on bands/perfortmers/artists, again very 'insider' in nature: NIN, Erasure, Daft Punk, Deadmau5, Kraftwerk, Bassnectar, BT, Mili, Fluke, etc. Another possible method of categorisation might be recording technology, wire, tape, multi-track, portastudio, DAT, CD, mp3, SD card, etc. 

But there's one pivotal hardware technology that most people assign to the sidelines...

Power cables. Yep, those IEC mains leads, USB cables, the often-unloved wall-wart adapters and their captive leads, and... guitar pedal cables. At the risk of sounding like a movie trailer (remember going to the movies pre-lockdown?): 

In a world where data seems to be going wireless and enabled by lithium-ion batteries, distributing power to gear is still physical wires. 

Allegedly, the world nearly had wireless power via Nikolai Tesla's Wardenclyffe Tower experiments funded by J.P.Morgan (yes, that J.P.Morgan!), and magnetic induction on the grand scale may now be impossible because of the way we have developed electronics, but applications like mobile phone charging are viable, albeit over very short distances. Instead, we have mains electricity, or batteries. Batteries are increasingly not the throw-away zinc-carbon et al cells, but rechargeable lithium-ion et al, and the current knowledge of physics suggests that there aren't any huge leaps in energy density - so significantly smaller/lighter batteries with huge power storage will require huge advances in physics. Lithium-ion batteries are increasingly used in power-banks that can power more than just phones, and USB has become a pretty ubiquitous delivery mechanism.

However, guitar pedals are different...

Unfortunately, guitar pedals come from an era of 9V batteries made up of stacks of six 1.5 Volt cells: PP9s as they were called before the modern obsession with renaming battery sizes every few years started, which sounds a bit like the way that USB connectors and video connectors get changed every few years. But modern pedals often no longer have any provision for a removable 9V battery, instead a centre-negative 2.1mm barrel connector provides the DC power. - from the mains! But that DC power is 9V, not the 5 Volts that you get from USB...

Up until very recently, that was the end of the story. Pedals were 9V, (not USB!) and you used a wall-wart power supply to convert mains to 9V DC, with daisy-chained connectors for pedal boards (or better, but more expensive: isolated outputs). However, the last decade has seen a lot of advances in Power Converter chips, and they have got smaller and lighter... To the point where you can put them into connector plugs. So it is now possible to convert the 5 Volts that you get from a USB charger to 9V with what appears to be just a cable.

A Deluge of Ideas

It was the Synthstrom Deluge FAQs that reminded me about USB-to-9V cables. The Deluge groovebox is quite unusual because it can work of an internal lithium-ion battery (Yep, it really is very close to the 'Novation Circuit on steroids, or Circuit 2' that many people have wanted for some time...). I've got a small 'classic' Boss BCB-30 pedal board that is mains powered, plus several pedals (An OWL, a Poly Digit and various other 'boutique' pedals that might get put onto a board eventually (none of which have 9V batteries!). But power has always been the problem, and it goes well beyond the usual 'serious' pedal board design advice:

'Don't daisy-chain one adaptor: Use a power supply with multiple isolated outputs.'   

Synthstrom Audible suggest that one way to power the Deluge is to use a lithium-ion USB power-bank with a USB-to-9V cable to do the voltage conversion. So I ordered a couple of cables from Songbird FX...

BirdCords from Songbird FX

Here's what I got: two bags (everything is in bags these days!) with the ubiquitous stickers! What looks like a cable with a 2.1mm barrel connector on one end, and a USB plug on the other end, is the USB-to-9V converter cable. It can provide a peak of 1 Amp, which means that as long as your USB power-bank (or USB charger/mains adaptor) can provide enough current, then you can power quite demanding devices. I tried my Deluge, and with my usual 'LEDs almost at lowest brightness' setting, the current consumption was just over 300mA, and with full LED brightness, it went up to around 425mA. The Default 'full brightness' LEDs on the Deluge is very bright, by the way:

The Deluge can be very bright!

I powered the Deluge through the USB-to-9V cable for just under an hour in an ambient temperature of 25 degrees Centigrade, and the plug only got slightly warm, so it looks like there's no problem with providing about half an amp continuously. 

The cable is disarmingly small and light - the plug isn't a big heavy blob at all! I then tried it with a pedal, captured here in an 'action' shot:

As you can see, the 9V connector is plugged into a pedal, and I'm just about to power it via the USB connector. Stunning cinematography, eh?

I'm very pleased with my BirdCords. They are small, neat, do what they say, and are useful gadgets to have around for emergencies, as well as a perfect way to reduce the proliferation of different mains adaptors. 10/10 from me.

Mobile

Okay, so the Deluge already has a battery inside, but there's lots of gear that doesn't! And none of my boutique pedals have batteries inside! So having USB-to-9V cables means that I can remove my dependence on mains power, by using power banks, which is great for live performance - especially unreliable mains power.  Even if mains power is available, then having just USB adapters/chargers means that I have more interchangeability in case something goes wrong... Losing power mid-set isn't my favourite experience: the thumps and clicks in the audio are bad, but having a laptop still powered up when your synths, drum machine and effects are all rebooting to an unknown state is pure stress and embarrassment. 

So my aspirational mobile rig would have a high power (20,000 mAh or more) USB power bank to power USB-powered gear, with USB-to-9V cables powering my pedal board. But my 'ideal' mobile rig would be to have two power banks with auto-switching between them... I'm trying to find something that does this...

Links

Songbird FX - BirdCords, including the USB-to-9V cable featured here.

https://synthstrom.com/product/deluge/ - The Synthstrom Audible Deluge web-page...

http://n.wikipedia.org/wiki/Lithium-ion_battery - Info about lithium-ion batteries...

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DIY MIDI Controller with LEDs

Possibly one of the least amazing titles for a blog articles! In these days where RGB LEDs feature on just about every specification list for MIDI Controllers, then the only difference is that it's a simple home-brew MIDI Controller - creatively mis-using a spare numeric keypad.

The numeric keypad is intended to be used with laptops that don't have separate number keys in a nice neat square form, and require the user to either use the buttons over the 'qwerty' row, or to do various extra key-presses to re-use other keys on the main qwerty keyboard. So the keys on the keypad just map into the standard key numbers as if this was a full external keyboard. To use the keypad as a controller, I have been working on a simple MaxForLive plug-in that intercepts the incoming key number messages and allocates them to functions in Ableton Live - this is still ongoing work, but the controller is finished, hence this blog entry!

The keypad as supplied is very boring: black plastic everywhere, and the only concession to RGB LED-ness is a red 'Num Lock' LED that isn't really relevant in this context. So this obviously needed augmenting. First task was to light up the keypad itself, and four blue LEDs did that very nicely. The numeric keypad came with a USB plug, so power was easily available, and I just added a few series resistors to the LEDs. I could have added more LEDs, but four was okay for this first iteration, and there is a definite limit to how much hot-melt glue you can use without waiting for it to cool down properly.

The flashing yellow circle came from a concert wristband that my son was about to throw away because the batteries had died, and so that was pressed into service (with an on/off switch). The flashing multi-coloured interior to the circle was one of those 'infinite mirror' displays where two mirrors bounce light back and forth many times giving an illusion of depth, and so that became the middle of the circle, again with a selector button to allow the choice of flashing mode.

The end result looks very flashy (deliberate pun!) but has one problem - the backspace and return key tend to be used in mot application UIs - and in Ableton Live the Backspace key deletes the active plug-in, which is usually the custom M4L plug-in, whilst the Return key tends to spawn a new version of the plug-in. Obviously these buttons are not very useful in a control context, and the simplest solution was to disable them - mechanically (you were expecting a software method, perhaps?).

 Disabling keys on keypads is relatively easy given the lack of travel of modern keypads - you just put lumps of blu-tack (or other similar slightly sticky substance) underneath them, so that pressing them doesn't result in any movement. Here are some photos showing bits of this process.

Prising keys off is usually pretty easy - I use a screwdriver. doing the blu-tack is easy, and putting the key back is normally just a question of pushing it back.

Please note that the lower cost the numeric keypad, the easier these types of mods tend to be. Levering out the keys on an expensive laptop (an Apple MacBook Pro for example) and trying to put them back with blu-tack underneath is definitely not recommended! (Just don't do it!)

To indicate that two of the keys were now disabled, I covered them with white typing correction fluid, something which used to be a standard home office accessory... I'm looking for a better solution, and 'sticky-back plastic' is definitely beckoning me!

And that's it. A spare (actually unwanted, although it sounded like a good idea at the time!) numeric keypad turned into something which looks like a MIDI Controller, and which may well be used when I iron the bugs out of the MaxForLive plug-in. In the meantime, it looks very good on stage, and isn't that one of the prime reasons behind all of those RGB LEDs anyway?

Now that I think about it, I probably didn't need to modify the keypad at all - I could have just assembled a few bits of LED toys and put them into a suitably technical-looking box and I'd have a stage box that smart-alecks and know-it-alls would look at and say things like: '...and there was this amazing home-brew controller...'. Maybe there's a business opportunity here?

[ Note that I'm not suggesting that you modify/wreck your own (or anyone else's) keypads, keyboards, laptops or anything else. I'm just showing that I sometimes do hardware as well as M4L! If you do make any modifications, then you assume full responsibility for them! ]