Using Rocksmith Real Tone cable with Guitar Rig 5

This christmas I picked up a copy of the game Rocksmith.  This half-game/half-tutor allows you to connect a real guitar to a console or PC and is basically Guitar Hero with a proper instrument.  Unlike Hero all the time you invest in getting better at the game actually builds real musical skills, rather than just coming away from it a highly talented coloured button masher.

You supply your own guitar and the connection is made by the Real Tone cable which is supplied with the game.  Inside it is a Hercules board which converts the analog signal from the guitar into a USB digital stream.

But not only can this game provide a leg-up getting the motivation to learn, but the Real Tone cable also allows amp modelling sims to be used outside of the game.  This is not something that is advertised by the game manufacturers but with a free driver, a little fiddling and a copy of Guitar Rig or Amplitube this is pretty easy to do.  And a standard interface for connecting guitar to PC will cost around $100, so Rocksmith really is giving you some excellent value beyond what is already a great game.

The driver that is needed is called ASIO4ALL.  This is because a standard audio interface has both input and output, but the Real Tone cable is input only.  In order to keep latencies low amp modelling software take exclusive control of the audio interface and they expect to only have to use one for both the incoming and outgoing sounds.  ASIO4ALL is needed to work as a ‘bridge’ so that the Real Tone can be selected as the input but a different device selected as the output (for example your motherboard sound chip).  I didn’t find ASIO4ALL super intuitive to use, so I will devote the rest of this post to explaining how mine is configured to get the sound working properly in Guitar Rig 5.

Once ASIO4ALL is installed fire up the amp modelling suite and select ASIO4ALL as the audio device.

Whenever a program starts using ASIO4ALL a little green triangle symbol appears in your system tray.  Clicking this brings up the ASIO4ALL configuration menu.  Here you should see your standard PC sound card (probably with a highlighted green symbol next to it indicating that it is the active selection) and your Rocksmith USB Guitar Adapter (which will probably not be selected).  Expand your PC sound card entry by hitting the + and exposing the inputs and outputs.  What you want to do is arrange it so that it looks like mine below, with your PC sound card output selected, your PC sound card input deselected and the Rocksmith USB guitar selected.

This might take a little bit of fiddling to select them in the right order – ASIO4ALL has a habit of going all-or-nothing, but trust me it is possible to do it if you find the correct order of operations.

Once this is achieved go back into Guitar Rig and make your input and output selections.  These can be found under the Routing tab.  You want USB Guitar Adapter as input and your PC soundcard as output.

While all this is going on I like to have the metronome going, because that way it’s really easy to tell when the output is correctly configured.  If you can hear the metronome and when you strum your guitar you get sound then all is good!

If you strum your guitar and you see the input VU meter move then you know that output is a problem.  If you can hear the metronome but when you strum the input VU does not move then you know that input is a problem.

Lastly, sometimes I have experienced some clicking and clipping using the Real Tone cable in this way.  Often just opening up the ASIO4ALL config menu makes this go away.  Certainly I don’t experience this problem all the time.

This is a different issue to simply interference on the analog side of the cable – which this set up can suffer from (like any guitar setup).  Running the cable too close to your PC, power cables and other electrical devices can impart a hum.  Either have a go at moving the cables around, or do as I do and simply slap a virtual Noise Reduction pedal into your onscreen setup!

Happy shredding…

(UPDATE: here’s a look at a proper dedicated audio interface)

LowBrau – Screen Protector

I am trying to keep the controller box as water-tight as possible.  Although I don’t expect it to be hosed down, I can see that with an inherently liquid-based enterprise it is entirely foreseeable that it’s likely to get the odd splash.  At the moment the LCD module simply pokes through a hole in the box, so it needs some sort of cover to seal it all up (as well as provide some knock protection).

All I really want is a rectangle of thin clear plastic.  So I went looking for some trash that could be repurposed.  My first attempt was using an old CD cover.  This proved too flimsy – once the edges were removed it was quite floppy.  In the end I used the plastic from a box of ex-Christmas Ferrero Roche.  I’m sure that an old iPod/iPhone box would work even better (not that I have many of them lying around).

The best way to work the material is to rough cut the sides off to leave a single flat sheet of plastic.  A hacksaw or Dremel cutting wheel works well for this.  To actually cut the final edges of the rectangle (ie the fine work) the best approach is one similar to glass cutting.  Score your line a few times with a craft knife and straight-edge.  The bend to snap along the score line with some flat-nosed pliers.

This way the rough stock can be made properly square (as in, given proper 90 degree corners) and the results are quite accurate, straight sides.  Any jagged edges can be knocked back to smooth with a light sanding.

Then all is needed are a few holes for mounting screws and (later) a little silicone sealant.

As you can see in the photo above, my box has a little dot imperfection where the injection molding has taken place.  I may end up sourcing a better piece of stock and remake using this one as a template.  If that were to happen this would actually be a very quick operation to duplicate the two (this one took about 5 minutes to make).  Or I may just live with what I have…

LowBrau – Low Voltage Wiring

Now that the major components have been fitted to the front and back halves of the controller box it’s time to start wiring up the low voltage components.

I started by installing an earth wire (green) to the LED bezels – as any conductive surfaces on the exterior of the box should be properly earthed.  Next the cathodes of the LEDs were bent together and soldered in place with a ground wire (black).  Each anode then got its own signal wire (orange).

Next the navigation buttons received their common ground (black) and individual signal wires (white/grey).  Each signal wire not only connects to an input pin on the arduino, but also connects to the 5V rail via a 10k pull-up resistor.  This circuitry, however, I will deal with soldered directly on the proto-board.

After this my LCD needed its leads, so I soldered together the connections in the pin header sockets using red for 5V, black for ground and yellow for data lines.

On the back panel the SSRs need their signals and common ground.  As the signal that triggers the SSR is physically the same pin that lights the respective LED I chose to use orange for these lines too.

All these various lines then connect each component to the arduino via a shield made from prototyping board.  I took strips of pin header and pushed the pins all the way through their black plastic strip so that I could keep the solder side towards the arduino.  Unfortunately the second bank of digital connections (data lines 8 to 13) are not aligned with the grid of the proto-board, so they need to sit on their own little board.  This is a slightly annoying feature of the way that the arduino has been designed – and the cynic in me wonders if it’s to create a market for people buying prototyping shields!

The main items that live on the circuit board are 5V, 12v and ground buses; the button pull-up resistors; the LCD contrast trim-pot and the buzzer transistor.  As a result, none of the circuitry is mind-boggling complex and a custom printed PCB is an unnecessary expense (although it would make for a far quicker job).

Once all this wiring had been completed it was time to flash the arduino and see if it all works.  And success!

Currently the LCD, navigation buttons, and LEDs are fully functional.  There are header pins for the SSR signal wires to plug into (allowing both halves of the box to split apart) and the transistor for the buzzer needs to go in.  My temperature probe has not arrived yet, so that only has some loose wires (purple) awaiting it.

LowBrau – Front Panel Hardware

After mounting the SSRs and heatsink to the rear half of the waterproof control box, I figured I’d plough on and fit all the front panel hardware.  As such this post doesn’t really have a lot of earth-shattering content, but I will run down a few of the items that make up this part of the build.

The green circuit board in the centre is the liquid crystal display which will provide the main interface for the user.  This module is a common HD47780 ($2.40) which is easy to interface with digital circuits – indeed arduino has a library specifically written to do just that, you simply need to specify which pins you have connected each of the LCD terminals to and away it goes.  I soldered some header pins on so that I can easily disconnect it from the rest of the controller wiring, should I need to.  I will need to work out how to protect the screen from knocks and liquid splashes, but that’s a challenge for another day.

Beneath the LCD sit four control buttons.  These provide the navigation inputs to allow the user to control the LCD.  I chose waterproof buttons, which don’t seem to be widely available cheaply so these ended up being close to $5 each!  Feels a little unreasonable but cannot be helped.

To the immediate right of the LCD are two LED indicators.  These will serve to provide a visual indication of the state of each output relay (ie whether or not the pump or heating element is switched on).  This might prove important in avoiding accidentally leaving the heating element on while the brew vessel is empty.

On the left side of the box is a power transformer to provide a 12V DC source for the arduino and buzzer to run off.  Again, this common 1A supply was quite cheap at only $7.50 delivered.

On the right side of the box is an IEC power socket to provide mains power to both the transformer and the heating and pump SSRs.  This socket was free because I simply unscrewed it from an old PC power supply – I can’t imagine why anyone would ever buy these new!

Finally, here’s a look at the front panel…

I think the layout is looking fairly clean and functional.  It has to be said that there’s isn’t much room for variation because the inside of the control box, once all the components are in, is going to be very tight for space.  The navigation buttons might look a little cramped but they’re entirely usable, line up nicely with the LCD and free up plenty of space on either side for more components inside the box (for example the transformer sits under the blank space to the right of the LCD and buttons in this photo).

I certainly find cutting the holes a bit of a chore.  All the circular components are a dream, but the square holes of the LCD, SSRs and IEC connector all involve a disgraceful amount of filing to get them right.  I’m sure there must be a more efficient way, but I have yet to discover it!

LowBrau – Solid State Relays

Work has commenced on the LowBrau controller with the installation of a pair of solid state relays (SSR) into a polycarbonate waterproof electrical box.

As the name suggests a solid state relay works very much like a standard electromechanical relay – using a low voltage, low current signal to switch a high voltage, high current on and off.  Where a mechanical relay uses an electromagnet to physically make and break the contact of a switch a SSR acts more like a transistor to achieve the same outcome without any moving parts.

Inside an SSR there is a light operated switch consisting of an LED operated by the signal and a thyristor switching the load.  This arrangement has some excellent advantages.

First, the LED side is low current and TTL which means that the SSR can be connected directly to the arduino without any need for transistors, resistors or any other components.

Second, the SSR can be switched incredibly quickly (milliseconds to microseconds) which means that pulse width modulation (PWM) allows for not only an on or off state, but also to vary the effective output level of the load by rapidly oscillating and varying the gaps of ‘off’ between the spikes of ‘on’ – in my case this will allow me to tail off the heat of the element to avoid overshoots.

Third, the SSR is fully opto-isolated (meaning that there physically is no connection between the low voltage circuitry of the controller and the household supply) and does not suffer from any of the back-EMF noise issues of electromechanical relays.

Lastly, my SSRs were quite cheap (~$3 each) so I bought two: one to modulate the heating element and the other to switch the pump.

Unlike a standard mechanical relay, though, SSRs do produce a fair amount of heat.  This will be particularly so for the SSR controlling the heating element because it will be performing rapid switching on a 2.4kW load!  To deal with this the SSRs have been mounted to a large aluminium heatsink which covers the back side of the controller box.  Thermal grease between the SSRs and the heatsink ensure good transfer.

It is also worth noting the importance of properly earthing the heatsink (along with anything else conductive on the outside surface of the control box) as a loose connection could easily turn the aluminium heatsink into a dangerous conductor.