Changing inlet stem on a Micromatic PremiumPlus regulator

I’m looking to add a nitrogen stout tap to the keezer.  As a result I need to add another gas cylinder to the setup – a 30/70 blend of CO2 to nitrogen.

In Australia we have a couple of different cylinder threads.  Standard CO2 comes in a cylinder with a Type 30 connection.  The new blend I will be using has a Type 50 connection.

I bought another Micromatic regulator to go with the new cylinder.  The original model that I bought is no longer locally available and the PremiumPlus model has taken its place.  This model comes standard with a Type 30 connector so I need to swap out the inlet stem with one compatible with Type 50.

Older model Micromatic regs use right-hand threads on the low pressure side and left-hand threads on the high pressure side.  This would be a massive problem because all commercially available inlet stems I’ve seen are for right-hand threads (left-hand threads seem to be a Micromatic idiosyncrasy).  I was really hoping that left-hand threads wouldn’t be applicable to the PremiumPlus, otherwise my options would be down to a custom fabrication or buy yet another regulator from different manufacturer.  Having emailed Micromatic about this I can say that, in my experience, as a company you should not expect any sort of reply – I certainly didn’t get one.  Not even an acknowledgement.  So I thought I would document my findings here.

The first thing to note is that all the fittings are sealed with thread-lock and assembled by sumo wrestlers wielding spanners.  They are not easy to get off and due to the limited purchase on the body of the reg you have to be very careful not to damage dials, etc.  You really have to build a jig like I have below.

Grab a sturdy off-cut of wood, drill a hole in it so that the regulator can sit flush against the surface.  The low pressure dial and outlet treads are held in place by coat hanger wire that is twisted tight on the back side.  You will also need to cut a notch so that the captive nut of the existing inlet stem can drop down exposing the hexagonal end of the stem.  You will also need to pry off the nylon washer that sits on the end that seals with the cylinder.

Grab the appropriate sized socket (metric) and you’ll need a long length of pipe to turn the spanner into a large breaker-bar.  I used a 1m length of cast iron gas pipe.  The thread on the inlet stem is right-hand (yay!) so apply controlled gradual anticlockwise pressure until the thread-lock loosens.  It’ll take a fair amount of torque.  I also recommend getting a friend to hold the regulator and be ready to catch it should the jig snap to stop it all crashing to the floor.

LowBrau morphs into a Raspberry Pi brewbot

It’s been 4 months since I last wrote about my automated brewing project.  LowBrau was meant to be a low cost single-vessel automated step mash and boiling system.  But, although the controller box was mostly complete, I ran into problems when I fried my Arduino.  That and the hellishly cramped nature of my project box (which was designed to sit neatly under the boiling vessel) really put the brakes on mentally for me – I just wasn’t super motivated to push forward.

Although I may have been silent on this one, I have been working on the next iteration of the project for the last couple of months.  It was always my intention to not simply clone the commercially available systems, but to better them where I see a feature that is clunky or limited.  As a result this hiatus seemed like the perfect opportunity to rethink the core technologies of the project.

The biggest change is that I have now decided to ditch the Arduino and base the control box off a Raspberry Pi.  At $35 this little embedded linux computer is vastly more powerful than an Arduino, yet it really isn’t much more expensive than a name-brand Arduino.  It will allow profoundly enhanced functionality.

I also bought a far bigger project box.  Rather than living under the boiling vessel this one will be fully detachable, with all inputs and outputs connected via sockets.  It can happily live on the bench next to the brewbot.  I divided it into two physical sections with an off-cut of PVC square-section drainpipe to separate the high and low voltage components.

I’ll write a bit of commentary about each main component pictured in the photo below…

As I wanted the control box fully detachable the AC power comes in and the pump and element connect via IEC sockets.  I went with snap in mountings rather than ones that require bolts/rivets, so all that was needed was an accurately sized rectangular hole to push them through.

The element and pump are switched by solid state relays.  Mine are Fotek 25DA.  I neither recommend or warn you off them – other than to say that they cost less than $4 each including postage and one of them came dead-on-arrival.  They’re mounted onto the heatsink used in the previous edition of the controller box.

Lastly in the high voltage area there’s the 5V 2A power supply module.  Everything else in the box gets powered off this 5V supply.  The RPi requires 1A, so there’s an additional 1A overhead for all the rest of the bits.

Down the left hand side is the Raspberry Pi (RPi).  The 26 pin general purpose input/output (GPIO) connector is connected to my breakout board via some grey ribbon cable.  I have thrown a very cheap $4 USB wifi (rtl8188cus chipset) on the RPi which will allow the advanced interface opportunities.

The temperature probe attaches via a 4 pin socket on the right.  The probe uses the DS18B20 chipset which is read natively by the RPi using the 1-Wire connector on the GPIO.  In linux the output of this probe appears as a text file for easy reading.  Couldn’t be simpler.

Along with wifi control, I also want to keep the option to control everything through the control box as usual.  I have selected a 20×4 LCD ($5), which provides more screen space than the Braumeister’s 16×2.  This in turn will allow me to implement a more sensible user interface that doesn’t require so many nested menus and laborious button pressing.  The LCD is a standard HD44780 chipset, however I do not connect it straight to the GPIO.  I have soldered to the back an i2c conversion board ($3) which further shrinks the number of IO lines to 2.  It also conveniently takes care of all the contrast potentiometer wiring.  Between this board and the RPi is a level shifter board ($2).  This is necessary because the RPi GPIO all works off 3.3V levels, not the 5V standard.  This board is bi-directional so it pumps 3.3V signals to 5V in one direction and 5V back down to 3.3 in the other.

On a related note, all the other outputs (SSR signals and LED indicators) are passed through a Darlington array (60c).  The 3.3V supply internal to the RPi only has a total capacity of 50mA – so even 3 LEDs would take it beyond its capacity!

The buttons are set with both pull-up resistors and current limiting resistors.  The pull-ups (10k) are required to stop the inputs from floating.  The current limiting resistors (1k) are often left out by people, but they’re a pretty good idea to do it correctly.  If your GPIO is always set up correctly as inputs then you’d never need them, but in the case that they get set erroneously as outputs they prevent them from creating a short circuit between the RPi output and ground.  I have also installed 100nF ceramic capacitors across the terminals of the buttons to hardware debounce them.  A quick circuit diagram is below.

And finally, there’s a speaker and amplifier.  One of the annoyances I find with the Braumeister is the incessant beeping that seems to accompany almost every step of the process.  Yet despite this it can also be surprisingly unapparent when everything has stopped waiting for you to press a button.  I have decided to solve these problems by replacing the buzzer in favour of voice prompts driven off the RPi audio output.  While a flashing status LED will give clear indication that a user input is needed.  The amp is a 5V D-class 3W audio amplifier ($3), which is commonly used in USB speakers and for that reason conveniently runs off my 5V supply and is plenty loud enough.

LowBrau – Setbacks and Delay

Anyone who has been following the progress on the LowBrau project would have seen a whole flurry of activity followed by a long period of silence.  Within 4 days of starting I had got to the stage where the case was drilled and filed for all components; the screen, buttons, LED indicators, temperature probe socket, buzzer, arduino and wiring shield were wired and mounted; the screen protector made and adhered with waterproof silicone caulk; and the SSRs and heatsink mated, mounted and wired up.

Pretty much everything was complete and ready for a test run.  And indeed I did, uploading my control software to the arduino, powering it off USB and everything ran as it should from menus to button presses, etc.  Excellent – all that remains is to remove the USB power and power it stand-alone off its own power supply.

This is where my cheap ebay power supply vendor threw a spanner in the works.  In a break from character I didn’t power it up and throw my multimeter over it before installing it in the LowBrau controller.  Unfortunately for me I was unaware that this power supply has been incorrectly labelled (the sticker placed upside-down).

I am also quite surprised that arduinos (especially being aimed at the hobbyist market) do not feature a diode to protect against a reverse polarity situation.  Incorrect supply wiring will instantly destroy an arduino, which is exactly what happened to mine.

Annoyingly the arduino cost far more than the power supply that took it out.  And without a spare I had to wait for a replacement and in the intervening time I lost momentum with it all.  But I still have plans to get back onto it in the future.

So if there was ever an encouragement to embrace the inner-pedant and check everything yourself, irrespective of what the manufacturer has written, then this is it!

Reducing Latency in Rocksmith (PC)

Recently I have been posting about the Real Tone cable for use as a guitar audio interface for amp modelling and other Digital Audio Workstation duties.  I’ve also been comparing its performance with a proper audio interface.  One of the areas that I noted a large difference was that of latency – the gap in time between plucking a string and having the computer emit the sound as a note through the speakers.  Lower latency of course is always desirable, but a little latency can be lived with without ruining the experience.  However, once it climbs too high it becomes unplayable.

What I haven’t discussed much is using the cable for what it was originally designed for: playing Rocksmith!  Plenty of criticism comes from the latency present in-game – and I agree, it can be distracting.  Ideally I would like to be able to use my new TASCAM audio interface as my guitar input, but Ubisoft also use the Real Tone cable as their form of copy protection.  You must own the cable to play the game.  There are No-Cable hacks which allow you to play the game using your on-board soundcard (which presumably would suffer from high noise issues without the proper pre-amps of an instrument specific interface), and this hack should allow me to use my hardware instead of the Real Tone (one should imagine).  But I’m loathed to hack about my game in a way that could make it look like I’m pirating something on Steam that I totally legitimately own, just so that I can use some hardware that never would have been considered when they designed this game for console (grrr, console-ports).

Thankfully however, there are some configuration settings that can be tweaked to improve the performance of the Real Tone cable.  The file that you’re looking for is rocksmith.ini located in your Steam/steamapps/common/Rocksmith directory.   And it would seem that these are set by default very conservatively (resulting in high latency).

The two key variables here are LatencyBuffer and MaxOutputBufferSize.  In effect, the resulting latency of the system is proportional to LatencyBuffer x MaxOutputBufferSize.  By default LatencyBuffer is set to 4 and MaxOutputBufferSize is set to 0 which means automatic, although in practice this almost always ends up being 1024 for pretty much all standard motherboard soundcards.

The purpose of the buffer is to provide uninterrupted sound when the processors cannot keep up and it does this by introducing a lag (hence, buffer) allowing time gap in which everything can catch up before you hear an interruption.    So the first thing to do is to set both variables to their default states of 4 and 1024, respectively, and then work them down until clicks and other artefacts start appearing.  Then just back them up a little.

Looking at the maths of it all, simply changing the value for LatencyBuffer is going to make a big difference so I started by moving it down from 4 to 2.  In one step this reduces latency by a full 50% and I found it to be the difference between a noticeably laggy, somewhat annoying in-game experience and a very playable, acceptable one!  And to put this in perspective I don’t have an epic gaming rig, yet making this change improved gameplay without degrading the sound at all.  Clearly those default settings are very conservative indeed.

I encourage all owners of Rocksmith to give this a go.  It’s not complicated or time consuming, and if it doesn’t work out then just bump the numbers back again.  But I’m confident that you’ll be pleasantly surprised at what a difference it makes.  Why this isn’t a prominent option available through the in-game menus boggles me – but then anyone who’s played the PC version probably knows it’s best not to get started on that infuriating menu system…!

TASCAM US-200 Audio Interface

Earlier I posted a guide to using a Real Tone cable (which comes with the game Rocksmith) to connect to Guitar Rig 5.  With the success of that experiment I went ahead and bought a proper audio interface.  In this post I will give a rundown of the rationale behind my decisions and highlight the differences between the two approaches.

The unit that I chose was the TASCAM US-200.  This USB audio interface has 2 microphone-in (one of which can be instrument); gain knobs for each mic input; selectable 48V phantom power for professional microphones; 4 line-out channels (channel assignment software configurable); 1 independent headphone-out (with dedicated volume control); MIDI in and MIDI out.  This cost about $100.

The benefits of running this unit over the Real Tone are:

• the Real Tone cable is only an audio input device so you need to use ASIO4ALL to bridge the sound output to your motherboard’s sound chip which can be annoying to configure (your settings don’t always ‘stick’)
• the software bridging performed by ASIO4ALL, combined with the fact that the Real Tone is a budget item, means that latency is high (eminently playable, but clearly noticeable)
• the TASCAM takes care of both audio input and output so configuration is super easy and reliable
• the TASCAM has knobs for input gains and output volume so adjustments don’t require driving a mouse around the screen (which gets old pretty quick while you’re trying to play an instrument)

So what have I thought of it so far? Well latency is significantly lower!  I also found the Real Tone cable prone to noise – both clicks from artefacts and analog cable noise.  There are no artefacts with the TASCAM and any cable noise is virtually eliminated (probably in part due to the fact that I can use my better quality instrument cables than what the Real Tone is made from).  Any residual noise, where it may exist, is ruthlessly gobbled up by noise gate settings in GR5.

I also am a huge fan of the ability to set my external speakers and amplifier to a direct line-out and be able to adjust my headphones with the volume control (ie independent of the speakers).  This is a far better outcome than trying to get the single motherboard output to do everything.

The MIDI interface is also a nice bonus.  Although I don’t actually own any MIDI devices I can see the appeal of, say, a simple MIDI foot switch array to mimic the functionality of a traditional pedal board (and to do tap-tempos, etc).  Indeed that might be an excellent project for a future post!

But it isn’t all good news… (the update after 2 months use)

While from a hardware perspective the US-200 is a great bit of kit, the drivers are truly horrendous.  There are a number of pretty big issues with the driver but the greatest is its inability to cope with an operating system that implements suspend or sleep modes.  This little gem is buried away on page 11 of the manual – and I would have thought that this limitation is pretty important information for a buyer to know before they make their purchase.  Windows users have had sleep/suspend for EIGHTEEN YEARS, and yet the plebs at Tascam still cannot wrap their puny minds around writing a driver that can cope.  The result is that any time my PC goes to sleep I lose all sound both in and out.  The only remedy is a full reboot!  Totally unacceptable.

Next, the line out connectors are software-configurable.  Yet the driver is incapable of retaining my choices for more than a couple of hours.  So on a very regular basis I get put into an audio black-hole until I work out that the output routing has changed itself (again!).

And lastly, the drivers periodically just totally crap out and require a complete uninstall and reinstall.  I have had occasions where I’ve wanted to play and then had to restart my computer no less than SIX TIMES to actually return everything to correct working order.  If you want reliability this product is definitely not the one for you.

I have contacted Tascam about all these issues and they don’t even reply to support requests (I’ve waited over a month).  This is not a new product and clearly no new firmware or driver updates are going to come out for it.

Would I recommend this purchase to anyone else? Absolutely not.  Would I buy again?  Absolutely not.  Would I buy another Tascam product after this experience?  No, I wouldn’t – I really can’t think of a more substandard buying experience.

And I have to say this is all such a shame, because when it all works properly it’s a good unit.  Clearly the hardware is sound.  But, my goodness, what a terrible software implementation!  Definitely get an external audio interface (they’re great), but don’t buy a Tascam and don’t buy this one!