Cheap Bastard: Power supply conundrum

As I’m quickly learning, starting a DIY modular is not for the faint-hearted. Of course it would be easy to cave-in, buy a basic setup and go from there. But that’s not in keeping with the skinflint ethos.

It’s when looking at how to power my modular that I fully realised how archaic and uncoordinated the Doepfer Eurorack format really is. Options for powering the thing are surprisingly limited, and connector conventions are known to vary between manufacturers. Just to get up-and running with the Doepfer PSU + Busboards + 5v converter comes to a total of 145euro. These are crazy prices. I went looking for reasonable alternatives.

The first question was whether I would build my own PSU based on the many specs found at Muffwiggler’s. After some consideration I decided not to go this route. Being still the newbie in this area, I decided against, if only because there is a real risk of frying myself and my surroundings if something goes wrong. So I’m better-off with a pre-fab PSU option.

Following-up a suggestion made on the Mutable forums (thanks yet again Frank!) I went for this one. For 24 euro it provides three power buses – 5v and +/-12v – and with a whopping 5A on the 5v bus.

The unit is heavy and seems quite robust, with clear connector options – if somewhat exposed. Handy enclosure to protect little fingers. There’s a prominent trimpot on the fron for adjusting the +5v bus. Not sure yet how noisy it is when plugged-in.

There is also a 5v =/- 15v version which will probably find it’s way here at some stage. But let’s keep focus for now.

I’m thinking to build the busboards myself using perfboard and some nice big capacitors, and based on schematics I found at Muffs.

Another option might be to just use a ribbon cable and connect the first modules in series until I can come to a more permanent solution. Much reading to do. Oh for some free time!

I have to face facts at the beginning that this modular won’t be a static device – it will likely grow and evolve as the addiction takes over. So I’ve got to be prepared to make big changes along the way, and try to anticipate my future requirements.

If I can get this PSU working as intended, I’ll be well-covered for power options.

Goodbye Tempest, Hello Freedom.

Well the Tempest turned-out to be a damp squib for me. Or rather DSI’s inability to implement features that were hotly discussed over a year ago. Maybe they will eventually pull the rabbit out.

Even so, there seem to be a lot of Tempesters who are perfectly happy with the current OS, and that has to be respected. As with everything else in life, people will have a different approach to, and expectations from, such an instrument. Everyone should come to their own conclusions.

[youtube http://www.youtube.com/watch?v=QereR0CViMY&w=400&h=255]

For me, the hardware interface, the sound and the overall concept were incredibly appealing. The forum was abuzz with excited discussions about the untapped potential, and we looked to be in line for a classic that would finally put the Roland box voodoo to bed. A powerhouse on paper, a legend in the making.

Now don’t get me wrong – in some respects it’s nearly there. I had fun designing sounds on this machine and I learned a lot along the way. The glass is definitely more than half-full, and I certainly do not regret the purchase.

But the sequencer is still too rudimentary for my needs. I didn’t see anything in the recent betas that give me confidence in user-requested improvements beyond the necessary bug fixes. DSI’s prolonged silences do not help. To me, most of the requests seem reasonable, and there appears to be broad agreement on the most important. The persistent bugs, though not serious, reveal a lack of attention.

Nobody is asking for a Cirklon-killer – only that the machine is given a sequencer worthy of it’s potential. And it seems so tantalisingly close.

At current pace, by the time the OS is ready, the second-hand market will already be mature, new competing products will have been released, and DSI will have lost sales. Brand damage has already occurred. I am amazed that the can’t see this! I would have said ‘bemused’, but it’s actually quite sad. I really want DSI and their products to succeed – the innovation is wonderful – but there seems to be no ambition to finish the job.

I can only speculate that the feasibility of new features is dependent on internal hardware limitations such as the the 4mb limit (honestly, what were they thinking!!), rather than the coder’s inability. He seems talented, if disorganized and overworked and, it would appear, fighting some serious battles to squeeze better performance out of this box.

Nevertheless, my biggest disappointed has been their habit of raising expectations and not following through. I honestly didn’t expect that, and I fell for it wholeheartedly.

They are also not giving the game away regarding what’s possible or likely to reach implementation. Engaging in further feature discussions seems pointless, as none have materialised. Beta testing has been the simple repetitive process of pointing-out the same few bugs in every release.

Admittedly my passion boiled-over after seeing the latest delay (of several months) was due to focus again shifted to the Prophet 12. OK guys, but at least tell us! It would be ridiculous to expect new product development to stop, but it is also reasonable to expect that existing products should receive the necessary attention.

In short, I am extremely disappointed with DSI’s behaviour. I would not have accepted this from another company, but I was rooting for DSI to succeed, and I trusted them. More fool me.

As a sweetener it was revealed that Tempest and P12 share a common codebase, and DSI have said that features will be rolled-back into Tempest. This sounds great, but makes me wonder, since the Oscillators are completely different, and P12 has no sequencer – the element that needs most attention. Time will tell.

I do earnestly wish DSI success with P12. It looks like it will be a winner and they have clearly worked very hard on it. They must be congratulated for the risks they are taking to innovate exciting new products. In the grand scheme of things, complaining about a few missing features seems churlish.

But when it comes to Tempest, I’ve simply lost faith. It had to go.

With the proceeds I have fostered a beautifully-built MIDIbox Seq4. Now THIS is a sequencer. It completely obliterates DSI’s effort. Open-Source with frequent updates still after 5 years of development. All that user input has been eagerly gathered and distilled into a great interface and a smooth, almost effortless workflow. And zero fuss from the unpaid developer.

There is more than enough cash remaining to start a nice modular and have a big party. I’ve already sourced the PCBs to make my own drum modules, which will be triggered by Seq4’s 8 analog outs. I can simultaneously sequence FM percussion provided by FS1r. What I lose in compactness I more than compensate for in flexibility and power.

Not only that, but there is still change to cover the entire expense of my 4×4 build AND to a fund a new build using a new third-party ladder filter in a 2-octave keyboard enclosure.

My first Eurorack module is ready to be assembled. Little Dieter is due to be born any day now…..

I’m sticking with open-source hardware from now on. No more ‘black boxes’. It’s AD 2013.

There will be no pining for Tempest.

Here are some Kits and sounds – the ones I managed to backup before the new owner ripped the Tempest from my arms. FWIW, he’s absolutely delighted with it.

Have fun!

I dedicate this one to DSI 😛
(One of my favourite basslines and easily possible on Tempest)

[youtube http://www.youtube.com/watch?v=e4OtIb6wDCQ&w=400&h=255]

4x4Pole: Controller decisions

The build is proceeding nicely…

Firstly, the boards have been populated with resistors and most capacitors. The digital control boards are complete save for the OLEDs, buttons and pots, which will be panel-mounted. Tragically, and despite my heroic efforts at military planning/sourcing, I didn’t order enough 100n capacitors for the filter boards. I now diligently plan my next components order.

Quite some time has already been spent working on the case design and front panel. Using Inkscape, I’ve already ordered and received some test cuttings in 3mm acrylic glass. I’ve firmed-up on some nice ideas that I will expand upon in another post. Still deciding whether to invest in wooden cheeks, but then again, they can come later.

I’ve flip-flopped daily over whether to implement the Shruthi XT programmer, or stick with generic midi control. I’ve now firmly decided to not use the Programmer this time – though I did grab 2 PCBs in the latest bulk order, and I’ve already gathered the parts. The reasons are:

Using the programmer would mean direct control over only one Shruthi, which would be fine in Poly mode, but not ideal for other configurations (e.g. 4 independently-controllable monosynths).
By using the programmer I would lose CV control, and thus the ability to indulge my current joystick fetish.
I’ve got other cool ideas for the programmer. Foremost of which will be a keyboard version of the new Ladder filter. 😎

So, MIDI it is, and by chance I have an old beat-up Evolution UC-16 which I will be cannibalizing.

Quite easy to take apart….

I thought there might be an extra MIDI port hiding in there, but alas…

Now, these pots are a bit worn so they need replacing. I suspected they were 10k linear pots. A quick test confirmed this. Problem is that these pots are so welded to the PCB that the cleanest route is to just cut them off…

So now I can add my own pots and arrange then as I wish on the front panel. By also adding the keypad I will have access to 25 banks of 16 MIDI CCs, each knob being freely assignable to any CC on any channel. That’s a lot of control!

Further, this can take MIDI input directly over USB, so I can sequence the whole caboodle from a DAW if I wish. But where’s the fun in that?

And why stop there? I’m also integrating my as-yet unbuilt MIDIpal to make this a super-charged master keyboard. Better than the plastic shit available these days, and fully customised. Cheaper too.

MIDIpal has 8 CV inputs = Joystick pron! hehe

The bonus is that, with 4 Shruthis I will also have a routable 4-in 4-out MIDI interface.

Rory Gallagher – Want Ad Blues

[embedyt] https://www.youtube.com/watch?v=wYSgooW1O7M[/embedyt]

4×4Pole: Doepfer MKE vs Novation – Revenge of the Wheels

I’ve had some time to return to and investigate the wheel connectors on the MKE.

Remember that, when I tested the Novation wheels the range was minuscule. It turns out that the wheel receivers are calibrated to Doepfer’s own standard. It also accounts for the narrow range wheels have normally, due to the spring on the pitch wheel and the large diameters.

A closer look at the Novation wheels revealed 2 x 5K linear pots like so:

The Doepfers are 10K so I decided to use a trusty joystick, this time with the spring intact, to see if it could be used as a mini pitch-wheel.

The result was disappointing. At rest pitch was always at maximum, and moving the stick to one side again swept through the range an a narrow band. No, this won’t do.

To see if I could exactly define this range, I attached a standard 10k linear pot. Again, same result. Hmmm.

So, how could I limit the range of a pot?

Thankfully the answer came quickly and it’s such a simple fix it’s almost embarrassing…

…how about if I just twist the Novation pots in their housing? This way I could tune the range by hand. So, after cleaning the solder off the pins, I plugged the Novation wheels back-in, loosened the pots and re-orientated them.

First, the potentiometer tabs needed to be clipped-off. (I now know what they’re for – holding the pot in place!)

Then plugged-in (after removing the solder I left on the pins 😛

And, by Jove, it works like a charm!

The main caveat is when re-orienting the pitch-wheel pot – you need to account for the spring, so best to have MIDIox or other such monitor open to see when you’re at zero before tightening the nut. The pots are d-shaft, so in this case I could easily find zero.

Here they are with their pots newly-oriented and wheels re-fitted.

Everything is now up-and-running with the MKE. Superb!

Buoyed by this success, I’ve decided to adopt a modular approach to the 4×4 pole enclusure, wherein the synth section will be detachable from the Keyboard.

Because, who knows, I might want to build a 4xLadder Filter at some stage…

😀