Drums of Doom!

drum on a breadboard

A drum on a breadboard

So, I’m currently enjoying a few days off work and have got some time to play.

This was originally meant to be a short post to update all that’s been happening here in the lab. As it turns out that’s quite a lot so apologies for the slightly epic length of the post. You may want to get a drink and a few snacks before you go any further.

What have I been up to you may wonder?

Well on Sunday like any other attic dwelling mad inventor I’ve come up with a drum circuit. Initially I started by putting another circuit I’d found together on a breadboard and promptly blew up the chip it was based around. Sadly there was no explosions or even a puff of smoke. It just ceased to do anything at all.

Anyway taking the basic idea of the circuit I decided to construct it using a hardier chip at it’s centre. After much head scratching, maths, scrabbling round in boxes looking for capacitors and nearly deafening myself with some rather loud high frequencies, I have success.

drum on a breadboard

Drum circuit on breadboard being driven by the TRG-1

I got a little excited and used it as the kick in a track I’m working on. Also featured is my half completed dronesynth in rhythmic mode.

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At the moment I’m still using the TRG-1 as a trigger conditioner and control voltage source for it. Eventually it will have it’s own dedicated circuit for this along with EQ to further shape the sound. I may even go crazy and add in a few other features depending on if I have any spare op-amp sections left over.

Dronesynth construction is still coming along nicely if a little slowly recently. more on that with the pictures below. First here’s a few more samples I’ve recorded along the way:

fuzzbox in progress

Fuzzbox assembled but still awaiting artwork.

To start with we have a little 6/8 number produced by subdividing the same square wave by different amounts to feed the tremolo circuits of each of the four voices. There’s some added delay which I was messing with as I recorded this.

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Next we have the four voices with their pitch being modulated by the psycho lfo output with no glide. the tremolo circuits are all being fed by the same square wave. There’s a little bit of delay and reverb added

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This next snippet reminds me rather of some of the Indian raga’s we studied at college many moons ago. Its just the voices with their pitch being modulated by the psycho lfo with a small amount of glide. Again there’s a bit of delay and reverb added.

finished fuzzbox

Fuzzbox finished and ready to play.

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This is a rough drone track I’ve thrown together in Logic. Just 5 tracks of the dronesynth recorded as I messed around with it layered up with a few effects added. It’s about 10 minutes long.

While you’re listening to that here’s a run down of what I’ve been building recently.

Firstly we have the fuzz pedal I’ve built for Dave (The Reverse Engineer).

I built him a preamp for piezo pick-ups for his thumb piano last year and this is a fuzz to go with it so he can get that Konono No. 1 sound. It’s based on an old circuit from Craig Anderton’s ‘Electronic Projects For Musicians’. It uses a logic chip rather than op-amps or transistor hence the name ‘Fuzzy Logic’ I’ve given it. The circuit is slightly altered from the original.

fuzzbox finished view 2

Another view of the finished fuzzbox.

In the process of building this I’ve managed to build myself one as well as the first one I made didn’t fit in the enclosure I’d bought. Having played with this a bit I’m really rather happy with it as it’s a nice sounding fuzz which really doesn’t produce a lit of noise. It’s definitely quieter than any of the other fuzz and distortion effects I own.

Next we have an idea I had one day and literally whacked together with a hammer! It’s a basic idea at present. You have a block in a chamber with switches at either end which connect to a midi interface.

It’s shaken as you would a real shaker and as the block hits the switches either end it sends key down command which controls a sound in a sampler. All very rough at the moment but it works. I’ll be coming back to this when I have a bit more time.

midi shaker prototype 1

A very rough prototype for a midi controller to emulate a shaker.

I’ve been doing my best not to get distracted by other projects until I’ve finished the dronesynth and on the whole have succeeded. The plan when it’s finished is to go wild and crazy and build a eurorack format modular synth. The intention is to make a large amount of it myself as there are some fantastic diy projects out there.

So far I’ve purchased my first board and have finished assembly of it apart from the connectors.
As I may have mentioned before it’s Thomas Henry’s Mega Percussion Synth. It appears to be a extremely versatile design and I can’t wait to be able to play with it.

Anyway, back to the dronesynth. Progress is coming along nicely. Since my last post I’ve added a power supply and the low frequency oscillator boards.

mps board assembled

Assembled board for Thomas Henry Mega Percussion Synth.

Initially I was using a battery to power my dronesynth as I developed it. It’s now reached a point where it needed more power than a 9v battery could supply for long. I tried a wallwart as a temporary measure as I don’t have a bench psu, but it generated so much noise I quickly abandoned that idea as I couldn’t hear what the synth was doing. So I knocked up the little number pictured.

I’ve been particularly pleased with the lfo’s. Initially I was just going to use the lfo based on Ken Stones Super Psycho LFO, but as this only outputs ramp and square wave pulses along with its main output I decided to also add another triangle/square wave lfo with a much wider speed range.

The additional lfo has a range from sub audio frequencies down to a several minutes per cycle. I wanted these slow speeds as it will be useful to modulate the filters when they’re built for slow subtle changes in tone.

I’m very happy with the Super Psycho LFO. It’s much better than I ever expected it to be and I’ll be re-using my adaptation of the design as a module for my modular when I have a chance. There are still a few modifications to be made before it’s fully complete.

super psycho diagram

A rough diagram to give some idea what the psycho lfo does. For simplicities sake I've just illustrated this with pulse waves. On the left you have the 4 waves that drive the circuit and on the right the output - the top being the sum off the four inputs and the bottom with a degree of glide applied.

dronesynth psu

Power supply for my dronesynth completed.

Adjustment is needed to the levels of the ramp wave to bring it up to the same level as the pulse waves. I’m also adding trigger pulse outputs to each of the 4 lfo’s which drive the unit. These will be used to drive the tremelo circuits in the voices and also to drive external sound sources such as the drum I started this post with.

So the modulation source currently has 8 possible outputs which can be used to modulate the voices and eventually the filters. They are:

  1. triangle wave [slow lfo]
  2. square wave [slow lfo]
  3. super psycho pulse/ramp 1
  4. super psycho pulse/ramp 2
  5. super psycho pulse/ramp 3
  6. super psycho pulse/ramp 4
  7. main super psycho output
  8. NAND mix output
lfo board being added

Lfo board (bottom) of the modulation section being added - thats 8 modulation sources there!

Still to be added is a board with two AR envelope generators which will take external inputs from any percussive signal. I’m also going to normalise them to two of the trigger pulse outs from the psycho lfo so when they have no input from the outside world they will work as 2 more lfo’s with adjustable rise and fall.

My idea to use an array of NAND gates to mix all four pulse outputs has worked amazingly well also. I spent a lot of time drawing up truth tables until I came up with what I thought was the best combination and I’m very pleased with with the pseudo random output the circuit generates. It’s also pretty useful for generating seemingly random percussive effects.

My thinking behind the whole of this build so far is to get the greatest amount out of each part of the circuit to make it as versatile as possible. many of the things I’ve learnt so far I intend to take forward into my modular as I build it. The dronesynth has already given me quite a few ideas.

lfo board having more wires attached

Lfo board having more wires attached.

The best thing though has been learning to play my creation as it evolves. It’s only been by playing it that a number of new possibilities have come to mind. I had vague ideas about what kind of things I could get out of this but the more I play with it the more I discover.

Sure, it has certain limitations. I’ve always found limitations to be quite inspiring. Being presented with infinite possibilities is quite frankly bewildering.

I think I’d better leave this now. There’s only so much time I want to spend here in front of this computer. I’m off to make some music while I have the time and space to do so. This is after all the reason I do all this 🙂

It’s been a while since I’ve been inspired to noodle an I feel I ought to make the most of it. Although it’s just occurred to me I haven’t written a post about my record habit for a while. Watch this space, I will be back…

current state of dronesynth

Current state of dronesynth

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