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a fancy new ring modulator

felix — Thu, 25 Feb 2010 15:10:31 +0000

The twisted sounds I’m squeezing out of the drum machine in this video are courtesy of my fancy new ring modulator.

(The pick was for scale but I just realised the plugs make it pretty obvious)

What a ring modulator does – as I understand it – is take two audio signals and combine them by multiplication rather than addition. The resulting signal contains the frequencies present in the original signals, plus the sum of those frequencies, plus the difference of those frequencies. And another way of saying that is “it uses one sound to totally fuck another sound up”.

Results vary somewhat depending on what you feed it but typical results involve lots of weird overtones, hollow metallic sounds, and discordant, chiming, grinding, squealing noises. Cool. The “Dalek” voice on Dr Who is also a product of ring modulation, a steadily oscillating sine wave modulating a human voice.

In the case of the aforementioned video I’m using a sine wave to modulate the drum machine. Sine waves work really well and are a good place to start but you can also use one synth to modulate another synth or an oscillator to modulate a guitar etc etc.

So what’s in it? If I’d known how simple these devices are I would’ve had one ages ago. If you want to make one like mine, here’s how, written for noobs like me.

Parts:

2 x small centre-tapped transformers (I just used the smallest ones I could find at Jaycar, they were about 5 bucks each)
4 x zener diodes (the ones I used are ~~0.3~~ 3.3 volts, 1 watt. they say germanium ones are better, maybe any diodes will do? I don’t know and I don’t care)
3 x 1/4 inch TS sockets

Really, that’s it. You probably want some kind of box to house it in, but that’s it. No power source needed, no moving parts, no switches and dials.

Assembly:

The diodes have a positive end and a negative end called the anode and the cathode. Don’t worry which is which but DO make sure they’re all facing the same way. You can tell quite easily by the markings. Solder them end to end in a square – anode to cathode, anode to cathode etc – this is the “ring”.
The transformers should have two terminals on one side and three on the other side. On the first transformer, take the two outer terminals of the three and connect them to two opposite points of the ring. Do the same with the other transformer and the other two opposite points of the ring.
Connect the two centre terminals (one from each transformer) to one of the 1/4 inch sockets.
Connect the remaining two terminals on one transformer to one of the sockets. Repeat.

And you’re done! Now connect two of the sockets to your instruments/sound sources and the other to an amp or mixer and modulate away. Any socket can be an input or an output but different configurations do sound slightly different.

Experiment and enjoy.

something to do on wednesday evening

felix — Sun, 06 Dec 2009 21:25:36 +0000

Those of you in Auckland are encouraged to get along to this, beginning this Wednesday the 9th, upstairs at Handmade (the old Brazil) on K’ Road.

Experimental music, experimental instruments both acoustic and electronic, kind of an offshoot of the long-running Vitamin-S but perhaps with more of a rhythmic and melodic focus.

Come to play and listen or just to listen. I’ll try to get there too.

more about plate reverbs

felix — Fri, 26 Jun 2009 12:17:24 +0000

UPDATED:

A few people have asked how this mixer operates and sounds so here’s a wee video:

As you can see there’s a scratchy pot or two to clean and I still need to make some knobs, but so far so good.

Since I posted here about my fancy new plate reverb I’ve made a few adjustments and tweaks.

I’ve chopped the frame down closer to the size of the plate (about 600mm x 1800mm) and stuck a couple more piezos on it, but more significantly I’ve just about finished building a fancy new mixer for it. And when I say “fancy” I really mean “it’s the first mixer I’ve built and it works!”

The piezos seem to give the best results nearer to the edges of the plate (don’t know why) so I’ve got one centred at each end and one centred at each side like a cross, and the inputs on the mixer are arranged to correspond to the placement of the piezos like so:

left long
left short
right short
right long

The switch on each channel is for determining stereo/mono. The two left channels can be switched LEFT or MONO and the two right channels RIGHT or MONO (e.g. in the picture above the channels are assigned to left, mono, mono, right). This simple arrangement allows for a surprisingly wide range of possibilities.

The mixer itself is insanely simple. It’s completely passive (no amplification) so it needs no power source. The circuit consists entirely of:

the 4 input jacks,
the 4 faders,
the 4 switches,
2 sets of 4 resistors in parallel,
and the 2 output jacks. In that order.

I used 4.7 k ohm resistors which seems pretty low according to what I’ve read and heard, but frankly I struggle with the theory of a lot of this stuff so I just tried a bunch of different resistors of different values until I found some which seemed to make everything work ok. The tin it’s all mounted in is mostly empty, so I should be able to fit plenty of other stuff (like preamps) inside without too much trouble if I ever want to.

Do let me know in the comments if you have any ideas or questions. I’ll post some audio clips here soon, probably after the weekend.

For now though, I’d just like to find some more screws and some fader knobs to finish it off. I’m sure there were some around here somewhere…

how to make a plate reverb

felix — Tue, 19 May 2009 12:58:17 +0000

enlarge

Today it stopped raining for long enough for me to do something I’ve been wanting to do for a while – build a stereo plate reverb unit. It took a couple of hours, was made mostly from stuff I found at the tip, cost about $10 and it sounds awesome. If you want to make one of these you can do so with some very basic tools, parts and skills.

The horizontal wires are unrelated. More pics below.

if you’re unfamiliar with how a plate reverb works:

It’s a matter of sending an audio signal to some type of transducer (in this case a speaker) which vibrates a piece of sheet metal (the plate). The vibrations travel though the plate as waves – like ripples from a pebble dropped in a pond – from the speaker at the centre to the edges where they’re picked up by another transducer (in this case 2 piezo buzzers). These convert the wave – it’s shape now altered by the plate – back into an electrical signal and return it as reverb to be blended with the original sound.

Yeah, you can simulate this digitally but analogue plate reverbs have their own special qualities, and if you make your own you’ll be able to create totally unique reverb sounds which are all yours.

As far as I know these type of reverbs were first widely used in the 60s and were considered to be a vast improvement on the earlier “spring” reverbs, the boingy sounding ones that you mostly find these days in Fender-type guitar amps, the ones that make those great clanging noises when you kick them. Don’t kick your amp.

Plate reverbs on the other hand create the rich, dense type of reverb we hear on records by The Beach Boys, The Beatles, Phil Spector, anything from Motown etc etc.

my one sounds like this:

Ok Lani isn’t going to be happy about this, but unfortunately for her this clip is just perfect for demonstrating reverb.

Here’s the dry voice:

and with the magnificent plate reverb:

Here’s a dry guitar track:

and with glorious stereo plate reverb:

the parts i’ve used are

An old steel bed frame (could just as easily be built from wood)
The side of a filing cabinet for the plate
Some small springs from another old bed
A speaker
Piezo transducers (1 for mono, 2 for stereo)
Some light steel wire
Some speaker wire
Some shielded audio cable
Some glue

tools

I used a drill and a pair of pliers. In a pinch you could do it without the drill. Or the pliers.

Oh yeah, you’ll probably need some sort of amp to drive the signal to the speaker. I’m just using my bass head at the moment but I’ll sort out a dedicated amp sometime. Probably.

enlarge

The shack I live in is pretty tight so for now the unit is hanging up on the porch. The plate is attached to the frame by springs at either end. I haven’t tried adjusting the tension on the plate or the placement of the springs yet, this is just as it happened to go together.

enlarge

The speaker is an old New Zealand made Plessey, suspended on wires (to keep the weight down) and positioned at roughly the centre of the plate.

enlarge

As you can see, the front of the speaker cone is about 10mm – 15mm from the surface of the plate. This is just where it happened to land but it seems to work pretty well.

enlarge

The piezo transducers are glued to the plate at each end – one for the left channel and one for the right. It sounds great in mono too but if you have a stereo return or a couple of spare channels you might as well give yourself the option.

what now?

I’ll definitely experiment with the tension of the plate, I think that could have quite a dramatic effect on the colour of the reverb. At the moment it’s quite dark which is nice for some things.
I might play around with the speaker placement, although I’m pretty happy with how it’s working the plate.
The piezos only cost a few dollars each so I might try some more in various places around the plate. I think the distance from the centre should relate to the length of the reverb but I’m not sure about that. With more piezos perhaps I could run several different sounding signals to a small mixer and play with them a bit before sending them to the desk.
Oh, and I want to build a box for it to live in or find somewhere quiet to hang it. It’s fairly sensitive to wind and dogs.

Any other ideas? Have any advice or questions about building these things? Let me know in the comments.

UPDATE:

I’ve now built a mixer for mixing four reverb returns. Read about it here.

robot monkey orchestra

felix — Thu, 30 Apr 2009 03:00:11 +0000

This Friday Auckland sees a rare appearance of the Robot Monkey Orchestra, which is the latest vehicle of head headless chicken Chris Matthews at Cassette Number Nine in Vulcan Lane, 9pm, $10.

Also playing: Charlie Ash, Bang! Bang! Eche!, DJ A.D.A.M.

bfm historical society

felix — Tue, 28 Apr 2009 10:12:08 +0000

Ok so I’m a bit late to this but every Saturday over at bFM, Dubhead has been running a very interesting documentary series on the history of the station.

Called The bFM Historical Society it’s a series of interviews with people who’ve worked in and around the b over the years, starting in the mid 80s which is about when I started tuning in.

It’s already up to episode 9 but you can easily catch up by downloading them all or listening to them online here.

how to pass the time at family gatherings

felix — Thu, 25 Dec 2008 03:58:53 +0000

First, sneak off and find a computer. Which we’ve just done, yeah? I have.

Now just drink until it passes. Here’s a couple of ideas to keep you occupied:

1. Play Auditorium. Speakers on.

2. Watch some hilarious clips of “live” electronic performers faking their shows at deadact.com. Do they think we’re stupid? (Hope that doesn’t ruin your tribal psy-trance raving at the festivals. Or do I?)

3. Listen to some Ricky Gervais podcasts.

Righto.

a couple of things you should know about

felix — Thu, 30 Oct 2008 02:33:08 +0000

First, sorry if you got an old email re-delivered today. I don’t know why that happens but sometimes it does.

Anyway, I want to let you know about a couple of tools for finding music online.

mtvmusic.com

MTV have opened up their huge catalogue of music videos and put them online here – it’s a bit like youtube but just for music videos. And just like youtube, you can embed the clips anywhere. Like this one:

Run-D.M.C. |MTV Music

(If you don’t see the video in the feed or email you might have to click through to bsidebeats.com)

SeeqPod.com

Wired magazine said “SeeqPod lets you turn the entire internet into your own personal iPod” and that pretty much sums it up.

I’ve been using this for a few months and it’s awesome.

Just type the name of an artist, song, album or whatever and it searches the web for any files it can play. It also finds blogs, wikis and myspace pages relevant to your search, tries to help you buy or download the songs you find and allows you to save and share playlists.

You can embed stuff like this playlist I made of a few of my favourite Daniel Johnston songs:

(Again, if you don’t see the playlist in the feed or email you might have to click through to bsidebeats.com)

Oh yeah and it’s free. It’s difficult to describe just how powerful this tool is but give it a try and you’ll see what I mean: seeqpod.com

instrumental for the people

felix — Wed, 22 Oct 2008 07:13:43 +0000

This is a rhythm track I’ve been working on with a lot of nice live percussion.

It does have some mean vocals but before I finish putting it together I thought I might release the instrumental to you all in case anyone else wants to use it. (creative commons license)

download mp3

Instruments used so far include:

more cowbell
agogo bells
my favourite shaker made from a shampoo bottle lid full of rice
a pickled ginger tin played with rubber mallets

If anyone wants higher bitrate copies of this track, hit me up: bsidebeats@gmail.com

good things about vinyl

felix — Wed, 02 Jul 2008 10:38:34 +0000

I used to listen to mp3s while working at the computer (because that’s where they live), but I’ve recently discovered something healthy about listening to vinyl:

You get the micro-breaks for free!

Because every 20 minutes you have to get up and flip the record.

Just one more reason why records are still the coolest format ever and CDs will never catch on.