Matrix Mixers, made, sold and available(ish)

It's been a busy few weeks...I finished this week the first run of four Mini Matrix Mixers

As you can see they're finished in lovely splatterpaint and I think they've turned out really well. I have been talking about these mixers for a while and a few people expressed interest even before I announced the prices. In fact three of these four are already sold with 2 in the post and 1 to be hand delivered tomorrow (brilliant random coincidence of being in the same city for a day out as someone who wants to buy one!)

So there is one more available currently although I'm sure I'll be making some more soon. These Mini Matrix Mixers cost £30 plus postage and packing which is £3.65 if you're in the uk..if interested ping me an email to: concretehub(AT)yahoo(DOT)co(DOT)uk and we'll work it out.

On a related thread I also made up these 2 prototypes of my passive 4 - 1 mini mono mixers and despite a little trouble (I'd made a slight error on the layout) they've turned out really well, one has gone to a good buddy and I'm keeping the other one, but I plan to do a short run of these this week. They'll be £10 plus p and p so again ping me an email if you're interested.

Mini Matrix Mixer piece

Heres a track I uploaded the other day, it's made from some edits from a jam session with 3 fx units and a circuit bent talking computer.

Help me...I'm Melting

So todays adventure...I managed to get my homemade furnace up and running and melt down a small amount of aluminium scraps and pour it into a crude sand cast to make a vaguely cylindrical bit o metal..

So above is the shot of my setup! Its an old paint tin into which I cut a hole and for a small tube to go into (about 15mm outside diameter about 12mm internal). In the bit of the tube that is inside the furnace I drilled a series of small holes about 10mm apart in a line to allow air to escape the tube. The paint tin was then lined with a 25-30mm depth lining of fire cement ( a lot of online guides for furnace making have quite complicated refactory mixes to line furnace but for a small one like this about 8quids worth (a large tub) of fire cement will do the job).

I did the cement lining of the base first up to the depth of the hole for the air tube, which I then cemented in place and then built up the sides.

On the end of the air tube is a cutoff plastic bottle top as a kind of wind funnel and then place in fron of the funnel is a hair dryer (set on cold..warm air is not as good and it would burn more electricity anyway). The piece of terracota pot on top was acting as a slight lid to try and keep as much heat in the crucible as possible. The heat is supplied by lighting a small fire of some broken down pieces of charcoal briquettes, incidentally the charcoal sold for bbq's will work (it's what I used today) but they say that better quality charcoal will burn hotter for longer.

I used a steel can as a crucible and after a while heating and adding aluminium scraps I poured the results into a crude sand mould which was a small tin filled with builders sand, very slightly moistened so it held shape.

Here's the result! Its vaguely round and although looks rough (due to the lack of resolution offered by building sand..oh and that I just pushed a lighter into the sand to make my mould!)..it would be round enough to put into a lathe to make something from...I WANT A LATHE SO BAD!

Next steps for this at some point are to buy a small amount of casting "green" sand and make a cope and drag (like splittable cases for sand moulds) and get casting some more interesting shapes.

If you're interested in casting metals please don't just read this...read as much as you can on the web as there is lots of safety stuff you need to follow...like don't wear any synthetic fibres as if you are splashed they will melt and stick....EEEK

Making Mini Matrix Mixers

So a bit late...Happy new year!

I've been continuing my odyssey into PCB manufacturing and have designed and built this small (10cm by 9cm) passive matrix mixer with 4 inputs and 4 outputs. I'm currently building some more of these and am going to try and sell them online which I'll announce here and via my twitter feed. If you're interested in these I've done a couple of videos, this first one explains a bit about how they work before venturing into some feedback sounds at about 3minutes..

New handmade mini matrix mixer from concretedog on Vimeo.

I've also done another video today featuring some crazy sounds from a gameboy running the mighty Trippy H...its a bit of a slow start but I like the sounds about half way through....

More Mini Matrix Mixer from concretedog on Vimeo.

Finally if you want further examples of matrix mixing on of the tracks of my album "The coracle and the yellow shell" was made completely from a matrix mixer setup with a string reverb and other bits...here it is..



So stay tuned and if you have any questions feel free to get in touch.

Getting my process sorted

Got a bit more time yesterday to build a couple more mixers based of the PCB I made. I am definitely a convert to PCB making as although it takes a good while to make, etch and drill the PCB's when they are done it takes no time at all to assemble them with the components. I've redesigned the board for these to accept phono sockets so after xmas I'll make some of these and possibly try and sell some...I am designing a larger more unusual mixer (more details soon) which is my main idea at the moment.

Making PCB's..thinking of manufacturing a few bits

So this week I've been experimenting making PCB's using a great freeware package for windows ExpressPCB

I'm using the toner transfer method, laser printing onto glossy paper and then heat transfering the toner onto the copper clad board (ironing the back of the paper on the hottest setting!) I'm then soaking off the paper and etching the boards using Ferric Chloride. Here's a board thats the result of this process.

The board above is for a simple 4 - 1 passive mono mixer which is based on the ones I've made for my CMOS synth stuff. I just wanted something relatively simple to make to get to grips with making the pcb's. Below is the resulting prototype a TINY mixer.

And another shot of her getting tested...

So I plan to make a couple of these for friends and maybe some more for myself, I realised that this board could also be built up with full size pots and audio connectors (jack/phono etc) and stuck in an enclosure so I am going to release a pdf of the board for if people wanted to build there own but I need to do a bit of documentation first. I may do a few boards and offer then for sale. I have more plans for PCB making though and have a few more ideas for small unique things I can make and maybe sell...so stay tuned!

The Missing link...diy usb otg

I've been playing with some old nokia tablets (thats right not phones!) I've recently picked up a nokia n800 and an n810 for the retro handheld collection...(I think I need a display cabinet soon...) The n810 is great and actually has many uses for me day to day. I've been away this week and its made a good hotel wifi browser, great note taker  document tweaker with its nice hardware thumboard, and a useful link/transfer device when I needed to get some large audio files off my zoom recorders sd card and into my phone for a bit of on the fly editing. As a transfer device the n810 is very useful as it has 2gig of built in storage as well as an sd card slot....sort of....its a MINI sd slot (not micro) and amazingly I had a micro sd to mini sd adapter from an old phone. This means you can drag stuff off a card and back onto another card although I just did some big bluetooth transfers.

Anyway I was aware that with a USB on the go (otg) cable you can actually connect stuff to the 810 with the 810 acting as host...I hacked together a cable today and got this working (albeit a bit limited) it seems to only work for pendrives but for me thats really useful. I've been playing with powering usb hubs to try and get harddrives running to it but no luck as yet!

To make a USB otg cable you basically have to cut 2 cables in half one that has the micro b connection for the 810 and one that has a femal usb socket. Each cable end should have 4 wires, red, black, green and white and also a bare wire earth sleave wrapped round the other wires. Firstly you have to connect these wire to each other matching the colours and also connecting the earth wire. Then the slightly tricky bit is that the micro b end needs to be opened up (I carved the plastic back off the connector carefully using a razorblade). Once you have exposed the connections to the micro b socket you should discover you have one pin that is unconnected. (this is pin 4 and a lot of tutorials on making these just say to connect "pin 4" to earth...I think it easier to just find the only unconnected pin as it is ALWAYS pin 4 that is unconnected). So then with all the connections visible you want to solder a small wire to the unconnected pin and the other end to the edge of the metal socket housing therefore connecting pin 4 to earth. MAKE SURE that you now only use this for usb otg type operations as when you connect this cable it will want to put the device into host mode.

Anyway, I'll continue to tinker with the n810 and any more useful stuff will be posted.