3.2 Digital Mixing Desk

Constructing a digital mixing desk is not as complicated as it sounds.

• IOs and CPU cycles will be provided inside a personal computer (may be equiped with dsp-power, we come to that later).
• Regarding Hardware (e.g. faders) starting point is - at the time of this writing - the MIDI Box project.

Figure 2: wired feeling. it works.

3.2.1 MIDI Box

1. ABOUT THE MIDI BOX PROJECT
   • MIDI Box is a microcontroller based DIY project. The controller (PIC16Fxxx) comes with a preinstalled bootloader, a complete java-2-MIDI control software, various operating systems and well documented source code. Big thanks to TK.
   • The PIC provides the typical 10bit ADC resolution. It can handle 64 faders, 64 rotary encoders and 64 knobs.
2. STANDART 7BIT RESOLUTION WITH 64 FADERS (58MILLIMETERS)
   • This is my first experiment. Finaly I found very cheap 58mm faders with a good feel. (see Galery)
   • Most of the time we use faders for doing a multitrack mix. Pan and EQ along with Efx are static most of the time even in Jazz and standart pop mixes. This is not desirable; but this is what practice shows when you work in a studio... just look at how others work. So... as a (bad) compromise I left these controls to be set within the computer monitors.
3. ... WITH ANTILOG FADER CONTROL

This is a topic I am thinking about for a long time: How about re-using logarithmic faders of the good old consoles to control digital mixers ?

First I thought of analogue antilog circuitry, but this is way too complicated (and too expensive).

Well, the solution is there with a bit of assembler programming. PIC16Fxxx is in the MIDI Box project. See here (yes link missing.) And it has a 10bit ADC. The assembler code is ready to use along with a bootstrap loader and a complete java interface.

I guess in the near future we have PICs that provide 14bit or more ADCs in affordable PICs - becoming suitable for a detailed lookup-table (needed eg. for those marvelous 150mm log faders in old -wasted- Siemens mixing consoles). Already 10bit seams to be an interesting option. And it’s already there. With motorfader support!

At the other side PD (or MSP) is there to provide you with a state-of-the-art digital mixing console.

3.2.2 A simple desktop PC will provide enough CPU cycles

1. It takes only a few hours to programm a mixer within Max. Your multitrack player will be rewire slave and IOs are the ones you provide within your asio setup.
2. For better latency we use Creamware Scope DSP cards. These are available at a price as low as 200.-EUR . I am speaking of the Pulsar PCI card, Revision I, with 4 shark DSPs and no less than 20 IOs (on ebay). These cards are cascadable. Moreover cards with up to 15 shark DSPs are avaylable. These a programmable with a interface comparable to the Max/MSP interface. Creamware provides ready to use mixers, which fulfill professional requirements. (more or less)