Remote studio experiment

For testing the different devices I design within the Electronics workshop, I build test-objects, that on itself are very interresting to work with.
The remote studio is one of those projects. For testing my OSC-DA convertor board, I implemented it with 8 old Sonology function (VFUG) generators, to see the possibilities.

The design and realisation of the remote studio started out with the testing of the OSC-CV boards (16 times 12 bit analog output). I wanted to have a possibilty to test the stability, functionality and precision of this board. We just renewed the VFUG's (voltage controlled function generators) from analog studio Bea-5 and the old VFUG's were abslolete. For me a good opportunity to bring them back to life.


 vfug front The VFUG
The VFUG is a Voltage controlled Function generator.
The module consists of several switches on the front: 

Function: switches between sinewave, triangle,, rectangle, pulse
Range: sets the maximum frequency
Fine: fine tuning of the frequency
Int/Ext: when frequency is not driven from an external source, it can be changed manually.
Control: switch between internal and external control
Fine On/Off: switches the fine tuning On/Off.
AC/DC: switches between AC and DC output (serial capacitor in/out).

rs daboard DA-Board
First I started with connecting the external voltage control of the VFUG generator to the output of my DA board and I was able to change the frequency, by changing the value between 0-5V.
But I was not able to able to set the 'range' and the ' function'. So the first setup of the remote studio was poor; pure testing of my DA board.
vfug side OSC-Relay board
To solve this switching problem, I designed a OSC-relay board, which could do the switching and overruled the rotating switches on the front. The relay board consists of 12 relays, a driver chip and a PIC18F1220 microcontroller.By sending the right OSC string to this relay board, the switches could be controlled from a Max patch.
remstudio 2

The remote studio
The remote studio has 8 VFUG modules. Each of them can separately be driven. So I made 8 x osc-relay board and bypassed all the switches on the front.
The next step in the setup of the remote studio was the osc-volume control. I wanted it to be possible to also change the volume per VFUG, so a nice mix could be made.

This osc-volume module was created by JoepJan vd Hoeve, who made it his graduation project for the HTS in Rijswijk (University of applied science). I was his mentor.

osc mixer

The OSC-volume board
The OSC-volume module is designed around SSM2164 VCA chip (or OTA) in combination of the DA board (2 x TLV5610).
In principe the design of the mixer is the same as the DA-board (more or less the same firmware), but the outputs of the DA chips are directly connected to the Voltage Controlled Amplfiers (ssm2164). In this way, every VFUG has it's own volume control.

rs matrix

OSC-Matrix (16 in/16 out)
To be able to connect different signals together and to be able to make the remote studio more dynamic, I designed a nice matrix board. This matrix is designed around the Analg Device chip, the AD75019. This CMOS chip has 256 switches onboard, that all can be put on/off seperately. The chip works with a balanced power supply, so it's ideal for switching audio. In case of the remote studio, the matrix can function as an 'old fashioned' patchpanel.

rs vosim

OSC-Vosim
To make the remote studio more fun to work with, I introduced two Vosim modules.
These Voice Simulation modules are connected to the matrix and can be driven from the VFUG generators. The vosim modules have multiple inputs and multiple outputs. How the Vosim is linked to the matrix, can be checked in the documenation of the remote studio (see the other tab).

 remstud patch14 Remote studio Patch
To be able to control the remote studio, you need to use the right patch, sending the right OSC strings. The patch can be found at the osc-download section.
In the next tab there is an explanation of the patch itself and how to work with it.
nicecast2

Itunes streaming
To be able to listen to the 'mixed' output of the remote studio, i have an dedicated minimac running the program Nice-cast. This program streams the output of the remote studio to the internet. By adding the right ip-address and port number into your iTunes app, you can listen real time to the remote studio, that you can control remotely!. So in fact you can work with these modules and have some good quality audio results on the fly.

 

Like explained in the introduction, the remote studio consists of a few different modules, that can all be controlled separately.

remstud patch14 Remote studio total patch
This picture shows a screenshot of the max patch version 12. On the top a row of 8 VFUG's. In the left corner the matrix. And on the right the two vosim modules.

vfug patch14 VFUG patch
The VFUG patch is more or less a copy of the front of the real one. with the big dail the frequency can be changed. The range of the frequency depends of the setting of the range, which can be changed with the small radio buttons (10, 100, 1k, 10k).

THe type of signal can be chanegd with the 4 radio buttons in the middle (pulse, Block, square, sine). The volume of the module is changed with the fader on the right side of the module.
vosim patch

Vosim patch.
A vosim can generate a (pulse)train of half sinewaves. The amount (n), the decay and the frequency of these half sinewaves can be manipulated. The trigger input is needed to give the 'train' a startpulse.
The Vosim patch and module have the following inputs:
- Frequency. this is the frequency of the sinewaves.
- Decay: If the decay is 'zero', all sinewaves have the same amplitude. When changing the decay value, the amplitude of the 'train' will decrease.
- N: this parameter determines the amount of sinewave pulses. The maximum is 12 pulses. The minimum one.
- Trig: this input needs some triggersignal to start the Vosim. Without a triggerinpt the Vosim will not work.

Both faders determine the volume ouptut of the vosim modules.

matrix patch

The matrix.
By selecting the separate bits within this patch, connection can be made between the serveral modules. The outputs of the VFUG are connected to 0 - 7 vertically. The horizontal connections are the ouptuts.

So if you only want to listen to the toutput of VFUG0, you have to select the red dot in the upper left corner (0,0) to make the connection. If you want to add the OUtput of VFUG1 to that, you can select red dot (1,1). And so on.

The two vosim's are connected to 8-15. (check the labeling). In the next tab, I will explain all connection with some block schematic overview.

 

Remote studio Setup

 

 remote studio setup2

 

In the block-diagram above, you can see exactly how the whole studio has been setup. The orange arrows indicate the different OSC -trings. So by sending /v1, you address the DA-board. By sending /sw, you drive the switches (sine, rect, 10 10k). Osc string /ma for the matrix and /g1 for the volume control.
At the left side the main DA board. This board has 16 outputs, from which the first 8 (0-7) outputs have been directly connected to the external frequency input of the VFUG modules. The output of the VFUS modules are connected to the first 8 inputs of the matrix.

Voltage outputs 9-16 of the DA board, are directly connected to the matrix, making it possible to patch them anywhere you want. The inputs of the Vosim modules are 'normalised' to output 9-16 of the matrix. The output of all modules are connected to the osc audio mix, making one mono signal mix. The output of the remote studio is connected to the minimac, streaming the audio to the net.

 



How to work with the Remote studio.

Before working with the remote studio it's important to know the following: For now (october 2013) it is only possible to work with the remote studio from within the Royal Conservatory. This has got to do with the internal firewall settings and policy. In time I will try to get a dedicated portnumber to work "in" the studio also from outside the Conservatory.

Step by Step:

1. Download the right max patch, install the patch and run Max/Msp
2. Make sure you send the OSC strings to the right ip address and port number. The ip address of the remote studio: 10.1.60.68. port number10001.
So the udp object will look like this: udpsend 10.1.60.68:10001

3. Run iTunes and open stream (cmd U). Fill in the ip address and port of the NiceCast broadcast: 10.1.15.250:8100
password: ipson and login: ipson. You can also fill this link into your browser: http://10.1.15.250:8100/listen.m3u.

4. At the start all volume is probably on zero. If you move the faders initially (so you send some volume inforation to the studio), the volume will be set and you can hear the streaming audio from the studio. Be aware: there is a siginificant delay between the moment you change a setting and the moment you will hear this change happening in iTiunes.

 

osc-relais

matrix v2