Amphibious Thoughts » Diskokugel

Trying to make Diskokugel louder

user — Tue, 01 Nov 2011 16:00:11 +0000

After my first experiences with the [Diskokugel] circuit building [Audioweb] and [AudioSphere] I tried to optimize the circuit for further use. That means I tried to look for a way to get some head room with the volume, since the current design didn’t quite satisfy me volumewise. I discussed the problem with Christian and we did some experiments using a [TDA7053a]. Not only would the TDA make a higher amplification available. Working on 5V instead of +/- 5v, as the transistor circuit works right now, it would have rid us of one power line that has to be transferred into the turning ball via a sliding contact. Also, soldering two chips on the board would have been much faster than soldering those 16 transistors.

The TDA7053 has a DC volume control input, which made us hope that we would simply connect it directly to the 4094 register to switch it on and off, making the 4066 switch obsolete. Unfortunately that didn’t work. The 7053′s offset voltage rises with the applied control voltage, thus producing a crack at the output when raised rapidly. Ultimately we got the thing working by keeping the control voltage at ~0.7V and switching the audio signal on and off with the 4066. However, since in this version all amps are constantly active, I am afraid the whole system would be prone to interferences and the power consumption would be very high. I had a very hard time testing the whole setup. I don’t know if it was my breadboard or whatever, but something started oscillating regularly and there was never a setup tat was save from that or other interferences. Christian told me however that he got something working.

I am not sure how to proceed yet. I think I will stay with the old circuit for now and see how far it takes me. After all, one result of the experiments with the TDA was that a higher volume makes it harder to locate the source of the signal. That would be sort of counter productive. It also shows that there are possibly limits to the use of this whole technique…

Audioweb 0.1

user — Mon, 05 Sep 2011 08:29:10 +0000

As a special gimmick for my birthday party i used the elements of [Audiosphere] to build a web o 6×6 speakers on a wall in my room. The sensation is, of course, a different one and since its now totally at hand, I will do some more experimenting in the next weeks.

the cable length of the sphere didn't fit, so it doesn't look perfect yet. I still like it :)

AudioSphere for PDCON

user — Sun, 14 Aug 2011 13:34:51 +0000

Having introduced the [Diskokugel] project at Berlins biweekly [puredata] [user group], I was asked to build an installation for the finalizing event in Berlins [LEAP] gallery. Being busy doing technical coordination for the [Über Lebenskunst Festival] this was quite a task.

I used the five prototype circuits to build a walk-in sphere of 40 speakers. The speakers were attached to nylon strings stretched from the ceiling to the ground, so you could bend them aside to step in. In an effort I provided a crude interface in PD that provided a joypad for people inside the sphere to select different programs, such a random, sound going in circles, etc.

Contentwise, we had placed a call for content, which resulted in one piece that was handed to me and which worked quite well. I have yet to get the adress of the composer to thank him again ;)

The result was quite to my liking and so was the feedback (apart from nobody understanding the interface, but in the end that didn’t matter much). The sphere was fun to use. I personally found it pretty dizzying standing inside the speakers while the sound came from a different direction every 25 milliseconds. Unfortunately, as of now there are no pictures to show. The installation stood at LEAP only for two days, in which I had forgotten to bring my camera. Hopefully I will find someone of the PDCON who made good ones.

[UPDATE: pictures of the building process and a picture from a mobile phone (thanks ckp and astring!)]

a picture by astring

in action. the nylon-strings could be bent apart to step inside. (pic by ckp)

arrangement of the circuits

some notes

more notes

1,2,3 test…(3)

user — Sun, 26 Jun 2011 14:53:31 +0000

I found the time to go to Leipzig and use the [sublabs] oscilloscope on my [Diskokugel] circuit. Actually Nobody did that, assisted by Christian. It took a while to get it to work and the result was both satisfying and not satisfying. Because there was nothing to see. The crackle we hear when switching a speaker on and of did not show on the oscilloscope, which means the circuit works perfectly, and leaves us clueless as to the source of the problem. I did some more experiments but still have no idea.

Well, I might just leave it at that. Since the crackle is only really a problem when switching extremely fast or when a pure sine is used. I need to get this ball done now…

nothing to see here...

1,2,3 test…(2)

user — Tue, 21 Jun 2011 09:28:26 +0000

I’ve been quite busy in the last weeks:

I presented my project at the [PD user group] in Berlin and got some interesting feedback. They would like to exhibit the Diskokugel or an installation based on it at the final party of this years [pd-con]. I feel honored but I have no idea if I can actually make it until then. Money is also an issue here. Having all the circuit boards made will cost…

I solved half of my clicking problem by getting the synchronization with the sound phase to work. Still, clicking occurs and since there was no oscilloscope at hand, I recorded it to make sure it’s not some kind of acoustic illusion due to differences in speaker loudness. The waveform clearly shows a distortion when the speaker is activated. When it’s turned off, something produces a sudden click and then the speaker swings out.

I will meet with Nobody and Christian (god praise his patience!) at the [sublab] this weekend and we will check the whole setup with an oscilloscope. I hope that we can fix this easily.

The noise occurring when a speaker is activated

When the speaker is turned of, something gives it an extra push.

1,2,3 test… (1)

user — Thu, 05 May 2011 14:18:31 +0000

Today I did the first test run with one of the soldered boards and the Arduino. After some adjusting it works but I am not quite satisfied.

On the picture below you can see the setup: 8 speakers, attached to the switching board. Between the switching board and the Arduino is a board that converts the Arduinos signals (0/+5V) to the current level used by the switchboard (+/-5V). This converter board also houses a TL072 for pre-amplification and an LM311 to detect the audio signal’s null phase. This is necessary to prevent the speakers from clicking when switched on and of. And it doesn’t work jet. Why, I’ll have jet to find out…

Speakers, switchboard and Arduino connected. To the right is a voltage divider, converting 12V to +/-6V and GND

Diskokugel Electronics

user — Thu, 21 Apr 2011 08:10:50 +0000

Christian provided me with some sample circuit boards which I assembled the last days. Christian already had soldered the smd parts in place . Considering my latest clumsy attempts with the icosahedron, this was a wise thing to do. It was still a lot of work to just get the ICs and transistors in place. Once done, I discovered a major flaw in our board design, since the connectors aren’t yet ready to cascade the things. Back to the drafting board…

However, now it’s done and I can run a test with 40 speakers!

: Five boards to run tests. The smaller one is the first Christian assembled, the others are ready to be attached to the icosahedron.

Re: Diskokugel (icosahedron 2) [Updated]

user — Fri, 08 Apr 2011 19:57:36 +0000

I can’t believe how much time this took. I tried to find someone to help me weld theicosahedron but whatever I tried, something always went wrong. So, finally, I did it by myself. The result is pretty ugly (compared with how it started) and I guess I’ll have to invest some money to have someone professional do this once it proves to be a working concept. Thank god I don’t rely on my soldering talent to survive…

: Not pretty. But robust.

UPDATE:

I took a part of the frame and used some acrylic compound to attach some bodies to it. I am not quite satisfied with the looks of the compound. I’ll try black hot glue the next days. Another alternative could be silicone.

Then I started to solder shims to the points where the frame will be attached to the icosahedron. Lot of work. Lot of progress.

: full view from above. You can see the icosahedron inside.

: From the inside you can see the chrome bodies

: another full view

(Deutsch) Diskokugel Progress

user — Sun, 23 Jan 2011 14:13:11 +0000

PD and Arduino

user — Mon, 18 Oct 2010 16:34:11 +0000

I explored some ways to use PD to communicate with an Arduino. There are wo ways to interact with an Arduio from PD: serial communication via the [comport] object and controlling the Arduino directly with [pduino] using the firmata firmware.

[comport] simply sends and receives serial messages. I found it a little difficult to convert those messages into the right format as to understand and further process them. The PD help file isn’t exactly helpful to that extend, but I found a patch called ArduinoPDMessageSystem that makes sense of the serial messages, even though I haven’t understood every objects function there yet.

So far, I have managed to send messages to the Arduino to interface a HCF4094 shift register controlling 8 LEDs. I use the same register to control my “Diskokugel”, so I heres for the next step to its completion :-)