rack: loaded and powered up

By Han-earl Park | Published: October 21, 2008

Here’s the test of the power supply and the power inlet of the patch panel.

rack, loaded and ready for power on test

rack, loaded and ready for power on test

rack, loaded and powered on

rack, loaded and powered on

Posted in construction, hardware | Tagged , , , , , | Comments closed

enclosure and power supply (intermediate version)

By Han-earl Park | Published: October 18, 2008

Here’s photos of the intermediate version of the power supply in its enclosure.

power supply loaded into enclosure

power supply loaded into enclosure

power supply loaded into enclosure (alternate view)

power supply loaded into enclosure (alternate view)

The front of the unit is at the top of the image, and the back is at the bottom. You’re also looking up at the the unit in these photos. Power switch and LED indicators are at the top left of the image, all external connectors are on the panel at the bottom (see the panel arrangement). The 12V supply is above the 9V in these images. The pre-amplifier is missing in this version (there’s a pass-thru as a place holder).

You might notice the slightly odd choice of securing the components to the top of the enclosure instead of the bottom (I hope this will not prove to be a problem in terms of heat dissipation). I’ve done this because it’ll be easier to access the internals of the device due of the arrangement in the rack case. We’ll see how well this works…

Posted in construction, hardware | Tagged , , , , , | Comments closed

power supply (early version)

By Han-earl Park | Published: October 12, 2008

The power supply has to provide, at a minimum, 0.7A @ +12V for the VL70m (power consumption measured at 0.6A @ 13.1V), and 1.3A @ +9V for the pitch-to-MIDI converters (GI-10: 0.26A @ 10.2V; GI-20: 0.8A @ 11.3V). Eventually, it will also provide bipolar power for the pre-amplifier (±12V or ±15V likely created using a charge pump converter).

Mains electricity is dropped down to 15V by a switched mode power supply (thus, I won’t have to work with 230V directly). The 15V supply is then regulated to 12V and 9V.

Quasar Electronics 3060 schematic

Quasar Electronics 3060 schematic (image copyright Quasar Electronics)

I use two 3060 kits from Quasar Electronics to provide 12V and 9V with the following changes:

  • use the L78Sxx regulators (L78S12CV for the 12V supply, and L78S09CV for the 9V)
  • use superbright LEDs (5.1kΩ current limiting resistor for the 12V supply, and 3.6kΩ for the 9V)

Additionally, I’ve modified the 9V supply as follows:

  • replace WO2M bridge rectifier with a 2W01G to account for the greater current
  • two heatsinks to help dissipate power (we’re dropping almost 3V @ 1.3A)
Posted in construction, hardware | Tagged , , | Comments closed

pre-amp outline

By Han-earl Park | Published: October 3, 2008

The old version of io connected the output of the synthesizer directly to the amplifier. [see: figure] This wasn’t too much of a problem since, though unbalanced, the signal was low-impedance, line-level.

There were, however, a couple of less desirable aspects to this. One was that the drivers (the woofer and the tweeter) would not be receiving signals tailored to their frequency response. Another was that there wasn’t any easy way to alter the signal level going to each driver.

io 0.0.1 beta++ will have a pre-amp that links the synthesizer output to the amplifier. Each channel will pass through a filter (optionally bypassed), a gain stage and a balanced line driver.

pre-amplifier outline

pre-amplifier outline

I haven’t decided whether the filters will be first-order, second-order or some combination of those (e.g. first-order for the bass driver, seconds-order for the treble). I’m planning to build this component into a separate board so that various filter response types and frequencies can be easily tested out.

The boost stage is something that I needed when dealing with some amplifiers in the past (I generally asked that the venue / space / promoter provide the amplifier). The actual gain amount will be set by an internal trim pot, but I’ll put a volume pot between this and the balanced line driver.

I initially planned to build the balanced line driver from a few op-amps and discrete components until I discovered the existence of ICs that implement these. (For example, the TI DRV134 and the Analog Devices SSM2142.) I plan to use one of these in the pre-amp.

Posted in construction, hardware | Tagged , , | Comments closed

enclosures: patch panel

By Han-earl Park | Published: September 19, 2008

One of the, again, less glamorous, but practical elements of io 0.0.1 beta++ is the patch panel. The panel holds the connectors that need to be accessed frequently (with the exception of the audio inputs to the pitch-to-MIDI converters since they already reside on the front panels).

Patch panel (bottom unit in rack)

Patch panel (bottom unit in rack)

The connectors are, from left to right, IEC power connector, two XLR audio panel connectors, two 1/4″ phone connectors (for use with the pitch-to-MIDI converters’ foot switches), MIDI input and output connectors (that allow one of the pitch-to-MIDI converter’s output to be intercepted, or to patch an external MIDI signal into io 0.0.1 beta++) and a 8-pin mini-DIN Mac serial connector.

Patch panel (left)

Patch panel (left)

Patch panel (right)

Patch panel (right)

Incidentally, if the rack case is placed on its side, the left side of the patch panel will be nearest the floor. Thus, if oriented that way, the power and audio output connectors (most likely heavier cables, and needing to trail a reasonable distance) will be lower, and the serial connector (most likely headed up to a table or chair) will be higher.

Posted in construction, hardware | Tagged , , , | Comments closed

enclosures: pre-amp and power supply panels (physical artifacts)

By Han-earl Park | Published: September 18, 2008

As an update to the previous post, here’re photos of the machined and loaded panels.

Front panel

Front panel

The front panel holds, from left to right, the power switch, 4 LED indicators (+15V, +12V, -12V and +9V), two filter bypass switches and two output level pots.

Rear panel

Rear panel

The rear panel holds, from left to right, stereo audio inputs (unbalanced), stereo audio outputs (balanced), power output connectors (two for the +9V supply and one for the +12V), power input connector (+15V DC).

Posted in construction, hardware | Tagged , , , , | Comments closed

enclosures: pre-amp and power supply panels

By Han-earl Park | Published: September 16, 2008

One handy box that forms a crucial (if unglamorous) part of io 0.0.1 beta++ contains the audio preamp (basically, a couple of filters, signal amplifiers and a balanced line driver) and power supply/distribution components (9V, ±12V). I don’t have a name for this box yet, but here are the layouts for the front and rear panels.

Front panel (click to see SVG image)

Front panel (click to see SVG image)

Rear panel (click to see SVG image)

Rear panel (click to see SVG image)

The enclosure I am using is the Hammond RMCS9018 half-width, 1U rackmount enclosure [see PDF drawing].

Posted in construction, hardware | Tagged , , , | Comments closed

site update

By Han-earl Park | Published: September 16, 2008

Been a little while since I last posted. Been busy with, among other things, io related business which I have unfortunately neglected to document here. (Some catchup will be necessary to bring this constructor’s diary up to date.) Anyway, shouldn’t happen again.

I have also learned a lot more about WordPress (with both Stet Lab and buster & friends powered by it), thus the revamp of this site….

More to come shortly.

update

I’ve moved this site from www.busterandfriends.com/io++ to www.busterandfriends.com/io (the side affect being that the old io 0.0.1 beta site is now archived at www.busterandfriends.com/io_archive).

Posted in website | Tagged , , | Comments closed

In Conversation with an Automaton

By Han-earl Park | Published: July 1, 2008

‘In Conversation with an Automaton: Identities and Agency in a Heterogeneous Social and Musical Network’, my article on io 0.0.1 beta, is published in the Leonardo Electronic Almanac.

Posted in theory | Tagged , , , | Comments closed

enclosures: rack spaces

By Han-earl Park | Published: February 3, 2008

Rackmount components: 2U or 3U?

Posted in construction, hardware | Tagged , , | Comments closed

schedule 0.0.1

By Han-earl Park | Published: January 5, 2008

Okay, let’s quickly revise the proposed timetable by shifting the start back by four months (i.e. to the present), deleting one of the breaks, repositioning the other, and see what we get.

intermediate objectives (projected)

initial design phase: january 2008–

Software: design, preliminary implementation and testing of software components.
Analog electronics: design and testing.

alpha build: may 2008

Software: initial working system.
Electronics: begin final build.
Hardware: begin construction.

break: june-july 2008
beta build: november 2008

Complete working system: testing carried out with beta testers.

final build: march/april 2009
Posted in construction, hardware, schedule, software | Tagged , , | Comments closed

schedule 0.0.0

By Han-earl Park | Published: January 5, 2008

This is/was the timescale as proposed in the grant application. With the (then unforeseen) delays of the funding process, all this will need to be revised.

intermediate objectives (projected)

initial design phase: september 2007–

Software: design, preliminary implementation and testing of software components.
Analog electronics: design and testing.

break: november 2007
alpha build: february 2008

Software: initial working system.
Electronics: begin final build.
Hardware: begin construction.

break: may–june 2007
beta build: august 2008

Complete working system: testing carried out with beta testers.

final build: november/december 2008
Posted in construction, hardware, schedule, software | Tagged , , | Comments closed