Cheap hardware

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This is one of a series of pages detailing attempts to play Ambisonic sound on cheap everyday equipment. This is not the ideal way to do it, but it does allow for experimentation. The faltering steps reported here are offered as one person's experience not as suggestions of how anything should be done!!

1. Chicken and Egg

Unless you have heard ambisonic sound how do you know if it is worth setting a system up?

I knocked up my first system using a USB 5.1 soundcard that was 'around' and two sets of PC speakers. I liked the result and decided to continue. I wanted 'height' (that is a periphonic system) and so was going to need eight channels of amplification and eight speakers. Musing over what must be the cheapest solution to this I found some slightly louder PC speakers and realised this avoided buying four stereo amplifiers as well.

2. The Speakers

I used Logitech X-140 speakers initially from the local supermarket (bought one pair to convince myself that they worked) and then (33% cheaper!) from Amazon.

Since then I have seen some Labtec ones in a shop window that look similar, but were about 20% cheaper still, and may have been marginally more powerful.

The speakers nicely divide the power supply input into one speaker and the audio input into the other. Presumably to cut down on interference. You can also feed the speakers via a jack socket on their front rather than by the lead (with jack plug) if you prefer).

As my room height was three metres and the speakers came with about two metres of inter-speaker cable, I decided to leave it be and not get into re-wiring.

The speakers tilt back on their bases. This angle is fixed. For my room I calculated that it was just right for getting the vertical alignment (nice that). So I just put up four brackets and four shelves and posed my eight speakers.

I decided to do a neat installation and thus installed power sockets on the ceiling in each corner, with a master on/off switch. The mains electricity wiring probably cost more than the speakers … and I always knew the ceiling was concrete, but not that it was 20cm thick …

3. Other

Otherwise a standard laptop (cheapest in the shop in 2006,1.5 GHz) and a USB sound card (Terratec Aureon 5.1 USB).

The big downer on this whole system is that basic computer equipment all uses those tiny jack plugs and sockets. The connection reliability is appalling. To get the speakers wired into the computer also needs some audio extension leads.(These seem to cost about 50% of what the speakers cost, and are often of very dubious quality.)

Sending unamplified (i.e. 'line' level) sound several metres down jack leads is not ideal. (One source suggests a limit of twelve feet for 'proper' (quarter inch) jack leads.) Sending it down mini-jack leads with a connector en route is far from ideal.

One 'solution' to the audio distribution might be to use two USB external audio cards. Installing one mid front and one mid back. The speaker cables would then need no extensions and the main cable run would be USB/digital cabling rather than analogue sound.

(I cannot see that any of this is worth investing serious money in. I presume it will all be optical (S/PDIF, or whatever) soon, so agonizing about lengths of jack cable runs and/or the appalling quality of extension leads is probably not worth it. This was a system to get up and running and to try a few things out on)

September 2007.

Copyright © 2007 Michael Chapman.