Did it help? Ask away if there is anything else you want to know.

Did we hear back from Noname on this one?

NoName will get a start when his rig has been repaired and is running again …[a speaker stack was knocked over by someone at the last party and will need to be completely overhauled – ie unloaded, all wiring checked and drivers inspected, fixed as necessary, reloaded and checked to make sure they still work :hopeless: ]

Seems I been volunteered (suppose that’s what I get for my lengthy wafflings on various parts of the board….:wink:)

As Raj says – I got a bit of work on at the moment with speaker stacks and a generator that needs making work, but winter is approaching fast (which means more time to be sat at the PC), so I will try and get stuck into it for you then…. I’ve actually started something similar on our rig forum (http://www.drumclinic.org), but not sure how much sense it’s making currently (I did most of it before party season started, and haven’t had chance to finish/edit it yet).

btw Biotech – I’m not actually against horn loaded cabs (used to run a rig with a great set of W folds on the bottom) – it’s more having long throw horns with no near field (which results in people hearing you miles away, but people at the rig not being able to hear it…) I’m happy to go into the theory and practical of their design, and have several good designs. I just don’t think they need to be used on any rig smaller than about 20K…

As for a how to – I would separate the planning, designing and building sections, so my opinions on horns/radiators would be given as opinions in the planning section…. I would still put horn designs etc in the designing and building sections….

And I would certainly welcome any help and input that is offered (as the subject in question could easily fill a book, and possibly two or three….)

But as I say – not ’til after Cluanie (which is our last party this year)…raaaraaaraaa

As for the original question – the easiest way to get a grip on how a rig works is to think of your speakers as linear motors (which they essentially are). Their job is to reproduce the sound encoded into either the vinyl of your record, or digitally on a CD etc…

Your vinyl has an audio wave pressed into it’s surface mechanically which is “read” by the stylus, and converted into an electrical signal by the piezo in the cartridge. Your CD has a digitally encoded version of the same signal which is decoded to analogue and sent out of the outputs. These signals are sent to the mixer, which mixes the various inputs as necessary, and then sends the signal to either your crossover, or to the inputs of your amps (we’ll ignore any compressors/eq’s at the moment).

If it’s sent to your crossover (ie if you have an external one), the crossover splits the signal – into low and high if 2 way, into low, mid and high if 3 way etc etc (basically, each output of the crossover has parts of the signal filtered out, so it can efficiently drive particular amps and speakers). This is what’s known as an “active” system – so called because you can alter the crossover points, and thereby tune the rig for particular acoustic spaces (you can also apply gain to particular frequency bands, delay particular bands and a bunch of other stuff that is very useful but not essential).

The signal then goes from the crossover into your amps (if you have no external crossover, it gets fed direct to the amps from the mixer, and the crossover filtering is done in the speaker box itself – more on that later).

The job of the amplifier (as the name implies) is to amplify the small signal (typically about 500mV, and maybe 0.2Amps) into a large signal (large power amps put out in the region of 70-100V, and 5-15Amps power at the outputs). The amp does this (in it’s most basic form) by the use of transistors, and the transistor effect. If you remember your high school physics, the transistor can take a small signal at the gate, and create a large signal going from source to drain – your amp essentially does this, to create a large signal that is (as far as possible) the exact replica of the input, only a lot larger. This is then sent to the speakers.

The speakers in a “passive” set up (ie one without an external crossover) then feed the signal into a crossover inside the speaker box (a collection of capacitors and coils), which split the signal into frequency bands in much the same way as the active crossover did (only without the control and tuning options – a passive is set, and can’t be altered).

In this way, the signal is finally fed (having been split into frequencies that the various speakers can handle) into the speaker coil. The speaker coil sits inside a huge magnetic ring, causing it to behave as a linear motor (ie when a positive current is fed to it, the coil moves away from the magnet, and when a negative current is fed, it is pulled towards the magnet). The coil is the centre of the speaker surface, and the cone and resonant box then amplify the signal further causing the reproduced sound wave to be transmitted through the air….

Essentially the aim is to reproduce the original signal as accurately as possible, but much amplified (engineers refer to the accuracy of reproduction as “linearity”). The signal can come from a range of sources (from the diaphragm on a mic, or the pickup on a guitar to the piezo on a turntable or the purely electrical “synthesized” output of a synth), but the idea is the same with all – reproduce in a much amplified way the sound wave that is presented to the inputs…

There you go – 2000 (or nearly) word waffling around the subject….:wink:

Hopefully it makes sense – let me know, and I will try and clarify if it doesn’t….:groucho:

some helpful and interesting stuff i didnt know in there, cheers for that