| Home | Hifi speakers | Pro speakers | Library | Designer's notebook | Sales | FAQ | About us | User group | Designer's notebook Overview Personal notes   Chapter 5: The four functions of the "crossover network" inside a Harbeth cabinet Pages: [5] - Current page: [1] Date created: 16 July, 2005 - time: 11:56 Comments: One of the least understood aspects of a loudspeaker system is the function of the electrical circuit ("the crossover network") and how it integrates the acoustic outputs of the drive units. This design task can only start after the cabinet dimensions are finalised, the prototype cabinet is assembled, internally lagged, the drive units fitted, and measurements of the frequency response of the 'raw' drive units taken, without a crossover, in their final physical position on the speaker's front baffle. We will cover the subject of actually making the measurements in another chapter but before we can turn to my Notebook, we need to step back a bit. Let's assume that we've taken the acoustic measurements of the 'raw' drive units and we can now start to think about the crossover. Below, I've drawn what seems to be most people's general impression of the division activity inside a two-way (woofer + tweeter) crossover. The horizontal (or x) axis is marked in frequency, and the vertical (y) axis in decibels. This chart could be telling us something about how the electrical signal is divided in the crossover between reaching the voice coils of the woofer and tweeter, and/or it could be telling us about the sound pressures generated by the respective drivers, as we would measure with a Sound Level Meter held some way away. What we hope for is that, in the crossover region, where the woofer's output is forced to fade out with increasing frequency (by virtue of components in the crossover network), that the increasing contribution from the tweeter (on its flare-in) will exactly blend together, with the net result that what we will measure on our SLM - or indeed hear - will be a perfectly flat, smooth, seamless transition from bass unit to tweeter. If only it were that simple the crossover could be designed in an afternoon, not three to six months. Turn the page for more on the fundamental problem that we have to solve, concerning real-world drive units mounted in real-world cabinets . . .   Harbeth Audio Ltd., 3 Enterprise Park, Lindfield, Haywards Heath, W. Sussex, RH16 2LH, UK This entire website is Copyright © 2007 HAL, England. All rights reserved. HARBETH is a Trade Mark/Registered Trade Mark. Site designed by Moose Web Design.