| # Speaker Project # Prototyping the Crossover

> > > We start by ensuring that the drivers are correctly set up. Open each driver (woofer and tweeter) and check the Properties to make sure that the Impedance and Frequency Response datasets are correctly mapped to the right datasets.

> > > Next we will build two small networks called Woof and Tweet. In the Woof network go to Network Properties and add the woofer driver. In the tweet network add the tweeter driver. We have to grab the components and move them around and reconnect nodes to get it to look like this. To connect two nodes just click the driver (it highlights) and then move the mouse into a node (the cursor changes to a large + sign) then press and drag from a node to the destination node. You can do this with the Ctrl key down to add a connection (which we don't do here).

> > > To move both components to the upper left - press the mouse and drag a rubber band box on the screen until it surrounds both components - release the mouse and they both highlight - then click a component and drag them both.

> > > The network now looks like this:

> > > I also double-clicked the LPG tweeter and changed the format to put the label on the right.

> > > The reason for creating two small network is that they will be used simply. Bring up each network properties and click on Network Impedance so an impedance dataset gets built.

> > > Looking at the impedance chart (here) we are going to want to compensate the woofer for its inductive rise. Go to the Woof network and select the (insert / Impedance Compensation command (via right mouse button or from the menu).

> > > The dialog looks like:

> > > And the circuit it builds is

> > > To see the compensated impedance just select Calculate Response (right click or menu) and we get the following

> > > Where the red chart is the original impedance and the black is the compensated impedance. Note the low resolution on the black chart - we don't need much resolution here because we are mainly dealing with higher frequencies.

> > > For the tweeter we need a different kind of compensation (or crossover adjustment) because of the resonant impedance peak at around 600Hz. If we don't compensate then any crossover we build will not drop off until below 600Hz due to the rise in impedance. This can be solved in a couple of ways but one way is another compensation circuit. Do the same process as for the woofer but use a resonant peak at 560Hz for the LPG to get the following circuit and chart.

> > > Having a consistent impedance for the crossover makes the design much simpler.

> > > On to the next page.

> > > last updated March 08, 2001