User's Manual

Manual System Optimization Tips

TIP: You may want to disable the TIME OUT feature located in the Utility menu before performing any of the following

system optimization procedures. This will ensure the PA2 does not revert back to the home screen throughout the process.

See ‘Utility’ on page 46 for more information on disabling this feature.

1. Set Crossover Frequency & Filter Settings

The active crossover in the PA2 is used to allow each speaker or driver in a multi-way loudspeaker systems to operate within

its frequency range limits. If you can’t find any tuning information for a particular speaker/driver, get the specification sheet for

it from the manufacturer. It can give you a good idea where to set crossover frequency settings by providing the speaker or

driver’s frequency response, which is the range of frequencies each speaker or driver is capable of reproducing.

If you’re bi-amping main speaker cabinets, the speaker manufacturer should be able to provide you with the recommended

crossover frequency settings, and oftentimes, filter types and slope rates. If you’re using subs and can’t find recommended

crossover frequency settings, you can dial it in by ear. Typically, subs and mains will be crossed over at around 80–100 Hz, so

somewhere in this range is a good place to start. You can then fine-tune the settings from there by ear using full-bandwidth

reference material that you are familiar with. When auditioning these crossover settings, it helps to first balance the amp levels

for all drivers or cabinets to achieve a frequency response that suits your taste. When auditioning the sound system, don’t turn

it up too loud until you’ve calibrated the gain structure – more about this later.

If you’re configuring a simple full-range system then you don’t necessarily need to enter any crossover parameters. However,

it is a good idea to take note of the speaker’s frequency response spec and set a high-pass filter at the lower frequency limit

specified (45 Hz, for example). This will prevent excessive driver excursion caused by subsonic frequencies and allow for more

headroom in your amp. You’ll then want to choose a filter type and slope rate that will effectively roll-off the low end without

dramatically compromising the low-end response of the sound system (try auditioning BW 24–BW 48 filter types).

Once the crossover frequencies have been set, it’s time to set the filter types and slope rates. Determining which settings to

use here can be a bit difficult. These settings are dependent on the natural frequency response and roll-off characteristics

of each speaker cabinet or driver. The goal is to achieve a flat frequency response throughout the loudspeaker system

with seamless transitions throughout the crossover overlap regions. For example, a midrange driver in a 3-way system may

inherently exhibit a fairly gradual roll-off up into the high end, whereas the tweeter may require a steep roll-off to protect it

from over-excursion. In this case, the midrange driver can be set with a more gradual roll-off to fill in the “gap” created from

the steep roll-off of the tweeter. You can use a combination of the RTA and your ears to dial in these settings. Just make sure

you don’t exceed the frequency range limitations of the drivers. The difference between the LR and BW filter type options is

in the way they sum together. You want to select the filter types that provide the flattest frequency response throughout the

crossover overlap regions. Note that it’s okay to mix and match these filter types if that’s what it takes to achieve a flatter

system response. Also note that you may not be able to achieve a flat response at this stage of the process due to driver

alignment and/or polarity issues. Therefore, just get it as close as you can for now. For more information on LR and BW filters,

see “LP TYPE” and “HP TYPE” under the section, ‘Crossover (XOVER)’ on page 41.

2. Set Driver Alignment Delays & Polarity

Once the crossover frequencies, filter types, and slope rates have been set, you’re ready to optimize the system’s phase

response. All drivers in the system need to work in unison in order for the sound system to sound its best. This is accomplished

by setting driver alignment delays to make up for any physical driver offsets and matching the polarity for all drivers.