Wisdom Audio DCAB-1 User Manual

Page 26

Advertising
background image

26

The first of the bassis controls determines the frequency of the midbass peak
you are trying to eliminate. In the conceptual drawing above, this would be
about 75 Hz. On Wisdom Audio systems (which have unusually good bass re-
sponse), this figure is more likely to be in the 40-50 Hz range.

boost

The bassis boost control determines how much the deep bass is boosted (the
left hand portion of Curve B, above). The effect of this control is not linear,
since most of the change comes early in its range. By the time you reach a 20%
boost, you have taken advantage of most of the available range. You will prob-
ably find that differences of even 1-2% in the first part of this adjustment are
audible.

When Bassis boost is set to 0%, no deep bass extension is added.

Qb

The Qb control determines the “Q” or damping quality factor of the overall
Bassis curve. This has the subjective effect of either creating a lean/tight deep
bass when the value it below 55%, or a warmer/fuller deep bass when it is
above 55%.

During adjustment, we suggest leaving the Qb control at 55%, which you can
think of as “neutral.” After everything is adjusted, you may choose to make small
adjustments in Qb to fine-tune the bass performance of your system to suit the
needs of different recordings (e.g., a particularly dry orchestral recording often
benefits from a slightly higher Qb setting).

Qs

The Qs control informs the Bassis circuit as to the native “Q” (or damping qual-
ity factor) of the speaker in the room. In short, it characterizes the shape of the
response curve in and just above the final roll off in the bass. There will be a
bit of a bump just before the native roll off of the speaker, because the Low Fre-
quency Regenerators are in relatively small enclosures.

In adjustment, you set the bassis Hz value to the lowest-frequency peak of the
speaker (leaving Qb at 55%) and will usually go back and forth between Qs and
bassis boost until the bump is removed. In the process, you will see and hear
that the deep bass is extended quite usefully, while the bass actually becomes
tighter (better defined).

notch 4, 5

The low pass portion of the crossover has two independent, parametric notch
filters that work in the same way as those on the high pass side. The first two
columns give you control over the center frequency (in Hz) of the filter, for the
Left and Right speakers, respectively. The next two columns give you Left/Right
control over the amplitude (or depth) of the notch. The last two columns give
you control over the Q (or width) of the notch. Taken together, these controls
allow you to tame the two largest or most troublesome peaks in the system’s
upper bass response, as measured in your own listening room. (Remember that
you will use the Bassis control for the lowest-frequency peak.)

Advertising