Ah, the technical stuff. If you don't feel
up to it, read it anyhow. The conclusions will still be helpful.
Let's look at the EQ subject. When it comes to Subs
this is a hazy subject as will be evident by what is presented here. The
Critical Q Sub actually has a simplified EQ system and while presenting
how it works, and that may be a bit difficult to understand, how to apply
it simply is covered in the
User Setup Page - so don't
despair.
Please note what is presented below is the
Amplifier's Frequency Response, as measured by an MLS signal into
the subject amp firing into an 8 Ohm dummy load. These are actual
measurements and not simulations. They should
not be
confused with the
Acoustic Response.
This is how the EQ looks in the standard Jaycar
AA-0501 Amp:
Can't say it looks great, in fact
it's awful. As a comparison to come, see that the -6dB points are 50 Hz
and 160 Hz - but considering this has a +4dB boost at 30 Hz, the real -6dB
point is 100Hz. The bass peak at 30 Hz and the rapid roll-off below means
this is not suitable as an Audiophile Sub, but rather for Audio Visual,
like thumping Movies, but not real Hi-Fi.
Now compare this with the Parts
Express 300-794 Amp:
Much
better, but suffers from similar LF roll-off, not as much.
The midrange suppression could also be better. That has to be improved!
Now compare this with our modified
amplifier (but final filter still missing):
Yes, very similar to the Parts Express 300-794, but now
flatter down to 20 Hertz and less LF Roll-Off. Also midrange suppression
needs improving.
FINAL
DESIGN
Much better midrange suppression.
The ultimate Low-Pass rate is now 3rd Order when
it previously was 2nd Order. That's 18dB/Octave
rather than 12dB/Octave. This prevents the Sub from messing up the
all-important midrange.
