Got me one o' they Behringer DSP1124 parametric EQ wossnames today.
Connected it between the active crossover and the bass amp, and did some
preliminary tweaking. Since it's only being used to EQ the bass, I set the
12 filters to the lowest sequence of default frequencies: 20, 25, 32, 40,
50, 63, 80, 100, 125, 160, 200, 250. This was handy, as it just so happens
that the bass/mid crossover point is around 250Hz.

Next, I set the bandwidth of each filter to 20/60 of an octave (it can do
1/60th of an octave, so I figured bandwidths of 1/3rd would be a good
starting point). I then tweaked the levels to get a more balanced sound,
using both music and the sine wave test CD I made a while ago (which only
goes up to 100Hz). The test CD revealed a noticable lift at around 30-35Hz.
The filters from 80/100 upwards only have a difference from 0dB of 1dB.

The first thing that has become apparent is that the speaker cabinets can't
handle the increased LF at loudish volumes - I expected this, since they're
oversise reflex boxes, tuned wrong, and with a bunch of slots cut in the
back panels. Basically, they're Flop City on National Flop Day.

The DSP1124 has ten user memories, and I saved my settings to preset 1. I
downloaded the Tatu track, rehydrated the MP3 to a CD, and found that the
34-28Hz portamento is pretty earth-shaking - too much for the cabinets at
sensible volume, and noticably more powerful than other music (in bypass
mode, this low bass note is barely audible). So, I reduced the levels of the
really low frequencies and saved this profile in a second preset. I'm
currently listening to Art Of Noise's 'The Seduction Of Claude Debussy', and
it's a tad too powerful at the low end as well. Methinks I'll probably make
up a few preset profiles to suit the music/volume. Changing presets is a
doddle - just twiddle a jog dial on the front panel, and the number on the
front panel changes. There's a short delay before a preset becomes active,
so that you can scroll through a few without the in-between ones creating
bursts of the 'wrong' tonal balance.

Switching the bypass in and out is very revealing: switched out, the bass
sounds rather middly and boxy, but this disappears with the EQ in - way
smoother and bags more low end. I think there'll still be some tweaking of
levels, but I think I'll leave the centre frequencies and badwidths as they
are for now.

I'm impressed so far. This thing has added low end that my speakers never
knew existed - at long last, it goes all the way down. I'm going to have to
stop using the speakers as shelves before things start falling off. And it
looks like it's getting close to the time for some serious thought on making
the first isobaric bass cabinet.

Oh, I bought it from an online retailer called Blue Aran - the gizmo, two
0.5m XLR patch cables, delivery, and VAT came to a total of 71 quid. It was
ordered late on Thursday night and arrived first thing this morning.


--
Wally
www.artbywally.com/FiatPandaRally/index.htm
www.wally.myby.co.uk