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Advanced Member
Username: crgaston

Post Number: 318
Registered: 11-2005
Posted on Monday, October 23, 2006 - 12:42 pm:   Edit Post

I have recently tried experimenting with my SF-2 in the stereo mode using a short patch cord to daisy chain the channels. This week we played a room with a hollow wooden stage that resonates badly. In the past, the bass has been a muddy mess, even with the bass knob of my F1X set to zero. I will share with you how I used the Superfilter to correct the problem, and also how I think it is working. If anyone has any insights or corrections to make, please share them.

On the first channel, I started by turning the direct gain up a little, then turning the filter gain all the way up. I had the filter set as a hi-pass, and began with the frequency at 45 Hz. Since the stage resonated the worst at a low G, I held that note and rolled the frequency knob up until the resonance went away, about 110 Hz on the dial. I then backed the filter gain down to about 7 (which I suspect is close to unity; can anyone confirm this?), and turned the direct gain to unity. The resulting blend of signals enabled me to turn the bass knob on the F1X up to 3 without causing the resonance to reappear. I believe what this does is basically set up a -(x)dB/octave slope below 110, as the combined signal consists of the flat direct signal and the -12dB/octave slope of the filter. The more I turned up the filter gain, the more I was cutting the lows, relative to the summed signal.

On the second channel, we have the direct gain, which now consists of the summed signals of the first channel, and the filter gain. Since I was playing a DeArmond Starfire with Darkstars (which explains the ridiculous gobs of bottom) and using a pick, I decided to use the second filter to shape the hi-end attack somewhat.

I started with the channel 2 direct gain at unity and the filter gain at max. With the filter on low-pass, I began picking a string and rolling the filter down from 6k until I was hearing the sound I wanted, which was around 700 Hz. I then reduced to filter gain to about 6. This process got me in the ballpark, and some more subtle tweaking yielded the best sound I have gotten in that room yet.

I believe that the signal at the output of channel 2 consists of the following:
1. The pure signal from the bass
2. The hi-pass signal from filter 1
(These are controlled individually on channel 1 and together on channel 2.)

3. The pure signal shaped by the low-pass from filter 2
4. The hi-pass signal shaped by the low-pass from filter 2
(These are present in the same proportions as on channel 1.)

I think, if everything were at unity, there would be an even mix of the 4 signals, but really I have no idea. What I do know is that the unit has become MUCH more sensitive to small movements of the knobs (especially on channel 1), probably because each knob is controlling the sound in more than one place. Also, it seems to bring out the mids somewhat, possibly because they are represented in 4 parts of the summed signal, whereas the highs and/or lows have been removed in all but one of the other parts.

This is really an interesting little box.

Advanced Member
Username: tbrannon

Post Number: 207
Registered: 11-2004
Posted on Monday, October 23, 2006 - 1:17 pm:   Edit Post

Sounds like you're having fun Charles- imagine when that Series II Dragonfly comes buzzing into the equation!

I'm glad you've found a solution for yourself. We played in a school hall a few months ago and I had the same problem. There was a wooden stage (about 1.5m high) and I couldn't get my G&L & 4x10 to sound like anything other than wet clay.

Loving the Rogue more and more everyday BTW- I put those Chromes on it. Words do not describe =) Thanks again.


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