VI. Q Filter

The Q Filter is actually found under the "Filter" category of effects, not "EQ". But...it's pretty much an EQ. You have 3 main options, whether it operates as a high-pass, low-pass, or band-pass filter. You have the usual Frequency and Q parameters, but additionally Gain and Mix.

%	Freq (HZ)	50%	805
0%	190	55%	920
5%	302	60%	1,030
10%	415	65%	1,140
15%	490	70%	1,220
20%	530	75%	1,330
25%	570	80%	1,590
30%	600	85%	1,860
35%	645	90%	2,120
40%	690	95%	2,400
45%	750	100%	2,670

Note: Certain Mix/Gain values cause a very steep, narrow band-stop at approximately the point where the "hump" from the Q-Filter's boost levels off on the high frequency side. So with Q at 0% and Frequency around 50%, the hump levels off around 5 kHZ. Here are some values where I noticed the drop-off was steep. Veering one parameter off of these values, while holding the other constant reduces the severity of it or causes it to go away completely.

Mix	Gain
80%	0%
70%	10%
60%	30%
50%	90%
30%	70%

The interesting thing here is how this effect kind of bridges the gap between EQ and Distortion effects. It provides the transparency and tweakability of an EQ, but the Gain control allows you to compress the tone and really focus on the selected frequencies. It doesn't get dirty like a Distortion but it definitely has big impact on the dynamic response and tone. I find this works well for a couple things when used as a boost. It causes the selected frequencies you want to peak for your amp distortion to be ever-prominent, whether you're chugging on mutes, playing single notes, playing big chords, sustaining notes, or have your guitar volume knob turned down. This is great to make sure your palm mutes get the same saturated chugging tone as your power chords, but if you use too much Gain all your playing sounds kind of stuck inside that one tone - I liken the effect to be similar to active pickups. It also helps from your guitar getting too dark when you turn the guitar volume knob down. I generally keep this setting low or totally down.

Mix works like Gain on an EQ, but it is a more appropriate term here, because you're not just filtering but adjusting compression on the selected frequencies. So mix is useful to blend in the right amount of Q Filter.

I like to use this to pre-EQ amp models. I'll use it as a band-pass and use a wide range of Mix, from 10 - 75% depending on how subtle or strong I want the effect to be. Q I set to 0% at least to start to get wide hump, not dramatically boosting any section of the tone over others. I'll tighten this up if I need a more focused tone later, but the higher you go the more of that cocked wah tone you'll get, especially with higher Mix settings. Frequency depends on the amp. For something like the Uber, where I need a nice bright boost to tighten up the amp and dial in more djent, I may go as high as 75%. For the Recto, I find it just needs a mild mids boost between 45-55%. For the ENGL and J800 models, I find they can get a little thin with a bright boost - I may use the Q Filter as a low pass (LP) or combine the band pass with some EQ to boost bass, or I'll use higher Gain to make sure my band pass is saturating the amp even during mutes. For Gain, I tend to remain in the 0-15% range. Many times I want it 0%, so the affect is more transparent, but other times I like it off 0% to get a little compression and feel like there's a little juice to the effect. But going too high can make the boosted frequencies too compressed, which makes the tone kind of stuck in the boosted sound, which sounds kind of fake, or similar to active pickups.

There's a wide range of tone in this relatively simple tool, and it's best to experiment. The more I use it, the more I feel like I need to add here. From a subtle presence boost to a midrange compression to an extreme almost-wah-wah filter, you can get a lot of mileage.