This month, I’d like to mention one of the coolest pedals Ibanez made in the ’80s. If you like envelope filters, particularly the Mu-Tron III, then you’ll love the Ibanez Auto Filter.
This pedal sounds as good as, if not better than, the bulky old Mu-Tron. Don’t get me wrong, I love the Mu-Tron III, but the Auto Filter does the same thing, it’s quieter, uses only one battery, has no separate gain control, and takes up much less space.
Apart from the noise, the main difference between them is the Auto Filter is a little more controllable. Like the Mu-Tron, the AF is a voltage-controlled filter (VCF) and offers sounds ranging from wah-wah to long, synthesizer-like sweeps. If you dig funk, there is no funkier envelope filter!
For a better understanding of what the AF does, compare it to a regular wah-wah. The sound is produced by shifting the center of frequency of a bandpass filter. On the Auto Filter, the frequency is changed automatically with the VCF by the input signal. The other filter ranges include high-pass and low-pass. These are great for creating the longer, synth-like sweeps. Low-pass is ideal for use with a bass guitar.
The controls on the AF include two sliders – one controlling the sensitivity of the VCF, the other for the peak, or length of the sweep. This slider also controls the amount of distorting. It will distort slightly, like a Mu-Tron III. Then there are three small switches; the first is the filter mode, where you can choose from high pass (HP), bandpass (BP), or low-pass (LP). The drive switch is for the drive of the sweep – from either low to high on the up setting, or high to low on the down setting. The last switch is for range, high or low. The low range sounds best for bass guitar. The pedal also offers an FET electronic switch for quiet switching.
The Auto Filter was offered first on the 808 series, as the model AF-201. This model has a slightly warmer sound and is the most soughtafter of the three. The second version was the AF-9. The first two offered the same controls, but the later version (the AFL) offered only high pass and bandpass frequency controls.
The Auto Filter was also offered as an option on some of the UE-300 floor effects, which offered three effects in one unit and was AC powered. The controls are the same as the AF-9, but knobs are used for the peak and sensitivity controls. Auto Filters have a tendency to sound great with phasers, flangers, and distortions. Be careful with the distortion before the Auto Filter because the effect becomes hypersensitive. Auto Filters are still fairly easy to find, but some dealers and collectors have driven prices up in the last couple years.
For a really cool-sounding, quiet, versatile, and compact envelope filter, try the Auto Filter. You can still get all the offerings of a vintage Mu-Tron III for much less money. And remember to get your questions ready!
This article originally appeared in VG‘s May ’99 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.