Ibanez AF9 Auto Filter


What is it?
Ibanez AF9 Autofilter. Made in japan in early 1980’s.

Even though i don’t see myself as a huge fan of autowah/envelope filter genre, i happen tohave a few specimens. The way envelope filters, aka autowahs usually work, is that there’s an driver part that triggers the filter when certain input level threshold is achieved. Then the filter sweep is mixed with the incoming signal. I do believe this design works in the same manner. Quick googling around did not give me the schematic. Because of this (and in part because i haven’t had the time to analyze the circuit more deeply),  i can’t offer deeper understanding of the circuit at the moment. Reliable sources tipped me off that this should be close to Ibanez AFL, the Auto Filter from the Ibanez L/Master Series.


Older Maxon/Ibanez PCB layouts are just beautiful pieces of art, don’t you think? The traces are like perfectly aligned acid trips. Just beautiful. Even the joints are beautiful.

I find all the controls useful. Sensitivity affects how easily the filter sweep is applied to the signal, Peak then takes care of how hard the sweep affects it. The slide switches alter the filter type between low pass, band pass and high pass, all of them affecting the different parts of the frequency range. The sweep can be driven from up to down and down to up with a switch. And finally, Range setting makes this usable with bass.

Apparently these boxes have quite a lot of user and collector value.

How does it sound?
Greatest sounding autowah i’ve ever played. Versatile, yet simple. Schoolbook example of how autowahs/auto filters should be made. It can do wild, almost synth-like sweeps and standard funk sounds. From rhythms to leads. Useful, even when your music isn’t funk.

The range of settings are good. None of them kill the signal or behave badly in any way. This unit makes me feel good in so many ways.


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