Unlike PAF-style humbuckers, not all Filter’Trons are created equal and dimensions and mounts vary. Before buying retrofit Filter’Tron pickups, you should check the heights, footprint and mounting method required with the manufacturer and measure your guitar accordingly.
The arrival of Filter’Trons coincided with Gretsch abandoning a conventional tone control and introducing a tone switch. Given its poorly chosen capacitor values, most vintage Gretsch players keep the tone switch in the bypass position.
Consequently, the inherent treble bleed of regular tone controls doesn’t apply. Many modern Gretsch guitars have tone switches with better caps or a no-load tone control. You’ll need one or the other if you want authentic vintage Gretsch tone.
Controls for Gretsch guitars equipped with two Filter’Trons generally included individual volumes, as well as a master volume. The pots are 500k units but the way they’re wired means the amplifier ‘sees’ 250k.
Filter’Trons are naturally bright and, with a single 500k volume control, they can sound too shrill. If you’re installing Filter’Trons in a Les Paul or a Cabronita Tele, combine them with no-load tone pots and 250k volume pots for the full Filter’Tron experience.
Filter’Trons are extremely sensitive to height settings. TV Jones recommends 5/32 inches (4mm) between the top of the cover and the bottom of the E strings on the bridge pickup. For the neck, it’s between 3/16 inches (4.7mm) and 7/32 inches (5.55mm) on the bass side of the neck and 3/16 inches (4.7mm) on the treble side.
Regard this as a starting point; much depends on string gauge and your own preferences. As a rule, things get louder and brighter as coils move closer to the strings and sound warmer and mellower as they get further away. Go too far, however, and the tone can be harsh or dull at the extremes.
Setting height with suspended Filter’Trons is easy but traditionally mounted Filter’Trons are screwed onto the top and sit inside routed recesses. TV Jones supplies foam spacers that allow a bit of movement. Alternatively, try wood shims under the ends of the pickups. You could start with foam to determine the optimum height before calculating the thickness required for the wood shims.
If it looks like the bridge pickup will need excessive shimming, try placing a thin rectangle of plastic or wood veneer between the bottom of the magnet and the base plate. That’s how Gretsch did things, but you can only do it on Filter’Trons with loose covers.
Before height setting, tighten the 24 pole screws all the way down, then undo each by half a turn. This allows for some upwards and downwards movement. Again, TV Jones provides guidance on screw-height settings but results will vary depending on string gauge and bridge radius.
Set a neutral clean amp tone, select the bridge pickup, form an A major barre chord at the 5th fret and pick through the strings as evenly as possible. Determine which strings sound balanced and which are comparatively loud or quiet. To increase the volume of an individual string, raise its corresponding pair of pole screws, and to reduce output, lower the screws.
Take your time, use your ears and be aware that the strings and pole screws don’t always line up. Vintage style Filter’Trons had 1.9-inch screw spacing in the bridge and neck. Consequently, the screw heights may look a little wonky once you’ve dialled in a balanced response.
Here, the only sets with vintage spacing are the High Sensitives, Ray Butts Ful-Fidelities and Mojotrons. All the others have two-inch bridge spacing, with the Sparkle’Trons measuring 2.2 and 2.1 inches.
Setting pole-screw height is the key to achieving the balanced growl that makes Filter’Trons so special and unique. Repeat the procedure for the neck pickup and, once you can switch between the two pickups with a consistent level and even string-to-string balance, the in-between setting will sound fantastic.