Gretsch FilterTron – a look inside

The Gretsch FilterTron is something rather special. Originally designed in 1954/5 by Ray Butts for guitarist Chet Atkins who wasn’t satisfied by the DynaSonic pickup he was using. It has become a classic but often misunderstood pickup.

It has left a distinct mark on the sound of Rock’n’Roll. It’s the sound of Malcolm Young, Brian Setzer, Billy Duffy and plenty more. That unmistakable ‘Clank’ on the attack of the note is the essence of the FilterTron.

I started playing guitar because of the sound of A FilterTron. Listen to Malcolm Young on the intro to “Jailbreak” – that’s what I’m talking about. https://www.youtube.com/watch?v=HRo2m6RYJpI

But you don’t only find FilterTrons in Gretches, there’s the rather cool Fender Cabronita Telecaster.

So how does it make that distinctive sound? What makes it so different from a PAF?

Here’s a vintage Gretsch FilterTron from 1961, let’s take a look under the hood.

Gretsch FilterTron

With the cover off it looks quite different from a PAF. There are 2 rows of adjustable poles and they’re bigger than on a Gibson. The top of the bobbins are rather neatly hidden by a thin plate.

Filtertron with the cover off
Filtertron underneath
Gretsch FilterTron

Here’s where it gets really interesting. Those are very narrow bobbins and this one measures only 4.2KOhms. Not a lot of coil strength there but look what they’re sitting on. That is one fat magnet. It’s an Alnico V and literally twice the thickness of the Alnico 2 (usually) that you’d find in a PAF. So not only more powerful magnetic material but double the amount of it compared to a Gibson.

So that FilterTron sound consists of a weaker, thin sounding coil so lots of highs and twang from the windings and getting the aggression, attack and ‘clank’ from the powerful magnet.

This is the original FilterTron, the design didn’t change much through to the late 60’s although there are plenty of inconsistencies. They can have a dc resistance from 4KOhms up to 5KOhms.

By the 1970’s they had changed the design and really they just didn’t sound like Gretsch’s any more.

Bobbins

A lot of the modern ones are simply small humbuckers with cool looking covers and just miss the whole point of the FilterTron sound.

It’s all about those weak coils and that monster magnet.

Gretsch FilterTron
Mr Glyns Pickups

My own version of the FilterTron will be available soon.

Feel free to get in touch for pickup repairs or new pickups mrglynspickups@gmail.com. 021 912 678 https://mrglynspickups.com/

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