The Fat Gett (7) – the finished article and version 2

After finalising the standalone ‘Gett’ fuzz, I decided to revisit the Fat Gett and try out the updated component and value changes. I couldn’t add the fluff or dunsh functions for space reasons, but everything else was doable on the Fat Gett PCB. The Fat Gett is a really tight build so there’s no space inside for off board wiring either.

Firstly, if you have read the blog post on the Gett, you’ll see that I made some booboos with the original Gett tonestack that I wrote about in previous Fat Gett blog posts. I’ve copy and pasted that section here:

The next change was the tone stack. I originally used an AMZ style tone stack with an A250K pot. On paper, this seemed like a good idea, and it was an improvement on an earlier version I’d used (you can read about this in the blog posts about the Fat Gett). The problem with a logarithmic (A) taper pot, which I realised after putting a few together, is that when the pot is rotated halfway, the pot is only at 10% of its resistance, all the action happens after that. For this reason it made more sense to go back to a linear taper to get an even sweep.

I also decided to approach the tone stack in a more logical manner. The Big Muff control allows you to move between a low pass filter and a high pass filter. With that in mind, I thought about what those filters should look like by themselves, rather than just playing with values in the Duncan Amps tone stack calculator. I decided that as these filters would overlap, it would be best to have a small hump around 1 KHz – 3 KHz, to boost the mids a touch. I worked out the values for a 1 KHz high pass filter and a 3 KHz low pass filter and inputted the values into the calculator as a starting point. Like the Fat Gett, I wanted to include a switch to alter the tone curve, providing a bigger mid hump. I played with the initial values until I found something that gave more functionality. In the new tone stack, at mid rotation the response is fairly flat with a slow roll off from about 2 KHz. At around 60% rotation, the response totally levels out with a slight hump from 1 KHz to 3 KHz. With the mids switch on, this hump becomes much more pronounced.

Here’s the curve for the old and new tone stacks without the mids switch on.

This slideshow requires JavaScript.

As you can see the old tone stack has a constant lower mids hump. Turned fully clockwise (treble) it lets pretty much all the treble pass, and it slowly rolls off from about 1KHz. The new tone stack is less treble-friendly and rolls of from about 3KHz, which is a little high admittedly but when the tone control is at around 1 o’clock it’s pretty much a totally flat response across all frequencies at -8dB. The old tone stack has a constant mid hump around 1KHz and is quieter at -11dB. Turned fully anticlockwise (bass) the old tone stack is pretty flat but at about -8dB then you get a mild hump from 200Hz to 1KHz, then it rolls of from there. With the new tone stack you’re getting a lot more bass pass throughout around 0dB, it hits the -3dB knee of its roll off at about 2.5KHz. The main take away from this is the new tone stack attenuates less, and it’s pretty flat.

Here are the old and new tone stack sweeps when the mids switch is on.


This slideshow requires JavaScript.

First off we can see in the old tone stack that there’s a huge hump from around 200Hz to 2KHz, the sweep of the tone stack basically rolls off everything above or below that. As there isn’t a lot of guitar that we need above or below that, it basically maintains the body of the guitar signal and gives you a minimal range to play with. The new tone stack is far more dynamic. In the middle of the sweep it also gives a nice boost to the middle frequencies that you really want in your signal. It’s not prefect yet, but it’s certainly an improvement. It definitely sounds better in practice too.

Having looked at the two more carefully, I think it might be worth experimenting with  values based on a low pass filter a wee bit higher than the current 3KHz- maybe 4KHz or even 5KHz, and a high pass filter anywhere down to 800Hz. Whilst most of the tone sweep is very useable, without the mids switch on, turned fully clockwise it gets pretty trebley, and whilst it probably does still have some application, I think there’s still scope to maximise it’s usage for this fuzz.

I don’t know whether I mentioned in previous posts, but I decided to use a 1590BBM enclosure for the Fat Gett. It’s basically a deeper version of the 1590BB. I also moved the DC jack from the right side to the top, so it goes nicely underneath the switch.

I’ve also decided to put the bloat function on a momentary foot switch as standard so you can cut out the oscillations you get when you leave the long gaps in your playing. latching foot switches will be available by request.

Here’s a couple of pictures of the last run I did. Depending on when you read this, they’ll either be up for preorder here, or in my Reverb store or with one of the dealers.

This slideshow requires JavaScript.

I still have a few of the original Fat Gett PCBs for the time being, but I had some issues with KiCAD shortly after I finished it, so I’ll need to redo the layout this year. I’m considering experimenting with a single TL072 to act as a buffer from the fuzz to the parallel glitchy suboctave circuit, and as a summing amp back to the bloat control. I have no idea how this will affect the sound, but it’s simple enough and I’m curious enough to give it a shot.

I’m also planning to extend the Fat Gett to the full Gett circuit including the fluff and dunsh functions. Watch this space!


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.