Mesa Boogie Grid Slammer

Mesa/Boogie describes its character as running "from sweet, subtle breakup to a harmonically smoldering overdrive that can both sting and sing"¹. What makes it interesting to circuit watchers is what is underneath: a trace of the pedal found it is nearly a stock Ibanez TS9 Tube Screamer with a different clipping stage¹.

The controls: Gain, Tone and Master Level

The front panel keeps things to three triangulated knobs for level, gain and tone⁵. Each does what you would expect from a Screamer-style pedal, with one notable extra: the amount of clean level on tap.

That +20 dB figure is worth pausing on. A stock Tube Screamer is not known for big level jumps, and the Grid Slammer's Master Level is closer to a boost pedal's job description. A builder who traced and built the circuit reported that the Mesa side behaves as "a VERY loud, cleaner Tubescreamer. Great for using to push a dirty amp, not brilliant on a clean amp"¹. In other words, its strength is driving an amp that is already working, rather than creating all the dirt itself.

Vintage Guitar's reviewer found the single tone control better executed than the one it resembles: "The Grid Slammer's single tone control is well-voiced and a bit more refined than the classic Screamer's, allowing for a smoother overdrive that is still very crunchy with plenty of bark"⁶.

A TS9 with Timmy-style clipping

The Grid Slammer's circuit story comes from the DIY community. Fredrik Lyxzén traced the schematic, and IvIark turned that trace into a stripboard layout published on Guitar FX Layouts in March 2014¹. The verdict on its lineage was blunt: "it is almost exactly an Ibanez TS9"¹. The 470R and 100K output buffer values are the TS9's own values¹.

The difference is in the clipping stage. Where a stock TS9 uses symmetrical clipping, with one diode in the positive and negative halves of the waveform, as Dan Steinhardt and Mick Taylor explained on That Pedal Show⁷, the Grid Slammer uses what the trace called "a Timmy clipping diode arrangement"¹. That arrangement, borrowed from the Paul Cochrane Timmy, is the pedal's main departure from the Screamer template.

For context, other TS9 variants take different routes to their clipping: the Fortin-Modded TS-9 uses red LEDs in the clipping stage for what its maker calls a more organic, amp-like tone, while the Maxon TS9 Tamura-Mod uses Vishay 1N914 diodes for a clipping signature distinct from both the stock TS9 and the TS808-TM mods. The Grid Slammer sits in the same family of TS9 reinterpretations, distinguished by its Timmy-style diodes⁸⁹¹.

Premier Guitar's reviewer put the practical result in amp terms, calling it "a very powerful tool for giving your tone a much more focused punch and tightening up high-gain amps that are a little flabby in the low end"¹⁰. That matches the builder's finding that the pedal shines pushing a dirty amp¹.

DIY layouts and the clipping toggle

The Grid Slammer has a second life as a DIY project. The Guitar FX Layouts vero layout, published 19 March 2014, adds something the stock pedal does not have: a toggle that switches between the Grid Slammer's clipping and stock TS9 clipping, effectively giving two pedals in one build¹. The blog specifies the clipping toggle should be an on/on DPDT switch¹.

A few build notes from the same thread matter to anyone attempting it:

• The tone control uses a 20k W taper pot, but a linear taper can be used instead¹.
• The Gain pot's lug 3 is unused; the pot works as a variable resistor, so linking lugs 2 and 3 is not necessary¹.
• The 4k7 resistor after the 47n cap off the drive/clipping circuit goes to vref, a virtual ground, not the ground rail¹.

In September 2025, GuitarPCB published a build document for a free bonus PCB based on the Mesa Grid Slammer, bringing the project to printed-circuit form⁴. The document notes that the stripe on all five diodes indicates the cathode, a detail worth checking before soldering⁴.

Where it sits in the Mesa/Boogie range

Within Mesa/Boogie's pedal range, the Grid Slammer sits closest to the classic Tube Screamer tradition: its circuit is TS9-based, with the 470R and 100K output buffer values matching the TS9's, and the main difference being a Timmy clipping diode arrangement¹. The clipping toggle is what separates it from a straight TS9-style pedal in the lineup, switching between Grid Slammer and TS9 clipping so one box covers two voicings¹. Its gain range runs from sweet, subtle breakup to a harmonically smoldering overdrive, which keeps it on the lower-gain side of what the range offers¹.

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