The GUP Tech GrindR is a clean boost pedal that offers what the maker calls "20db of clean boost, with a bypassable (left switch) preamp (bass and treble control)"1. In its current form, sold as the GrindR EQ - Boost, it is a three-in-one: a clean boost, a preamp with bass and treble controls, and a choice of two EQ voicings, all selected from the pedal's front panel. GUP Tech describes it as "a three in one, including the old school popular Integrated Preamp, switchable with the left toggle"2.
The GrindR is built by GUP Tech, which makes all of its pedals itself in Saguenay, Quebec, Canada1. The standard GrindR EQ - Boost is listed at £77.00 GBP on the maker's page1.
What the GrindR does to your sound
The core of the pedal is a clean boost: up to 20dB of level you can use to push an amp harder or lift a solo above the band, without adding distortion of its own. On top of that sits a preamp section with bass and treble controls, which you can switch in or out with the left toggle. GUP Tech describes the result as "a three in one, including the old school popular Integrated Preamp, switchable with the left toggle"2.
The right toggle chooses between two EQ circuits: the original "Grind" or the "33" EQ1. Delicious Audio, writing about the related Mad Chiou double pedal, describes the GrindR side as "a 3-in-one based on the TC integrated preamp with the Grind/33 EQ high pass filter"2. So the pedal gives you a clean boost, a two-band preamp, and two fixed EQ voicings, all in one box.
Controls and how they interact
The GrindR's controls change depending on where the left toggle sits. In "P" (Preamp) position, the Bass and Treble knobs become active. In "B" (Bypass) mode, only the Level control and the EQ type selection remain1.
| Control | What it does |
|---|---|
| Level | Sets boost level; active in Bypass mode1 |
| Bass | Low cut or boost; active only in Preamp position1 |
| Treble | High cut or boost; active only in Preamp position1 |
| Left toggle | Switches the preamp in ("P") or out ("B")1 |
| Right toggle | Selects the original "Grind" or the "33" EQ1 |
Power is 9V DC only, center negative. GUP Tech warns that "anything over 9V will blow the pedal"1. Current draw is 21mA1.
Where the GrindR comes from, and its editions
The GrindR has been around long enough to pick up several editions through GUP Tech's Custom Shop, all with the same boost power but different finishes. In September 2025 the standard GrindR EQ - Boost received "new design, same boosting power, with new boxes"1.
- GrindR EQ - Boost: the standard version, in Black or Red1.
- GrindR Douche Edition: Chrome Green and Metallic Green finishes, with the same 20dB clean boost, bypassable preamp and 21mA draw3.
- GrindR Plem Edition: a Custom Shop edition announced 16 August 2021 with a Blue look4.
- GrindR Truck Driver Shawn Edition: a Custom Shop edition with the same boost power and a new sparkly look5.
- GrindR DerrylV Artist Edition: announced 5 August 2021, with parts handpicked by Derryl himself: black footswitch, black laser etched design, green LED and all black knobs6.
The GrindR circuit also appears inside other GUP Tech pedals. The left side of the Baby Honker dual overdrive and boost is the GrindR, with the same 20dB clean boost and bypassable preamp7, and the Mad Chiou doubles the GrindR with the Le Chiou Boost-EQ pedal2.
A metal player's use
GUP Tech publishes a player review from Carl Pace, a metal and hardcore guitarist who detunes to a low G on 7-string guitars. He tested the GrindR through a Peavey 6505 with a Solar 7 fitted with Seymour Duncan pickups, and also tried an Ibanez with EMG active pickups1.
"I plugged it in to my Peavey 6505 with a Solar 7 w/Seymour Duncan pickups, (I used an Ibanez with EMG's too and actives"
His setup, with its low tunings and high-gain amp, is the kind of context where a clean boost in front of the amp is a common choice, and where the preamp's bass control can help keep a detuned 7-string from getting muddy.
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Questions
Is the GrindR based on the TC Electronic integrated preamp?
Yes, in part. GUP Tech describes the GrindR as a three-in-one pedal that includes the old school popular Integrated Preamp, and Delicious Audio describes the circuit as based on the TC integrated preamp. The preamp is one of the modes you can switch in or out with the left toggle, alongside the clean boost and EQ options.
What colors does the GrindR EQ - Boost come in?
The standard GrindR EQ - Boost is offered in Black and Red. The Douche Edition variant comes in Chrome Green and Metallic Green, the Plem Edition in a Blue look, and the DerrylV Artist Edition in Black with black knobs, a black footswitch and a black laser etched design.
Where is the GUP Tech GrindR made?
GUP Tech builds all of its pedals itself in Saguenay, Quebec, Canada, including the GrindR. The company also runs a shop there at 6182 Boulevard Talbot, where pickup is usually ready in 24 hours.
Does the Level knob work when the preamp is switched on?
The Level control is described as active in Bypass mode, where GUP Tech says you only have Level and EQ type control. In the Preamp position, the Bass and Treble controls become active instead, so the tone shaping moves to those two knobs.
Sources (7)
- GrindR EQ, GUP Tech (guptech.ca), 2025-09
- GUP Tech Mad Chiou Double Boost + EQ, Delicious Audio, 2022-08-02
- GrindR Douche Edition, GUP Tech
- GrindR Plem Edition, GUPtech, 2021-08-16
- GrindR Truck Driver Shawn Edition, GUPtech
- GrindR Derryl Vi Artist edition, GUPtech, 2021-08-05
- Douche Edition, GUP Tech
