The Seymour Duncan Diamondhead is a two-in-one distortion and boost pedal from Seymour Duncan, the Santa Barbara maker better known for its pickups. Announced in November 2019, it is described by the maker as a Multistage Distortion + Boost pedal that "captures the tone and feel of a hot-rodded tube amp being pushed by a drive or boost pedal, the guitar sound that defined classic 70s and 80s Metal and Hard Rock"1. Gearnews summed up the pitch as "an effect that gives you the feel of a cranked all-tube amplifier, which is then hit hard with an added boost"2.
The idea, as the launch press release put it, is that instead of paying thousands of dollars to modify a classic amp, a player can use the Diamondhead's distortion, stack the boost on top, and get an all-out attack from one box1. The pedal reached stores on November 12, 2019 at a street price of $2291, a figure Guitar World and Gearnews both repeated at launch32, and the maker's own product index listed it at $229.00 as available132.
The controls
The control layout is two rows. Guitar World describes a three-band EQ with bass, mid and treble knobs on the top row, and boost, level and gain knobs below3. The Drive knob "will deliver anything from raw medium gain sounds to screaming high-gain distortion"5.
The EQ is active, and each band works at a fixed frequency:
| Control | Frequency | What Seymour Duncan says it does |
|---|---|---|
| Bass | 80 Hz | A tightly defined control that boosts and cuts "with surgical precision, making the low end huge, but never muddy"1 |
| Mid | 800 Hz | A broader control that "allows for massive scooped chunk, hyper aggressive modern attack"1 |
| Treble | 6 kHz | "Adds sizzle, cut, and attack"1 |
Guitar Pedal X lists the three EQ bands at plus or minus 13 dB each, alongside the +15 dB boost, Level, Gain and the SAT on/off switch6. Gearnews adds that the highs "add some shine at 6KHz"2.
The SAT switch and the 805 Overdrive circuit
Under the Gain knob on the bottom right sits a toggle switch called SAT, short for saturation5. The SAT switch is based on Seymour Duncan's in-house 805 Overdrive52, which Guitar World characterizes as a TS-style pedal3.
When switched on, the SAT circuit "adds a 24dB pre-gain boost that tightens up the low end for more aggressive and defined attack"1. It also subtly rolls off lows and highs, which Seymour Duncan says lets the midrange cut through and creates "chewy, harmonic saturation"1.
The 805 Overdrive itself was designed using the legendary 808 chip, with an expanded gain range and an active EQ7, and Vintage Guitar reported it uses a glass-diode, back-to-back stack distortion circuit, wired true-bypass and for AC/DC operation8. A reviewer found its EQ controls "perfectly dialed in to ideal sweet spots for a variety of rhythm and lead guitar tones"9. That EQ heritage is what the Diamondhead borrows for its saturation stage.
The boost section: up to +15dB
The boost is an independent circuit with its own footswitch, the left one, and its own level control15. It offers 0 to 15 dB of available gain and, per Seymour Duncan, "can be used as a lead boost or to push an amp on the edge into overdrive"1. Guitar World confirms the boost section "operates independently of the drive circuit"3.
Because the two sections are separate, they can be used alone or stacked. Seymour Duncan recommends using the boost with a slightly dirty amp as the first gain stage, then adding the drive section for higher overdrive sounds3. Stacking both is what the launch material calls the all-out attack1.
"Instead of laying down thousands of dollars to modify a classic amp, dig into the Diamondhead's distortion, pack on the [boost]"
As a preamp
The Diamondhead also works as a preamp. Seymour Duncan says it "shines as a pre-amp. By running it into the effects return of your tube amp or in front of our PowerStage power amps, you'll be rewarded with a hot-rodded high gain amp tone with body, bite, and character"1. Delicious Audio carried the same claim at the pedal's first appearance in January 20195.
Delicious Audio also noted at that early showing that it looked like the pedal could work at 18V, which would add extra headroom5.
What reviewers said
Guitar Pedal X reviewed the Diamondhead alongside the Polaron phaser and found it "great authentic high fidelity sounding Marshall style distortion," saying it "covers Plexi and JCM800 tones with ease" and that the profile "leans modern and searing"6. The same review lists the full control set: Bass, Mid and Treble at plus or minus 13 dB, a +15 dB Boost, Level, Gain, and the SAT switch based on the SD 805 Overdrive, with separate boost footswitches6.
Where it sits in the Seymour Duncan line
The Diamondhead is one of several gain pedals from Seymour Duncan, a maker known primarily for its pickups but long active in pedals as well5. The 805 Overdrive supplies its saturation circuit5, and the Diamondhead sits among the maker's overdrive and distortion offerings at a list price of $229.00, where it remains available4.
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Questions
Can the boost be used without the distortion on?
Yes. The boost is an independent circuit with its own footswitch and its own level control, activated by the left footswitch, and it operates independently of the drive circuit. Seymour Duncan says it can serve as a lead boost or push an amp on the edge into overdrive, and recommends using it with a slightly dirty amp as the first gain stage.
What frequencies does the Diamondhead EQ work at?
The three-band active EQ operates at 80 Hz for bass, 800 Hz for mids and 6 kHz for treble. The bass control boosts and cuts at 80 Hz, the mid control sits at 800 Hz and allows scooped or aggressive settings, and the treble control at 6 kHz adds sizzle, cut and attack. Guitar Pedal X lists the EQ bands at plus or minus 13 dB.
Can I run the Diamondhead into my amp's effects return?
Yes. Seymour Duncan describes the Diamondhead as shining as a preamp: running it into the effects return of a tube amp, or in front of the company's PowerStage power amps, is said to give a hot-rodded high gain amp tone with body, bite and character.
How much did the Diamondhead cost at launch?
The Diamondhead reached stores on November 12, 2019 at a street price of $229, and Guitar World and Gearnews both listed it at $229 at launch. The maker's own product index also showed $229.00. Guitar Pedal X later noted a $229 list price, with the UK price at 229 pounds on the Seymour Duncan webstore.
Sources (9)
- DIAMONDHEAD: New Multistage Distortion and Boost guitar pedal announced by Seymour Duncan, MusicPlayers.com, 2019-11-13
- Seymour Duncan's new Diamondhead multistage distortion pedal takes us back to the 80s, gearnews.com, 2019-11-14
- Seymour Duncan shoots for hot-rodded hard-rock and metal tones with the Diamondhead Multistage Distortion + Boost pedal, Guitar World, 2019-11-14
- Seymour Duncan Overdrive & Distortion, Seymour Duncan (www.seymourduncan.com), 2019-12-09
- Seymour Duncan Diamondhead Distortion And Boost, Delicious Audio, 2019-01-29
- Guitar Pedal X, Guitar Pedal X, 2026-01-23
- Seymour Duncan Introduces 805 Overdrive Pedal -Demo Video, Guitar World, 2014-07-02
- Seymour Duncan Launches 805 Overdrive, Vintage Guitar magazine, 2014-07-02
- Review: Seymour Duncan 805 Overdrive Pedal, Guitar World, 2015-03-04
