The Audiostorm Quad Screamer is an overdrive pedal built in the UK by Audiostorm, and it takes the classic Ibanez Tube Screamer circuit as its starting point. What makes it different from most Tube Screamer variants is its clipping stage: instead of one fixed pair of diodes, it gives you four switches, silicon, LED, MOSFET and germanium, that can be mixed in any combination1.
The range that opens up is wide. Delicious Audio, which covered the pedal in 2022, described its span as going1:
"From subtle and silky clean asymmetric NOS Germanium drive through to tight, harmonically rich hi-gain MOSFET shred with sustain for days"1
Delicious Audio1
A Tube Screamer with four mixable clipping options
To understand what the Quad Screamer changes, it helps to know what a stock Tube Screamer does. The original TS-808 clipped the signal symmetrically, producing a smoother voice than the harsher pedals of its day, and it is remembered as possibly the first "soft clipping" distortion pedal23. The clipping amplifier in the circuit is what shapes the character: with the gain set to minimum, a stock Tube Screamer stays clean for small input signals, and as the gain rises the diodes progressively round off the waveform4.
Most variants keep that clipping stage fixed. The Fortin-Modded TS808, for example, adds a secondary diode clipping stage for increased saturation and uses red LEDs in the clipping stage for a more organic, amp-like tone56. Ibanez's own TS9DX Turbo Tube Screamer took a different route, mounting several sets of diodes on boards behind the control knobs and switching between them with the MODE knob7.
The Quad Screamer's approach is to put the diode choice on the player's side. Its four switches select silicon, LED, MOSFET and germanium clipping, and because they can be engaged together, the four switches allow up to 15 different clipping combinations1. Where the TS9DX switches between fixed modes, the Quad Screamer lets you stack clipping types, which is closer to blending two overdrives into one circuit.
The clipping switches: SI, LED, MOS and GE
Each switch has its own character, as described by Delicious Audio1:
| Switch | Clipping type | Character |
|---|---|---|
| SI | Symmetric silicon | The classic 'screamer sound |
| LED | Symmetric red LEDs | A bigger, slightly warmer, more open sound |
| MOS | Asymmetric MOSFET | A tighter, more aggressive sound with rich harmonics |
| GE | Asymmetric NOS germanium | Subtle, silky drive |
The germanium position is the most distinctive. The Quad Screamer uses genuine NOS (new-and-unused old stock) germanium diodes sourced from Ukraine, hand selected and arranged in an asymmetric configuration, and supplies of those diodes are very limited1. Asymmetric clipping, where the two halves of the waveform are clipped differently, is the same idea behind the Boss SD-1's design, which contrasts with the Tube Screamer's symmetrical clipping stage8.
Hi gain and Bright switches
Alongside the four clipping switches, the Quad Screamer carries two more switches, labeled Bright and Dirty, placed unusually on the back of the case1:
- Hi gain (Dirty): boosts the dirt right at the front end, giving a more full-range boost than the usual Tube Screamer1.
- Bright: reduces the usual Tube Screamer high-frequency roll-off, allowing just a touch more brightness1.
Both switches attack known traits of the stock circuit. The Tube Screamer's mid-focused, high-end-rolled voice is part of its character, but players who want more range or more aggression out of the same box can flip these to get it. With the clipping combinations and the Hi gain and Bright modes together, the maker counts 60 unique overdrive possibilities, all of which Delicious Audio called highly usable1.
The op-amp and the build
The Quad Screamer ships with the well-respected TI 4558 dual op-amp chip, the same family of chip associated with vintage Tube Screamers, and it is user swappable: a player who has a vintage chip can install it1. That makes the pedal a platform for op-amp experimentation as well as clipping experimentation.
The rest of the build is specified with named parts: ALPS switches, described by the maker as the best in the business for long life and reliability, Cliff jacks made in the UK, Alpha footswitches, and Alpha metal shaft pots1.
Power
The Quad Screamer operates off any standard 2.1mm 9V DC power supply, and the power supply is not included1. It also accepts other DC voltages from 5V to 30V, which the maker says gives increased clarity and headroom1.
No power supply comes in the box, so you will need a standard 9V DC supply with a 2.1mm center-negative-style barrel connector to run it. Higher DC voltages up to 30V are supported for more headroom.
Videos
Audiostorm
Audiostorm
Audiostorm
Questions
How many sounds does the Audiostorm Quad Screamer have?
The four clipping switches (SI, LED, MOS and GE) can be mixed in any combination, giving up to 15 clipping options. Add the Hi gain and Bright switches on the back and the maker counts 60 unique overdrive possibilities in total.
Can you swap the op-amp in the Quad Screamer?
Yes. It ships with a TI 4558 dual op-amp chip, the well-respected type associated with the Tube Screamer sound, but the chip is user swappable, so a player with a vintage chip can drop it in.
Does the Quad Screamer come with a power supply?
No. It runs off any standard 2.1mm 9V DC power supply, which is not included. It also accepts other DC voltages from 5V to 30V, which the maker says gives increased clarity and headroom.
Where is the Audiostorm Quad Screamer made?
It is made in the UK by Audiostorm. The build uses ALPS switches, Cliff jacks made in the UK, Alpha footswitches and Alpha metal shaft pots.
Sources (8)
- Audiostorm Quad Screamer Overdrive, Delicious Audio, 2022-07-25
- Ibanez Tube Screamer, Vintage Guitar magazine, 2014-03-08
- Best Overdrive Pedals: Top 5 classic stompboxes to heat up your tone, gearnews.com, 2021-05-28
- Tube Screamer Analysis, GuitarPCB
- Fortin-Modded Ibanez TS808 Tube Screamer Overdrive, maxonfx.com
- Fortin-Modded Ibanez TS808 Tube Screamer Overdrive, Godlyke Distributing, Inc.
- Ibanez TS9DX Turbo Tube Screamer, Analog Man (aNaLoG.MaN), 2015
- Boss SD-1 review, Guitar.com, 2025-04-29
