The Kasleder FX Dirty Little Thing is a hand-built overdrive pedal from Kasleder FX, a German builder of high-end stompboxes. It is a take on the Tube Screamer, specifically a recreation of the pedals Maxon designed for Ibanez in the early days of the Tube Screamer saga, meaning the TS808 circuit1. Kasleder's builder states he spent 13 years working to replicate the sound of a perfectly authentic vintage Tube Screamer, and hand-builds each pedal1.
What sets it apart from a straight clone is a set of deliberate changes to the original design. Delicious Audio's Paolo De Gregorio sums them up: "Unlike in the original, you have now True Bypass, less bass loss, more drive, and on minimum drive setting a totally transparent" sound1. The Tube Screamer circuit is famous for cutting bass as part of its voicing, so less bass loss is the headline change for players who find the original too thin-sounding.
What it does to your sound
Delicious Audio describes the pedal's voicing as "The tube like overdrive sound, smooth clipping distortion, the sustain you need for your solos"1. Pedal of the Day frames it the same way, calling it an overdrive with boost that delivers tube-like overdrive, smooth clipping distortion, and sustain for solos and lead runs2. In practice that covers the usual Tube Screamer territory: from blues grit up to metal players using it as a boost in front of a driven amp, tightening the lows and pushing the mids so the guitar cuts through a busy mix1.
The parts choices are where Kasleder claims its improvements. The upgraded components in the circuit are12:
- Made in Japan 4558 op-amp1
- Wima high-end audio capacitors1
- Nichicon gold series capacitors1
- Nichicon green series capacitors2
- NOS carbon comp resistors2
- NOS "mojo" diodes for clipping2
Versions and the 15th anniversary
The Dirty Little Thing dates back to 2006, and Kasleder marked its 15th anniversary in 2021 with a limited edition1. Pedal of the Day, reviewing in 2020, described the pedal as "13 years in the making," which lines up with the builder's own account of the development period2.
| Version | What sets it apart |
|---|---|
| Original | The first Dirty Little Thing, dating to 20061 |
| V2 | The current version, shown in Delicious Audio's demo rather than the anniversary edition1 |
| 15th anniversary (2021) | Limited run; op-amp chip slightly different from the one in the TS808, sourced from the last pre-production run1 |
The 15th-anniversary edition is a limited run with a different op-amp chip than the standard V2, so the two versions will not sound identical. If you are comparing units secondhand, it is worth knowing which one you are looking at.
What reviewers said
Reviews have been favorable on the same point: that this is more than a Tube Screamer rehash. Pedal of the Day's verdict was that "it's not another version, it is a next level effect"2. Delicious Audio added the pedal to its article on the Best Tube Screamer Clones and Evolutions, placing it among the designs that push the original circuit forward rather than simply copying it1.
For context on where it sits among Tube Screamer alternatives, other builders have taken different routes entirely: the Catalinbread Dirty Little Secret reinterprets overdrive through a Marshall-style amp circuit instead, and Kasleder's own Toxic Twins is a dual-channel overdrive with switchable clipping. The Dirty Little Thing is the more conventional of these on paper, but its changes to the TS808 formula are aimed squarely at the circuit's most common complaints31.
Videos
Kasleder Fx
Kasleder Fx
Kasleder Fx
Questions
Is the Kasleder Dirty Little Thing true bypass?
Yes. Delicious Audio notes that unlike the original Tube Screamer circuit, the Dirty Little Thing has true bypass, which is one of the changes Kasleder made when reworking the design. The same rework also brought less bass loss, more drive on tap, and a more transparent sound at minimum drive settings.
What op-amp does the Dirty Little Thing use?
The Dirty Little Thing uses a Made in Japan 4558 op-amp, the same op-amp family associated with the original Tube Screamer. Kasleder pairs it with Wima high-end audio capacitors and Nichicon gold series capacitors as part of the upgraded parts selection.
What diodes are in the Kasleder Dirty Little Thing?
According to Pedal of the Day, the Dirty Little Thing uses NOS "mojo" diodes for its clipping, alongside NOS carbon comp resistors, a Made in Japan 4558 op-amp, and Nichicon gold and green series capacitors.
What was different about the 15th anniversary Dirty Little Thing?
The limited 15th-anniversary edition, released in 2021 to mark 15 years of the pedal, used an op-amp chip slightly different from the one that went into the TS808, taken from the last pre-production run. Standard V2 units use the regular circuit.
Sources (3)
- Kasleder FX Dirty Little Thing, Delicious Audio, 2021-12-03
- Kasleder FX Dirty Little Thing Overdrive Boost, Pedal of the Day, 2020-04-07
- Guitar Pedal X - GPX Blog - Catalinbread unleash the Deluxe edition of their Dirty Little Secret Plexi Drive - to go head-to-head with the Tsakalis AudioWorks Room #40, Guitar Pedal X
