LowVoltTube is an original pedal that combines two references of the guitar sound :
— A preamp-overdrive, TS9 type, with its tone control …
— A tube stage included to generate a real “tuby” grain.

The tube is a 50s NOS model, specially designed to work directly with automobiles batteries.
Boutique quality, but for a moderate price !

LowVoltTube preamp/overdrive - Logo

LowVoltTube. Préamp/overdrive with JRC4558 and NOS tube 6ET6 (EF98)

LowVoltTube — First issue, 2018.

OK, the tubes are an essential reference in electric guitar sound …
The problem is they need an anode voltage at least 80/100 volts. This is why the pedals including a tube are expensive and more fragile because of the voltage booster circuit, or disappointing when they dare to implement a 12AX7 under low voltage …

However, naturally working tubes between 6 and 12V have existed: Around 1955, one were already trying to free auto-radios from the constraints of high voltage. A latest generation of tubes has been developed , designed to work with a simple car battery. Almost everyone has forgotten these tubes, but not Guitar Poppa!

I had the idea to update this technology in the LowVoltTube preamp. It was propitious :
I had a big stock of vintage NOS tubes, perfect for this use…

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LowVoltTube Préamp / overdrive with JRC4558 and a NOS Tube 6ET6 (EF98)

Open case detail: the JRC4558D preamp and the TungSol 6ET6 tube.

Main Features

TS9® type input stage.
Classic controls: gain / tone / volume.
Overdrive stage with a low-voltage tube from the 50s :
6ET6 TungSol or EF98 Telefunken (equivalents).
2 voicings: hot / smooth
Output stage with TS9 type Tone Control.

Soon, one will click here to hear samples … In the meantime :
LowVoltTube samples on Facebook

And download a technical notice …

Contact us for more informations

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To order :

1. Specify the delivery area.
2. Click <add to order>.
3. Click <cart> on the main menu to finalize …

LowVoltTube. Préamp/overdrive with JRC4558 and NOS tube 6ET6 (EF98)LowVoltTube
Single version
169 €

• Classic “Drive / Tone / Volume” settings.
• “Hot” and “Smooth” tone presets.
• Preamp equipped with JRC4558D.
• Drive stage with a NOS 6ET6 / EF98.


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Technical details


Gain adjust

• 8.00 to 10.00 : Typical tube sound, barely overdriven.
• 10.00 to 13.00 : Crunch, with persistence of clean harmonics.
• 13.00 to 17.00 : More and more fat and saturated sound, but not harsh.

The tube “works” as soon the pot reaches 9.00.
The TS9 circuit begins to drive in turn from 13.00 and then pushes on saturation without hurting the ear.


• Type TS9, more effective and regular. Neutral at 12:00.
• Softens harmonics to the left. Sharpen the acute to the right.


Hot : Well bound midrange and treble, slightly boosted medium to the American taste.
Clear and overdriven sound are warm but keep all their mordant…
Good for single pickups and bridge pickups.
Smooth : hollowed medium to associate roundness in bass and a fresher treble outline.
Overall, the tonality and saturation sound cleaner.
Good for neck pickups and too bally humbuckers.


• Standard guitar level when control set around 11:00.
• Maximum level: at least 0dB, (800mV RMS).

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Power supply

The circuit is intended to operate between 9 and 12V.
Consumption : 330mA

• This consumption requires an external power supply.
• Classic Boss type power supply or high frequency switching model …
• Connections: 2.1mm standard coaxial socket, center negative.

The headroom (clear range of sound before crunch) and the dynamics are a bit more important with 12V.

Filtering and regulation

LowVoltTube has internally all what is needed for the security of the tube and its silence :
• Stabilization of the heating voltage will smooth any surge.
• Active filtering on the power supply of the preamp, eliminating “hiss” and “hum” …

LowVoltTube under construction on the workbench.

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