D-PRE - Mini-Marshmallow Preamp Kit


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D-PRE is based on London Power's Mini-Marshmallow amp, which was a tribute to Howard Dumble. The basic topology is here with typical values. Although many amp designers used the "overdriven Fender amp" as the basis for the preamp in a master-volume amplifier, Howard's is the most famous.

D-PRE provides two distinct sounds: classic warm clean and late-over-drive distortion. We've added an extra 'Drive' control to the Dumble topology, making it more useful to a wider range of players. Two 12A_7s provide all functions in a pure tube audio path.

• Clean Volume
• Treble
• Mid
• Bass
• Mid-shift (sw)
• Jazz-Rock (sw)
• Over-Drive Level
• Early Drive
• Late Drive

Use two RLY kits for basic mechanical relay switching, to switch between the two sounds.

D-PRE kit

Power requirements: 12V-300mA; 160-450V-5mA
Use our PSU-PRE Power Supply Kit for Tube Preamp or similar to build a stand-alone preamp.
Combine with AMP-10 or AMP-25 to build an integrated amp.

This item includes PCB, tube sockets and components, and helpful installation notes including layout and schematic diagrams of the kit.

Would you like to receive this pre-assembled? Add PRE2-BLT to the order.

For more info on London Power Preamp Kits, see our Selecting a Preamp Kit page.

Need a chassis for your preamp project? See our Rack-Mount Chassis page, or browse under Building Supplies.


PCB size: 7.2 x 1.5", 183 x 38mm

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About London Power

London Power was founded in 1990 by Kevin O'Connor, after two decades of research into innovative audio amplification techniques. Kevin is an audio designer, author and speaker, known for his proprietary methodology called Power Scaling, and for his eleven books on audio subjects. Whether you seek amps, kits or information, you'll find useful answers here on not just the "how" but the "why" of audio amplifier design. Please enjoy the information on this site, and don't hesitate to contact us with questions.

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