L2P Assembly Guide

Safety Precautions, Warranty, and Disclaimer Improper soldering and handling of electricity can cause serious injury and damage to your property. Read and understand the instructions below before beginning your project. Follow the instructions, build carefully, and use the appropriate tools. Build at your own risk. DIY Recording Equipment, LLC is not responsible for any damage or injury resulting from the assembly or use of your kit. You are the manufacturer of your kit. It is your responsibility to turn this group of parts into a working piece of recording equipment. DIY Recording Equipment, LLC does not guarantee the success of your project and disclaims any Implied Warranty of Merchantability. Please visit the support forum for assembly support.
Damaged or Missing Parts All kits and parts are checked before being shipped to you. If something arrives damaged or if your kit is missing a part, please open a support ticket to inquire about a replacement. Missing parts will be replaced at our expense. Damaged parts should be returned for verification. If the part shows signs of use beyond what was necessary to determine that it was damaged, DIY Recording Equipment, LLC reserves the right not to replace the part.
Welcome to the L2P Assembly Guide

Thank you for purchasing a L2P Passive Line Attenuator Kit!

If this is your first DIY project ever, we recommend reading our Getting Started Guide.

Table of Contents

Required Tools

You'll need the tools below to complete this build.

Soldering Iron
We recommend an adjustable-temperature station, such as the $40 Weller WLC100.

You can use 60/40 "leaded" solder or lead-free. We recommend 60/40 because it flows better and is easier for beginners to use.

Wire Cutters
You'll need a pair of good "snips" for cutting of the excess leads after soldering.

Optional Tools

These tools aren't strictly necessary but can make your build a bit easier.

If you find the color bands on resistors a bit hard to read, you can use a meter to sort them with absolute confidence.

Desoldering Pump
If you accidentally solder something in the wrong place, a desoldering pump can save the day.

Assembling the L2P

Idenfity Parts

Take a moment to identify all the parts of the kit:

  • L2P Case
  • Foam Pad
  • L2P PCB
  • Front and back panels
  • Input 1/4" jacks (2x)
  • Output XLR jacks (2x)
  • Toggle switch
  • 2.7k resistors (6x)
  • 150 resistors (2x)
  • Screws (15x)

Sort and Bend Resistors

Idenfity the two 150R resistors and six 2.7k resistors. Bend their leads near the body before inserting them into the PCB.

Place Resistors

Place the resistors according to the values marked on the PCB.

Notes: Since resistors don't have any polarity, it doesn't matter which way the leads are facing. And, since this resistor will not be letting off significant heat, you can place the body flush against the PCB.

Bend Resistors Against PCB

Before soldering, bend the resistor leads agains the bottom of the pcb.

Solder Resistors

Solder the resistor to the PCB. Here are a couple good soldering practices to observe:

  • Heat the pad and lead together for 2-3 seconds before applying solder
  • Apply just enough solder to cover the entirety of the pad, so that no gold is showing through
  • Leave the iron in place while you are adding solder and for 1-2 seconds after
  • The entire soldering process should take 5-8 seconds
  • Allow the solder joint to cool for about 20 seconds before soldering another lead of the same component

Place Input Jacks

Remove the nuts and washers from the 1/4" input jacks. Then place them in the areas labeled "J1 / INPUT 1" and "J2 / INPUT 2." To keep the jacks in place, bend the leads back with a small flat-head screwdriver as shown.

Solder Input Jacks

Solder the leads of the input jacks, leaving about 10 seconds between each joint.

Place & Solder XLR Jacks

Place the XLRs jack in the "J3 / OUTPUT 1" and "J4/ OUTPUT 2" positions on the PCB. Lay the jacks on their backs with the PCB lying on top of them to solder.

Solder the three metal pins of the XLR jack. Don't solder the two plastic mounting pins.

Place & Solder Switch

Place the switch in the "DPDT" position, and bend the longer leads to keep it in place. Before soldering, attach the front panel via the input jacks' mounting nuts and washers.

Once the front panel is mounted firmly, solder the switch to the PCB.

Trim Excess Leads

Trim away the excess pins and leads with a wire cutter. Cut each lead as close to the solder joint as possible, without compromising the joints themselves.

Slide Assembly into Case

Slide the assembled PCB into the lower channel in the chassis. The front panel should be on the side of the case nearest the "L" in "L2P."

Screw on Panels

Screw in the eight remaining mounting screws. Since these screws are cutting their own threads in the aluminum, you'll feel a healthy amount of resistance the first time you put them in.

It's a good idea to install all four screws on one panel loosely before tightening each one.

Apply Foam Pad

Remove the backing and apply the neoprene foam to the bottom of the case.

Using the L2P


The L2P (Line to Preamp) is a two-channel, line-level, balanced attenuator. It has two primary applications in the studio:

  • Place it after colored mic preamps set on the -10 setting to drive the preamps harder without clipping converters
  • Place it between line outputs and and mic inputs on the -30 setting to add preamp color to tracks during mixing


The L2P accepts two balanced inputs via 1/4" TRS jacks 1 and 2. The toggle switch sets both pads to either -10dB or -30dB.


The padded signals exit the L2P via two 3-pin XLR jacks. You can patch the padded signal to any balanced piece of gear, including converters, mixing desks, mic preamps, and signal processors.

Final Checks

Before you wrap up, check the following things:

  • Resistors: Do all of the resistor positions correspond the chart and/or sorting sheet?
  • Soldering: Is every solder joint shiny and clean? If one is cloudy or misshapen, try reheating it for 8 seconds and adding a tiny bit more solder.
  • Trimming: Are all of the excess leads trimmed down as close to the joint as possible?

All good? Congrats on finishing your build! Have a question or problem? Drop us a line.

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