Line 6 DL4 Mods (also MM4, DM4, FM4)


Get A Quote & Start Your Order

(Full details about mods below the form.)


Video Demonstrations




With great sounds, lots of presets, and a cheap price, the Line 6 DL4 has become a “new classic” among guitarist. But there’s more you can do with your old friend. Many of these mods will also work for the other pedals in the Stompbox Moddler series like the MM4, DM4, and FM4. Use the form to get a quick quote and start your order. Select package deals if you want to save some money, or simply select the individual mods you want. You can also select a package deal and add mods from the check list. Once you have what you want, submit the request and you’ll hear back from us quick.


Shipping Your Pedal

Once the order process is complete, we will give you an address for shipping your pedal to us. International rates will apply. Make sure to include the invoice in the box with your pedal. Usually, USPS Priority Large Flat Rate or Regional Flat Rate (A or B Boxes) are the cheapest. We will use these shipping methods for returning. Please pack your pedal well. We’re located in Lyman, SC, and you can use the shipping calculator to get a return shipping estimate.

Full Mod Details


About Refurbishing

Is your DL4 dead? That’s ok. Luckly, we can order a brand new PCB for you and rebuild the entire inside to be brand new again. This method is usually much cheaper than buying another used DL4, and better because you’d still be buying something used. We can repaint yours, install a new PCB, and your DL4 is functionally brand new again. If you need a new PCB with your mods, please select this option above.


1) Volume Drop Fix – $35

Do you notice a volume drop when you engage your DL4? It’s a known problem with the circuit. We simply fix that! However, we suggest getting this “whole” mod for perfect adjustment by adding the output buffer control knob below. Depending on your setup, the “simple” volume fix still may not be a perfect unity match.


2) Output Buffer Control – plus $20

This is an extra mod to the for the volume drop fix which adds a control know that allows you to tweek exactly how much volume output you need. Maybe you want a slight increase in volume when engaged, or you just need to fine tune your DL4 output with your setup.


3) Double Preset Switch Mod – $40

A preset switch will allow you to select a second setting for each delay preset on the DL4. Different than the expression control, the switch will select quickly back and forth between two settings. The LED indicator for the switch will turn on with your second setting is engaged. Easy to use. Save your first setting by dialing in your sound and holding down the A, B, or C switch until it’s saved. Then engaged the mod switch, make a new setting with that first delay and hold the A, B, or C switch to save again. This mod will also work with the MM4, DM4, and FM4.


4) Switch Replacement Mod – $50

One of the most common reasons the DL4 stops working is because the switches go bad. Switch Replacement consists of changing out all of the factory switches with heavy duty “soft-touch” switches that will make your life a lot easier, especially for that tap tempo switch. This mod will also work with the MM4, DM4, and FM4.


5) Pot & Knob Replacement – $80

More expensive yes, and most difficult to install. However, like the switch replacement, cheap dead pots are another common reason the DL4 will stop working. When a pot starts to wobble and go bad, then the whole DL4 can start going crazy- constantly changing values, settings, etc. This mod replaces all of the cheap, plastic shaft pots with much better quality metal shaft pots. New knobs added as well.


6) Loop Switch Engage Mod – $40

Engage the looper/recorder on-the-fly! No more bending down and turning the knob to engage the looper. Simply hit the looper switch that will be installed and start recording.


7) Expression Knob Mod – $40

Similar to the preset switch mod, the expression knob will switch between two settings, but will also mix between then. So if you want to morph from one delay setting to the next setting instead of quickly switching, this is the mod you’ll want. This acts just like an external expression pedal will act, just installed inside the DL4. Also easy to use. Save your first setting by dialing in your sound and holding down the A, B, or C switch until it’s saved. Then turn the knob all the way to the right, make a new setting with that first delay and hold the A, B, or C switch to save again. Then morph between the two. This mod will also work with the MM4, DM4, and FM4.


8) LED Replacement Mod – $30

Get a custom look. Do all multi LED colors (standard mod), or replace all the standard red with a different color. This mod will also work with the MM4, DM4, and FM4.


9) Tap Tempo Sync (Tap Output Jack) – $25

This adds a tap tempo out connection. Do you have on of our Multi Tap Tempo pedals? This mod is useful if you have other delay pedals on your board with tap tempo connections and want to link up your DL4 with. Connect to the sync out jack with our Multi Tap Tempo pedal to sync your delay pedals together.


* 10) .8th Note Tap & Double Preset (Dual Mod) – $90

Install a smart switch that doubles as a double preset switch when held down for 1-2 secs adding a second setting to each switch, and use the same switch to tap DOTTED EIGHTH NOTES with any delay preset on your DL4. Yes, really. You can still use the DL4 tap tempo switch like normal too. Add the tap tempo and toggle sync control to this mod for only $40 extra.


11) .8th|1/4 Note Toggle Mod (for the Tap Tempo Sync Out) – $30

When ordering the .8th note and dual preset mod, this toggle allows you to control which type of rhythmic signal is sent to your Tap Tempo Sync output jack. You can choose between sending the standard DL4 tap tempo signal, or sending the .8th mod signal. Once an external tap tempo pedal is connected, that pedal will tap whichever signal is being sent. An example of what this is and how it looks.


12) Feedback/Swells Hot Switch w/ Mix Max 100% Toggle – $50

Unique and fun. Add a stomp switch that will engage your feedback to 100%, instantly. The Mix Max 100% Toggle adds the option for the mix to also max out when the Feedback Hot Switch is engaged. For players who love creating sound effects, ambiance, swells, etc., this is the mod for you. These two mods also act different depending on what type of delay is used. Some get crazy quick, others are lighter and produce beautiful soundscaping ambiance. This sounds are also impacted by how soft or hard you play the instrument. For nice, warm sounding pads and swells, use your volume controls and play soft. For harder out of control feedback effects, use an analog delay, engage, and play hard. We can also change up this mod. Note: in the video, this mod is shown without an LED, but we DO install an LED indicating when the switch is on- this is shown in other images in the gallery.


13) Custom Paint Jobs – $50

Really make your modded pedal stand out aesthetically! Custom paint jobs start out at $50. We can paint your pedal just about any color you want. We remove all labeling plates, clean the pedal, and then go through the painting process. We can match the paint jobs with knobs, or do a cool color theme with the LEDs, knobs, and paint job.


14) DoublePre-Expression-Knob Toggle – $20

If you’re wanting both an expression knob on the side and the ability to have a double preset switch, then be sure to add this mod at the top. It’s a toggle that allows having, and switches between, these two great mods.



We highly recommend getting the full Volume Fix w/ Amount Control Knob. Most all DL4s we encounter have a volume level, or unity, problem when engaged. This full mod will allow you to adjust the perfect amount of unity when engaging your DL4, or you can even use it as a boost.



Please know that many of our mods may fix some of the issues with your DL4- because the parts we replace were the parts causing the problems. Also, many problems are fixed by simple factory resets and readjusting the main chip. However, we cannot perform miracles. Issues that are digitally related and/or power related, we do not fix. If your DL4 has issues coming in, it’s possible there will be issues coming out of the mod process. We can give you our professional opinion- but it’s only an opinion. If you’d like to start out with a problem free DL4, we suggest starting out by letting us replacing the main PCB first, then installing mods. This will basically make your DL4 brand new again. This route is also much cheaper than buying a new DL4.