MOONDROP Free DSP Review (Including PEQ Guide) – IEM Upgrade Cable With 9-Band PEQ

Moondrop FreeDSP is a premium USB Type-C DSP IEM upgrade cable with high-quality audio components for enhanced sound performance. It has high-purity silver-plated copper and Oxygen-free copper wire cores arranged together in a Litz structure for enhanced sound signal transmission. FreeDSP features an all-new interactive online DSP, allowing users to play with different DSP profiles and parametric equalizer, and also enables the sharing of different DSP profiles online using the Moondrop Link 2.0 application.

DSP stands for Digital Signal Processing. There are many things possible with DSP now with Moondrop’s all-new Interactive online DSP. The FreeDSP with the support of the Moondrop Link2.0 application allows the user to download different DSP profiles, and adjust parametric equalizers. Users can also share their customized profiles with the community.

The FreeDSP cable has a 75-core arrangement featuring high-purity oxygen-free copper(OFC) and silver-plated copper mixed hybrid design structure arranged in the Litz structure. This high-purity core structure enables smooth sound signal transmission with low internal resistance. The cable has a sweat-resistant and high-permeability PVC outer covering that protects the cable from accidental damage as well. Its also soft enough and handles very well in the hand.

The Moondrop FreeDSP cable is compatible with most latest-generation devices with Type-C termination. Nowadays, smartphones, tablets, and even laptops and PCs are equipped with Type-C ports, the FreeDSP cable helps you to enjoy your favorite IEMs straight with your devices. And its interactive online DSP allows you to play with different sound signatures.

Moondrop FreeDSP cable is available with universal 2-pin 0.78mm connectors. 2-Pin 0.78mm connectors are widely used among the IEMs.

FreeDSP has independent in-line control plus a high-quality microphone. Three control buttons for adjusting the volume, play/pause, or answering calls.


  • All-New Interactive Online DSP Cable.
  • Fully-Balanced Audio Architecture.
  • Premium-Quality USB Type-C Termiantion.
  • Four-Layer Gold-Sinking Circuit.
  • High-Precision Components.
  • Clear Sound With Ultra-Low Distortion and Improved Dynamics.
  • Compatible With New Moondrop Link2.0 Application.
  • High-Purity 75-Core OFC & Silver-Plated Copper Mixed Hybrid Litz Cable.
  • Isolated In-Line Microphone Design.
  • Convenient Three-Key In-Line Media Control.
  • 0.78mm 2-Pin Universal Design.
  • Price: $29.99

I would like to thank Shenzhenaudio for providing me with the review sample of FreeDSP.

Moondrop Link App


After you plug the FreeDSP cable into your phone and give permission to the Link App to access it, you click the plus sign and choose the cable from USB devices. After that, you can see 2 rows that show the cable’s features. The first one is the EQ presets that you can apply to your IEM immediately, which are Normal, Bass+, Bass++, Sound stage+, and Treble+.

The second and more interesting feature is the PEQ option. First, you see the main screen which is 9 lines of frequency ranges that you can manually put the values in. When you click “download” at the bottom you see another page with 3 tabs again. The first tab named “Official” contains PEQ presets for your Moondrop IEMs. For example, if you have the Moondrop LAN model you can choose between basshead, no bass, and low bass presets. If you have Stellaris you can choose between VDSF and Bass+ and so on.

On the third tab “Featured” there are presets that are uploaded from other FreeDSP users. Sadly most of them are in Chinese and you can’t know which IEM is used, but there are some English presets too.


The second tab “Mine” contains your presets which you have uploaded before. Let’s dive into the most important feature of the FreeDSP, which is how to create your own preset. Visit or any other that contains your choice of IEM models.

MOONDROP Free DSP Review 20

First, choose the models, one is your own IEM attached to FreeDSP, and the other one is the model which you want to choose the tuning from. In my example, I’m using Yanyin Canon 2 as my IEM and choosing Moondrop Blessing 3 for its tuning. You can do this under the “Models” section. Then click the “Equalizer” section. Click “Choose EQ model” under the Parametric Equalizer tab and select your model.

Second, click the minus button to decrease the frequency lines from 10 to 9 (FreeDSP supports 9 lines). Third, put the AutoEQ Range from 40-10000Hz (FreeDSP supports these ranges). And lately, click the “AutoEQ” button.

Canon 2’s tuning aligned with Blessing 3’s tuning

Put these values in the Moondrop Link App under the PEQ section.

MOONDROP Free DSP Review (20)

After you click “apply” your IEM will sound as close to the target IEM. We need to put the values manually, sadly Moondrop Link app does not support’s exported formats so we cannot use the import function here.


Now here is the good news, The latest PEQ presets that you uploaded to your FreeDSP will stay in the memory. This means to can unplug it and plug it into another phone or PC, it will have the latest tuning. Here is proof, I measured the Canon 2 attached to FreeDSP with Blessing 3 tuning.

Yanyin Canon 2 vs Moondrop Blessing 3
The start of the sub-bass is not aligned because of the 40Hz start range of the FreeDSP.


I was waiting for a DSP cable with an onboard PEQ function for quite some time and finally, Moondrop came up with the FreeDSP. Some people ask on Reddit why we need something like this when we have the Wavelet App (the best App with PEQ support on Android) already. Well, the answer is very simple. First, we don’t need any external USB DAC when using the FreeDSP, secondly, we can use it cross-platform between different operating systems without needing to upload the PEQ preset that we want, it’s already stored on the memory.

The only downside of the FreeDSP is it doesn’t support the recessed 2-pin connectors (models like DUNU SA6 MK2). Other than that, even without the EQ functions, it’s a good-quality Type-C cable for $29.99 and it has enough output power to drive most of the IEMs on the market.