DIY Sound Upgrade for Leteng E500 Speaker

If you're interested in DIY Bluetooth speakers or radios, this article might be just what you're looking for. The Leteng E500 is a compact device that can function as a USB speaker, card-in speaker, or Bluetooth speaker. It's small, yet delivers exceptional sound quality. However, the sound can be a bit muffled, so what can you do about it? You can try polishing it up a bit.

Unlike the earlier version, the new version's circuit has been slightly reduced, with the amplifier adding a 220u electrolytic decoupling. If you have this version, you can follow the steps in this article.

The old version is shown below:

The new version's circuit is shown below:

There are only two chips: one amplifier (for both amplification and headphone use) MC4863, and one main control AC**** (which manages everything except the amplifier function).

The culprit for the muffled sound and scattered bass is the Cvdd decoupling in the amplifier. You'll need to remove it and replace it with a 47u or 100u. Use a 105-degree electrolytic capacitor (like KZH or ZLH), reducing the capacity by half and connecting two in parallel. If you're replacing it with MLCC or polymer capacitors, you'll also need to remove the 1.5u capacitor on the outer part.

Replace the 3u Bypass capacitor with a 1u.

If you're picky about the sound quality of card-in playback, solder a 0.1u + 10u or 22u or 47u capacitor to pins 4 and 6 of the TF card slot. You can also remove the capacitor at the bottom-right corner of the slot.

After completing these three steps, the previously dull bass will be gone, and the sound will be noticeably clearer. The mid-high frequencies' harmonics and layering will stand out. However, while the bass has become cleaner, it lacks the previous "depth" of the fake low-end. The mid-bass may sound a bit thin. If that's the case, you can replace the speaker wires with 22 or 24awg high-quality copper wire. This will make the sound more comfortable, and the mid-bass will no longer sound thin, while the bass texture will return. Of course, the bass might still lack some presence, but that's the inherent limitation of full-range speakers.

If you can find documentation for the Jieli AC**** Bluetooth chip, you can make further improvements.

Also, take note that the left and right speakers in the diagram are reversed. If the wires are long enough, you can simply swap them around.

That's it!