When we connect an Acoustic Guitar to the mixer, it sounds "thin" and "tinny"
Acoustic Guitar Filter Cable:
When a passive Pickup is installed in a Guitar, the sound from the Pickup is often "thin" and "tinny". A number of factors contribute to this such as pickup type and location. An active pickup (battery operated), on the other hand, includes a preamp with built in corrective equalization and usually tone controls. This overcomes the problems associated with its passive counterpart.
With a passive pickup, you often hear too much of the High Harmonics and you lose the Low Harmonics. Often the amplifier or mixer you connect to doesn't have enough EQ or Tone Control range to regain the natural sound of the Guitar.
The best solution is to feed the guitar pickup through a Guitar preamp such as those made by Fishman before going to your DI box, mixer or amplifier. The controls on these preamps will generally enable you to regain the rich and natural acoustic sound of the guitar.
Alectro Systems also makes a CAULPTS Cable. It has a built in Low Pass Filter which also helps to correct this problem. The cable itself reduces the High Harmonics producing a more natural Guitar sound for the amplifier or mixer.
Although it doesn't have all the features of a preamp, it is less expensive, easier to use, and doesn't need batteries. In many situations the CAULPTS will provide the EQ tweaking you require in order for your mixer controls to do their job effectively.