CA Guitar Repair Blog: Fishman Matrix Infinity VT

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Matrix Infinity VT Preamp Module

The Matrix Infinity VT Preamp Module is, as stated before, mounted to the endpin jack. The module itself is contained within a black plastic "newly designed soft touch housing." This housing consists of two congruent halves, the upper half featuring "Fishman" and "Matrix Infinity" labels. The lower half houses a large slotted screw, which may be unfastened with a coin. This screw holds the two halves of the housing together, and secures the PCB contained within.

Preamp Module - Top

Preamp Module - Back

Moving on to the end of the module that's inside the guitar, we see a thick black cable on the extreme left. This is the Control Module Cable, which transmits signals between the Preamp and Control modules. Next, the thinner black cable in the center is the Acoustic Matrix® Undersaddle Pickup Signal Cable. This coaxial cable transmits impulses from the undersaddle pickup to the preamp. To the right of the pickup cable is a small LED. This LED functions as a low battery indicator, only lighting up when the battery is running out of juice. Finally, on the extreme right, there are a pair of red and black cables. These are the positive and negative cables from the 9V battery.

Preamp Module - Cables and LED

Matrix Infinity VT Preamp PCB

I've just loosened and removed the large slotted screw securing the upper and lower halves of the Matrix Infinity VT Preamp Module housing. Now the the two halves of the housing can be separated, fully exposing the preamp PCB for closer scrutiny. Seen below are full-length images of the top, back and sides of the Matrix Infinity VT Preamp PCB. We will not be identifying individual PCB components at this point, as these will be covered later.

Preamp PCB - Top

Preamp PCB - Back

Preamp PCB - Right Side

Preamp PCB - Left Side

Preamp PCB - Control Module Cable Connector

Here we are, looking at the top of the Matrix Infinity VT Preamp PCB, specifically, the upper half. On the left is the Control Module Cable five-pin connector and terminal block. From left to right, the individual conductors within the Control Module Cable are as follows - braided shield/ground [in black heat shrink tubing], yellow, red, black, and white. To the right of the Control Module Cable connector/terminal block are the Preamp PCB DIP Switches.

Preamp PCB - Control Module Cable Connector

Preamp PCB - DIP Switches

On this particular Yamaha F-210, the Matrix Infinity VT Preamp has been installed with the Matrix Infinity VT Control Module; an installation considered "normal" by Fishman. Alternatively, the user may choose to omit the Control Module, and only install the Infinity VT Preamp. In this scenario, the DIP switch labeled "1" must first be set to its "ON" position. Following this, the DIP switch labeled "2" may be set to yield either a "Bass" [bass boost] or "Flat" [neutral] preamp voicing; as shown in the image below.

Preamp DIP Switches - Settings

Preamp PCB - Pickup Input Terminal Block

Although we're still viewing the top of the Matrix Infinity VT Preamp PCB, the current focus is on the lower half. Right in the center is the Pickup Input Terminal Block, which is divided into two halves, or sides. The hot [+] lead of the pickup cable is connected to the left side of the block, and the braided shield [ground], the right. To the right of the Pickup Input Terminal Block, you can see where the red and black 9V battery cables are soldered to the PCB.

Pickup Input Terminal Block - Top

For a better understanding of how the pickup cable is connected to the Pickup Input Terminal Block, let's look at the LED end of the PCB. Here, we see a slotted screw on the left [+] side of the block, and a similar screw on the right [ground]. Tightening these screws secures the connections for both the hot [+] lead and braided shield [ground] of the pickup cable, without the need for solder.

Pickup Input Terminal Block Screws

Preamp PCB - Underside

I've included two detailed images of the underside, or back, of the Matrix Infinity VT Preamp PCB. The first is of the upper half, and the second, the lower half. In the first image, you can see exactly where the ground lug of the Switchcraft® endpin jack, Control Module Cable terminal block, and Preamp DIP Switches are soldered to the PCB. Meanwhile, the most standout features in the second image, to me at least, are the two 10uF 16V electrolytic capacitors and low battery LED. I'm no electronics whiz, but am confident that electronics-savvy readers will be able to identify the rest of these components.