Build your own Preamp – FABModules – FiveFish Audio Building Blocks for DIY Projects Blog Articles

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FAB2120 – Carnhill Input Transformer Module

This is similar to our FAB2110 Input Transformer Module… but instead of using a CAN type transformer, we’re using a Carnhill/UK Input Transformer, (model VTB-9045) typically used in Neve preamps.

The VTB-9045 Carnhill Transformer is a Low Level Audio Signal Transformer, with a turns ratio of 1+1:2+2.  DC Coil resistance is 24+24:130+130 ohms.

To mount the Carnhill transformer horizontally on this FAB board, a separate Carnhill PCB Adapter is also required.  Both boards will be provided when you purchase this FAB board.

CarnhillPCBAdapter

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FAB2110 Input Transformer Module – Prototype with parts

Populated our FAB2110 Input Transformer Module with parts.  Here are some photos showing a Jensen JT-11K8-APC Input Transformer mounted on it.

The board looks good, but I’d probably add another mounting hole on the lower right corner, just because the board is a little unstable with a heavy transformer mounted on it.

I’ll build another prototype using a different Input Transformer, like an Altran or EA brand.

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FAB2110 Prototype PCB

Received our FAB2110 Input Transformer Module. Looks good.  No corrections needed, it’s just a very simple PCB. You can use a Jensen, Cinemag, Altran, EA Input Transformer for this PCB.

So let’s say you have a few of these FAB 2110 boards, you can solder a different kind of Input Transformer on each FAB board, and you’ll be able to swap them in and out in your circuit, and compare the sound flavors of each other.

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FAB2110 – Input Transformer Module

Introducing – our FAB2110 Module.  This is basically our Input Transformer Module.

This FAB module will accept CAN type transformers like Jensen, Cinemag, Altran Input Transformers with it’s typical (8) pins.  CAN Transformer dimensions are 1.13″ diameter (28.7mm) with 0.15″ pitch pins.

FAB2110 Input Transformer Modules are designed to mate with our FAB2010 XLR Input Modules.  This allows you to create a complete Transformer-based Input Stage for that Mic Preamp or gear you’re building.

The FAB2010 XLR Input Modules require power (V+, 48V) for proper operation of it’s relays (controlling the -20dB Pad and Phantom Powering) and 48Volts Phantom Power. These power requirements cam be supplied via the POWER INPUT headers of the FAB2110 Input Transformer Module.  You can use a 2×5 (10-pin) Ribbon Cable to connect this POWER INPUT header to our FAB Power Supply*. Continue Reading…