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

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FAB3110 – Output Transformer Module Prototype

Here’s a photo of a fully assembled FAB3110 Output Transformer Module.

You can use any API-type output transformer on this module. Shown here is an EA transformer, but you can also use transformers from Cinemag, Crimson Audio, etc…

There is a Logic control on the FAB module, allowing you to switch your transformer ratio from 1:1 to 1:2 (+6dB gain). Just apply any +3.3V, +5V or V+ voltage on this logic pin.

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Passing your Audio Signal through an Input Transformer

Here’s one of the simplest way to use our FABModules….  Hook up the following FABs together:

FAB2010 – XLR Input Module
FAB2110 – Input Transformer Module
FAB3010 – XLR Output Module

All that’s missing is Power, if you want to enable the -20dB Pad, Phantom Power and Polarity Reverse functions. Otherwise, it will still work without power applied. After all, it’s just an input transformer inserted in your signal chain.

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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 – 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…

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