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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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, typically used in Neve preamps.

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.

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Sample FAB Setup – Power supply and other stuff

 

 

 

 

 

 

Here are some photos showing the FAB1215 Power Supply Module powering some FAB modules via a ribbon cable.

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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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