This video demonstrates the build and assembly of the "990XF," a transformer-coupled circuit upgrade for the venerable MXL 990 condenser microphone. We present the complete assembly process, using the 990XF kit that we sell at MicParts.com. We also show off and demonstrate two new large-diaphragm capsule options for this circuit.


Table of Contents
0:00 - Introducing the 990XF
0:31 - Introducing the RK-47C and RK-87C capsules
1:49 - Compatibility with MXL 990
2:10 - Why build a DIY microphone?
3:39 - Preview of the microphone build guide
3:58 - 990XF Kit Overview
4:34 - Lead Bending
4:54 - Diode Installation
7:23 - Resistor Prep & Installation
10:00 - Ceramic Capacitor Installation
10:40 - JFET Prep & Installation
12:01 - Input Circuit Installation
13:30 - Output & Filter Capacitor Installation
14:55 - PCB Cleaning
15:46 - Input Terminal Installation
18:47 - Transformer installation & Wiring
21:53 - MXL 990 Disassembly
22:57 - New Capsule Installation
25:46 - 990XF PCB Installation into MXL 990
26:47 - XLR Wiring
29:03 - Capsule Wiring
31:30 - Microphone Assembly
32:32 - JFET Voltage Test
34:18 - Audio Test
35:33 - 990XF Demonstration with RK-47C and RK-87C


The 990XF employs a single stage JFET/transformer design pioneered by Neumann, many years ago. We implement it with high-quality parts, including a vintage JFET, European film capacitor (on the audio output), NO input coupling capacitor (the best capacitor is no capacitor at all!). Our implementation boosts the sensitivity and improves the DC noise filtering over the original design.

For more info on DIY microphone kits, see MicParts.com

For more info on the 990XF specifically, see:
https://microphone-parts.com/products...


For other capsule, grille, and circuit upgrade options for the 990, see:
https://microphone-parts.com/pages/mx...