DIY-Central.com - Go Create something! - PCB Design, Electronics

Yes, build your own pads. By pads, I mean "attenuation pad."  These are devices or circuit meant to attenuate or insert a loss in your signal path.

There are 2 kinds of pads you can use... The first is called a "T" pad and is mainly used for unbalanced lines.  The second is called an "H" pad and is mainly used for balanced lines.

We'll be building an "H" pad.

If you want a -10dB attenuation on your signal, use the values 150ohms for Ra, and 430ohms for Rb.  These values are meant for a 600 ohm line, which is the impedance typically used in pro gear.

For other values, see table below:

dB Loss	Ra	Rb
1	8.2	10K
6	100	820
10	150	430
20	240	120
40	300	12
50	300	3.6

This is a DIY Signal Isolation/Unbalanced to Balanced Converter Box. I'm using high-quality MADE IN USA Audio Output transformers to create this SI/UnBalanced-to-Balanced (or Balanced-to-Unbalanced) Converter Box. In addition, a Ground Lift switch is provided.

On this picture, you can see the 4 TRS jacks (2 per channel x 2 = 4), the 2 large audio output transformers, and the ground lift switch in the middle.

And this is the picture of the finished project. The switch on top is the GND LIFT switch.

The jacks from left to right, are Unbalanced in/out, Balanced in/out (for Channel 1), Unbalanced in/out, Balanced in/out (for Channel 2).

The unit can perform as a Unbalanced to Balanced converter, or as a Balanced to Unbalanced converter.

It's done... some pictures.  Using my custom PCB for the power supply, and an MCI output transformer on the outputs to convert it to balanced outs.

It works... sounds nice and clean!  The EQ lets you sculpt the sound nicely. No hum, no noise. It's great!