Direct Box

Does anybody have a schematic for a DI box? I'm wanting to build a two in one DI (one mono for acoustic and the other stereo for click/loops) anybody?
Thanks,
-Foster

Balanced outputs?
Isolation?
Passive?
Active?
Equalization?

There are many ways to go.

Balanced outputs?
Isolation?
Passive?
Active?
Equalization?

There are many ways to go.

Balanced outputs. Preferably isolated. Passive or at least be able to run on phantom. And no equalization. Just ground lift.
OR whatever you think would be best for these two applications!

Isolation requires a transformer. They are pretty specialized and therefore expensive, but easy to use. The Jensen schematic requires a line level input because the transformer is basically a short to a guitar signal. While it is passive, the buffer circuits is not. It can be your choice, either a stand alone op amp circuit or a bypassed guitar pedal (that is not true bypass, like Boss).

If you want to avoid the transformer, the output side of the Celtic schematic is a method for balanced output. For stereo, or dual mono, it's just more buffer circuits.

Gyraf and AMZ are an examples of simple buffer circuits. 1-4 op amps in parallel make good buffers depending how long your cables are.

I don't recall anything phantom powered, but running an op amp from a 12V or 15V zener in series with a resistor may work well. Some say that method is too noisy, but op amps have terrific CMRR specifications that have never caused alarm to me.
125876

125877

125878

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Isolation requires a transformer. They are pretty specialized and therefore expensive, but easy to use. The Jensen schematic requires a line level input because the transformer is basically a short to a guitar signal. While it is passive, the buffer circuits is not. It can be your choice, either a stand alone op amp circuit or a bypassed guitar pedal (that is not true bypass, like Boss).

If you want to avoid the transformer, the output side of the Celtic schematic is a method for balanced output. For stereo, or dual mono, it's just more buffer circuits.

Gyraf and AMZ are an examples of simple buffer circuits. 1-4 op amps in parallel make good buffers depending how long your cables are.

I don't recall anything phantom powered, but running an op amp from a 12V or 15V zener in series with a resistor may work well. Some say that method is too noisy, but op amps have terrific CMRR specifications that have never caused alarm to me.



The Celtic schematic looks promising! What would I need to change in order to make it stereo inputs that wouldn't have any bleed over?

Your simply build two of them. One right, one left.