DIY Passive DI box transformer advice

[sandall]

My DIY ones are basically just an Eddystone box with an old BBC LL/76 transformer inside, but I also have a stock of MTR DI-1Ps, which do the job well & are pretty indestructible.

[haymere]

1555862776[/url]' post='573336']

My DIY ones are basically just an Eddystone box with an old BBC LL/76 transformer inside, but I also have a stock of MTR DI-1Ps, which do the job well & are pretty indestructible.

 

I have used MTR & they are really good and I used EMO’s when I had my hire business. So many things I have sold on over the years that wish I had kept

[ojc123]

Interested in this topic, because I am in the same place. Orchid active DI’s are brilliant but I am after some Passives & as I wire Electronic Control panels for a living this wouldn’t be hard. I would be interested if you ever took any photos of your results or noted any of your findings

In the way of things we had a play. We made a working DI box with the transformer linked to above and a generic circuit diagram from the net. It was a breadboard effort and would never have stood up to any kind of use. We did try winding our own 10:1 transformer with a core from the Science department. It worked in the sense that it made a noise which came as a surprise to all of us.

 

Our purpose was just so the students and I could understand the principles, not to make a proper one. We didn't bother taking pictures or doing any comparison with proper DI boxes. Nothing spoils a fun lesson more than having to write it up after you've done the fun bit.

[Brian]

As promised...

 

 

 

 

So it's a parallel pair of jacks for 'amplifier in' then a resistor to the single 'line in' then a resistor to the pair of 'inst in' jacks, which has a resistor to ground making an attenuator, then the transformer.

 

The two output winding each feed an XLR output connector with only the 'main out' having its earth connected.