DIY DI box?

[jsv08]

Yep, lookin to get a line-level signal out of my amp for DI purposes. I know these sorts of boxes must exist, but honestly, I haven't looked into them, because I've heard it is extremely easy to build one yourself!! heh.. Can anyone point me to a link or give me some somewhat detailed advice on constructing one of these?? Thanks!

[Ethan Winer]

JSV,

> Can anyone point me to a link or give me some somewhat detailed advice on constructing one of these?? <

A passive DI box is extremely simple. All you need is a high quality audio transformer with a ratio of about 100k Ohms to 150 Ohms. The problem is that high quality transformers are very expensive. $100 per unit is typical for the good models.

Then there are active DI boxes, which can be much cheaper to build and potentially are even higher quality than the best transformers. These can be built with a single FET input op-amp for an unbalanced output, or a pair of such op-amps if you need a balanced output.

That said, to get a line level output from a guitar or bass amp is simpler still. If the amp is tube based then the output is already balanced and floating, so all you need are three resistors to pad the speaker level output down to a level suitable for feeding your mixer.

Have a look at "Mike pads and other small gadgets" about half way down the list on my Articles page:

www.ethanwiner.com/articles.html

I'm not sure if there's any one schematic that does exactly what you want, but that article can get you started anyway.

--Ethan

[DigitalDon]

Have a look at a couple of these on the Jensen transformer site. They make the best transformers hands down but they don't come cheap. Ya get what Ya pay for. Here's the link. Look at AS061 and AS045. Lots of DIY stuff here dealing with Jensen transformers. http://www.jensen-transformers.com/apps_sc.html#musical

DD