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Active and passive DI boxes. would someone enlighten me ?
- Thread starter cnltb
- Start date
From Sweetwater:
The most obvious difference is that passive DI boxes don’t need to be powered. Active DI boxes require a power source, usually batteries or phantom power over an XLR jack. But the differences go deeper than that. Passive DI boxes are basically “just” transformers; they contain a transformer to perform impedance matching and balancing and very little else — the strength and impedance of the signal hitting the transformer depends on the source. This could be a disadvantage if your source signal is particularly low-level or low impedance, since the DI can’t do anything to “improve” the signal. However there are also advantages to passive designs: no noise added by active circuitry, no power required, and in some cases, a desirable coloration from the transformer.
An active DI box includes a preamplifier to provide a stronger signal and higher input impedance. This means that it can handle lower-level signals and still sound good. And, active DIs can be designed to be extremely quiet, hi-fi, and transparent tonally.
These days, there are excellent passive and active DI boxes. Many studios and sound companies have an assortment so that the best choice can be matched with each source.
The most obvious difference is that passive DI boxes don’t need to be powered. Active DI boxes require a power source, usually batteries or phantom power over an XLR jack. But the differences go deeper than that. Passive DI boxes are basically “just” transformers; they contain a transformer to perform impedance matching and balancing and very little else — the strength and impedance of the signal hitting the transformer depends on the source. This could be a disadvantage if your source signal is particularly low-level or low impedance, since the DI can’t do anything to “improve” the signal. However there are also advantages to passive designs: no noise added by active circuitry, no power required, and in some cases, a desirable coloration from the transformer.
An active DI box includes a preamplifier to provide a stronger signal and higher input impedance. This means that it can handle lower-level signals and still sound good. And, active DIs can be designed to be extremely quiet, hi-fi, and transparent tonally.
These days, there are excellent passive and active DI boxes. Many studios and sound companies have an assortment so that the best choice can be matched with each source.
In passive DIs, it's a transformer. One side is high impedance for the instrument and the other side is low (600 ohms is standard). The transformer is also wound to reduce the signal level to mike level, about 10 DB or so. Any pad switches just bring resistors into the path to further reduce the level.
The impedance and level matching in an active DI is just a simple buffer circuit, not that different than an onboard preamp in an active bass. Whether pads are simple resistors or a gain trim on the buffer depends on the particular design.
The impedance and level matching in an active DI is just a simple buffer circuit, not that different than an onboard preamp in an active bass. Whether pads are simple resistors or a gain trim on the buffer depends on the particular design.
In the bass world, you are also going to come into contact with preamp/DI units such as those made by SansAmp and Darkglass. Usually you can deactivate the controls and more-or-less have a transparent DI on your hands, but I believe when the tone shaping capabilities are activated they are more accurately described as a preamp. IME I have gotten a lot of value out of having a Sansamp/preamp rather than a stand-alone passive or active DI.
Interesting ...someone here will have experience with this device - a thread maybe?
To answer your question, I always have a DI when I gig. It’s my “back-up” amp and gives me a handy connection to the PA if needed. If you do live sound at all, you’ll definitely want one on hand. I like an active one so I have a level control close by - handy if I’m not running the board
.I do mostoly recording work at the momen and when I gig , venues tend to have DIs, but I'm still interested in it as the electricity in our house is a bit prehistoric and i do hear clicking when someone turns on teh light in another room, or the oven or even the water in teh bathtub. That gets annoying when it happens in the middle of an other wise useable take...Interesting ...someone here will have experience with this device - a thread maybe?
To answer your question, I always have a DI when I gig. It’s my “back-up” amp and gives me a handy connection to the PA if needed. If you do live sound at all, you’ll definitely want one on hand. I like an active one so I have a level control close by - handy if I’m not running the board
I have a preamp which sounds perfect and also functions as DI but it is a 19' rack unit which I do not currently have room for on my desk...
I do mostoly recording work at the momen and when I gig , venues tend to have DIs, but I'm still interested in it as the electricity in our house is a bit prehistoric and i do hear clicking when someone turns on teh light in another room, or the oven or even the water in teh bathtub. That gets annoying when it happens in the middle of an other wise useable take...
I have a preamp which sounds perfect and also functions as DI but it is a 19' rack unit which I do not currently have room for on my desk...
Quick derail. Get a couple of these (or similar) and mount your preamp under your desk. Rigging something in the back to hold up some weight should only require basic hardware too.
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