Active/passive DI boxes

[Telecruiser]

Why would you use an active over a passive or an passive over an active DI box? Advantages/disadvantages??

[Gordon Sound]

Depends on the application, actives generally sound better, but passives can be more conveinient.

[jgthatsme]

Generally, if the instrument pickups are active (such as an active guitar pickup) or if it's putting out a line-level signal (such as a keyboard), a passive DI is what you'll need. If the pickups on the guitar, bass, violin, etc. are passive, then you'll need an active DI box. You can probably use an active DI box in all situations, but if the source is active or line-level, it's generally more of a DI box than you'll need, and much more money than you need to spend.

[fdew]

Both Active and Passive have there strong points.

 

Here is a good article on the subject from Radial.

http://www.radialeng.com/pdfs/Radial-DI-Selector-w-text.pdf

 

Frank

http://lbpinc.com/DI.html

[Dogoth]

Generally, if the instrument pickups are active (such as an active guitar pickup) or if it's putting out a line-level signal (such as a keyboard), a passive DI is what you'll need. If the pickups on the guitar, bass, violin, etc. are passive, then you'll need an active DI box. You can probably use an active DI box in all situations, but if the source is active or line-level, it's generally more of a DI box than you'll need, and much more money than you need to spend.

 

Correct.

 

Just some additional info. Most active electronics (other than maybe a few archane tube circuits - but we won't side track) are fine seeing a realtivly low inpedence output load. By this I mean somewhere between 5k & 50k ohms. Most D.I.s are somewhere between 20 & 100k ohms so all is good. Many passive instrument pickups want to see a much higher impedence (more on the order of 200k to 2m ohms - more like an active D.I.). If these passive pickups are loaded down too much, (too low of an impedence) the tone will suffer.

 

The point in using an active D.I. is to present a higher impedence load to your instrument's output. Higher impedence will not hurt (tone wise - the higher, the better) but it requires some kind of current gain after being converted to a low impenence load (required by most modern mixers), hence added noise. Be careful here as high & low impedence are not exactly defined terms. An inexpensive piece of equipment may say Hiz next to the input jack, but it may only be 50k to 200k ohms. High quality Direct boxes are 1m ohms & higher and use very low noise circuits.

 

I only use active DIs when needed due to the added noise and the phantom power requirments. If you need an active DI, don't buy a cheap one as it will not preserve the tone of your instrument and will add noise to boot.

 

If you must go active, the best lower cost one I've found is the EWI (look up www.audiopile.net). My favorite ones are Countryman, Radial, Whirlwind (in that order (but they are not cheap :>)).

[Flogger59]

^^What he said^^

[agedhorse]

Passive DI's generally offer better isolation, especially at higher frequencies. This is important under some circumstances when active electronics are involved.

[DBR]

I use a passive for active electronics, basses, keyuboards and triggers. I'll use the active DI for non-active basses. This does seem to enhance the tone somewhat.

 

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