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When do you not use an active DI?

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  • When do you not use an active DI?

    I have seen here from time to time that passive DI's are used in place of active. When is this? What dictates this?
    Do not remove this sig line

  • #2
    I'll offer as a general rule of thumb: Use a passive DI on active electronics, and use active DI's on passive electronics. If in doubt: use an active DI as an active DI will generally do the job in-place of a passive DI, but possibly not the other way around.

    That seems to hold true.
    Last edited by Audiopile; 07-27-2014, 09:50 PM.
    I need to catch up with those guys, for I am their leader.

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    • #3
      Keyboards, acoustic guitars with onboard preamps, and laptops can all use passive DI's no prob. You probably should use an active DI for a passive bass but I haven't found any "tone suck" to be noticeable for my own use.

      "We Have Met the Enemy and He is Us" - Walt Kelly​

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      • #4
        When you need galvanic isolation. Active DIs probably won't provide that.
        Don Boomer

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        • #5
          I have to say that somehow I have never owned an active DI. Thousands of gigs on rapco di100 and di101s as well as the ewi stereo DI's. Maybe I'll buy the ewi active, maybe not.
          www.rock-bot.com
          Live-Band-Karaoke

          bassist and sound reinforcement

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          • #6
            Originally posted by Unalaska View Post
            I have to say that somehow I have never owned an active DI. Thousands of gigs on rapco di100 and di101s as well as the ewi stereo DI's. Maybe I'll buy the ewi active, maybe not.
            That's funny, for the longest time I had never owned a passive DI! I always used Country Man Type 88's. Now I have some Whirlwind boxes and a nice Stereo Whirlwind with Jenson transformers. To tell the truth, as long as it is a quality DI, I can't say I have noticed a difference in actual performance.

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            • #7
              http://www.radialeng.com/di-jdi-faq.htm
              The further away I am, the better I sound....

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              • #8
                All mine are passive. one reason is they are so simple I trust them to work every time. Another is I want the minimum number of switches and controls on the platform.

                Nothing wrong with Active DIs. If I needed one I would use one.
                http://LBPinc.com/di

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                • #9
                  If you are asking about sound quality ... I think you will find that more closely linked to max input voltage capability. As a very general statement, I believe that more cheap active DIs will handle more input level than cheap passive ones will.
                  Don Boomer

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                  • #10
                    Inexpensive DIs both active and passive have issues. Some cheap active DIs don't provide a true ground lift as they are getting phantom power from the ground. You have hum, throw the switch and you still have hum, now what? Example Samson S-direct

                    The Radial J48, Countryman 85, and the Countryman 10is are example of a active box that does provide a true ground lift but it requires a switching power supply, a transformer, and a DC to DC converter to do it. http://www.radialeng.com/j48-specs.php
                    http://LBPinc.com/di

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                    • #11
                      The only time that an active DI is NECESSARY is if the source is a hi z passive source. Not using one in this case can muck up the tone. OTOH a passive DI doesn't add any noise and lessens the chance crackle/pop from phantom & bad connections (In a perfect world these things never happen but......... :-).

                      Recently had a fiddle played (great tone BTW) who asked if we had an active DI instead of a passive whirlwind director. He said I'd rather have a preamp in line for tone reasons. I looked down and saw that he was already going through a set of pedals. I just shook my head :-).
                      J.R. Previously jrble

                      See my Dog Of The Hair studio at: http://www.dogoth.com/studio/

                      Quote from someone: Flat response? Get out the jack and change the tire.
                      If you think "power is knowledge", you have it backwards.

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                      • #12
                        I've run into problems with stand up bass pickups every so often, some weird amp loading effects using the standard supplied passives at a couple of my gigs. beyond that I rarely have problems. I do find the Radial to clip earlier than my Whirlwinds...and that's a completely non scientific observation. They do have a pad. It's one of those situations where the keyboard or bass player holds back at sound check then whammy... up it goes during the set. So, on one man gigs I have to go up onstage, hit the pad and watch the mean look on the face of the player when their monitor mix drops 15 dB

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                        • #13
                          passive DIs tend to have better galvanic isolation, this can reduce noise in many instances where very high input impedances are not required.
                          -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                          Former product development engineer: Genz Benz, a KMC Music/Fender Musical Instruments Company, continuing factory level product support and service for Genz Benz

                          Currently product development engineer: Mesa Boogie

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                          • #14
                            Funny how whenever I read "galvanic isolation", I think of the marine applications. Comes from spending an entire boating season arguing with a certain outdrive manufacturer to get warranty coverage for a $5,000 drive that mysteriously dissolved over the course of 2 years. Galvanic corrosion, galvanic isolation, bonding, electrolysis...all terms I became very familiar with.
                            .....

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                            • Craig Vecchione
                              Craig Vecchione commented
                              Editing a comment
                              Yep, Ron, I've seen them go porous in a real hurry. In my case the marina's electrical system was very good and there was very little stray current...Merc checked several times. They then tried to tell me I used the wrong anodes. When I pointed out that they were sold to me by their top-performing dealership, and that it was kinda funny how they'd redesigned the outdrive housings several times (adding more and more coatings in an attempt to isolate zinc housing from two large stainless props) over the past several years, they finally caved and sprung for a new housing assembly. I didn't take any more chances, and sold the boat within a year.

                            • Mike M
                              Mike M commented
                              Editing a comment
                              hey Craig....do you use zincs on your outdriI'm a boater....
                              Mike M

                            • Craig Vecchione
                              Craig Vecchione commented
                              Editing a comment
                              Mike, I had a Merc Bravo III drive on that boat. It had several (inadequate) zincs...the usual pair on the drive rams, the trim tab, and the drive housing. Newer versions of the B3 model added an additional trim tab zinc and a prop shaft zinc. But the real problem was using stainless props on a twin counter-rotating prop design...way too much noble metal way too close to a soft metal housing.
                              IMHO the only decent outdrive Merc sells is the Bravo II. But that's a misnomer, as there really isn't a good outdrive. They're all just mechanical failures waiting to happen.
                              Last edited by Craig Vecchione; 08-01-2014, 05:11 AM.

                          • #15
                            Originally posted by witesol View Post
                            I've run into problems with stand up bass pickups every so often, some weird amp loading effects using the standard supplied passives at a couple of my gigs. beyond that I rarely have problems. I do find the Radial to clip earlier than my Whirlwinds...and that's a completely non scientific observation. They do have a pad. It's one of those situations where the keyboard or bass player holds back at sound check then whammy... up it goes during the set. So, on one man gigs I have to go up onstage, hit the pad and watch the mean look on the face of the player when their monitor mix drops 15 dB
                            A stand up base will push a DI. If you get the chance sub in some different brands, at those low frequencies and high outputs (active pickup) the transformer matters. BTW in a passive DI with the pads and filters switched out there is nothing but a transformer and one resistor in the audio path so nothing but the transformer matters (assuming good connections)
                            http://LBPinc.com/di

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