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Using a DI box with an amp head that already has a DI output

Discussion in 'Live Sound [BG]' started by Syl_Funky_bass, Mar 22, 2019.

  1. Syl_Funky_bass


    Jun 4, 2016
    Hi All,
    I'm planning to get a passive DI box for studio recording and possibly for live gigging with IEM in the future.
    The one I'm planning to buy is a Radial Pro passive DI for my active 5-string Jazz bass.
    Here is a my first question:
    In addition to the use of a DI box for bass recording and going direct into a mixing table, could you please tell me whether there would be any use for a passive DI box in combination with an amp head (Little Mark III) that already has a DI output?
    I have a Little Mark III and a 4x10 Markbass cabinet.

    I'm wondering whether a DI box would add anything soundwise combined with my amp head that already has a DI output.

    Can I sort of bypass the Little Marks III DI with an extra (external) DI box? If so, is there a difference in quality between the built-in DI of my amp head and a reasonably good passive DI box such as the Radial Pro passive DI for instance?

    Or would it be completely useless (for live gigging) to have a DI box if one already has a good amp head with a DI output like mine?

    In other words, is there any added value to having a passive DI box in addition to a Little Mark III on stage?

    Thanks a lot in advance for your help.

    I'm totally new into the live sound thing.
    Last edited: Mar 22, 2019
  2. Pat C.

    Pat C. Supporting Member

    Jan 1, 2005
    Tuscaloosa, Alabama
    A good quality external DI will sound better than the built in amp DI. How much difference it makes live is up for debate.

    The Radial stuff is nice. With a passive jazz bass I'd go with an active unit. Even Radial suggest an active DI for passive instruments. The J48 is a great option for recording and live. I owned the JDV for a while, it sounded great. It had a slew of features that I thought I'd need but didn't so I traded it out and ended up with a Countryman Type 85, which also sounds great.

    As far as 'bypassing' the amps DI, you just wont need to use it. The external DI will run between your bass and the input of your amp.
  3. Wasnex


    Dec 25, 2011
    The quality of DI built into amps varies pretty drastically. Some are really good and some are horrid. Also many built in DIs give you the choice of selecting Pre or Post EQ. Post EQ can give a bit more of the flavor of the amp, but can also be noisy. Also, if you are not using a full range flat response speaker the DI signal will be very different than the sound your rig produces. In my experience, most audio techs prefer Pre EQ, but there are circumstances where Post EQ is useful.

    Usually when you use an separate DI it goes between your bass and your amp, so your amp does not color the signal in any way. Sometimes DIs are used at speaker level. This has many of the same benefits and problems as a Post EQ DI, plus your Master volume also impacts the signal level. Another issue is you can't safely use a speaker level DI with an amp that is operating in bridge mode. FYI many Class D amps operate in bridge mode.

    If the your sound is highly dependent on their rig, I would suggest mic'ing your cab. In the studio, it's fairly common to blend a mic and DI of the bass signal.

    Whether you use a passive or active DI depends upon the sound you want. I have a Radial JDI Duplex and a Radial PZDI. The Duplex is essentially a stereo JDI with some extra patching options, and without the speaker emulator circuit. The PZDI is essentially a J48 with switchable input impedance and few other features. My bass is active and it sounds really good with both DI's, but I slight prefer the PZDI with the input impedance set to 1 Meg. Honestly the difference is very subtle. FYI, the input impedance of the J48 is 220K; when I set the PZDI to 220K, the sound seems a little darker and heavier. Some may prefer this, so it's a matter of taste, which DI is best.
  4. tshapiro

    tshapiro Gold Supporting Member Supporting Member

    Aug 25, 2015
    Jax Florida
    The Radial JDI definitely affects the sound. To my ear, it adds a slight natural compression and smoothes the highes. Some people might not like that but it works well for how I use it. Note that unless your bass has a high output you’ll probably need a pedal inline prior to the JDI to increase your signal level. I use the output level of my compressor which I leave on all the time. If I didn’t have that I’d probably use an MXR Microamp. I faced the same question you are now and after running things different ways I go JDI to the board and bypass the amp.
    Wasnex likes this.
  5. Stranger Danger

    Stranger Danger Feel Like A Stranger Supporting Member

    Jan 3, 2010
    In most cases I’d say the Radial would be superior. But the DI on the Markbass is actually superb and it has a separate level control so you can be louder or lower than the signal from the amp. You won’t get that with most DI boxes. I think in your case it’s just throwing away money.
  6. s0c9

    s0c9 Supporting Member

    Jan 9, 2014
    1964 Audio artist, Fractal Audio Beta Tester
    As @Pat C. alluded to, the difference between the signal DI from your Markbass DI and that of a countryman or radial for LIVE use is debatable.
    I've used many different DI's (I'm talking simple DI's.. not the stompbox pre-amp type loosely called DI's) while running FOH over the years, from top of the line like REDDI, Radials and on down to EDB1's and no-names with no transformers, no pads, a 1/4" in/out and a XLR out on the other side.
    By the time you've got the whole band going with a crowd out front.. There's NOT a lot of [noticeable] difference between them IMHO.

    When playing, I usually run direct from the DI on the back of my SVT7 or stomp-box DI (if going amp-less) and not one single FOH guy has complained.
    Now, studio is a whole other ball game.
    I wouldn't worry about going DI from your Markbass.. Should be fine for live use.
  7. dannylectro

    dannylectro Supporting Member

    Aug 2, 2010
    Atlanta, GA
    My experience is that the DI on the Mesa Subways and the the GKs are superb. When I use other amps, or for home recording, I use the Countryman Type 85 and I never have any complaints about the sound.
  8. Either is acceptable. It depends on how good is the sound out of your particular amp compared to your particular DI.
  9. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    In general, unless we arranged otherwise ahead of time, if you show at a gig where my company is providing. We will provide a DI for you. Passive Radial for active basses or Countryman Type 85 for passive. We will put it after your pedal board, before your amp.

    If you roll in with something really impressive for an amp... we may opt for a mic on your cabinet... rare but it happens. I had a vintage Showman and 2x12 last weekend for one band and a cherry SVT and SWR Goliath for another. Each of those guys got the mic.
    40Hz and Wasnex like this.
  10. Bassworship1

    Bassworship1 Supporting Member

    Jun 20, 2013

    What Mic do you use for live gigs? Interested because I’m wanting to get a good mix for live gigs using my Genzler stack. Very good sounding bass rig.
  11. 4Mal

    4Mal Supporting Member

    Jun 2, 2002
    Columbia River Gorge
    Basically anything reasonably flat or with a presence peak well outside the fundamental range. It has to handle high SPL and be ‘Plosive resistant. In a pinch, Shure sm-57 with the Shure factory wind sock or Audix I5 with a sock. Me, I would pick the Audix. They are built like tanks and a workhorse in my Sound co setup.

    A more Gucci choice is Sennheiser 421 mk II. I buy them used in very good condition at around $225 -$250. These are fabulous mics and IMO the basis for a good mic locker... beware the non standard mic clip/holder. Do not lose it and if you buy one with out, figure $40 to replace... I have sung on a 421, used one for kick, URB (close in, pointed at the sound board just behind the bridge) sax as well as bass. It was the sound of the 70’s through 90’s on rock and roll drum kits with monster tom racks. 5 position roll off. Mine are set on 3 and rarely move.

    I have not tried the Sennheiser e906. This is the step up version of the flat faced e609. It features a 3 position roll off switch that does flat and 2 low pass settings. I have a pair of those as well as a couple of 609’s. The 609’s only come out on double header days as the 906”s are just a bit more clear. It is probably a good candidate as well.

    heil Pr-40. A one time fav of @JimmyM Heil is a really easy company to work with parts wise. I tried one of these and it didn’t blow me away. It was good.

    There are probably a number of other good choices.

    What I will not use. Any kick mic. They all suck. D6, D112, Beta 52... no matter way too colored.

    One thing with your genzler stack, if it is based on the 12/3 array, you are going to have to experiment with placement and get real precise in where exactly you put the head of the mic. Getting a balance between the woof and tweet may be problematic. If you find the sweet spot. Mark it. Mark it in a way that won’t easily come off the cab.

    In a festival, short band change setting, I would honestly rather see your Firefly as there really is never time to do a super thoughtful mic placement on a multi-way bass cab. Give me a 4x10, SVT, 1 or 2 by 10, 12 or 15 cab, I can get a mic placed in a minute and get on with then next instrument knowing that I’ll have a signal I can work with at FOH. 2 and 3 way cabs are a crap shoot...
    s0c9 likes this.
  12. walterw

    walterw Supportive Fender Commercial User

    Feb 20, 2009
    if you don't like the tone of your amp then yeah, use the DI before the amp to bypass it.

    if you do like the tone of your amp but sometimes have trouble with its built-in DI (hum, whatever) you can try using the DI box fed with a different output from the amp, like say the 1/4" FX loop send or "preamp out".
  13. JRA

    JRA my words = opinion Supporting Member

    probably not. or: probably not enough to warrant the extra fiddling at the gig.

    in the pro world: a DI converts the instrument signal to a low impedance signal without coloration. DI's which add "sounds" aren't usually the choice of either studio engineers or FOH at the gig. the best DI's = have no "sound."

    if you can't hear the difference between your DI and the amp's low impedance output: why bother with the DI?
    Bodeanly and Mushroo like this.
  14. Zbysek


    Mar 23, 2017
    Czech Republic
    Yes, there is.

    First, the DI box can serve as a back up. It will keep on sending the FOH signal even if your amp stops working.

    Second, you can send the FOH two signals: one unaffected by EQ and/or effects from the DI Box, one affected-from the amp.

    Third: External DI box is neccessary in some situations. On evening, there was buzz coming from my amp's DI output even with the ground switch engaged. External DI box saved me that evening...

    Ps: I have been using Markbass Little Mark III as my main gigging amp for several years. The DI output on this particular head is a good one, IMHO. That doesn't mean you can't get even better results with some good DI boxes out there...
    Mushroo likes this.
  15. s0c9

    s0c9 Supporting Member

    Jan 9, 2014
    1964 Audio artist, Fractal Audio Beta Tester
    The ground switch on most amps does nothing for the POWER ground.. it lifts the ground on the DI output, on the XLR...NOT the input power.

    That kind of buzz is caused by bad power, and the only solution is to find another power source. DO NOT LIFT the ground on the power supply..

    Been thru it a number of times myself at a number of local venues and one major (national acts) local venue. It's why I always carry a 50ft 14-3 extension cable with a 4-gang on the end.
  16. Zbysek


    Mar 23, 2017
    Czech Republic
    I am not sure how to respond. I tried to lift the ground on the amp's DI output.

    I don't know what you mean by "lifting the ground on the power supply"...?

    The fact is that na external active DI box saved me that evening...being plugged in the same power source as the amp...
  17. s0c9

    s0c9 Supporting Member

    Jan 9, 2014
    1964 Audio artist, Fractal Audio Beta Tester
    Right... but that usually that does NOT stop hum induced by bad power, ground loops, etc. it WILL solve grounding issues between your amp and the console.
    The external active DI probably saved you because you bypassed your amp and may have an internal transformer that solved the hum... or there was no differential between the Di and the console.
  18. tadawson


    Aug 24, 2005
    Lewisville, TX
    Actually, it *should* stop hum from ground loops, in that it removes the alternate path to ground which makes up the loop. If the console isn't junk, it should be seeing purely the differential balanced signal, and any common mode noise will cancel . . . hum included . . .
  19. bigswifty1


    Dec 8, 2011
    I also own a LM III and have done many hundreds of gigs with it and my opinion is that it's DI is really very good. Good enough that I was able to sell two of the best DI's ever made and not miss either of them (Aguilar DB900 and Amp SVT DI).
    Zbysek likes this.
  20. Zbysek


    Mar 23, 2017
    Czech Republic
    And that exactly was my original point: external DI box can save the day...in some situations...
    Wasnex and s0c9 like this.
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