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DI -> Power Amp Question

Discussion in 'Effects [BG]' started by IcedEarthWOM, Jan 12, 2006.

  1. IcedEarthWOM


    Oct 2, 2005
    Most of you probably know my plans for "completing" my bass FX board: buying the SansAmp Programmable Bass Driver DI
    (my wah is my mid controll.... long story)
    Now, this thing has a 1/4" boost and XLR pad switches which means that I could crank the shiz out of this thing hit both and have a mic level sig from the XLR (for the board) and louderthanshiz comin' from the 1/4" to feed a power amp

    What I plan on doing after acquiring the SAPBDDI, is collecting different preamp pedals with 1/4" and XLR outs such as the Para Driver (can't have enough SansAmp, eh???), Radial BassBone (Y adapter my bass signal=two channels :D ), and the MXR Bass DI+ (just cus........ :ninja:).

    My problem is that unlike the SansAmps, none of the others seem to have the ability to ouput a different level from each out. The solution I've come up with is to set up each of the pedals for mic level and then put an MXR Micro Amp (or other such thing) after the 1/4" out in order to run a power amp properly.

    Comments, Questions, Concerns, Warnings :eek: and/or Threats :spit: ;) :D please....
  2. Hello,

    What was suggested to me with my BDDI from Lloyd at Tech 21 for that situation was the Ebtech Line Level Shifter. It converts from an unbalanced -10dBV signal to a balanced +4dBV signal and vise versa. It's also a hum eliminator. They make them in 2-channel and 8-channel versions.


    I don't have one yet, so I can't comment on how good they work.

    Hope that helps,

  3. IcedEarthWOM


    Oct 2, 2005
    I'm not looking to "balance" the signal (the XLR out takes care of that....) I'm just looking to boost the shizzle out of the 1/4" to go to a power amp. The new SansAmps - programmable, bass, and para - all have the ability to output "line" level from the 1/4" while outing mic level from the XLR for a mixer/PA.

    I'm just wondering if I can use the Micro Amp as the 1/4" boost if the DI (the MXR for example) does not have the ability to boost the 1/4" separatly from the XLR

    EDIT: I'm just not sure that the 11 dB would be enough (I think that the MA does alot more...)
  4. Man, I'm totally lost. Your setup appears to be evolving into a needlessly complex (and therefore unreliable) monster, but that's just my opinion. Please consider the feelings of the sound engineer as well before you start putting 11dB boost (or whatever) on the line running to his mixing desk!

    I will say this though;

    Any amplitude variation at the 1/4" output jack of the BDDI will be reflected in the XLR output as well. That includes changes to the drive level, volume level, boost switches, previous effects gain changes etc etc etc. The same does NOT apply in reverse - ie; if you change the XLR pad switch, it doesn't affect the 1/4" jack.

    Seems to me you're missing the point of a DI box. The reason many bass amp heads are fitted with DI outputs is so that the DI feed encompasses all of your effects. That is to say, the DI should normally be the very last thing in your signal path, immediately prior to the amplifier. That way, whatever you do (boosts included) to you sound is reflected in the feed to the mixing desk.

    So, if you're hung up on using the BDDI as a preamp or a booster or whatever it is :)confused:) then don't use it as a DI. Get a separate DI to plonk right at the end of your chain.
  5. IcedEarthWOM


    Oct 2, 2005
    the chain would go:

    Preamp/DI -> XLR to Mixing Desk
    Micro Amp
    Power Amp

    I'm looking to get all my "color" from the preamp/DI (hence owning more than one).

    Again the list for my collection is (so far):
    -Bass Driver (Programmable)
    -Para Driver
    -MXR Bass DI+
    -Radial BassBone

    Oh and the Micro Amp would only be for the non-SansAmp DI's because the SA's have a boost that only effects the 1/4"
  6. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Which power amp do you have? It must be very sensitive if the Radial Bassbone will drive it. The Bassbone is not a preamp in the preamp to power amp sense, it produces instrument level outputs.
  7. IcedEarthWOM


    Oct 2, 2005
    Quoted myself....
  8. i was thinking about a similar set up but only usin a sansamp PBDDI to power amp but i am still unsure
    and one question why do you need 4 preamps???
  9. IcedEarthWOM


    Oct 2, 2005
    What you do is set up the level for an appropriate mixer level, then hit the 1/4" Boost button. This boosts the 1/4" out to better feed a power amp but the XLR is still at the previous level

    Or to go X-Treem to the power amp: press the XLR Pad button, then set up the mixer level. At this point the levels should be approximatly the same as above. Then you can hit the 1/4" Boost as well to further increase the level from the 1/4" out while leaving the XLR at mic level.
    X-Treem..... :eek:
    Why not???? Thats like asking why one would climb a mountain.

    (answer: "Because it's there....")
  10. fair enough .... each to his own
    and thanks for the info on setting up with a power amp will come in useful soon ....
  11. Ok, and you're also using the power amps DI? So two feeds to the sound desk? I'm still intrigued as to why you want a booster after the (first) DI feed.
  12. hey just a quick question IcedEarthWOM what power amp are you using
  13. IcedEarthWOM


    Oct 2, 2005
    I'm useing my stereo for now (250W) until I can get a "real" one
  14. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    Ahhh, that explains it. I was wondering how you where getting enough gain out of an MXR Microamp to power a power amp.
  15. IcedEarthWOM


    Oct 2, 2005

    Somewhere along the line this thread got REAL confusing. So, let me start from the top again.

    Now, I don't acctually own any of the following but am going to buy the first one and am thinking of getting the rest as well:

    - SansAmp Programmable Bass Driver DI
    - SansAmp Para Driver DI
    - MXR Bass DI+
    - Radial BassBone

    Hear is the setup I'm trying to achieve:

    Bass -> FX -> DI -> Power Amp

    All the DIs I have listed above have both an XLR and 1/4" outputs. Both the SansAmps have a way of getting different levels from each of the outs. The PBDDI has an XLR pad and a 1/4" boost, and the PDDI has separate switches for each output to select between regular and boosted output.

    Using those controls I can have the XLR going to the board at mic/instrument level and the 1/4" going to a power amp at line level.

    As for the MXR and Radial models there is no way of boosting the 1/4" separatly from the XLR. What I am wondering, then, is if I can use something like an MXR Micro Amp to boost only the 1/4" out to get to line level.

    As for using a stereo, I realize that the signal from anything would get "pre-amped" then fed to the power amp. I'm only going to use it until I can get a proper power amp and cabinet(s). The reason I plan on using it is because I only have a 15Wer in my practice combo, and the volume control on the front is only for the pre, not the power amp. Its gain is preset :(
  16. seanm

    seanm I'd kill for a Nobel Peace Prize! Supporting Member

    Feb 19, 2004
    Ottawa, Canada
    The answer is a definite maybe :meh: The Micro Amp is a booster, it produces instrument level outputs. This *might* be good enough, depending on the sensitivity of the power amp. It won't be optimal, but it might work.

    The biggest problem you will have is input impedance. The micro amp is designed to plug into a preamp. It probably assumes a minimum impedance of 100k and closer to 1000k. Power amps have input impedances closer to 10k. You may loose all your gain to impedance mismatch.

    Two other problems you may encounter: very clipped output from the micro amp if you don't keep the volume on the bass down and you may not get the full power out of the power amp.

    A better solution all around would be to buy a real preamp. They are designed to drive power amps. It's all about headroom and with the booster you will have none.
  17. Right, so in other words all you're asking is "how can I get line level amplitude from an instrument level signal so I can feed a power amp from the jack socket whilst leaving the DI XLR feed at a sensible level?" Am I with it now?

    Assuming I'm on board, the MXR will probably do it, but it largely depends on relative amplitudes. For instance, if your bass output is weak, then the MXR may just have enough gain to drive into "line level" territory. However, if you bass output is strong (like an 18V active) then chances are it could almost drive line level all by itself! Even into a power amps input impedance.

    Higher input impedances will not hurt your gain structure. It's only when a device with a high output impedance drives a relatively low input impedance that you'll have troubles.

    My god man, all four?! Maybe I still ain't getting it. :confused: You have two tasks, DI and boost, which would be best achieved by using two devices rather than fiddling with gain pads to make one box do two tricks. Get the MXR and your pick of one of the others for a DI and save your money for something less utilitarian and more interesting!

    Or, you buy a preamp with a DI output and to hell with all the rest of this guff!
  18. Passinwind

    Passinwind I Know Nothing Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Just another suggestion:

    Lose the Microamp. Set everything that needs to be at line level there. Then externally pad down anything that needs to be at mic level and now can't be switched there separately. I'd bet you'll get best signal/noise performance with this approach. I don't see anything wrong with just using the last box in the chain all the time as a DI though? No sound man is going to be too happy to give you more than one DI channel at the board, in my experience.

    Game over.:cool:

    or not...
  19. IcedEarthWOM


    Oct 2, 2005
    Before I start, I'd like to thank everyone for putting up with me :D : Thanks!

    After all the info, I'm gonna eventually do that (get one with an XLR DI out). My biggist problem is space. I don't have any, which sucks when your a bass player. I was looking for an easy fix for now, using what I own now.

    My dream rig has alway been a 4x10" and a 15" cab run by as much power as I can get :D . Now that I've really thought about it, getting 4 DIs is kinda ridiculous :rolleyes:

    What I've decided to do is save up for a really good bass :bassist: and hope I'll eventually be able to get the rig :(

    Good News: I've got my pedal rigs "compleated" and should be posting pics soon.

    "Main" (Noisy) Rig: Bass -> Boss TU-2 -> Boss NS-2 (Send) -> Dunlop Dime CryBaby From Hell -> Aphex Punch Factory -> NS-2 (Return) -> Dunlop HighGain Volume -> Amp

    Mini (Band, if I was in one :oops: ) Rig: Bass -> Boss TU-2 -> EHX English Muff'n -> Amp
  20. squeezing "line level" like gain out of stomp boxes might work, but is likely to create more issues than it solves - headroom, peak distortion etc.