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Why have DI out placed before effects loop?

Discussion in 'Amps and Cabs [BG]' started by PraiseBassing, Oct 26, 2018.


  1. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    Unfortunately, my amp has no effects loop. When I bought it I was using no effects, so it didn’t matter to me at that time. In the future I will be looking for the loop. One thing I have noticed is that not all DI out’s are after the loop, why would this decision be made? Is it that the thinking is that players who use effects and would run them to the board will likely use a separate DI?
     
  2. el murdoque

    el murdoque

    Mar 10, 2013
    Germany
    Well, the FX loop has to come after the preamp, else there would be little sense in that.
    Most DI outs offer a pre/post switch - so when you have to make certain adjustments on your EQ to accommodate the cabinet on stage, FOH will not be forced to live with those when you set it to pre.

    Are there amps where the DI in post mode does not catch the FX return signal?
    I've used several heads where I just went into the FX return straight from my board, bypassing the preamp entirely, but sending a DI signal from the head to FOH with no complaints.
     
    cosmicevan likes this.
  3. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    You should experiment to see what works best. You might find that some of your effects (particularly pedal-style) sound better between your bass and amp, as opposed to through the effects loop.

    To specifically answer your question: Some sound guys prefer a "pre" or "dry" DI (no effects/EQ/compression/etc.), while others prefer a "post" or "wet" DI. Personally, I like gear that has a "pre/post" switch, so that I can offer the sound guy whichever option he prefers. Many popular amplifiers these days (like Ampeg, Mesa Boogie, etc.) have the "pre/post" option.
     
  4. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    By looking at the Block Diagram of the D800+, the effects loop isn't in it at all. After looking at a few more manuals and diagrams of other companies, it looks like most have the effects loop included in "post" signal. I guess if you have effects needing to be in the loop you should just use minimal eq? It must be too difficult/not realistic to have the loop included but not have the eq included. Maybe manufacturers assume if you are using the preamp gain at a high enough level that you need modulations and reverbs after it for it to sound right(general rule), you aren't actually going to use those effects.

    Correct, I am just thinking if I want to add reverb and mod, I would ideally like it after my preamp gain and eq but to be send to the board, which seems like it won't happen. For now, it's not a big deal, I use my cab as just a monitor now, and get my tone from my pedal board so I'm not sending any drastic eq changes.

    Really just thinking out loud and wondering if effects loop included without eq is actually possible.
     
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I almost never use effects loops. I prefer the sound with the instrument plugged into the effects chain and the effect output plugged into the amp’s input. The pre amplifies and runs this mix through the EQ.

    The only times I use the effects loop is when I’m patching in an outboard rack effect that has a high level output.

    Don’t worry about not having an effects loop.
     
  6. Most pedals don't work too well in fx loops anyway. It's a hotted up ''line level'' signal at that point.
     
  7. Jazz Ad

    Jazz Ad Mi la ré sol Supporting Member

    Yeah fx loops are mostly useless, the only use they tend to see is as a patch between preamp and power amp
     
    SactoBass likes this.
  8. lz4005

    lz4005

    Oct 22, 2013
    Having a pre-everything DI out on the amp lets you use the EQ on the amp to adjust your monitor tone while not changing the signal that goes to the PA.
     
    Zbysek likes this.
  9. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    While I completely understand and completely agree with this, as well what everyone else has said, “what if” I find a rack unit I want to use and want it to be a part of my sound, but don’t want the “post-eq” going through the DI.

    It’s mainly a devil’s advocate situation here. I’m guessing the way the signal’s are routed in the amps are just the best set of compromises for the largest groug of buyers?
     
  10. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Everything is a compromise. No question of that.

    If you have specific needs you have to understand the options and look for an amp that meets those needs before you go shopping. This can make things difficult.

    Instrument level, line level, and send/return level can mean different things depending on the product. There is no universally adopted standard that manufacturers adhere to. Some outboard gear had too hot a signal level to be used at the input of an amp like an effect pedal can. If you hope to use it, you pray that the effect send and return can accomodate it. Some of this equipment has balanced ins and outs. So conversion to unbalanced is needed for it to be used.
     
    Wisebass likes this.
  11. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    Luckily for me, I don’t eq at the amp. This is most likely just my mind staying busy on my day off and nothing I will ever deal with or be bothered by. It’s just interesting to me that it’s either post-eq to get the loop in the di, possibly upsetting engineer’s(whoppty-do), or pre-eq no loop and IF you do have something there, it’s not going to the board.

    I will add that the two pedals I have that I would let the thought of throwing them in the loop cross my mind with, operate at line level. Again, most likely won’t ever actually have to have this thought again.
     
    beans-on-toast likes this.
  12. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Yet another reason why I never ever use loops.
     
  13. Wasnex

    Wasnex

    Dec 25, 2011
    Not necessarily true.

    The schematics for my Trace Elliot and Asdown tube amps show the effects loop is located between tubes triodes V1a and V1b. The pre EQ DI signal is taken of the output of V1b so the effects loop is captured regardless of how the DI is configured.

    I believe someone mentioned the EA doubler is configured this way.
     
    Wisebass and PraiseBassing like this.
  14. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Good question.

    Often, it depends on other signal routing options that are provided.

    For example, on many of the amps I've designed, it depends on if the amp has an aux input the routing will be such that the post DI for the instrument input does NOT include the aux input so that it can be used with a pedal preamp (such as the Rosette or Subway PRE-DI) as a second channel with its own DI separated from the main DI. This means that you have a main channel and aux channel DI with the aux channel not in the main channel.

    Usually, design the DI out in post position to take its signal post effects loop (but not always depending on other factors) so I checked and it looks like an incorrect version of the block diagram is in the manual. I will work on correcting this, but here's a copy of the correct one:
     

    Attached Files:

  15. Wasnex

    Wasnex

    Dec 25, 2011

    True. Although the effects loops in some amps can be configured for line or instrument level. Unfortunately placing pedals in an amps effects loop often creates a noisy ground loop :banghead:. That's been my experience anyway and I am running an isolated power supply with my pedal board. This is unfortunate because my amp has a parallel loop which is cool for blending in distorted tones :(.
     
    Last edited: Oct 26, 2018
  16. Same here. I don't even know if my own amps di's are before or after fx loop. Or even if the jack plugs will come out in one piece after being there so long.
     
    beans-on-toast likes this.
  17. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    On amps without an aux in, but where the effects return might be a possible location for an external second preamp, these may work better coming after the post DI take-off point for the reasons I mentioned before.

    It really depends on the inherent routing and needs of the player.
     
  18. PraiseBassing

    PraiseBassing Supporting Member

    Mar 6, 2017
    California
    Well that makes a lot more sense than what is there now! Thanks for the update.

    Was it more common with tube amps to have the loop between preamp tubes and has moved to being after the eq now?
     
  19. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    It all depends, but probably more typical in a tube amp
     
  20. Wasnex

    Wasnex

    Dec 25, 2011
    I have tube amps that do it both ways.
     

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