Using XLR connection from Pre to Power

Discussion in 'Amps and Cabs [BG]' started by jnprather, Nov 23, 2005.

  1. Hi guys,

    I searched a bit for this but couldn't find much. Basically, I just got a BBE BMax preamp, which has an XLR Balanced output. I am very close to pulling the trigger on a poweramp. On my shortlist, some of the power amps have an XLR input. I was wondering if there is any advantage whatsoever to running an XLR connection from pre - power as opposed to a 1/4" connection. I dont really know if it's even a viable option or even if there's any benefit to it, but i'd like to know before I invest in an XLR-XLR cable to find out :) Thanks guys,

  2. ESP-LTD


    Sep 9, 2001
    It probably won't make a huge difference. The XLR connectors are nice sturdy connectors to use. The wiring (balanced) can be accomplished with a 3-conductor phone plug instead of XLR's. But, since you are only needing about a 2' cable, the amount of noise you save will probably not be that important so a regular 2' unbalanced cable would probably be just as good.
  3. zombywoof5050


    Dec 20, 2001
    The balanced input impedence on most power amps is usually double that of the unbalanced, which I imagine should be of some benefit. Probably not enough to nitpick about though.
  4. Thanks for the replies guys, I just wanted to extend my question to include my XWire wireless unit.

    I just noticed that my XWire wireless has an XLR out in addition to the 1/4". I could theoretically be able to do a full XLR connection from wireless ---> power amp.
  5. Just have a read of your manual;

    Some poweramps (mine included) have a BALANCED XLR, but the 1/4 inch jack input is unbalanced. Just depends if you can tell the difference by ear :smug:
  6. patrickj


    Aug 13, 2001
    Baltimore, MD
    Sure, go for it if it's useful. If you've got the whole rack setup running right on top of each other though, probably not worth the expense of going XLR. Won't really hurt anything, but doubt it'll help anything.

    I have my whole preamp/effects section on the floor (Sansamp DI, Bod XT Live, stomps, etc). The only thing I have with the power amp(s) is cabinet(s). I've found XLR much more lasting and sturdy than 1/4".

    It's one of those things where if you have the need, go for it. Otherwise, avoid it.
  7. Depends on if you need to use your XLR DI out of your BMax
    to go to a board for live sound or not. You could always get
    a cable that had 1/4" male out from your BMax to XLR in to
    your power amp.
    I leave mine racked and connected all the time. That way,
    when I get to the gig, set up time is minimalized. Wireless,
    tuner, effects unit, preamp, and power amp all plugged into
    my trusty Furman power conditioner all in one rack that only
    takes up one outlet in the wall.

    Anyway, just think about whether you're going to need to use
    the XLR out on your BMAx to go to the board for live use.
  8. Mario Lewis

    Mario Lewis

    Jul 6, 2001
    Clinton, MD
    Going from your X wire to your pre will require going out of the back of your X wire to the front of your pre unless it has an INPUT (either XLR or 1/4") on the back - there is no output on the front of the X wire as I recall, I could be worng, but I've owned two x wires, so I son't think my memory is that bad.... so that's one cord that's going to have to go outside of your rack in the back and around the side to the front. You can MAYBE bring it back through your rack for an all internal set up if you have the room between components.

    THen you can go out of the back of your pre to your power amp using whatever you want.

    I've found no real advantage to using either XLR or 1/4" from pre to power amp.
  9. You're exactly right. I found out earlier that I did indeed have to a 1/4" from the back of my X-Wire to the front input on the BMax. I tried plugging it into the effect return on the back but of course that gives me a POST-EQ line which isn't uh, ideal :)

    From the responses I get the impression that each of these units have XLR sends simply to send to a board or other unit that needs it, and that there really is no benefit of using it between two units on the rack itself (that are going to a cabinet).

    I appreciate the responses. The bottom line is that I didn't understand the difference between balanced/unbalanced connections and 1/4" vs XLR other than "XLR lets you send straight to a board/console".

  10. Interesting article I found just now:

    Particularly the part here (stating this as a benefit of using balanced connections):

    I wonder how much truth there is to that.
  11. WalterBush


    Feb 27, 2005
    Yuma, Az

    Balanced signals have better common-mode noise rejection, i.e. they're less likely to have hiss or hum problems, and they're less likely to pick up the local AM sports station when your noise gate is off.
  12. CetiAlphaVI


    May 27, 2005
    Not knowing the BBE product too well, is the 1/4" out balanced or unbalanced? That does make a difference (TRS vs TS). TRS cables have the stereo 1/4" ends (2 click rings), and TS have mono 1/4" ends (1 click ring, like on your instrument cable). A TRS cable as stated earlier offers the same "balanced" benefits as an XLR cable. Then you have also freed up the XLR output to go to the FOH or recording board.

    Also, those 1/4" jacks at the mixing console right above the XLR input are most likely TRS inputs, not TS. So either balanced signal will get you where you want to go.
  13. I would bet none at all for a preamp. The current/signal levels in question are pretty small. My thought is it would take a pretty crappy power supply to not be able to handle current fluctuations inherent in creating a 2.8V output signal driving a many Kohm to multi Mohm input to a power amp.

    The high current fluctuation thing at least theoretically affect a power amp's power supply. Bridged power amp output is essentially a balanced output, by the way. They just don't use the third shield wire, cause how much noise can you pick up that will amount to anything next to a 1500W audio signal... Unless you wrap your speakers around power line transformers before routing them to your speakers... :D

  14. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Not much truth. Balanced connections are great, but not for the reasons cited there. ;) They're far more immune to picking up noise. For a short run, though, unbalanced will work perfectly well.