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phantom pwr into my amp D.I. output?

Discussion in 'Amps and Cabs [BG]' started by Son of Bovril, Mar 7, 2005.

  1. I was at a gig recently where they were using a small desk that only allowed the soundie to put phantom power over all/none of the chanels - he had to have it on for the vocals and acoustic guitar...

    I usually use the DI out on my amp head to get my particular sound, however, the soundie told me that I couldn't use it, because it would risk damaging my amp due to the phantom power? I had to use a DI-Box istead, sending my guitar sound directly to the desk and using my amp only as an onstage monitor.

    is this true that the phantom power could damage my amp? :bawl:
  2. Lowtonejoe

    Lowtonejoe Supporting Member

    Jul 3, 2004
    Richland, WA
    That's a good question. I haven't really thought about that before but I see how it could be a problem for me too.

    I think you should also post what kind of amp you have.

    I have used the DI on both my Sansamp RBI and my GK 700RBII. I wonder if they are safe from phantom power also?

    Maybe someone else could give us both an idea.


  3. I'm running a Trace AH300 head, but I'm interested to know in general if this will damage all amps, or do cetrain manufacturers build in protection for this but not others?
  4. Thanx that was very usefull - seems like this is a common problem - so all these folks with nice expensive amps aren't even sending their preamp sound to the desk!!! - seems like people are spending big bucks on amps just to have nice monitors on stage!?

    why don't amp manufacturers pick up on this simple problem and put in DIs that can take the phantom power? seems like a neccessary fix to me!?

    does anyone know if it would then work to run the Di-out from the amp into a DI box to protect it from the phantom power? or does the preamp juice the signal too much for the DI box?
  5. TaySte_2000


    Jun 23, 2001
    Manchester, UK
    Endorsing Artist: Mojohand, Subdecay, Overwater, Matamp
    I emailed ashdown about mine awhile ago and it appears all ABM EVO II's have built in protection for this sort of thing.

    I think it should be in the manual maybe.

    I would ahve thought the DI on the RBI would take it but can't promise anything.

    Hope this helps
  6. Well, i think most good quality amps built after 2000 have protection, so i guess the manufacturers did look into this problem; now it is time for those soundmen to update their opinion about DI-outs on bass-amps. Ans yes, you can use an outboard DI-box to solve this problem, just be sure that it is good quality and has protection!
  7. SWR says "no phantom" point-blank in their documentation. They state phantom power will destry their DI circuitry.

    If in doubt, use an external DI.
  8. Th9nker


    Mar 18, 2002

    I just checked the manual for my ABM 500 EVO II, it reads:

    "It (The D.I.) is unaffected by Phantom Powering on the microphone input"

    It also goes into detail about the built-in floating ground that is referenced to the mixing console which eleminates the need for ground-lifting...

    So there you go...
  9. maxvalentino

    maxvalentino Endorsing Artist Godin Guitars/ Thomastik-Infeld

    I ruined a wonderful SWR Baby Blue amp due to phantom pwr being sent to the amp. Due to this I now always carry a stand-alone DI around.

    I now use A Demeter HBP1 preamp, and in the manual, James Demeter states clearly that no pahntom power should be applied to the balanced output or it will ruin the unit. I spoke with at NAMM about this and he told me that after the first couple of these units he made he changed the DI circuitry to allow for phantom pwr to be applied, stating that a pure, transformerless sound is better, as there is no electronic "penalty" which is applied to compromise the sound but "it is just too dangereous out there with soundmen not knowing the damage which can occur".

    As I understand, transformer based DI's can handle phantom power but most OpAmp dervied (electronically balanced) DI circuits cannot. It is best not to risk it, and a decent DI box which CAN handle (and in some cases can even be powered by) phantom power is not that expensive.

    So why have one...in addition to the DI on your amp? I stated this in another DI thread, but I will repeat: most DIs which are included in amps are an "extra"; a bell and whistle type selling point. Most are made of infereior components (hence the meltdown with phantom pwr)...this is why soundmen, when having a chance, will drop a Countryman DI on your rig regardless of your amp and its' DI. They know it will perform better with a result they can handle at the desk without suprises like hum and buzzes (or extreme low-end roll-off)..or the question of phantom power capable or not.

    Players tend to get hung up on "their" gear; wanting to use their amp and their sound. Actually, except in cases where there is no or little PA support (or the bass player is just ignorant), our amps are just on stage monitors: their presence is to allow the other players to hear us and for us to hear ourselves. It is quite normal for the soundman to ask for a pre-eq DI line, or drop one in before your amp. Your tone, though it may sound marvelous onstage, will more likely than not sound absolutely dreadful in the house. That thick low end will envelope everything and turn into a mushy, boomy ill-defined sonic mess, and in turn make the band sound similarliy disgusting. Acosutics on stage are much much different than out front, and players have a very difficult time both coming to terms with this or assessing this anomally.
    So, why have a big expensive "monitor sysytem" when the house sound does not want or need "your" sound and would prefer a dry line from your bass? Because what you hear affects how you play greatly. How you adjust your onstage tone has a great deal to do with your feel, time, and presence. It affects the other players as well. Have your sound on stage...but give the house something they can work with and scupt to fit in the (sometimes atrocious) acoustics of the room.

    When I play with bands I plug into my Demeter Tube DI which runs a straight, dry yet full and warm, signal to the house. It also splits to my amp which I eq for the band/stage. I run (and insist others do as well) very low stage volume...saves my hearing and allows the house engineer to really mix the band (the louder you are onstage...the less control the engineer has and hence the crappier mix you shall receive).

    And...the other thing about preamp sounds is they give a world of versatilty in studio recording. You can create incredibly complex bass sounds with your preamp (and dry DI sounds mixed in) in the very controlled acoustics of a studio which is difficult if not impossible in live venues.

  10. DWBass

    DWBass The Funkfather

    I always use a DI box. I never use the ones on my amps for that very reason! We have a Mackie board that has the 'all on or none on' phantom power deal! We always have problems with the vocals as well because our drummer uses 1 frikkin' mic that requires PP so now all the mics (Shure SM58's) are now powered up and we get feedback galore! I told the drummer to buy a small sub mixer with PP that he can feed to the main mixer!
  11. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL

    great post, max... :cool:

    and all the more reason people should invest in a Sadowsky. ;) my rig before my sudden obession with tubes, was nothing more than a mere "onstage monitor" to best reproduce that Sadowsky punch. mostly comprised of an Avalon U5, power amp, and Acme cabs.

    like it was pointed out, with a good soundman, my Sadowsky, or any bass for that matter will sound killer out in the house.
  12. Eric Moesle

    Eric Moesle

    Sep 21, 2001
    Columbus OH
    I just read this today, and sent my regular soundman an e-mail about it, inquiring whether he ever sent phantom power to my Eden Navigator rig's DI, which he ALWAYS taps into.

    He informed me that all of the three systems his company uses except one has a mixer which sends global phantom power, so yes, for the last three years he's been sending phantom power to my Eden's DI.

    Thankfully, no damage, so the Edens must be fine with it. (whew!!!)
  13. This is the response I received from Rick Jones. (Acoustic Image)


    The Focus will be fine connecting the DI to a mixer with phantom power, nothing will happen to the amp.

    I will send a bag as soon as we get them.

    Rick Jones

    Still waiting on the gig bag. :D
  14. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    since we're posting reports, here's what i got...

    Demeter - i was told the VTBP-201s is fine, BUT, am not sure about the HPB-1. but their Tube DI will be fine under phantom powered conditions.

    Aguilar - same. both the 659, 680, and the DI from the 359 will be fine.

    Euphonic Audio - said the iAMP-800 is safe, but they might be referring to the newer ones. people with older models like myself should be careful still.

    Epifani - the Quest preamp and 502, 902 heads might not be able to handle the phantom power and its not recommended.

    These are only my general findings, but best to call the manufacturer yourself to make sure.

    shame about the Epifani, cause HOLY CRAP, DI'ed into a non-phantomed board, its sounds like heaven.

    but that begs the question, why do some high end makers not do this? does an "unbuffered" DI sound better? i highly doubt the DI is an after thought on an Epifani Quest.
  15. tornadobass

    tornadobass Supporting Member

    Nov 20, 2000
    Iowa City, Iowa
    Endorsing Artist: Black Diamond & SuperSensitive strings
    Here's the related question...if you go with a DI to avoid phantom power ruining your amp's DI, where do you put the DI?

    For example, when using my passive Bugbass, the signal to the amp is weak and thin if I go into the DI first and then jumper to the amp...even with a Countryman. In those cases, I send something on the other end of the amp, such as the preamp or effects out.

    That's why I like using my amp's DI...and the SM-400 has a nice DI. My 700RB's DI isn't so bad, either.
  16. Interesting.
    Our behringer desk sends global phantom power. I never had any issues with my Hartke.
    Anyone have any experience with the Thunderfunk?
  17. Steve Clark

    Steve Clark

    Jan 9, 2004
    London ON
  18. Finger Blister

    Finger Blister

    Jul 8, 2003
    Instead of Plugging into the XLR input,
    just plug into a 1/4" jack instead.

    You have your DI mixer feed;
    Everybody has Phantom Power;

    I use one of these with my SWR DI Out.

  19. jokerjkny


    Jan 19, 2002
    NY / NJ / PHL
    i literally got off the phone with a gent from EA, and he said it was cool. go ahead and call or email the shop. i'm sure they'd make it clear for ya. might as well get it straight from the horses mouth.

    but now you're making ME worry, cause mine is one of the earlier 800 models with the regular "series" loop and built in Sabine tuner. maybe the shop gent was referring to the newer models!