Powered mixer help!

Discussion in 'Location Recording' started by callmeKeith, Jan 15, 2009.

  1. callmeKeith

    callmeKeith Guest

    Hi all,

    I'm looking for a powered mixer for my ceilidh band. 6 channel and the ability to isolate the phantom power to a few channels.

    Seen this:

    http://www.reddogmusic.co.uk/PA-and-Live-Sound/Live-Mixers/Powered/Behringer-PMH1000.html

    I presume "switchable +48 V phantom power" means you can switch it off channels that don't need it?

    I haven't seen anything else in that sort of price-window that can do this. Does that mean I should really splash out and this one's pretty poo? We're not after AMAZING sound, it's basically just loud music to dance to.

    Thanks for any input :)
    Keith
     
  2. GeckoMusic

    GeckoMusic Guest

    switchable phantom power typically means that you can turn it all on or all off. Not on a per channel basis. Why do you need to turn it off per channel? It's only on the XLR jacks, and almost all microphones don't mind phantom power. (The call it phantom because if you don't need it, you don't even know it's there.)

    The only time I have had an issue is when I was doing something weird like splitting a microphone and running it to another mixer. Or once in a pinch I connected a direct out from one board into the XLR of another that had phantom power on. (that made a pop and a big repair bill)
     
  3. Boswell

    Boswell Moderator Distinguished Member

    Hi Keith,

    Switchable phantom power doesn't usually mean individually switchable per channel. Powered mixers tend to have globally switched PP, and you have to go to much more expensive mixing consoles to get it. I don't know of a powered mixer that has that facility.

    Why do you need the facility? I assume you know it's OK to use dynamic mics with PP enabled (not advised with ribbons, though), so I suppose you must have synths, keyboards or amplifiers with built-in DI that have XLR outputs that you don't want phantom power to get to.

    Two solutions then: (1) 1:1 isolating transformers for these sensitive channels. These pass the signal but block the d.c. phantom power. (2) find a powered mixer that has both TRS and XLR inputs for each channel but where the TRS input is not padded by 20dB. Use XLR to TRS cables for these inputs. However, if your sources are synths etc, then level should be adjustable such that a 20dB pad is not a problem, and the TRS inputs on most powered mixers would work.

    I would personally steer clear of the PMH1000 or anything else from that particular manufacturer. If you want a unit that will withstand a fair amount of knocking about, then Peavey has a good name for that type of use.
     
  4. callmeKeith

    callmeKeith Guest

    Hmmm, ok thanks for the replies. Yea I see what you're saying, I must be looking for something far over our price-range! The problem we encountered was a buzzing from our accordion when PP was switched on.

    I don't know why it happened but when PP was switched off and we used a separate PP unit for the 2 mics (the flute and the violin) the sound disappeared. You're right, we also have an electric piano.

    Flute - Audix ADX10-FLP condenser.
    Violin - audio-technica ATM350 condenser.
    Accordion - K&K Accordion Mic System. http://www.kksound.com/accordion.html
    ePiano - MIDI out I presume.
    Drums - unmic'd.

    We currently have the PP unit for the flute/violin (XLR) with the piano being plugged straight into the mixer. The accordion is also TRS (same as 1/4 jack, yes?) in.

    At the moment there is one out and we have 2x SRM 450s in daisy chain. Probably not the best way to do it, but at the moment it's the only way, our 17th century mixer has one main out only.

    Let me know if I haven't explained things correctly, I'm not very good with the jargon.

    So...we need a new mixer, just a regular one now by the sound of it, PP, 6 channels. I may be getting it wrong, but is the preamp what powers the mic using phantom power? Or is PP the thing that powers the mic and the preamp only boosts the signal? Or is boosting the signal and powering the amp the same thing?

    Thank you for your patience. If there was a way I could repay you it would be done :)
     
  5. RemyRAD

    RemyRAD Well-Known Member

    It sounds to me you may have also had your accordion plug into a amplifier? That could be ground loop? Or you may perhaps need a matching transformer. A transformer will block the Phantom Power. And you may be able to ground lift?

    Squeezebox. Not mine.
    Ms. Remy Ann David
     
  6. TheJackAttack

    TheJackAttack Distinguished Member

    So here are some simplified definitions to help you out.

    preamp-this is what raises your microphones (powered or unpowered) to line level signal.

    phantom power-dynamic microphones do not need this but other microphones require power to actually operate. Phantom power is what makes these mic's function. Phantom power should not be available or active on a 1/4" jack.

    amp-is a separate stage of your mixer from the mic preamp side. This main amp is what drives your PA speakers. It takes the line level signal and amplifies it.

    TRS-is a 1/4" (or 1/8") phone plug or jack that has a tip ring and sleeve. It is a balanced connection.

    TS-is a 1/4" (etc) phone plug or jack that has just the tip and sleeve-no ring. It is an unbalanced connection. Most jacks on a cheap powered mixer are these. Also, according to the specs on your accordian mic's, this is the proper cable for that preamp.

    Signal flow is all gozinta and gozouta. Instrument gozinta the mic. Mic gozinta the cable. Cable gozinta the preamp/channel. preamp gozinta (in your case) the mains. Mains gozinta the amp. Amp gozinta the speaker cable gozinta the monitor.

    You get the picture.
     
  7. GeckoMusic

    GeckoMusic Guest

    Is this the way you have it set up?

    Flute - Audix ADX10-FLP condenser --> XLR on mixer
    Violin - audio-technica ATM350 condenser. --> XLR on mixer
    Accordion - K&K Accordion Mic System. --> mono 1/4" cable to 1/4" on mixer
    ePiano - MIDI out I presume. line out --> 1/4" on mixer

    I can't see why turning on the phantom power would make a buzz caused by the accordion because there is no phantom going to it.

    ...Oh wait what is the manufacture of the powered mixer? (just kidding)
     
  8. dvdhawk

    dvdhawk Well-Known Member

    Hi Keith,

    Have you considered this one? Soundcraft's Gigrac line is a little more costly, but I think you will be much happier with the integrated (Crown) amps section and Lexicon FX. The rack/case is a nice touch too.

    It does have a global Phantom Power switch. I don't think I've seen anything in this class with individual PP switches on each channel.

    http://www.reddogmusic.co.uk/PA-and-Live-Sound/Live-Mixers/Powered/Soundcraft-Gigrac-600.html?osCsid=t4a6vto8f2v5tor1kf4stnbhu1

    And like some of the previous contributors, I'd recommend you check your cables to make sure you've got the right XLR / TRS / TS connections. From what I see on you KKSound specs, the accordian is a standard TS 1/4. Using TRS connectors would force the preamp to try to balance it.

    Best of luck!
     
  9. callmeKeith

    callmeKeith Guest

    Flute mic -> XLR -> PP unit -> XLR -> mixer
    Violin mic -> XLR -> PP unit -> XLR mixer
    Accordion -> TS 1/4" -> mixer
    ePiano -> phono out (TRS by the sound of it) with 1/4" jack -> mixer.

    Sorry Remy, I didn't understand much of your post. We have no amplifier, only powered speakers? Ground loop? Ground lift? I understand the transformer bit though :) We don't have one.

    Squeezebox indeed ;)

    That mixer's a bit more expensive than I'd anticipated paying.
    PP on inputs 1-4 only.
    PAD buttons for loud inputs? What does this mean? And what sorta things is this used for?

    edit:http://www.reverb-store.co.uk/product-detail.asp?prod=3293
    Yes, discount. Interesting :)

    Thank you again
     
  10. GeckoMusic

    GeckoMusic Guest

    This is a problem, but not the cause of the buzz. A head phone jack has left and right signal on the tip and ring. These are in phase. A balanced TRS line signal has the rip and ring out of phase. The mixer will invert the out of phase signal and add it to the in phase to eliminate any noise that may have been induced on the cable. When you connect a head phone out to a TRS the right channel is inverted and added to the left. The result is that the center disappears! And of course, the center is where the bulk of your sound is. So you are left with a very weird sounding piano.

    Either use a line out of the piano, or a 1/4" TS cable from the head phone output instead of a TRS cable.
     
  11. callmeKeith

    callmeKeith Guest

    Ah OK! Thanks, man I have a LOT to learn! This subject's a mine-field lol! I really appreciate you guys helping out, you must be tired by the n00bs asking daft questions sometimes.
     
  12. dvdhawk

    dvdhawk Well-Known Member

    Keith,

    Can you clarify something for me...

    If you've got the self-powered Mackie SRM-450 speakers, why are you buying a "powered mixer"? To power monitors?

    dave
     
  13. Codemonkey

    Codemonkey Well-Known Member

    Late in here, but ...
    Our Phonic K-16 has per-channel Phantom Power (ain't we special).

    £600 new, now discontinued though.

    "This subject's a mine-field lol!"
    Well, PA guys don't spend years slogging away for nothing. It's to cram all the factors into their heads so musicians can get on with concerts and paying us to do it for them :twisted:.
     
  14. dvdhawk

    dvdhawk Well-Known Member

    CM,

    Keith seems to be shopping in the £230 price range.

    dave

    BTW, your signature line a la Yakov Smirnoff, makes me laugh everytime I see it :lol:
     
  15. Boswell

    Boswell Moderator Distinguished Member

    Keith,

    A simple (and relatively inexpensive) thing to try first is to get a PASSIVE DI BOX for your accordion. This is a transformer whose output connects to an XLR mic input and whose input can be a guitar pickup or other unbalanced source such as the little mixer amp that is part of the accordion mic pack.

    Use a guitar lead (TS -TS jacks) to connect the accordion mixer box output to the passive DI box input and a mic lead (XLRF - XLRM) to connect the DI box output to a mic channel on your mixer. The passive DI box does not care whether phantom power is enabled on the mixer or not. You may have to adjust the relative settings of the accordion mixer amp gain and the input gain trim on the mixer to get the best sound, but this configuration should solve your noise and phantom power issues with your existing rig.

    Transfomer-based passive DI boxes can be had for about £15 -£20. Have a look at Ebay (UK) items 370142061878, 140294302090 or 120312817772.

    After you have got this working, sit back and take a bit more time to work out what you really need in order to replace your present rig.
     
  16. diablo

    diablo Guest

    +1 for the Soundcraft Gigrac. I have the 1000 ST which I use for a small vocal PA. It's a decent little mixer amp and good value. It can be split with one channel of the amp for FOH and the other half for foldback, or can be run in stereo. 4 channels have phantom power. All have combined XLR / jack inputs and IIRC a couple have phono ins as well. The onboard FX are half decent too. It's a capable all round handy unit to have and comes in a handy carry case. Jeez, I sound like an advert for Harman here.... I don't work for them or have any affiliation!
     
  17. Codemonkey

    Codemonkey Well-Known Member

    Ah... our desk does have 14 mic inputs though, and there's a smaller version available. The £600 was also about 2 years ago.
    The preamps are weak though.

    A ceilidh band came to our church one time and had one of those small powered mixers that come in a small fat box (we have one too) and they're easy to use, and designed for this purpose.
     
  18. IIRs

    IIRs Well-Known Member

    I was wondering the same thing... :?:
     
  19. callmeKeith

    callmeKeith Guest

    Really just to give us more options in the future. There may be monitors and I fancy micing drums at some point. Having PP will let us power the condenser overheads?
     
  20. Codemonkey

    Codemonkey Well-Known Member

    Having PP will let us power the condenser overheads?

    Yeah. You *can* get external phantom power supplies that you can run cables into/from.
    Some condensers also have batteries in them that you can use instead.

    Or do what I do and use 2 cheap dynamic mics as OHs. Then pretend it's good.
     

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