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Do I Need A Separate Mic Preamp In This Situation?

Discussion in 'Amp Tech Center' started by Bill Sheehan, Oct 21, 2020.

  1. Bill Sheehan

    Bill Sheehan Tele-Meister

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    Hi friends, I realize this isn't Tele-related, but would greatly appreciate any thoughts you might have:

    I'm wanting to do very small-scale solo and duo performances with acoustic guitar and vocals, utilizing a single condenser mic, "bluegrass style", to pick up everything, and ultimately running it into my Kustom PA-50 portable p.a. unit.

    I have an inexpensive condenser mic which requires 48v of phantom power. (The Kustom PA-50 provides 15v of phantom power.) I also have an inexpensive 48v "free-standing" phantom power supply.

    If I were to run the condenser mic into the 48v phantom power supply first, and from there directly into one of the mic channels (XLR) on the Kustom PA-50 (which then has dials for volume, treble, bass), am I likely to get a desirable result? Or do I still need to add a separate "mic preamp" to kick up the mic signal before it goes into the p.a. head?

    If the answer is absolutely "yes", then I suppose I should ditch the separate 48v phantom power supply and just get a mic preamp that includes 48v phantom power, would that be correct?

    Finally, in either event, is it a problem to feed in 48v of phantom power "on top of" the 15v phantom power already provided by the Kustom?

    Thanks for any thoughts you might have!
     
  2. Ash Telecaster

    Ash Telecaster Friend of Leo's Silver Supporter

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    I would be concerned with feedback using a condenser mic in that scenario. A dynamic mic or preferably two or three dynamic mics would probably serve you better.

    As far as the "mic pre-amp" question I don't think that would be needed.

    If the head has phantom power I would try that first. Use the external phantom power only if needed. I see no value in enabling both. It probably wouldn't do anything but I don't think it would help anything either. Phantom power provides power for the mic to function and is not needed by the channel input.

    Based on your description it sounds like the external power supply would be needed.
     
    Last edited: Oct 21, 2020
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  3. KATT

    KATT Tele-Meister Silver Supporter

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    I've just looked up your PA and it has a mic input, therefore has a mic preamp built in. So as you say, run the mic into the 48v power, then to the PA.

    I would also be concerned about feedback issues, especially as you presumably will have to have the mic at some distance to pick up both guitar and vocals I'df each person equally.
     
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  4. Bill Sheehan

    Bill Sheehan Tele-Meister

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    Thank you, Ash!
     
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  5. Bill Sheehan

    Bill Sheehan Tele-Meister

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    Thanks, Katt! So, when there's an XLR mic input jack on a p.a. head, does that mean there's a built-in pre-amp associated with that input?
     
  6. KATT

    KATT Tele-Meister Silver Supporter

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    That would usually be the case. You could theoretically have an xlr input that did not have a mic preamp, but I would expect that to say "line" instead rather than "mic" as would probably be a Line level input.

    I'm not sure about using the 48v power with that PA though as I've just looked through the manual and see that you can't turn off the 15v supply.
     
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  7. Jakedog

    Jakedog Doctor of Teleocity Ad Free Member

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    You can try this, but I don’t think you’re gonna like it. Using a condenser mic bluegrass style is really not a good way to gig in club/bar situations. But give it a shot. See how it goes.
     
    Last edited: Oct 21, 2020
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  8. 41144

    41144 Tele-Afflicted

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    Surely the PA-50 has 2 channels both with line and mic inputs?
    If so, run the mic as described and then buy (even) a cheap DI box (c.£20+) and run the guitar into the other channel as Line-in ... for much better clarity at least?

    But, as Ash Telecaster said, be wary of feedback using a condenser mic in anything like close proximity to the speaker.

    Edit .... of course the above presumes (always dangerous) that said guitar is an electro-acoustic, if not ... then, given the 2 channels, I'm with the two dynamic mic setup - even if they're decent clones of, say, SM57 & 58s!
     
    Last edited: Oct 21, 2020
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  9. schmee

    schmee Doctor of Teleocity Silver Supporter

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    I would just use a dynamic mic in that situation.
     
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  10. Bill Sheehan

    Bill Sheehan Tele-Meister

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    Katt, I suppose I could try the condenser mic straight into the Kustom (without using the 48v phantom power supply), just to see if the Kustom's "complimentary" 15v of phantom power will be enough to "fire up" the mic, but I suspect that it won't be enough. And if it's not, then hopefully I wouldn't be hurting anything to introduce the separate 48v phantom into the equation.

    Feedback-wise, I'm planning to avoid the noisier situations and stick with the small coffee house, winery, and retirement home situations, so hopefully I'll be able to manage that...
     
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  11. tubegeek

    tubegeek Friend of Leo's

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    15V may well be enough to turn on the mic. What model mic is it? Do you have the manual or a spec sheet?

    If the PA has phantom power it must have mic preamps behind the XLR mic inputs. No* line level equipment requires phantom.

    *unless it's really really weird.
     
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  12. Edgar Allan Presley

    Edgar Allan Presley Friend of Leo's

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    I've done plenty of bluegrass gigs with a single condenser mic. It doesn't work very well in a space with lots of crowd noise, but it can work great outdoors, larger stages where you're farther from the chattering crowd, or in quiet listening gigs. It also takes practice. It's a different mic technique than most of us are used to.
     
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  13. tubegeek

    tubegeek Friend of Leo's

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    I would imagine a figure-8 pattern setting would give a whole lot better sound than cardioid or even omni, but a lot of work getting folks positioned in the right place at the right moment.
     
  14. Bill Sheehan

    Bill Sheehan Tele-Meister

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    Thanks, Tube! The mic is a Neewer NW-700; not exactly what you'd call top-of-the-line, but it seems to get favorable reviews.

    The free-standing 48v power supply is likewise made by Neewer.
     
  15. David Barnett

    David Barnett Doctor of Teleocity

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    In Bluegrass they call that "the dance".
     
  16. tubegeek

    tubegeek Friend of Leo's

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    @Bill Sheehan So far I haven't been able to find a full specification for the mic's phantom requirement - try it and see seems like the advice that makes the most sense so far.

    As @David Barnett alluded to, bluegrass performance style is pretty well accustomed to one mic and a bunch of shifting around it. The part I'm worried about is, it really should be an omni or a figure 8 and your mic is a cardioid which would mean your band members would have a pretty narrow sweet spot to step into when it was their turn to come forward and they'd "dim down" quite a bit when they step aside.

    Fortunately you undoubtedly have actual bluegrass band members reading this board who can tell you way better than I can whether a cardioid will cramp your style or not. And David is not without significant live sound expertise so his advice is more relevant than mine.

    I'm the sound guy in a very musical church.

    When I point a cardioid large diaphragm condenser at a duo, everybody else pretty much shuts up and listens. I keep them 15 feet from the drummer and 10 feet from the piano and they sound great and are able to get on-mic successfully. But it's not a comparable venue, is it? I have over 100 feet to the back wall, for example, and collection plates are a lot quieter than cash registers, and I'm not looking for high SPLs, and my monitors are really low, and my main array is 30 feet in the air. I'd be curious to hear what some club sound veterans think.
     
    Last edited: Oct 21, 2020
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  17. Bill Sheehan

    Bill Sheehan Tele-Meister

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    Tubegeek, in looking at the Neewer website, and also at an independent consumer review on this mic, I see some indication that a mere 5v of phantom power may actually be sufficient for this mic.

    So maybe I'll try just running the mic straight into one of the XLR mic channels on my Kustom PA-50, and see if the Kustom's built-in 15v of phantom power gets the job done. If it doesn't, then I can try adding the separate Neewer 48v supply and see what happens. Thanks to all who have offered their thoughts! I'll update you after I have a chance to do some experimenting!
     
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  18. Edgar Allan Presley

    Edgar Allan Presley Friend of Leo's

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    A cardioid pattern is perfect. That way it rejects sound from the crowd side and picks up the front and sides, and it isn't flat like a figure 8 would be, so it picks up guitar from below and vocal and fiddle from above.
     
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