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Phantom Power

Discussion in 'Recording' started by Doublehelix, Nov 18, 2002.

  1. Doublehelix

    Doublehelix Well-Known Member

    I have an outboard preamp setup with 8 mic pres, each with selectible phantom power, the problem is, the design of the system sucks! They put the phantom power switches on the back of unit (rack mounted) along with the XLR input jacks. I have moved the XLR jacks to the front of the rack via an XLR patchbay, but still have to reach around the back of the rack to activate the phantom power...what a poor design!

    Any suggestions here? How about recommendations for an outboard phantom power unit (8-channel) with the switches on the front!
     
  2. knightfly

    knightfly Active Member

    James, unless you're lucky enough to have some ribbon mics, just leave the phantom turned on. No modern dynamic mic I'm aware of (other than ribbons) seems to care one way or another. (Not sure what some battery powered electrets would do under these conditions)

    Or, you could mount the pre's backward with an offset bracket, then you could reach around back to adjust the attenuators, etc... :=)
     
  3. Doublehelix

    Doublehelix Well-Known Member

    No, I don't have any ribbon mics, although I have been looking at a few on Ebay as of late <drool>...I use mostly condensers and a few dynamics, especially for guitar cabs...

    I have always heard that you should never, ever plug/unplug any condenser mic with the phantom power turned on...the "manual" that I got with my latest Rode mics was very clear on this point as well...Hmmmmm...what is the worst that can happen here, and why do manufacturers warn very *sternly* not to do this?

    Thanks!
     
  4. RecorderMan

    RecorderMan Distinguished Member

    not only that...but since everyone here is always in search of excellance....I was told by Keith Olsen once that phatom messes with the top end. And he therefore had a penchent for tube mics (no phantom) on drums, ect.
    Hassle though it is, I'd just turn it on when necessary.
     
  5. Kurt Foster

    Kurt Foster Distinguished Member

    DH,
    Never, never, never, leave the phantom power turned on when connecting and disconnecting your condenser mics. This is very hard on the phantom power supply and can lead to damage. Plus if you accidentally leave your monitors on it makes a nasty noise. Always turn off the phantom power when you're not using it and allow it to drain for 30 seconds or so before disconnecting any mics. I personally don't mind XLR's on back panels (IMO it's where they belong) but I do think the phantom power switches belong on the front panel. Very inconvenient ... That thing about phantom lousing up a signal, I've heard that too but the solution was to use an outboard, battery driven, phantom power supply. I personally don't hear the difference but I suppose some "Golden Ears" do. I differ to their ears. This is one of the reasons mic manufacture CAD uses rechargeable nickel cadmium batteries to power their mics. ......... Fats
     
  6. Doublehelix

    Doublehelix Well-Known Member

    A friend of mine suggested that I leave the phantom power switches activated at all times, but turn the **mic pre** off and on between the pluging and unpluging of mics...pretty clever, eh? I seriously doubt that the phantom power will hurt the dynamic mics if it is on all the time, right?

    Anybody see any problems with this approach?
     
  7. Jax

    Jax Guest

    I'm plagued by a problem with powering my KM184's. With the gain turned all the way down on any preamp, I'll switch on phantom power and the level from a 184 seems to be way too sensitive. IOW, very loud. I record into PT, and I don't use the oft described method of "getting the hottest level possible", so using my 184's as drum overheads is especially problematic.

    I don't have the same problem with any other mics. I've asked this question on other forums before, and most people answered that it must be the mic's output is very hot. The only reason I don't accept that answer is I never see anyone else posting with the same problem. Knowing that 184's are ubiquitous, I would think this would be more widely discussed.

    What can I do about this? I like these mics.
     
  8. Kurt Foster

    Kurt Foster Distinguished Member

    It sounds as if your Neumanns are really hot! I have the same problem with some clip on AT Pro 35's...real hot. I got some switchable pads that bring the level down -10, -20 and -30 dBs. About $30 bucks each ....... Fats
     
  9. Jax

    Jax Guest

    I hear ya Fats, but I still say what's going on with my 184's can't be right. I mean, going thru any of my outboard pre's with NO gain, they're already louder than I can ostensibly use.

    There must be others here who use 184's. Anybody have a similar experience with them? Maybe it's just drum OH's that are affected?
     
  10. Kurt Foster

    Kurt Foster Distinguished Member

    Jackson,
    That's exactly what I am talking about with these ATM pro 35's. With the attenuator turned all the way down they clip the inputs of anything I have ever plugged them into. If you were having the problem with just one of your mics I would suspect a problem but since they both exhibit the same problem I suspect you need to pad down the input level.
    ……… Fats
     
  11. Jax

    Jax Guest

    Hey Fats, now that I've started with my grievances against the 184's, I might as well get tehm all off my chest! :eek:

    When I've switched in the pads on my preamps it helps. I'm not really a purist or audiophile engineer, but even with my Great River MP-2 there is a slight veil put over the sound with the pads in.

    It bothers me that some of my preamps have a few optimum settings that I can't achieve with the 184's. For example, on my Flamingo if I want to switch in the Fat or Iron amps and overdrive them by attenuating -6dB to every +6dB of gain (or more depending on how much distortion I want), I don't have that option with these mics. Same goes for wanting to drive the tubes in a Manely 40dB.

    There are several other preamps I have or will be adding soon that can be overdriven to achieve some character.

    While I'm whining, there's no way to safely flip on phantom power to the 184's, except for preamps that slowly ramp the phantom up. If you turn on the preamp first, let it warm up, then flip on phantom power, a 184 will POP in pain. If you have phantom switched on and then switch on the preamp's power, POP. If you plug the mic in with the pre all ready to go, POP. Bad for the mic, the pre, and it can damage the speakers!

    I suppose the only way to handle my 184's safely is with preamps that have output level controls, pads, or slowly ramped phantom.

    Still surprised I've never seen this mentioned as a problem before.

    Hey recorderman, if you read this I'd like to know if you have any similar problems with overly hot mics and how you deal with them. Thanks!
     
  12. Kurt Foster

    Kurt Foster Distinguished Member

    The inline pads I keep mentioning will take care of all these problems your speaking of. They are a barrell connector XLR M on one end and XLR F on the other with a small slide switch that attenuates -10dB -20dB and -30 dB. They cost about 30 bucks each. ...... Fats
     
  13. Jax

    Jax Guest

    Ok, I don't mean to come off 100% stubborn, so tell me - do you hear any alteration (veil or otherwise) with the XLR pads?

    I will probably try them out. Got a link or a source?

    Thanks
     
  14. Kurt Foster

    Kurt Foster Distinguished Member

    Well it's hard to tell because I can't use the mics without the pads but they sound fine to me...
    Fats
     
  15. jajjguy

    jajjguy Guest

    You have a Flamingo and a Great River and a Manley and you're reluctant to shell out for a simple pad? Jeez.

    On another note, I've heard some people say that with very hot mics on loud sources, you can actually skip the pre and plug right in to whatever's next, be it a compressor or your tape deck. Of course you still won't get the cool sounds of your preamps...
     
  16. Kurt Foster

    Kurt Foster Distinguished Member

    Wow,
    That is a cool idea... you would need to get a outboard phantom power supply but other than that you might be able to use the compressors inputs for gain control in.......cool! Fats
     
  17. knightfly

    knightfly Active Member

    Hey DH, Fats - Sorry for the mis-communication, once again I ass-u-me'd that someone else works the same as I usually do - Fats' comment, "Never, never, never, leave the phantom power turned on when connecting and disconnecting your condenser mics." - is of course right on.

    In my studio, I tend to leave things powered up and plugged into specific channels, since I usually work alone. When I want condensers, I already have them plugged into the first group of channels, and I just move them physically to where I need them. Besides the usual batch of dynamics (57's, 58's, several AT's and some Sennheisers, I have an AT4033, a pair of Oktava's and a pair of Marshall V67's so far, planning on adding a pair of AT3035's and a matched pair of Rodes for overheads in the near future, and once I have a better acoustic space I'm drooling over the new Royer ribbons and several others.

    After 30+ years of repairing/aligning various gear, I tend to leave stuff powered up
    most of the time, with the possible exception of gear that has moving parts. (Leslie cabinets, capstan motors...) Over the years I've found that this makes for less repairs needed due to turn-on transients, dried out electrolytic caps, etc.

    If you're plugging and unplugging things, ANYTHING that requires ANY kind of power (phantom or otherwise) should NEVER be hot-plugged, unless the design spec specifically says it's OK. (an example of this type gear - USB, Firewire, NON-phantom mics into NON-phantom powered connections, ONLY with speakers muted and/or faders pulled down)

    Several home and project studio pieces of gear, in order to cut costs, tend to use one phantom power switch for multiple channels - Recorderman's comments about phantom messing with dynamics' response aside (I tend to agree about that) , sometimes it's necessary due to shortage of available channels, to have dynamics on the same bank of channels with condensers. That would be the only time I'd have phantom on a mic that didn't need it.

    Again, sorry about the mis-info. I'll try to ask questions about how other people work before answering too quickly again... Steve
     
  18. Jax

    Jax Guest

    You say I'm reluctant, I say I'm finding out about inline pads for the first time.

    I have a Vintech 1272, a 1969, and a Soundcraft Ghost (whoopee) also. The point is I don't like the sound of the pads in any of them. Veil. Inline pads may not be as noticeable. I'll see.

    For now I can still work the work the way I have been, but I will be trying some inline pads soon.

    There's no rush.
     
  19. Kurt Foster

    Kurt Foster Distinguished Member

    Jackson,
    I wonder if you're really hearing a difference in quality vs. a difference in volume? The human ear hears things that are louder, as better, due to the Fletcher Munson curve. That is highs and lows aren't perceived as well at lower volumes. That's why a lot of people like to hear their audio loud. An interesting experiment would be to run one of your Neumann's into the 1272 with the pad in and one with the pad out at equal volume. Have an assistant switch back and forth between the two without you knowing which is which ( A/B blind test). See if you can really hear the difference. The pads in a Vintech / Neve design pre should be relatively good, although 1272's weren't really designed to be a mic pre. It should still be better than either the Drawmer or the Ghost pre's. My MCI 636 had gain switches that added gain rather than padding down and I still had to use the inline pads for real hot mics. You should have a few of these things in your audio toolbox anyhow. ...... Fats
     
  20. Jax

    Jax Guest

    Fats,

    I can do that with other pre's, but the Vintech doesn't have pads - not that it matters for the test you describe. FWIW the sound of the Great River's pads is subtle but distinct, so I don't think it's a question of volume. For instance, not every snare hit clips, but switching in the pad and then comparing the unclipped hits with the padded hits at approximatated equal volume (bringing up the fader), I can hear an obvious difference.

    Next time I'm up there, I'll have my friend chop on my snare and try the test you mentioned thru both sides of the Great River. The hell with driving up today. Bay area traffic sucks cranberry sauce!
     

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