Ongoing probs with church pa

Discussion in 'Location Recording' started by PJay77, Apr 23, 2007.

  1. PJay77

    PJay77 Active Member

    Hi all - been pointed in this direction from another forum - good to meet you!
    I have to say straight off that, although I'm quite happy to be 'IT and Publicity' coordinator at our church, I was a bit doomed when I found out the sound system came into my brief as well! I only know what anyone who's done a fair bit of home studio recording and played in a live band would know - so please bear with my ignorance. Anyway, I have a number of irritations with our current setup [but apart from knowing that the desk is a 16 channel Spirit Live I'd have to go and look at things to find what we have].

    Right.
    1. Feedback can happen when gain is too high for volume - is that right? [had a look at the article mentioned in the sticky]. But why do we get feedback if one of the guitar amps is left ON but the guitar is UNPLUGGED - when using the omnis on the chancel and the music group channel [ie the group with all the mics etc] turned off.
    2. Random 'whispering' over the main speakers - have an idea it's due to earthing, but need to know more about it before I hit the electrician who's recently rewired the place round the head.
    3. Right channel of the desk keeps dying for no apparent reason - don't think it's dodgy cable or socket 'cos wiggling the cable doesn't make a difference - then it'll suddenly come back for no reason
    4. Placing of monitors / amps - shouldn't they be facing backwards not forwards?
    5. Tieclips [lavaliers] - how do I stop them sounding like the speaker has his/her head down a toilet? Have messed about with the EQ but still sounds weird.

    Have a nasty feeling we're going to have to call in a pro to dismantle and rewire the whole lot - but the, what sort of pro? PA specialist? Someone from a recording studio??

    Posting this as a starting point, so will check back often and try to clarify.
    TIA
     
  2. Boswell

    Boswell Moderator Distinguished Member

    Wow - lots of ground covered here.

    1. Feedback - you are miking the guitar amps, right? It doesn't matter whether the guitar is plugged in or the amp is switched off, if the mic is live it has susceptibility to feedback. I was disturbed to read of omnis in this context, but I wasn't sure which mics you were referring to.

    2. Random whispering - describe it more: whistles, "birdies", buzz, hum, voices?

    3. Right channel of your desk dying: your desk needs a service.

    4. Amp and monitor placing: conventionally, the amps face the audience and are placed either behind the performers (backline) or alongside them. Foldback monitors sit in front of the performers facing them, i.e. away from the audience. These rules are not hard and fast. It's down to type of band, venue, and performer preferences.

    5. Lavs - are these the bog standard ones? It's difficult to comment on this without hearing a sample, but I don't think the toilet effect is a matter of EQ. If these are wireless types, it would be worth trying a wired model to see if it gives the same problem.

    I would be surprised if total re-wiring was necessary. Expert advice, perhaps, and generally not a recording studio guru, unless that studio also does external live sound gigs. It's a different world, especially when it comes to fault diagnosis and venue problems.
     
  3. PJay77

    PJay77 Active Member

    Thanks for getting back to me.

    1. No - guitars plugged into amps, amps plugged into DI boxes, DI boxes into break-out box at end of 50' long muti-core that goes under the floor.

    Brief description probably in order here;
    16 channel desk;

    1 + 2 - radio condensers attached to lectern and pulpit respectively. Don't actually know if they're omnis [just my loose way of talking], but they have a good pick-up range.
    3 + 4 - tie-clip / lavalier radio mics - for when the preacher needs to wander
    5 - hand held radio condenser - not often used

    6, 7, 8, 9 - vocal mics for band - wired XLR to XLR [all same make - I think they're Shures]
    10 + 11 - guitar amps as above
    12 - flute pick-up - goose neck expensive job XLR to XLR
    13 - bass amp as above
    14 + 15 - keyboard in stereo

    Occasionally we have a set of tablas mic'd with a condenser - that gets bunged into whichever channel isn't being used on that particular morning. PITA because it picks up everything else...

    All the band controls are grouped as 1/2 - so when said slider is down nothing comes through [rather than messing about with individual sliders / switching off at button

    16 - pzm on back wall - this has NEVER worked properly so it's usually off and with slider down

    Said feedback has only been happening over the last few weeks - but I can't think what's changed in that time scale

    2. Whispering - rustling, maybe? We did have a bad case of budgies in the system - traced that to the power supply of the laptop used for recording - so we now just run it off the battery.
    Said noise happens at random at any time - including in the evening when the powerpoint computer, recording laptop and band equipment all switched off and unplugged. Does literally sound like someone's fondling the mic - but I can see they aren't! I might be able to extract a chunk of last Sunday's recording for you to hear what I mean.

    3. OK - will see who I can find in the area

    4. Tend to use amps as monitors rather than backline because everything goes into the desk for recording purposes. We do have a recording computer as well with an 8 channel breakout box [I use the direct outputs from the desk] - but that's only used for 'studio' work. Live recordings are just done in stereo controlled from the desk - so the mix has to be complete.

    5. If you could see our vicar when he gets going, you wouldn't suggest a wired mic - he'd garotte himself...
    Do you remember that stupid song 'Video Killed the Radio Star' - that's the kind of vocal effects we're getting. Head in a metal bucket rather than a toilet, perhaps.

    I know it's a lot of ground, but I've rather inherited the set-up and I'm not a happy bunny. We will be making certaing changes to the band / desk setup soon, and I'd like to be a more certain of my ground before I start asking for new equipment / wiring / ways of doing things!
     
  4. sheet

    sheet Well-Known Member

    I bet the "whispering" coming from the speakers is closer to static coming from the Rf mics possibly? I suspect the shreaking noise is not feedback either.

    I wish that we could help more. But seriously, you need to call a local contractor for a troubleshooting service call. It would be unrealistic for us to expect to diagnose all of this stuff here. It could be wired correctly, but could be a matter of tweaking a few things.
     
  5. pmolsonmus

    pmolsonmus Well-Known Member

    Your noise may also be sweat/body heat affecting the transmitter on the lav mic.

    We traditionally put the battery pack/ transmitter inside a non-lubed condom (I'm not making this up) for theatre use. This is standard practice because of noise created by sweat/ proximity to heat of the body.

    Phil
     
  6. sheet

    sheet Well-Known Member

    Can you imagine the small town married pastor going to the convenience store, placing the horse sized condems on the counter....yeah. Imagine the gossip.
     
  7. moonbaby

    moonbaby Mmmmmm Well-Known Member

    I would think that they'd BOOST the "shrieking noise"!
     
  8. PJay77

    PJay77 Active Member

    Somehow I don't think I'll be suggesting that one...
    Anyway, once we've got the projector repaired we'll see about calling someone in. In the meantime, I'll go and have a quick test of some of the cabling, and see if I can persuade the group to let me alter the postions of their precious amps and things.
    Thanks for all the help.
     
  9. BobRogers

    BobRogers Well-Known Member

    I'm with everyone recommending that you get someone in to work things over. But with these installed church systems that get used by a lot of people it is often a good idea for a few people to just spend a Saturday and unplug the whole thing and start from scratch. Get some cans of compressed air and some contact cleaner and clean everything. Test all cables and toss out any that look bad. Rethink your rack arrangement. It sounds like the the Ghost could use having (at least) the pots and faders cleaned, but I'd leave that to someone else if you are uncomfortable. At least move every pot and fader back and forth a couple of times. Push all the buttons a couple of times. Set everything off or neutral. Get a couple of new cables and use the cable tester to check each channel of the snake.

    Hook up the system one item at a time. Get the PA working with a CD player. Use something with a fairly consistent volume and an even stereo field. (Bach is good in a church.) No effects sends or monitors yet. Pan back and forth between left and right channels. Check each stereo of the stereo inputs by moving the CD player around. Make sure the pan and eq all work on each channel. Now use one channel of the CD and move through the 16 channels. Make sure all knobs and switches work (other than the aux sends. Next I'd hook up the monitors and test the aux sends. Finally I'd get any effects you are using. At this point you should have a working PA with nothing plugged in.

    Start with the wireless units. I have a suspicion that this is the source of your "whispering." (You may need to invest in better transmitters and receivers. But you can try playing with new channels and other settings here.) Plug them in one at a time and get them working. Run them at full volume. Then plug in the snake and hook up the wired mics one at a time. Instruments go last.

    At the very least you will get everything cleaned and you'll probably learn a lot about the PA. Take notes as you go, especially on things that don't work.

    If you can get your pastor to wear a Countryman E6 you will see a vast improvement over any Lav I've seen. Our pastor won't wear one. Says too many people think he looks like a televangelist as it is.
     
  10. PJay77

    PJay77 Active Member

    That sounds like a good idea. We're due a major rewiring soon as we're losingtwo pews at the front to give the group more space [I wish we could lose all of them, but some of the older members are rather against the idea]. Also, the desk, amps, computer etc. are all in a solid box which is a nightmare when you want to try and change anything - so I'll deal with that and check all the wires at the same time. It's certainly very dusty underneath, but at the mo I can't get at it.

    I'm not sure it's the tie-clips at fault with the whispering, though. It happens occasionaly at the evening service when the only mics are the ones fixed to the pulpit and lectern. Someone on another forum suggested it might be interference from another appliance somewhere else near the church. I don't know what the range of these things are, but that would certainly explain the randomness.
     
  11. Boswell

    Boswell Moderator Distinguished Member

    The way you describe the "whispering", it's almost certainly due to a dry joint in one of the connectors or even the desk. You need a service for the Spirit (apart from the ones you have all the time). That and Bob's suggestion of re-plugging everything may well sort it out.
     
  12. BobRogers

    BobRogers Well-Known Member

    Nice. :cool:
     
  13. PJay77

    PJay77 Active Member

    I'll have to pass that one onto the vicar... :D
    The work starts tomorrow, when the heater in our corner goes [not before time - talk about in the way!]. On Saturday the two front pews go... so I think I'll go in on Saturday afternoon to do some wiring checks before everything gets put back. Maybe take my cans of switch cleaner and compressed air with me! Will also need a small child to crawl under the floor and put the wires back so that we can run the chancel speakers [sadly the days of climbing boys are long gone, but I'm sure I can persuade at least one of them that it'll be fun and he* might get some sweets out of it]

    [* - saying 'he' because for some odd reason all our older group - ~12 of them on a good day - are boys]
     
  14. PJay77

    PJay77 Active Member

    Well, I haven't got round to the switch cleaner yet, but we had to unplug and shift everything for the work to be done - and this morning there wasn't a trace of a whisper on the system or on the recording...
     
  15. PJay77

    PJay77 Active Member

    ...but there was in the evening. Last Sunday was just there all the time. Gave all the cablens, plugs and sockets I could get at a good clean the week before as well.
    [Haven't been on for a while 'cos I lost the forum when I had to reconfigure my computer!]

    Narrowed it down to the desk, amplifier, speakers and power supply for the desk [which is something]. Unplugged the PSU and gave it a good blast with the compressed air, and rocked the switch several times.
    When I turned it back on the rustling had disappeared. Faint whisper from the chancel speakers until I unplugged them and treated the sockets with the air as well.
    So could it just be a bad attack of dust and mucky contacts? Courtesy of the bright spark who built all the IT stuff into a very smart but very solid and unmoveable box, getting at anything is a bit of a nightmare.
     
  16. Kent L T

    Kent L T Active Member

    With that many rf mics I would have a radio guy come in and check the place out for rf. You can get all kinds of strange noises from rf interference.
     
  17. PJay77

    PJay77 Active Member

    would we still get intereference when the mic receivers are physically unplugged from the desk?
     
  18. sheet

    sheet Well-Known Member

    Dust can cause noise. If you do not have sealed pots on your gear, then that can cause scratchiness when adjusting them. Every knob should receive a twist every now and then so the wiper can clean the path.

    Dirty power adds noise and can cause your system to under perform.

    Degrading cables can add noise.

    Lights, ballasts and dimmers can add noise.

    You really should get someone in there to help you trouble shoot.
     
  19. PJay77

    PJay77 Active Member

    Well, I've found a couple of companies who will check the desk over if I take it to them, but so far no-one who'll come out and take a look in situ. However, I had another go last night - and the rustling noise comes through the ehadphone socket when everything else is either switched off or unplugged. So I suppose it has to be the desk or its power supply.
    I'd really like to find another power supply to test it with before I dismantle everything but so far I'm having no luck in Leeds...
     
  20. sheet

    sheet Well-Known Member

    Do you have a Mackie SR series console by chance?
     

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