PA Issue...

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Currently in a 3pc modern rock covers band and have been gigging for the last 18months with great success in the local area.

Our drummer recently upgraded his PA from 2 Passive Laney CX15 cabs and 2 subs, to 2 x Mackie SRM650. His mixing desk is a Behringer PMP6000 which has a built in amp. We never used to use the amp previously as he had a better quality power amp anyway so used the 'Main Output L&R' into the Power Amp out to the speakers. We had researched this method and found it was fine to do.

Now with the new speakers we have far less gear to lug around and are now using IEM as well, super light weight rig compared to the previous lot...pukka!

The issue we have is the old power amp was run on about 2/3 and was super loud, the new SRM650 speakers are actually rated the same, hence why he bought them, but we are having to run the speakers flat out, and the mixer and input gain pot way higher than before and we're struggling to get the vocals loud enough to be heard when previously it wasn't an issue at all.

Any thoughts on why this may be??

Just to recap, old rig

Laney CX15 x2 250w RMS ea

Laney CX Sub x2 250w RMS ea
MyAudio power amp, 800w RMS ea (I think) per side
Laney active wedge monitor x2 approx 200w (can't remember, didn't use them for long!)
Behringer PMP6000

New rig

Mackie SRM650 800w RMS ea set to PA mode. Not sure what the feedback eliminator is set to
Behringer PMP6000

I appreciate there were two extra speakers (subs) but cant imagine they would make that much difference?

Any help much appreciated!
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Comments

  • I appreciate there were two extra speakers (subs) but cant imagine they would make that much difference?


    I think you are realising they make a lot of difference
    Adding a sub back in with a crossover would really help. Speakers oscillate at different speeds at different frequencies which all take energy
    you are asking your new speakers to do it all in one cone where as previously the heavy stuff was ‘subbed’ out ;)

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  • Fair enough! Didnt realise we would have to push everything so much harder to compensate for it that's all and it would make that much of a difference. Thanks fo the reply though @Cabicular
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  • ICBMICBM Frets: 71950
    What are you putting through the PA? If it’s just vocals then the subs won’t make much difference. If it’s kick drum and/or bass as well then it will make a huge difference - in fact I would say don’t do that without subs.

    If it’s just vocals, it’s possible the input sensitivity of the Mackies and the output level of the Behringer are not well matched, so even with everything apparently flat out, the speakers aren’t getting enough signal to drive them fully. Just because they are the same power rating doesn’t mean much either - it’s also possible that one of them is more optimistic than the other...

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Thanks @ICBM, Usually vocals with a bit of kick just for clarity, bass and guitar amps we are usually able to get loud enough in the room to not bother going through the PA, but if they do go though the PA it's just to add a bit of reinforcement, so we're not relying on the PA to project the gtr and bass. 

    Not run the gtrs and bass through the new PA speakers yet, just 2 vocals and kick so far really as we've only played pubs with the new setup ... Again, confused as to why we're cranking so much and not getting close to the previous amount of output with less running through it. I had been contemplating using a modeller and no amp, but at present no chance as the PA doesn't appear to be up to it. 
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  • ICBMICBM Frets: 71950
    If you’re putting kick through the PA then you need subs, period. The Mackies will not handle the low-end transients properly and it will take away headroom and clarity from everything else going through them.

    I also think the levels are mismatched if you’re turning everything up full and it’s just quieter, rather than distorted or compressed - that implies the Mackies aren’t getting enough signal to drive them fully.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Cool. Yeh the signalsounds clean , it's not distorting, just perceviably quieter than the previous PA setup.

    How do we address the signal mismatch @ICBM ;is that an easy fix?
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  • ICBMICBM Frets: 71950
    You may need some sort of two-channel booster. How are you connecting the outputs of the desk to the speakers - just with standard 1/4” instrument cables? If so you might be better using a pair of DI boxes and then XLR cables to the speakers, but I don’t know whether the sensitivity would be higher without trying it.

    You could also return the subs - assuming he hasn’t sold them - without adding any other gear, if you drive them with the Behringer’s own power amp - if they have their own crossovers, which I assume they must if you were running them from the same power amp as the tops.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Yeh 1/4inch jacks to the speakers..... Come to think of it, they're pretty heavy duty leads, if they're speaker leads would that have an affect??

    He's sold the old PA
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  • ICBMICBM Frets: 71950
    Yeh 1/4inch jacks to the speakers..... Come to think of it, they're pretty heavy duty leads, if they're speaker leads would that have an affect??
    No, other than possibly increasing noise.


    He's sold the old PA
    Oops.

    Now you have no means of patching a backup solution using the Behringer’s power amp if one of the Mackies goes down either... which you could with spare passive cabs.

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • I think he has a backup pair of the CX15 tops come to think of it, but not subs. 
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  • JalapenoJalapeno Frets: 6378
    If the old speakers were 4ohms and the new ones 16ohms that'd make a difference.
    Imagine something sharp and witty here ......

    Feedback
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  • Good point
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  • ICBMICBM Frets: 71950
    Jalapeno said:
    If the old speakers were 4ohms and the new ones 16ohms that'd make a difference.
    No it won’t. The Mackies are powered cabs so impedance matching is irrelevant.

    There are no 16-ohm PA speakers anyway, after about 1975...

    "Take these three items, some WD-40, a vise grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone." - Walt Kowalski

    "Just because I don't care, doesn't mean I don't understand." - Homer Simpson

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  • Fair do's!
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  • Danny1969Danny1969 Frets: 10356

    Are you running proper wire balanced leads from desk to active speakers ? You can get a drop in level in some cases if pin 3 is shorted to ground ..... if desk has XLR out then it;s just 2 mic leads from desk to speakers. If jack outputs then should be TRS jacks wired to XLR in balanced config
    www.2020studios.co.uk 
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  • I think they're just standard speaker leads, jack to jack. Mixer has jack or Speakon connections
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  • John_PJohn_P Frets: 2744
    I think they're just standard speaker leads, jack to jack. Mixer has jack or Speakon connections
    The active speakers wouldn’t be connected to the speaker out sockets though - those are for passive speakers using the power amp.      If you are using a jack to xlr cable then it’s easy to have one that is wired wrongly as Danny describes.  

    I think you need a sub or two but as well as that go through the signal from mic to speaker making sure everything is set at the right level and has enough gain, you should have a decent vocal PA with that set up if it’s run correctly.  
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  • Correct, jack to jack leads coming out of two unpowered jack outputs labelled Main Out L&R.

    ive suggested we bypass th mixer and try a vocal mic straight into the PA speaker and see Howe that sounds and then with the mixer to see if there's any differences, try and eliminate that way.
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  • Danny1969Danny1969 Frets: 10356

    The SRM650 normally have combo sockets, balanced. I doubt the Behringer ones are though. Don't use speaker leads though, the leads from the desk should be shielded otherwise you will amplify any noise picked up between the desk and the active speakers. That can be quite a bit on an 8 metre or so run

    I think as ICBM said you have a sensitivity mismatch ... you need a higher level driving into the Mackies. There are ways around it but personally I would buy another non powered desk ... since digital took off older desks are cheap as chips to buy 

    www.2020studios.co.uk 
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  • What sort of specs do we need to be looking at to sort this out? Is this a similar issue to how some pedals behave dependant on output/input impedance? Do we need a certain type of output impedance to help drive the signal more, or is it a case of a couple of DI boxes as previously mentioned.

    Background / unwanted noise doesn't seem to be an issue at all surprisingly! Just the noise we do want thats the issue
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