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Noob advice on a PA system
Noob advice on a PA system
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Old 11th June 2019, 08:49 AM   #1
nicenswift is offline nicenswift
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Default Noob advice on a PA system

Hi,

My daughter is in a band and we have just had donated a PA system for them to use.

It consists of (please bear with me as I am a complete novice)

1 Mackie CFX12 Mixer
1 Amp (Not sure on make)
4 Speakers (Peavey) 2 x big bass 2 x smaller on stands

So far I have 2 basic questions

The speakers use speakon cables and I presume we connect the larger speaker (Bass) to the amp and them connect the smaller speaker to the lager one, is this then running in parrallel and if so which speakon port do i use to do this as both the larger and smaller speakers have 2 speakon ports.

I have researched about using gain to set the levels but is it best that once the gain is set that all the faders should be best set at unity and then control the colume with the amp

I appreciate any help and please excude my lack of knowledge.

Many thanks for your time.
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Old 11th June 2019, 09:07 AM   #2
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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If the crossover is in the bass box, connect the amp to the bass box then up to the mid/top.
Use 1+ and 1- for the connections in your Speakon.
Use the gain controls to 'trim' the required gain giving about 6db headroom before overload then the sliders are your volume controls.
Once the gain is set, any adjustment on the gain control will also adjust any foldback, so leave it alone.
The main slider is your overall volume.
Set the amp volume to about 50% to start with and adjust as needed.
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Old 11th June 2019, 10:37 AM   #3
nicenswift is offline nicenswift
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Quote:
Originally Posted by JonSnell Electronic View Post
If the crossover is in the bass box, connect the amp to the bass box then up to the mid/top.
Use 1+ and 1- for the connections in your Speakon.
Use the gain controls to 'trim' the required gain giving about 6db headroom before overload then the sliders are your volume controls.
Once the gain is set, any adjustment on the gain control will also adjust any foldback, so leave it alone.
The main slider is your overall volume.
Set the amp volume to about 50% to start with and adjust as needed.
Many thanks for the reply.

Both the large and small speakers have 2 speakon ports on each.

They dont seem to be labeled in anyway so how do I know which is an In and Out on each or does it not matter.

Thanks for your time
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Old 11th June 2019, 11:35 AM   #4
indianajo is online now indianajo  United States
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Peavey speakers typically have opposite phase on two different input ports. What Peavey speakers you have matters. In most cases Peavey speakers do not have internal crossovers (frequency filtering) so wiring them in parallel halves the load resistance to your amp. Whereas an actual crossover splits the frequencies between the large and small diameter speakers and keeps the impedance at the full rating. If you can get a model number off them, you can access a user manual from peavey.com or their phone #. If you show a picture and some driver dimensions, somebody here or on the Peavey forum may be able to identify them for you.

If the mixer has speaker outputs, then those go to the tops (high frequency speakers) and the subwoofer output goes to the amp and the large speakers. That is a common modern setup. Look for a 150 W or 75 W rating on the label of the mixer, that indicates a mixer/amp.
Some amps are 4 ohm rated so if you have 8 ohm speakers you can wire them in parallel. Use a decent ($30) VOM to measure the speaker resistance. Impedance is about 20% higher, as a 6.5 ohms speaker is nominally an 8 ohm one.

If speakers are 4 ohm (3 measured) I suggest to be safe to buy an actual passive crossover from parts-express.com (If you live in North America). These have an ohms rating a power rating, and input port, and two output ports high & low. The low output goes to the big speaker, the high to the small. If the big speakers are 12" or smaller, I would use the 2000 hz crossover version. If the big speakers are 18" subwoofers, you'd use a 200 hz crossover.

Or more to the point you could buy another amp that has an internal frequency filter and bi-amp the 4 speakers. There is less likelyhood of blowing amp output transistors doing that.
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Last edited by indianajo; 11th June 2019 at 12:03 PM.
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Old 11th June 2019, 11:38 AM   #5
nicenswift is offline nicenswift
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Quote:
Originally Posted by indianajo View Post
Peavey speakers typically have opposite phase on two different input ports. What Peavey speakers you have matters. In most cases Peavey speakers do not have internal crossovers (frequency filtering) so wiring them in parallel halves the load resistance to your amp. Whereas an actual crossover splits the frequencies between the large and small diameter speakers and keeps the impedance at the full rating.
I suggest to be safe to buy an actual passive crossover from parts-express.com (If you live in North America). These have an ohms rating a power rating, and input port, and two output ports high & low. If the big speakers are 12" or smaller, I would use the 2000 hz crossover version.
Or more to the point you could buy another amp that has an internal frequency filter and bi-amp the 4 speakers.
Thank you.

I am not sure what model the larger speakers are but I can check. (they are in my friends garage)

I have just checked on the smaller ones and they are Peavey Hisys 6 XT

I appreciate your help
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Old 11th June 2019, 05:41 PM   #6
ICG is offline ICG  Germany
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Quote:
Originally Posted by nicenswift View Post
It consists of (please bear with me as I am a complete novice)

1 Mackie CFX12 Mixer
The mixer isn't something sensational but it's not bad either, it's a 'care-free budget mixer with it all'. It got FX, it got subgroups, an (output) EQ, channel EQ with semi-parametric mid and phantom power. The ony things that could be useful and that are missing are phantom power (for the electret mics) could be switchable for every channel and a compressor for the mics are not included.

Quote:
Originally Posted by nicenswift View Post
So far I have 2 basic questions

[...]

I have researched about using gain to set the levels but is it best that once the gain is set that all the faders should be best set at unity and then control the colume with the amp
No, that's not the best way to do it at all. Firstly, at the soundcheck, set the channels gain. Press the 'solo/PFL' button next to the channels fader, that gives you the pre fader level to the VU-meter. For voice mics, press the low cut, as that will take out the most of the 'pop'. Set the gain (top potentiometer for each channel) so that the loudest of the instrument or mic reaches ~0dB. Place the 'position' right/left with the pan pot (best like they are standing on stage), usually the max on the pan should be mid to max 1/2 to either side. EQ the channel to a realistic sound, that's done with the channel EQ knobs. The Aux is usually used to 'feed' the monitors, the knobs for aux 1 and 2 should be for vocal monitors and instrument monitors, you need to 'mix' them for monitoring so the artists can hear themselves. Push the PFL button again so you get the overall level on the VU meter again. Repeat for each channel.

Assign the channels to the subgroups (1-2 or 3-4), that way you can change the subgroups volume by the subgroup faders, i.e. subgroup 1-2 the singers mics, 3-4 the instruments. The balance between ie. 2 singers should be done with the channel faders, analog the same to the instruments etc. Try to find a balance of everything within the soundcheck and try to find a balanced EQ. After the audience is there, the sound will change (as the bodies will absorb sound), so you have to correct the output EQing. Check for reasonable monitor volume, avoid feedback, if you get fb, place monitors or mics differently. Soundcheck done.

The amps should be on 100% and the level control is on the main fader as the (wo-)man on the console should be controlling the level aswell as the sound and balance between the channels. On the amp it's useless as it's close to the speakers and there you don't have any feeling (or actual measurement) on how loud it is in the audience, it will never be right.
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Old 11th June 2019, 08:53 PM   #7
indianajo is online now indianajo  United States
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Excellent tutorial ICG. When my audience gets bigger than 9 I'll take those subgroup ideas to heart. Right now I'm still not using electricity in my performances (except room lights).

Peavey.com has the user's manual for the hisys 6 xt. See support owner's manuals/operating guides, then click on archived manuals, then click the H selector. Then click on hisys 6xt. At upper right is a down arrow which is the download button (puts it on your hard drive). File downloads to a pdf file, which you can get software to read if you don't have it from irs.gov.

It is a mid/top made for use with a subwoofer. The nominal impedance is 8 ohms. It has two drivers including a highly effective RM22 tweeter. It has an internal crossover for separating the sound for the two internal drivers. You can turn it into a biamp setup by disconnecting the internal crossover, but I suggest a beginner band not bother. The two speakon connectors are wired in parallel.

If your other speaker is a hisys112-xt as they suggest you buy, then that is a subwoofer. The presence of one 12" driver would be a big tipoff. If that is 8 ohms impedance, and the amp is 4 ohm capable, then you can wire the two speakers on one channel in parallel to the amp. Just run a speakon cable from the hisys 6xt second connector to the hisys112.

If you blow up an amp, it was not 4 ohm capable. Best of luck.
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Last edited by indianajo; 11th June 2019 at 08:56 PM.
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Old 11th June 2019, 10:11 PM   #8
ICG is offline ICG  Germany
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Well, the mixer advice aplies to all speaker/sub configurations. Ofcourse, the amp/speaker/sub situation may change a lot of the sound, the go-to does not change however. Also, the physics don't change, no matter what provider and type of speakers/amps are in the game. So, whatever speaker/sub/amp configuration you'll chose/use, that will still apply. Your main concern should be the quality of sound you're providing out of your mixer. Unless you have to provide the whole PA, everything after the mixing console out is the local audio tech's field. Provide a good bands audio and you'll get a great result.
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Old 13th June 2019, 09:38 AM   #9
nicenswift is offline nicenswift
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Thanks guys for some fantastic advice, I feel a lot more confident and will be putting the above into practice at our next rehersal.

On a side note the Mackie has a button called "Low Cut 100Hz" I have been told its to do with bass frequencies but I am not sure if it needs to be on or off for the kick drum and bass guitar ?

Again many thanks for some great advice and tips.
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Old 13th June 2019, 11:40 AM   #10
indianajo is online now indianajo  United States
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Primary reason for the low cut is to reduce stage rumble from the microphones. Most floors are not as fixed as a concrete slab. Secondary reason is to remove hand shake rumble from hand held microphones. I'd say leave it on everything; the amount of sound below 100 hz is insignificant in a beginner band.
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