PA setup advice please

[mjojom]

hi, im new here.
ive been searching net for clues even spoke to few shops but no one wants too give me any advice because they did not see the venue.. althrough i understand they point of view im not after perfection here.

ive got warehouse, main area is 5.5k sqft that will become a gym. im thinking a 4 pendant speakers for zone1: http://www.aandcaudio.co.uk/tannoy-ocv8 ... 0v-p281520 or
http://www.aandcaudio.co.uk/tannoy-ocv6 ... 0v-p281519

the music wont be blasting, as most people have private music with them.
for amp i was thinking: http://www.aandcaudio.co.uk/adastra-rm1 ... th-p288674

the same amp should be able to handle changing room speakers 2 each so 4 ceiling speakers but controlled as second zone: http://www.aandcaudio.co.uk/tannoy-cvs4 ... 0v-p281515

so the question really is, is the speakers/amp correct match?

now there is more to it so maybe i can explain further if the thread not going to get buried. its a gym, so im not looking for high fidelity sound, itll be mono setup anyway.
not sure if above is making sense, but if you could help me itll be great.

thanks
jo

 

[nigelwright7557]

You need to match the impedance of the speakers to the amplifier.
There are numerous configurations that will work.
You need to work out the sum of all the speakers then work out impedance to match your amp.

If you have a 4 ohm amp then you can have 4 off 16ohm speakers in parallel.

If you need more speakers then you can use serial/parallel combinations to get to 4 ohms.

 

[mjojom]

hi thank you,
the links in my post to see actual items you have to copy/ paste them inc numbers behind to work. this will be a parallel setup as it it 100v speakers and amp. twwo zones so i can separately adjust volume in gym and changing rooms.
just in case, main speakers for zone one are either; Tannoy OCV8 8" Pendant Speaker 100V or Tannoy OCV6 6" Pendant Speaker 100V.
amp in question is;Adastra RM1202 2 Zone Mixer Amplifier and ceiling speakers for zone two are;Tannoy CVS4 4" Ceiling Speaker 100V


thank you
jo

 

[chris661]

When it comes to distributed line systems, all you need to do is add up the wattages. If you think the speakers you've chosen will be enough, all you need to do is find a 100V amplifier that can supply the total power required.

Chris

 

[mjojom]

right, ive read that. but thats the confusing bit

8" speeakers : Power Handling Average: 70W, Programme: 140W, Peak: 280W
Recommended Amplifier Power 140W @ 16 Ohms

amp: Output power 2 x 120W rms, so 120w per zone

so what you are saying is o add programme wattage of speakers? so 4x140=560

so r we saying i need amp that can handle 560w per zone??

or i got it completely wrong?

sorry, when you guys trying to help treat me as numpty in this field

 

[mjojom]

anyone could please explain?
thanks
jo

 

[conanski]

You will be setting up what is known as a distributed sound system here where multiple speakers are connected via transformer taps to the 100v output of the amp. Download the operators manuals for all devices and you will begin to understand.
On the speakers there are multiple settings for transformer taps such as off/15w/30w/60w for the OCV-8 for example. If you want to attach 4 speakers to each zone of this amp then the math looks like this, you have a total of 120w amp output, divide that by 4 and you get 30w so select the 30w tap on all speakers and you are good to go. The transformers isolate the speakers and provide a stable load back to the amp so that you can parallel connect many more speakers than you normally could with straight wire.

 

[chris661]

The transformers isolate the speakers and provide a stable load back to the amp so that you can parallel connect many more speakers than you normally could with straight wire.

Right, except you need to keep the total wattages in mind. So if you wanted to double the number of speaker driven by the amplifier, they'd each need to be at half the wattage.


mjojom, it helps me to consider it in a similar way to mains electricity. One of our UK mains sockets will put out around 3000w. With that, you could plug in 300 USB chargers at 10w each, or a hairdryer (2000w) and a toaster (900W) and 10 USB chargers. Both would result in the socket being at capacity.

Of course, you might not need all that. It might turn out that running 10 USB chargers is enough for you, in which case you only need 100w capability.

The difference for the 100v audio systems is that you get to choose how much power goes to each speaker, by picking the transformer tap. Say you want one speaker to be 6dB louder than the rest of them, all you do is move the input connector to the one that's 4x more power (+3dB = 2x power).

If you set off with a 200w amplifier, it can feed four speakers at the same level (50w each), or you could give them all different volume levels (100w, 25w, 50w, 25w). So long as the total power settings for the speakers do not exceed the total power the amplifier will give out, you'll be fine.

Chris

 

[mjojom]

this is great advice thank you.
so if amp has got 120w /4 speakers i need to set speakers to 30w each and if speaker sensitivity is 90db @1w, at 30w i should be able to pump out 108db per speaker, correct?
this begs the another question: since amp will be constantly at 120w, would this be too much for amp to handle?
also, given 5.5k sqft @4-5m height would the 4 speakers be enough?

and lastly, looking at speakers data sheet, there is the information ofower Handling Average: 70W, Programme: 140W, Peak: 280W
Recommended Amplifier Power 140W @ 16 Ohms

the above info about power handling and recommended amp power is quite different to the calculations on top, which one is correct or this is mixing apples and pears ie: calculations i made is for distributed system and data sheet is for conventional setup?

cheers
jo

 

[chris661]

The amp will only be running at 120w when you turn it up. Not something you need to worry about unless you want to run everything close to the ragged edge.
I make it 105dB per speaker. For background music, I'd expect it to be fine.

And yes, it sounds like they're quoting numbers for a conventional (low impedance) setup.

Chris

 

[mjojom]

some fantastic help here guys.
thank you so much. i can get the project underway

 

[conanski]

so if amp has got 120w /4 speakers i need to set speakers to 30w each and if speaker sensitivity is 90db @1w, at 30w i should be able to pump out 108db per speaker, correct?

About 105dB actually.

this begs the another question: since amp will be constantly at 120w, would this be too much for amp to handle?

No the amp won't be at 120w constantly it will still vary with the volume control setting. Don't confuse Volts with Watts they are not the same thing.

also, given 5.5k sqft @4-5m height would the 4 speakers be enough?

That you're going to have to try out and see. If it is strictly for background muzak you will be fine but fill the space with active people and equipment and the system probably won't be capable of making announcements over top of that racket.

and lastly, looking at speakers data sheet, there is the information ofower Handling Average: 70W, Programme: 140W, Peak: 280W Recommended Amplifier Power 140W @ 16 Ohms

the above info about power handling and recommended amp power is quite different to the calculations on top, which one is correct or this is mixing apples and pears ie: calculations i made is for distributed system and data sheet is for conventional setup?

Those speakers can handle a lot more power and get quite a but louder with it so you could use a more powerful amplifier.

 

[jaddie]

I see a couple of possible and very common errors here. We're talking about a 5.5kft area, but only 4 pendant speakers.

What's the distance from the speaker to ear level? And from that, how much area will each speaker cover effectively? You may have a high ceiling and a fw speakers may be enough, but typically too few speakers are installed, and the system ends up with hot spots. Also, from that distance you can back into required power for a target SPL. Power per speaker will most likely change, perhaps a lot.

Many think only in terms of the typical stereo power amp, but there is product made for distributed systems specifically.

Here's one example.

Here's another.

If you will want the same music/announcements in both zones, just at different volume levels, one amp will be fine. You may want a volume control for the second zone, like one of these. If you need separate music/announcements in different zones, you have a slightly different problem.

It's usually best to get an amp ready to drive a 100V or 70V system, and not get a stereo receiver and add transformers. That can work, but sometimes doesn't because of the potential for an odd load that consumer receivers aren't always up for.

 

[jaddie]

this is great advice thank you.
so if amp has got 120w /4 speakers i need to set speakers to 30w each and if speaker sensitivity is 90db @1w, at 30w i should be able to pump out 108db per speaker, correct?
this begs the another question: since amp will be constantly at 120w, would this be too much for amp to handle?
also, given 5.5k sqft @4-5m height would the 4 speakers be enough?

Ha. Writing a post while others post...always fun.

Speakers almost always have a coverage angle of 30 degrees for full bandwidth, 90 for mid-band. So at 5 meters, mid band coverage is about a 5m circle, full bandwidth is about a 2.3m circle. Remember to figure this based on speaker to ear height. It sounds like you need more speakers, but it's hard to do this layout with only the total square footage.

At 5m, the peak SPL at 30W will be 90dB, but that's peak, not average. Take off 10dB or so for average, you're at 80dB, which is pretty loud.

and lastly, looking at speakers data sheet, there is the information ofower Handling Average: 70W, Programme: 140W, Peak: 280W
Recommended Amplifier Power 140W @ 16 Ohms

the above info about power handling and recommended amp power is quite different to the calculations on top, which one is correct or this is mixing apples and pears ie: calculations i made is for distributed system and data sheet is for conventional setup?

cheers
jo

Ignore the recommended power, you'll be well below average and peak power, but are these 100V or 70V speakers, or just 16 ohms?

 

[mjojom]

Ha. Writing a post while others post...always fun.

Speakers almost always have a coverage angle of 30 degrees for full bandwidth, 90 for mid-band. So at 5 meters, mid band coverage is about a 5m circle, full bandwidth is about a 2.3m circle. Remember to figure this based on speaker to ear height. It sounds like you need more speakers, but it's hard to do this layout with only the total square footage.

At 5m, the peak SPL at 30W will be 90dB, but that's peak, not average. Take off 10dB or so for average, you're at 80dB, which is pretty loud.

Ignore the recommended power, you'll be well below average and peak power, but are these 100V or 70V speakers, or just 16 ohms?

Hi Buddy,
thank you for the reply but from what others said and from what have you written all the kit ive suggested in first post should work just fine.
the amp you have suggested have output of 2 zones both 120w, same as what I have, my amp will have separate volume controls per zone an I am also able to play different or same inputs to both zones.
as per speakers, they are 100V. but all that has been covered in earlier posts and as you have written I have roughly 5m circle per speaker, so 2 rows of two speakers give me 30m width/length where my zone 1 is only 25m wide, and 20m long so seems to me the "square" of the zone should be well covered with 4 pendants?.

cheers
jo

 

[jaddie]

The basic height/dispersion angle spacing concep really only works in spaces with relatively low reverb time (RT60). In reverberant spaces, large speaker to ear distances result in poor %ALCONS, which is a metric of Articulation Loss of Consonants, a means of measuring relative loss of intelligibility in sound systems, based on reverb time and direct to reverb intensity ratios.

You might want to look at that.

 

[mjojom]

Right, not sure if you're actually read the whole thread but when I mentioned at the beginning that I know literally nothing about whole this I meant it. So your post above is meaningless to me and not helpful at whole. Now Im happy and appreciate all the help I could get here, but if you are trying to help bud, you going to have to try differently. Also I've mentioned, this will be more of background music as majority of customers will be having personal music and headphones on, so I'm not after music fidelity here and I have feeling that's what you're trying to get to?
Jo

 

[jaddie]

Ok, tell me about the space. Are the floors carpeted? Are the walls all hard materials? Is there anything in the space to absorb sound?

 

[mjojom]

right,
its a warehouse that will be split with mezzanine (zone 1 and 3)(zone 2 = changing rooms). its a gym, so bricks for walls, rubber matting for floors and loads of kit, all that is constant, + people - thats obviously not a constant. so all that is there to break the wave bouncing and stop the echo. its got 7m high ceilings but need to bring speakers down to 5m level so i dont get much crossover of sound over the mezzanine to the zone 3 - studio

 

[jaddie]

OK, well to meet your goals, drop the speakers down to 2.5 meters and place a speaker every 3m or so on an imaginary grid. For spaces like that you need lots more speakers much closer to the ear level. You can run them all at a much lower tap, like 5 or 2.5W. If you include an equalizer you can use less expensive speakers, more of them, and do a much better job. Setting the equalizer is not a small task, but we can coach you through it. You'll also need a means of making measurements for your equalizer, so will you use a laptop or tablet for that?