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Old 18th February 2013, 06:38 PM   #11
Mooly is offline Mooly  United Kingdom
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This is very difficult to advise on, for one thing I'm no speaker expert.

Lets see what we can make of it all though. The information you have added (the 2.5 volts rms) I take to be from the test I linked to in post #2. Yes

If so, then that equates to an amplifier "power" of around 6.25 watts into 8 ohms. The only difference 4 ohm loading makes (if 2.5 volts rms still give the level you want) is that the amplifier must be able to supply double the power... around 12.5 watts.

If its a venue that will fill with people then absorption will be a real issue so we could safely guestimate that a 40 watt/8 ohm amp should be plenty.
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Old 19th February 2013, 01:02 PM   #12
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Thanks all of You, I got a lot data from your team. Hope I will find a solution...anyway I let you know if it will be a study smoke or anything else. I really appreciate your help...I'll be back soon ...
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Old 20th February 2013, 04:52 PM   #13
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[indianajo;3375015] QUOTE:_For that you would need minimum 18 ga, for long runs you would need 16 ga wire
The wire gauges mentioned are for A merican W ire G auge. You have since listed your location, which I don't recognize but your suppliers probably sell metric sized wire. I don't have wire amp tables for metric wire, you'll have to look up the wire.QUOTE...

I found out the following equivalent, Hope it's right !
AWG..........mm...............Metric New standard
18 ............1.02 ..............24/0.25
16 ............1.29 ..............30/0.25
14 ............1.62
12 ............2.05
13 ............1.82 ...............50/0.25 (with this size the entire load remains 8 ohms)

QUOTE:- Wiring 50/0.25mm as mains to each speakers circuit and further with 30/0.25 to other speakers. QUOTE.

Thanks for all...

Last edited by Steeveax; 20th February 2013 at 04:59 PM.
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Old 20th February 2013, 09:06 PM   #14
JMFahey is offline JMFahey  Argentina
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Dear steveax, please define your sound needs with a little more precision.
You speak of a 15x15M room .
You also speak of a 9 speaker cluster "24M away".
Confusing.

Will you put all speakers together (for some reason you don't explain) 24 M away from the amplifiers *or* you want to distribute them all around or as roof speakers for even sound coverage?
What will that room be used for?
Church/dance hall/school/sales room/...... ?
Draw a sketch of the room and where do you want your speakers.
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Old 20th February 2013, 10:51 PM   #15
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am i understanding the new metric standard. correctly.
24 strands of .25 mm are equivalent to 18 gauge and 50 strands of .25 mm are equivalent to 13 or 12 gauge?
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Old 20th February 2013, 11:56 PM   #16
JMFahey is offline JMFahey  Argentina
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Not quite.
1 strand of 0.25mm diameter wire is 1/4 the diameter of a 1mm diameter (AWG 18) and 1/16 the section so you need 16 strands of them.
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Old 21st February 2013, 01:14 AM   #17
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The AWG to mm(diameter) part of the chart is correct.
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Old 23rd February 2013, 03:09 PM   #18
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Quote:
Originally Posted by JMFahey View Post
Dear steveax, please define your sound needs with a little more precision.
You speak of a 15x15M room .
You also speak of a 9 speaker cluster "24M away".
Confusing.

Will you put all speakers together (for some reason you don't explain) 24 M away from the amplifiers *or* you want to distribute them all around or as roof speakers for even sound coverage?
What will that room be used for?
Church/dance hall/school/sales room/...... ?
Draw a sketch of the room and where do you want your speakers.

Be free to rectify my setup if wrong.
Wish to install in small Religious conference/hall 15 x 15 meters x 3 H: 2 channel of 9 speakers each (Speaker 8Ω - 50 watts each) in series/parallel with Resultant Impedance 8Ω (8Ω x 3sp = 24 / 3 = 8Ω)per channel, the max continuous demand output per speaker is 10 watts with 15 watts PEAK from time to time, depends on speech rates (NO crying).

The total length of wires for one channel is 35 meters from amp to last speaker. Just soft talk and some classic music at 15 watts per speaker from time to time.

SPEAKER:- 4- 8ohms 50-100watts
NO Woofer or Sub woofer - Just midrange/ medium
Bass control will set at lesser
Treble control will set at haft
Speakers will be fixed surrounding four central concrete column
at mounting height 2.5 meters from floor

Would like to know: type of amp, output, watts. wiring size.

This conference will be held in two month time.

Thanks for help
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Old 24th February 2013, 12:01 AM   #19
JMFahey is offline JMFahey  Argentina
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OK.
***Practical*** no frills answer.

Make 6 small columns with 3 speakers each, wired in series, so each column will be 24 ohms impedance.
You will have 3 such columns for each speaker channel.
Spread them evenly around the room.
You may mentally divide it in 6 sections, as in:
1/2 : Front L/R
3/4 : mid L/R
5/6 : back L/R
Each column should be pointed to one of those 6 room sections, to guarantee even coverage.
Connect all 3 left columns in parallel using 2 x 1 MM "220V type" cable, to the left channel, which will see an 8 ohms load.
Do the same on the right side.
If you can afford 1.5 mm or 2mm cable, even better, but if not, power loss into a 24 ohms speaker, only 15 meters away is nil.
And if the speakers in the back are actually slightly attenuated respect to the front ones, even better.
A 2x100W amplifier is more than enough.
In fact, any cheap 100W/4 ohms (obviously mono) powered mixer box will probably be enough to drive all 18 speakers.
But if you want to use more power, be my guest.
I have made tons of similar installations in small Churches, or larger Shopping Malls, etc.

Getting into line transformers and such is fine, but in much larger/complex situations, such as multi-story Hotels, Shopping Centers, Hospitals, etc.
Not *really* needed within a 15 x 15 meters single room.
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Old 24th February 2013, 02:33 PM   #20
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Hi JMFahey
Make 6 small columns with 3 speakers each, EXACTELY
wired in series, so each column will be
24 ohms impedance.

You will have 3 such columns for each I'LL DO IT
speaker channel.
Spread them evenly around the room.

You may mentally divide it in BE SURE IT WILL BE
6 sections, as in:
1/2 : Front L/R 3/4 : mid L/R 5/6 : back L/R

Each column should be pointed to one of YES
those 6 room sections, to guarantee
even coverage.

Connect all 3 left columns in parallel using IT WILL BE
2 x 1 MM "220V type" cable, 30/.025mm SHORT RUN
to the left channel, which will see an 8 ohms load.

Do the same on the right side. NO PROBLEM

If you can afford 1.5 mm or 2mm cable, LONG RUN 50/0.25mm
even better, but if not, power loss into a
24 ohms speaker, only 15 meters away is nil.

And if the speakers in the back are actually OK
slightly attenuated respect to the
front ones, even better.

A 2x100W amplifier is more than enough. OK

In fact, any cheap 100W/4 ohms SHOULD I CONNECT TO 4 OHMS
(obviously mono) powered mixer box AMP OUTPUT WITH 2 CHANNEL
will probably be enough to drive IN PARA, WHEN YOU SPECIFIED
all 18 speakers. 100W - 4 OHMS OBVIOUSLY MONO ?

But if you want to use more power, be my guest. THANKS
I have made tons of similar installations in
small Churches, or larger Shopping Malls, etc.
Getting into line transformers and such is fine,
but in much larger/complex situations, such as
multi-story Hotels, Shopping Centers,
Hospitals, etc. Not *really* needed within THANKS FOR CONFIDENT YOU
a 15 x 15 meters single room. MAKE ME FEELING...

QUESTION: can I connect a sub amplifier from PRE-AMP or LINE-OUT of Master
amplifier, to drive speakers over Stage as return speakers ?


I REALLY APPRECIATE YOUR VALUABLE HELP, SINCERELY AM VERY HAPPY FOR YOUR
EXCELLENT AND TECHNICAL SUPPORTS.

Thanks once more for all.
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