Power to the People?

[PropellerHeadCase]

I was tootling about a wedding forum yesterday and some DJ was suggesting that an 800W sound system was sufficient, if not actually quite loud, for 200 people. I know some people hereabouts have said that 10W per person is a good rule of thumb (and that gels with what I've heard elsewhere), and frankly I wouldn't be too happy with my 2500W system for more than 150 (for modern dance music) or 200 (for purely retro).

So, what are people's thoughts? Is he totally talking out of his orifice?

[sleah]

800w is potentially quite adequate for 200 people. Depends on what the function is, the venue (layout etc), the type of music, average age of the audience and if the client has asked for it to be specifically loud or quiet etc.

For say a 50th it would be more than enough, for an 18th, no where near enough. Even the height of your speakers will make a difference. If your speakers are at ground level up against the dance floor, 800w may struggle, but at eye level back from the dance floor and 800w will be fine.

Ohh, we are talking RMS aren't we????


Now, how long is a piece of string?

[PropellerHeadCase]

I suggested in my response that 800W would be fine for a room that only just seats that 200 and you're playing Neil Diamond or Nat 'King' Cole but in a larger room with modern more bass-heavy music that 800W was far from adequate.

[Corabar Steve]

But don't you only want it to be loud around the dancefloor area & merely audible (so they know what is being played, but are still able to hold a conversation) elsewhere in the room? It is very unlikely that all 200 would want to dance simultaneously.

[Dragonfly]

But don't you only want it to be loud around the dancefloor area & merely audible (so they know what is being played, but are still able to hold a conversation) elsewhere in the room? It is very unlikely that all 200 would want to dance simultaneously.


you mean you don't get EVERYONE up dancing Steve :eek: :eek: :eek: :D :D :D :D

Id agree with what you're saying though thats what I aim for particularly the not blasting people out that wish to talk.

[PropellerHeadCase]

But what if you do get everyone dancing? Then you're stuffed.

[Corabar Steve]

But it never happens, I don't dance & there are plenty of others like me (so the likelyhood of everyone wanting to dance at the same time is remotely slim)

Also I like to be able to have a conversation without shouting when I'm out with friends / relatives, there needs to be a quieter area in the room unless the room is in a multi room venue where for example the bar is in a different room.

[Solitaire Events Ltd]

But what if you do get everyone dancing? Then you're stuffed.

I don't think that would ever happen.

As others have said, you only really need the sound on the dance floor. There are other factors involved here too. The efficiency of the speakers and also the size and shape of the room.

If you've got a room where sound is bouncing off walls, then it wouldn't sound much louder if you had an 800w per side system.

[Paul James Promotions]

I
As others have said, you only really need the sound on the dance floor.

You still enough enough power for microphone use for everyone in the room to hear.

[PropellerHeadCase]

Folks hereabouts seem not do many 'up for it' weddings, then. All it takes is a mostly young group of guests with somewhat similar tastes and it's easy to get the bulk of them dancing.

I still think that 800W for 200 people is leaving yourself open for disaster.

[Solitaire Events Ltd]

I still think that 800W for 200 people is leaving yourself open for disaster.

And as I said, surely this depends on the size of the room and efficiency of your equipment. I'm not sure how you can really generalise on issues like this?

[spin mobile disco]

When I reset up my rig about 2 years ago after a year absence from DJ'ing I bought a very nice BMA 500 watt amy providing 500 watts 150watt watts rms per channel at 8ohms. I paired this with 2 skytec 15inch drivers with wide horn piezo's Rated at 150watts rms each.
I played quite a few 200 people type gatherings with this sound system and for weddings etc it was fine. Ran a little near max a lot of the time but gave no problems. Good quailiy sound no complaints of to loud or to quiet.
Now I know a lot of people go uhhhhh skytec, pants toilet etc. But fact is I ran with those cabs for a year with no hint of problems sound reproduction was great . Good clear treble punchy bass.
Now I may have gone to a more upmarket sound system now with a lot more power etc but to be honest the 300 watts rms was more than enough for weddings , birthdays etc. (excluding a 200 people 18th but as I never did any of these it wasnt a problem)
I mean If you times this sound system by 2 and have 4 full range 15" drivers with matching amp you are still less than 800 watts rms and I bet you could make em wish you would turn it dow.

[Dragonfly]

Folks hereabouts seem not do many 'up for it' weddings, then. All it takes is a mostly young group of guests with somewhat similar tastes and it's easy to get the bulk of them dancing.

I still think that 800W for 200 people is leaving yourself open for disaster.

personally think disaster maybe a little strong :confused: :confused: :confused:

using a 35 year old tape deck with 1 90 minute tape with no songs after 1950 and no back up is leaving yourself open to disaster ;)

I regularly play to 200 kids 12-15 (the noisy lot) in their drama studio mostly i use srm450s and my 1501 ...... but on occasion I have just used the 450s............. every month the teachers tell me to turn it down without fail.

[rob1963]

In my opinion 800 watts for a gig where there are 200 people is plenty.

I have used my 600 watt system in some large halls for more than 200 people (in one case, all 16 & 17 year olds - who usually like the volume louder) and I've had no problems at all.

A colleague of mine has an amp with a total output of only 200 watts, and he uses that every week for gigs of 100-150 people with no problems.

The other thing to remember (as already mentioned) is that regardless of the number of people there or the size of the room, the dancefloor is only likely to be 20 or 30 feet square, and the disco will probably be set up right in front of it, so you only need to be able to project music for about 30 feet at a decent volume level for dancing...and I think 800 watts is MORE than sufficient for that.

:)

[CRAZY K]

In my opinion 800 watts for a gig where there are 200 people is plenty.

I have used my 600 watt system in some large halls for more than 200 people (in one case, all 16 & 17 year olds - who usually like the volume louder) and I've had no problems at all.

A colleague of mine has an amp with a total output of only 200 watts, and he uses that every week for gigs of 100-150 people with no problems.

The other thing to remember (as already mentioned) is that regardless of the number of people there or the size of the room, the dancefloor is only likely to be 20 or 30 feet square, and the disco will probably be set up right in front of it, so you only need to be able to project music for about 30 feet at a decent volume level for dancing...and I think 800 watts is MORE than sufficient for that.

:)

Hi Al, ive got a 1000 watt peavey mixer amp that drives 4 cabs--two tops--2 subs--

Ive played in big big Barns (thats not a typo) over here at Barn Dances and Weddings , never got near max volume and been pretty loud I can tell you with 200 people.

Depends what these watts are--are they

RMS continous
program
peak

Those are the definitions Peavey give offically.

They differ wildly , ONE top speaker PRO 15 ALONE is rated 250 rms, 500 program 1000 peak THATS ONE CABINET.

I have 3 more of course :D

So I dont really take a lot of notice of watts--there isnt much point.

Perhaps you ought to point this out to the DJ on the Wedding site:D

Good point Jamie, but if you have a foghorn voice as some of us do for our chosen job :D you dont need a massively loud set up--just voice projection lessons--

CRAZY K

[Excalibur]

When I reset up my rig about 2 years ago after a year absence from DJ'ing I bought a very nice BMA 500 watt amy providing 500 watts 150watt watts rms per channel at 8ohms. I paired this with 2 skytec 15inch drivers with wide horn piezo's Rated at 150watts rms each.
I played quite a few 200 people type gatherings with this sound system and for weddings etc it was fine. Ran a little near max a lot of the time but gave no problems. Good quailiy sound no complaints of to loud or to quiet.
Now I know a lot of people go uhhhhh skytec, pants toilet etc. But fact is I ran with those cabs for a year with no hint of problems sound reproduction was great . Good clear treble punchy bass.
Now I may have gone to a more upmarket sound system now with a lot more power etc but to be honest the 300 watts rms was more than enough for weddings , birthdays etc. (excluding a 200 people 18th but as I never did any of these it wasnt a problem)
I mean If you times this sound system by 2 and have 4 full range 15" drivers with matching amp you are still less than 800 watts rms and I bet you could make em wish you would turn it dow.

I agree with you totally in principle. ( Just substitute Peavey for Skytec!) Two 15" full range, 200w per side RMS, loud enough for 90% of my gigs. As I'm sure Mr Scott will soon say, it's not what you've got, it's how you use it! ( ooh er, missus!) No actually how efficient! There are many smaller outfits which can sound as loud as bigger ones, because of how they work/are designed. Simply looking at the amount of Watts is no indication at all of noise levels achieved!

[Excalibur]

Good point Jamie, but if you have a foghorn voice as some of us do for our chosen job :D you dont need a massively loud set up--

CRAZY K

Or even a PA system.:p

[Danno13]

I'm firmly of the belief that its far far better to have more than you need, than to not have enough. For that reason, i'd never do a gig without at least one sub unless it was just mainly background music like a christening or something.

There are some gigs where you just need to have that power.. and not necessarily because of the size of the room/dancefloor, and i don't just mean 18ths and 21sts.... people getting married now grew up during the 90s dance era.. so aren't afraid of good bass!

[CRAZY K]

Or even a PA system.:p

ER yes I do have one--doesnt need to be very loud though :D

YEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE-HA!!!!

CRAZY K

[Corabar Steve]

I can vouch for that! :sj:

[PropellerHeadCase]

I think the points here are good - when I talk about my 2,500W system, that's peak, at the amp (1400W peak at the speakers - 600W bass and 2x400W tops). The 800W may well be RMS, which would be more reasonable.

I played to 300 15-18 year olds on Saturday and I was caning my system, which on that occasion was about 1200W peak for the bass (driven by about 2000W peak) and about 1400W peak for the mids/tops (driven by 2500 peak), with the crossover at 100Hz. On numerous occasions, with 200+ on the floor their yelling along with the lyrics was louder than me.

For the record my mids/tops are always set at head-height or higher.

And yes, OK, maybe not disaster, but if you had an 800W full-range system and 150 of the 200 were up for some Electro you'd sound weak.

[Thames Valley Discos]

I suggested in my response that 800W would be fine for a room that only just seats that 200 and you're playing Neil Diamond or Nat 'King' Cole but in a larger room with modern more bass-heavy music that 800W was far from adequate.

It really depends. Just because you have a larger amp, it does not Necessarily follow that it will be louder. An amp can only amplifier what its fed with. I think people get too carried away with watts/power of their systems. Yes if we start talking 20kw sure you'll see a difference, but 500W,800W, 100W, na i don't think so.
most of us play halls or Hotels, so no need for great big sound systems.

[rob1963]

Just because you have a larger amp, it does not Necessarily follow that it will be louder. An amp can only amplifier what its fed with. I think people get too carried away with watts/power of their systems. Yes if we start talking 20kw sure you'll see a difference, but 500W,800W, 100W, na i don't think so.

I'm not sure whether I agree with this.

As I understand it, if you double the power, it sounds 50% louder (It wouldn't sound twice as loud - due to the way our ears work).

Therefore, if you upgraded from 200 watts to 800 watts, it would literally sound twice as loud...and I suggest that difference would be very noticable!

[TonyB]

I'm not sure whether I agree with this.

As I understand it, if you double the power, it sounds 50% louder (It wouldn't sound twice as loud - due to the way our ears work).

Therefore, if you upgraded from 200 watts to 800 watts, it would literally sound twice as loud...and I suggest that difference would be very noticable!

To double the volume output, you have to increase the power by a factor of 10 so if you had an 800w system, you would need a 8000w to provide double the volume.

Its late and my brains a bit fuzzy but if I remember correctly, doubling the power provides a 2db or 3db increase in volume so the difference between a 800w and 1600w system (assuming the speakers were of the same efficiency) would hardly be noticeable.

I personally use a 800w RMS system (400w a side) but it is bi amped and the tops have a high spl of 110db. Biggest function I have done with my rig is 190 people in a large hall with a high ceiling and even then I wasn't pushing the amps to full capacity (the BKE amp has a graduated LED VU meter and it wasn't anywhere near the red).

For teenage parties I have put the subs together under the deck stand so you get acoustic coupling and makes it louder but it was too much so I usually have a bass bin either side with a pole for the tops.

[BeerFunk]

To double the volume output, you have to increase the power by a factor of 10 so if you had an 800w system, you would need a 8000w to provide double the volume.

Its late and my brains a bit fuzzy but if I remember correctly, doubling the power provides a 2db or 3db increase in volume so the difference between a 800w and 1600w system (assuming the speakers were of the same efficiency) would hardly be noticeable.
As I've always understood it, you have the first part wrong, and the second part right :)

A 3db increase in volume requires double the power input, but to double the actual volume you need to go to +6db, which is double again. So, to double the volume, you need to quadruple the power input (a few assumptions made, naturally!)

[PropellerHeadCase]

I meant to comment on this in my last post...


I'm not sure how you can really generalise on issues like this?

This is kinda my point - if you go into a place expecting to be able to get away with 800W, and you only have 800W what happens if you are wrong?

I always try and build redundancy into every environment I set up in. Just in case, like.

[rob1963]

So, to double the volume, you need to quadruple the power input

Yes Beerfunk...that's exactly what I said (see quote below) :)


if you upgraded from 200 watts to 800 watts, it would literally sound twice as loud

[BeerFunk]

To be honest, I've never had an overly loud PA, and the only issues I've had with the volume is when I've been asked to turn it down. I've never been asked to turn it up, and found myself unable to oblige.

I suppose what I'm saying is that even though a system may not seem loud to us - it is to the general public (more often than not - too loud :))

Yes Rob, I did see that, but I felt the urge to quickly reply to Tony's post as soon as I saw it :D

[rob1963]

even though a system may not seem loud to us - it is to the general public (more often than not - too loud :))

Yeah...especially the OLDER members of the general public!

(When did you last have an 18 year old ask you to turn it down?)

[BeerFunk]

Yeah...especially the OLDER members of the general public!

(When did you last have an 18 year old ask you to turn it down?)
Very true... but I've never had them ask me to turn it up either! (not that I can remember, anyway)

[NiM]

(When did you last have an 18 year old ask you to turn it down?)

The last prom I did..

It was at that point I knew I needed to quit..

[Thames Valley Discos]

i have only ever been asked to turn it down, and don't forget we are stood behind the speakers and as such it always sounds quieter than it actually is.
1000W system is more than enough for my needs. If i bi amp and use 2000w, the sound just sounds better not louder.

[TONYTIGER]

For most jobs i use a 2.4kw RCF active system 2x800w subs 2 x400w tops all ways got plenty in hand and you can all ways turn it down. Bit like a car really small engine and you thrash it wont last long!

[TonyB]

As I've always understood it, you have the first part wrong, and the second part right :)

A 3db increase in volume requires double the power input, but to double the actual volume you need to go to +6db, which is double again. So, to double the volume, you need to quadruple the power input (a few assumptions made, naturally!)

Nope first part is correct, it works on a logarithmic scale so it is 10 times the output to double the volume. Not accounting for the logarithmic element, each doubling of the power increases the volume by 3db. So 1600w would give a 3db increase, 3200w would increase by a further 3db, 6400w would give a further 3db so an increase to 6400w would roughly achieve a 9db increase.

But if you can achieve a 110db output with 800w, it is unlikely that you will ever need to double the output to 220db - would be a bit deafening and painful :)

[DJWayne]

I have to say this thread has made me chuckle.

I don't look at a booking and say "there are 200 people going willl X amounnt of watts be enough?" I think its daft go back a few years to the late 80's when i started as a DJ and most people went out with amps that were 100 or 200w and did venues of every size imaginable. Its not the output numbers on the cabs or the amp that matter its what people hear.

I use a QSC PLX3402 amp which will chuck out 3,400 watt at 2ohm but it has never been anywhere near its peak at either 8ohm or 4 ohm. I only ever use 4 speakers in very large venues and then my amp running at 4 ohm puts out about 2kw into my martin f12 tops and s15 subs and i have yet to find a venue i can't fill with sound and have never needed more volume than i have had actually the amount of volume i have had left has been scary i wouldnt like to turn it up as it would probably wake the dead :). At the end of the day i personally think its about quality not numbers if you buy a quality amp and speakers and then compare them with a cheap amp and speakers at the same power ratings you will see a substantial difference even though if you read the specs they will be the same.

[TonyB]

I have to say this thread has made me chuckle.

I don't look at a booking and say "there are 200 people going willl X amounnt of watts be enough?" I think its daft go back a few years to the late 80's when i started as a DJ and most people went out with amps that were 100 or 200w and did venues of every size imaginable. Its not the output numbers on the cabs or the amp that matter its what people hear.

.

I agree. For a few years I just used a Fender mixer amp with a total output of 300w with a pair of 12" tops. I still have it and volume wise, it seems equal to if not louder than my 800w rig. Maybe something to do with the shrinking watt these days (or the different ways they measure output).

[DJWayne]

Just as a side note does anyone remember those old 100w H+H amps a lot of disco's used? 100w yeah right i have seen 600w amps struggle to keep up with one of the H+H amps and they were virtually indestructable unlike some of todays kit :)

[BeerFunk]

Nope first part is correct, it works on a logarithmic scale so it is 10 times the output to double the volume. Not accounting for the logarithmic element, each doubling of the power increases the volume by 3db. So 1600w would give a 3db increase, 3200w would increase by a further 3db, 6400w would give a further 3db so an increase to 6400w would roughly achieve a 9db increase.If it was on a logarithmic scale, you couldn't directly link the input power to actual volume (as you have, with a factor of 10), as the graph of these two values would be curved, not a straight line.

I'm not sure where you are getting your information, but I am quite sure that if you quadruple your input power, you double the resulting volume.


I have to say this thread has made me chuckle.

I don't look at a booking and say "there are 200 people going willl X amounnt of watts be enough?" I think its daft go back a few years to the late 80's when i started as a DJ and most people went out with amps that were 100 or 200w and did venues of every size imaginable. Its not the output numbers on the cabs or the amp that matter its what people hear.
I agree, quality amps make a big difference, but you still need a rough idea of the power you will need.

[Thames Valley Discos]

I'm not sure where you are getting your information, but I am quite sure that if you quadruple your input power, you double the resulting volume.


.

Don't think so. If you have say a 500W amp and you quadruple the input to the amp, you will still get 500w, you would just have to turn the gains on the amp down otherwise you would clip them.

[BeerFunk]

Don't think so. If you have say a 500W amp and you quadruple the input to the amp, you will still get 500w, you would just have to turn the gains on the amp down otherwise you would clip them.
No, you mis-understand, when I say input power - I mean the power of the amp! The power of the input to the speakers, if you like :)

[Thames Valley Discos]

No, you mis-understand, when I say input power - I mean the power of the amp! The power of the input to the speakers, if you like :)

oh sorry:D

Found this on the net
http://users.chariot.net.au/~gmarts/amppower.htm

[TonyB]

Sorry, end of my last post should of said 120db not 220db.

By quadrupling power you would get a 6db increase in volume which is double the amplitude so mathematically that should equate to double the volume. But the human ear is not governed by mathematics so for a human ear to perceive a doubling of volume, a 10db increase is needed.

So it seems we are both correct, 6db or quadrupling the power with result in double the volume being produced but the human ear does not perceive that the volume has doubled until the level is increased by 10db.

Just need to do some more Googling to find out how someone has measured the "perceived" figure :)

Perhaps this is more relevant to a DJ - http://www.discjockey101.com/apr2004.html

[PropellerHeadCase]

Nice article, thanks.

[Creature]

due to ilness i am currently covering 99% of my bookings with 2 x xt500 cabs and a litle kam 740 amp (540 watt rms per channel) ok so i have had to raise the speakers so they sit just under light bar for large venues or at normal height if on a stage - this is just about manageable for me at the moment and so far have not had any complaints...