Power Amp Vs Speaker

M

mugsy

New member
This forum has been very helpful to me over the past few years, most recently "bigfoot" has helped me out. The people involved with this forum are far more knowledgable than the average "music store guy". Here's what I've read. The power amp wattage should be "twice the speaker's continuous IEC power rating. I recently bought a Mackie 808m (300w per side at 8 ohms) and I asked the salesman which speaker cabs should I get. He told me to get the Yamaha S115IV's. I've used this setup for a month, and the speakers, to me, seem way under powered. So I ask the following. Whats the wattage needed to properly drive the following speakers? (in the past I've always used more wattage than the rated watts, i.e. 250W speaker: 400W amp)

Yamaha S115IV:(8 ohm)
PGM:250W
MAX:1000W

JBL418S:(4 ohm)
power capacity:600W
peak power capacity:2400W

JBLMP215:(8 ohm)
power capacity:250W
peak capacity:1000W
 
Hey Mugsy, this probably won't help much, but here is a quote from a guy who's been in the business for years.I was asking a similar question, and this is what he said:

"Okay, first, NO MATTER WHAT they tell you in 'The WIZ' you can NEVER 'overpower' a passive monitor!!I'd use the highest wattage amp I could afford, and just use an inline fuse for protection. MORE speakers are fried by sending them a distorted, clipped square wave, than by hitting them with too much power!! Now, the way a particular amp/speaker combination works, or sounds, depends more on the characteristics of each of the components, than on the power, assuming that there is ENOUGH power to drive the speaker, comfortably... This is also assuming that CORRECT impedance matching, between the speakers and the amp, is employed!! "

Hope this at least sends you in the right direction.

Have a nice one.
 
Thanks for the advise deep......but the problem is the Mackie 808m. With only 300W per side @ 8 ohms, I can't find any quality speakers to run with this head!!! I'm getting an additional power amp (with enough power this time) and a couple more speakers to get more sound, but I hate to waste the 600W thats built-in to the 808m. Any suggestions on speakers that will sound good and loud with 300W will be greatly appreciated. Hell, I even settle for some 10in speakers w/horn or 12in speakers w/horn.
 
How is 600watts not enough power for studio monitors? I run 2 yamaha ns10m with a 100w amp and I have plenty of headroom.

If your talking about PA speakers then get some good JBL's or EV's and they will suck up any power you can throw at them.
 
mugsy,

First of all, what quality are you looking to get out of your speakers? Looks like you're mostly interested in loudness, correct?

Speaker power ratings alone are not very informative. In fact, most often they are meaningless. Max power for what? Max power they can take long term? 1 hour? And with how much distortion?

What you probably are more interested in is the efficiency:

Yamaha S115IV = 99dB/W/m
JBLMP215 = 99dB/W/m

This spec tells you how many decibels you get for a given wattage. 99dB/W/m is pretty standard for PA speakers. Every 6dB/W/m doubles the loudness. So a 105dB/W/m speaker for example, would be twice as loud as the S115IV or MP215 for the same power input. Just remember that higher efficiency speakers often have lower sound QUALITY.

barefoot
 
Thanks for the input guys I really need it. Tex this is a PA setup, and its not a total of 600W as they advertise, but 480W. Barefoot, you're right, at this time I'm looking for more volume. The LED's on the 808m are peaking and the sound barely fills a 24' x 24' portion of my basement. I know I'm an "old deaf musician", but come on. Back in the 70's I could fill a room of 400+ people with 4 of these Yamaha's and 1000W. I think I understand the speaker sensitivity as you explaned it, (I'm a newbie when it comes to certain specs) but if I were to drive each S115IV with 500W would I gain more volume? One fellow on another bbs suggested I try some Yorkville 4ohm speakers rated at 350W 100db/W/m. Here's the spec's on the S115IV & MACKIE 808m. Again thanks!

EIA: 250W
PGM: 500W
MAX: 1000W

Mackie 808m
Rated power:240 watts per channel into 8ohms
340 ....................................4ohms
 
Ahh, PA, makes more sense.

You could get another mackie and use them bridged mono for each speaker.

QSC has always had decent amps at a good price.
 
mugsy said:
Back in the 70's I could fill a room of 400+ people with 4 of these Yamaha's and 1000W.
Click to expand...
Using multiple full range speakers is almost always a bad idea unless they're specifically designed to be arrayed. The all of the speakers you've mentioned are not. You'll get more volume, but you're also likely to get nasty comb filtering effects.

Go with a 4 Ohm speaker to get the most power out of your amp/mixer. 99dB versus 100dB makes very little difference, so buy the best sounding speakers you can afford in that efficiency range.

A next step would be adding a crossover, amp, and subs. This will probably double the volume you can achieve.

barefoot
 
I beat this dead horse long enough! Here's what I plan on doing. First, I'm giving the 808m to my wife for her karaoke setup. She can use this with a couple of old cab's of mine.
I have $2500-$3000 to spend on a new setup. I'd like to use the (2) S115IV's if possible, and I already have a monitor setup. I'd like to do it right this time, that means I need some help. So, I have $3000 for sub's, amps and a mixer. I'm looking for a system that can fill a medium sized (300-400 people) club. We do weddings and private parties, and play everything from Beatles to Creed. Thanks for all your help!
 
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