Here is my quandary:

As I have previously posted, I am in the process of buying a complete setup for my son's fledgling dj venture. I wanted to start him off with adequate equipment to be able to handle gigs of 30-50 people (mostly home parties) and, this being the Miami/Ft Lauderdale Florida area, many of these venues are outdoors. Therefore, sufficient power is an issue.

So, I bought a pair of Vidsonix speakers rated at 250 rms/500 watt peak, 12" woofers with 58 oz magnets, SPL 95 +/- 2dB - decent speakers I would think. When they arrived, I tested them on my Kenwood VR-507 home A/V receiver, which delivers 100w X 5 and cranked it up to 3/4 power. Indoors, the sound was loud enough that my wife had to leave the house (tested with great remix of Information Society's "Running").

I figured I would get the kid an amp powerful enough to be a keeper, so I bought a Pyramid PA1800X, which delivers 1800 watts (specs read "900W X 2 into 8 ohms, 2 X 250 rms, 1800W X 2 into 4 ohms, bridgeable to 1800W X 1 into 8 ohms").

When I plugged the speakers into this supposedly powerful amp, one per channel or at 8 ohms, I was clipping the amp and the sound wasn't nearly as loud as on my Kenwood A/V. What's up with this???

I suspect that since I have 5 speakers in the Kenwood, when I connected the Vidsonix's (without disconnecting the other speakers) I was running them at 4 ohms. If this is correct, then the answer lies in getting 2 more speakers and running at 4 ohms on the amp (I can run the 2 I have on one channel in mono, but it sounds awful).

If this is the solution,

a) will I run the risk of blowing the speakers since they are rated 250W rms?

b) will my wife kick me out of the house because I've spent nearly $1,000 US on the whim of a 13 year-old kid???

All advice is welcome.

Do you know what the impedance (ohm rating) is for the speakers?

The speakers are rated at 8 ohms.

Hi Jorge,

First of all the amplifier is a good purchase, especially for somebody just starting out. Always try to choose equipment based on the "RMS" rating rather than any other Peak or PMPO figure, since RMS is the industry standard for Disco / P.A equipment and a more accurate measurement . Based on this your sons amp will deliver 2x 250W RMS into an 8 ohm load. A figure which I often recommend to my customers when just starting out, so no problems so far!.

Okay, with regard to your hi-fi amp and the test that you mentioned. Did you have any other speakers connected at the same time as you tested your Speakers?. Most hi-fi (Dolby Surround Sound) type speakers are rated at either 6 or 4 ohms and so the combined load would have dropped well below the 4 ohm figure resulting in far more power flowing from the hi-fi amplifier and hence a louder output.

Technically if your Son's speakers are rated at 8 ohms (Check on their specs) and the amp delivers 250 Watts per channel into an 8 ohm load, then you should get the full 250W x 2 which you would expect. The only time that I would expect this to be lower is if the speakers are rated at 16 ohms?. - although this would be very unusual!.

Just a couple of questions:-

(1) Does the music sound clear when coming from the Speakers even if it's lower in volume

(2) What are the impedance of the speakers in ohms?

(3) What signal are you plugging in to the amp, is it the output from a mixer or direct from a cd player?. If you are using a mixer, then make sure that you plug the amp into the "Amp" or "Master" outputs rather than any "Rec" outputs. (Record outputs tend to be at lower levels on some mixers).

You should also make sure if using banana plugs (4mm plugs) and cable to connect between amp and speakers, that you make sure that the polarity of the speakers matches that of the amp output. example:- "+" output on the amp goes to "+" on the loudspeaker and "-" to "-".

In answer to your questions:-

Thanks, Chris.

The speakers (2 Ways) sound excellent even in low volume. But I just thought of something that might make a difference in the power: I tested them with a CD player as direct input to the amp. In other words, I did not have the mixer (Stanton Pro30) connected to the amp. Since the mixer has a volume control of its own, I suppose it makes a difference. I'll test that and let you know.

In the meantime, I'm thinking of getting a beatkeeper to help the kid out, since the CD decks (also Stantons) don't have this feature. Additionally, some basic starter lights (reasonably priced, but attractive) might be in order. Since I am a firm believer in capitalism and global economic theories, how's about some suggestions from your shop??? I've had goods shipped from the UK before and, if one is not in a hurry, the rates aren't excessive.

Thanks,

Jorge

Hey, any good trailer parks in your neighbourhood