I have 2 amps and few old speakers. I want set a PA system with FOH, monitor speakers and a sub speakers:
Here is what I have:
Amps:
- Yamaha P7000S (8 Ohm: 750W x 2 Or 4 Ohm: 1100W x2)
- QSC PLX3402 (8 Ohm: 700W x 2 Or 4 Ohm: 1100W x 2 Or 2 Ohm: 1700W x 2)
Speakers:
Front House: 2 Yamaha 15" BR15 speakers: 400watt AND 2 Yamaha 12" BR12" 300 Watt
Monitor speakers: 2 EV monitor speakers FM 1502ER: 300 Watts each
Sub Woofer: JBL Subcompact 18" 300W
Here is my connections:
Yamaha Amp: I connect each channel with 1 Yamaha BR15 + 1 Yamaha BR12 (total 700W 4 Ohms)
QSC PLX3402: 1 channel for monitor speaker (2 EV FM1502: total 600W 4 Ohms) and other channel for the JBL Sub (300W)
I scare with will burn my speakers because the amps is strong. Can I connect 4 FOH speakers in 1 channel? What is the best way.
Thanks a lot for all of your responses.
Hello,
With any combination of the speakers you have the amps will have more power,
All of your speakers appear to be 8Ohm apart from the sub (which I cannot find).
You can only connect the speakers in parallel to get more power as the amps do not drive 16Ohm, and as such when you lower the impedance the amps drive harder...
What I would say is that The amps are only delivering 1100W, or 700W when the volume knob is at 10. If you turn it down, they deliver less power.
So just don't get carried away and turn it up to loud and your speakers will be fine.
When you have it set up how you want, Play what you think is the loudest song you will play (also the one with the most bass as the bass requires higher power) and turn it up slowly until the sound becomes distorted, then turn it down a couple of notches and drawn a mark on the control so you know where to stop.
If you connected the 4 FOH speakers into one channel, you would lose the ability for stereo? I don't know if that would be a problem.
If you did that you could either get a total of:
2Ohm 1400W
8Ohm 1400W
The general rule of thumb is to have speakers capable of handling twice the power of your amp to avoid problems so the 8Ohm combination would work.
But you would still have issues with the other channels and not turning them up too far, so it may be worth leaving it how you planned and finding the max volume you can use.
Hope this helps.
Dean
Hi Dean,
Last Sunday I setup in a club, it was fine but the master volume knob I could not raise up much. It was around 5 or 6.
If I raised it up, I got strong feedback and vibrating sound.
For your reply, I still don't understand when you said "The amps are only delivering 1100W, or 700W when the volume knob is at 10.". I thought when you turn volume up the amps will deliver more
Secondly, "The general rule of thumb is to have speakers capable of handling twice the power of your amp to avoid problems so the 8Ohm combination would work" . I thought the amps watt is twice the power of the speakers. Example: for a channel with 2 parallel speakers 300W (8 Ohm) (Total = 600W 4 Ohm) should connect to an amp with capacity of 1100W (4 Ohm) each channel.
Thanks for your caring posting
Hi,
With your first point, from what you have asked it sounds like we are trying to say the same thing,
If a 100Watt amp is at full volume it delivers 100Watt, but if it is at half volume it will only deliver 50Watt.
The second point the reason speakers need to handle more power than the amp can provide is to stop them burning out.
If a speaker is rated to 100W you should only give it 100W and no more. Also the value stated on most high quality amps is an RMS value and the peak power can exceed this when here are large surges, which could damage the speakers if they are not rated to withstand it.
Hope this clears it up?
Dean
