Impeadences

[outlawmusique]

Hi

Im trying to work out the best way to go here and would appreciate some experienced opinions.

I run a PA system for my gig work.

One Power amplifier running in Stereo Mode each channel feeds an 18inch bass bin 8R 400W RMS with an internal Xover, then the high pass of the Xover feeds a full range cab 8R 350W RMS.

The amplifiers output specs are per channel
4R 650W RMS
8R 450W RMS

My first question is, does the amplifier see 4 or 8 ohms in this setup, ie does the Xover effectively seperate the two cabs in impeadence terms, or are they still seen as 2x 8R cabs in parallel with a drive impeadence of 4R ??

Next is that I lack headroom, to drive this setup for an outside gig the amplifier starts clipping just as I get to the power level I need, SO.... Ive bought another amp and an active Xover filter, and Im thinking of Biamping the setup, the new amp is larger so will deliver the following per channel

4R 1200W RMS
8R 750W RMS

I was thinking of keeping the existing amp on the bass bins and the new amp on the full ranges, and at a later stage adding another 8R 350W RMS full range cab to each side (which would reduce the imp to 4 R on each side and up power to 700W RMS.)

Will this give me the headroom and increase in operational power I require ? Is there aything else I should be thinking of.

Thanks

 

[rexter]

Just think of the amplifier as if a water tank; if a larger pipe can produce an X amount of water with thinner sidewall and the pipe do not burst. A pipe in half its size will need then have higher pressure to produce the same amount of what the larger pipe would produce. You’ll then need to increase the sidewall thickness of the pipe so it will not burst. Now that you have transfor X amount of energy, your container (speakers) must be capable of holding that amount safely.

So lowering the impedance will get you higher wattage but you'll have higher risk of damaging your system if something goes wrong.

My first question is, does the amplifier see 4 or 8 ohms in this setup

If your amp specs said 4 ~ 8 ohms then it's capable up to 4 ohms so you can put 4 or 8 ohms speakers and just follow the specs guide.

Next is that I lack headroom, to drive this setup for an outside gig the amplifier starts clipping just as I get to the power level I need

Rules of thumb, if your amp can produce 100W @ 8 Ohms, your speaker must be at least 150W to 200W @ 8 Ohms. Always follow speakers specs when making your own speaker box and adding crossover. Creating one yourself is not as easy as going with numbers and putting it together, making the sound quality the way you want is going to be trial and error.