Math quiz and speaker logic 1

[LkEErie]

I am trying to be inexpensive and buy a powered mixer for a small PA system. The mixer is rated at 150 Watts over 4 ohms and math tells me that 150x4 is 600 which is close enough to 25 volts for me

Did I miss anything? I only need to tap 5 speakers at 1/2 or 1 watt and I'm way too cheap to buy an LT-70v to do the step-up.

LkEErie

 

[jeffmoss26]

I'm not sure how that would work, if your amp does not have a 25V line out. The powered mixers I have used have like 6 mic/line channels and the amp built in...but it's an 8 ohm amp. I've tried wiring two transformers back to back to 'trick' the amp but it does not always work.


jeff moss

 

[donb01]

How much are you spending? I think the bogen classic series amps are only a few hundred bucks and have several inputs on them and some basic tone controls.

 

[LkEErie]

$119 including freight

 

[TouchToneTommy]

If I remember ohm's law correctly,

E=I*R, and P=E*I

So, P=E²*R, or I²/R

 

[TouchToneTommy]

And, press Preview, not Submit!!

Anyway, 150 Watts divided by 4 ohms, gives 37.50 volts², and the square root of 37.50 is 6.12 volts.

 

[TouchToneTommy]

And apparently, I don't remember ohm's law well enough!!

It is actually E²/R or I²*R

So, E²=150*4 = 600, and the square root of 600 is indeed 24.49! I'd say you're good to go!

 

[Sympology]

Am I cracking up or is this a Telephony forum????????

Only the truly stupid believe they know everything.
Stu.. 2004

 

[LkEErie]

No, it's a Telephoney Forum. The motel wants me to add ceiling speakers in the conference room. I get to unload 2 Quam's without volume control and 4 Bogen's with. Where I work, you do Voice, Data, and Video, so paging systems are just an extension of voice and PA systems for small rooms are part of that.

A call to Pyle Audio tech support confirmed that I was on the right track. I also found a reference on the Yorkville web site (touting their LT-70v's). Exchange rate and shipping doomed the use of the product as I never found an American source and price.

I needed a constant voltage system, because I need to turn off the speakers in the 2nd and 3rd conference rooms if the dividers are in place. I assume they will have to tune the acoustics for a small or large area. I'll probably take a blank stainless steel faceplate and mount two switches on it to control the speakers.

Piece of cake.

LkEErie

 

[hawks]

Here is a pretty good site for future reference

http://www.the12volt.com/ohm/ohmslaw.asp

 

[LkEErie]

Wow. Beats the pie chart I had in electronics school. Just look up and go Thanks a bunch!

LkEErie