L-Pad as Volume Control - HELP!

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Archived from groups: rec.audio.tech (More info?)

Hi all,

I'm hoping someone out there can help settle an issue for me. I am in
the process of building a basic 2-way floor/stage monitor (wedge type,
8"woofer, 3" piezo tweeter with a 6.0 uF cap in series to cut the low
frequencies, woofer running full range)to be used as part of the sound
sytem set-up for a small kids show. I'd like to build in a simple,
effective volume control. My question is will an L-pad of sufficient
wattage do the trick?

Here's my set-up: One old but functional Realistic MPA-80 PA amp rated
at 80 watts @ 4 Ohms. Currently I run a pair of 8 Ohm 2-way PA
speakers in parallel (4 Ohm load). I plan to run the 3-speaker setup
in series-parallel at a 5.33 Ohm load. By my calculations, each
speaker should then be getting about 60 watts of actual power.

On the face of it, I would assume that a 100watt 8 Ohm mono L-pad
would allow me to effectively reduce the output from the floor
monitor. Is this a correct assumption, or will I just burn out the
L-pad? Is there a different switch/pot I should be using instead?

Your input is greatly appreciated.

 

[mark]

Archived from groups: rec.audio.tech (More info?)

In article
<19dc4d66.0406040921.2738649c@posting.google.com>,
clemon@yourprivatechef.ca says...
> I am in
> the process of building a basic 2-way floor/stage monitor I'd like to build in a simple,
> effective volume control. My question is will an L-pad of sufficient
> wattage do the trick?
>
Yes

> Here's my set-up: One old but functional Realistic MPA-80 PA amp rated
> at 80 watts @ 4 Ohms. I plan to run the 3-speaker setup
> in series-parallel at a 5.33 Ohm load. By my calculations, each
> speaker should then be getting about 60 watts of actual power.
>
You're thinking about this backwards, which isn't at all
unusual. Many people do.

Speakers CONSUME power, amps PROVIDE power.

Your speaker is rated to consume X watts. As long as it
doesn't fail and you don't run it beyond its' rated
frequency response, it won't consume more than that.
Therefor as long as you use an L-Pad that's rated for more
than the speaker, you'll never (theoretically) have a
problem.

Your amp, on the other hand, will provide X watts at Y load
(again assuming it hasn't failed and is running within its'
rated specs). So as long as the load doesn't fall below
its' minimum rating, and you don't run the amp into clip, it
will never provide more power then it's rated for.

NOTE: This is an intentionally simple explanation. Those
that know this stuff, don't start bustin' my balls.

--
Mark

The truth as I perceive it to be.
Your perception may be different.

Triple Z is spam control.