Powering A PA speaker?

J

Jeepster4wd

NAXJA Forum User

Location

socal

• Nov 23, 2003

• #1

Hey, i have cb and orginallyad a small 30 watt speaker.(have heard the cb only puts out abotu 15 watss or so to the PA) i now have a 200watt police PA speaker. and im trying to figure out how to give it the full amount of power. I was thinking of a 200watt audio amp? but all of the amps i have seen require rca inputs? radio shack sells these rca plugs that can connect to wires would it be possible to connect the wire exiting out of the PA output out of the cb into a RCA plug and then plug it into the amp?? any ideas??????

 

S

satan

NAXJA Forum User

Location

Lakewood, CO USA

• Nov 24, 2003

• #2

The audio output from your CB (to it's PA) would most likely be in the 4-6 watt range -- you could use a line-level converter to attenuate that to the ~<= 1V p-p needed for line level input to some audio amp - or just locate an audio amp that accepts speaker level input.



something like this one Run it bridged with the High pass filter set to about 250Hz to keep from feedin' that speaker stuff it can't handle anyway... (assuming that this is a driver/horn type of set-up with an impeadance ~ 8 ohms or so...)

 

J

Jeepster4wd

NAXJA Forum User

Location

socal

• Nov 24, 2003

• #3

well this is the speaker i have

http://www.whelen.com/hires/sa314p.jpg

what does ~<= 1V p-p mean???

 

5-90

NAXJA Forum User

Location

Hammerspace

• Nov 24, 2003

• #4

It means approximately less than or equal to 1 volt peak-to-peak. He's referring to peak signal amplitude, rather than RMS (root-mean-square) which is more commonly used in audio - but peak is a more useful value.

You may want to check with Gall's for their PA amplifiers - www.galls.com. I've dealt with them for years with no trouble (as long as you don't order blue lights...) and they should have what you are looking for - or a reasonable analogue. Their support is quite good, so drop them a line if you get stuck. They carry Whelen products, and their prices are usually better than Whelen direct.

5-90

 

S

satan

NAXJA Forum User

Location

Lakewood, CO USA

• Nov 24, 2003

• #5

Well if you're talking about the Whelen sa314 series - that's a 100W unit (good for 123dB at 10' though - damned loud!)

So you could find a simple 'el-chepo' amp that could be bridged to to 100W with speaker-level inputs (like this one for $80) so you could run right off of the output of your CB's PA...

 

J

Jeepster4wd

NAXJA Forum User

Location

socal

• Nov 25, 2003

• #6

iv actual got A 200 watt amp I got from walmart i was thinking of using. U think i Could use this? Set it to treble so it wont play any low frequecneys.

 

S

satan

NAXJA Forum User

Location

Lakewood, CO USA

• Nov 25, 2003

• #7

Hey - give it a try (can't see/hear it from my garage!)

Should be OK - if the amp has speaker level inputs ...
... all really depends on what amp - if the 200W is a peak value, a per-channel value and the rest of the specs etc....

 

J

Jeepster4wd

NAXJA Forum User

Location

socal

• Nov 25, 2003

• #8

it has those rca inputs. radio shack sells rca male ends which can connect to the PA out wire. then into the amp input. you think this will work???


rca plug
CB-------->]AMP}------ |PA|

 

S

satan

NAXJA Forum User

Location

Lakewood, CO USA

• Nov 25, 2003

• #9

If it's their attenuating connector (RS 274-378) then it should do it for ya (it'll take the speaker-level drive from your CB's PA outout and lower it to a line-level drive for the amp... (kinda Rube Goldberg, but it'll do)

 

J

Jeepster4wd

NAXJA Forum User

Location

socal

• Nov 25, 2003

• #10

ok thanks satan il let you know how it works.