amp questions

(ladythump) · (ladythump) **Join Date: Jul 2004** 01-31-2005, 2:55 PM

My speakers are rated at 220 watt peak. What is the biggest size amp I should get? Should I get a 4channel to run 4 speakers in the boat? or a 2 channel to run 4 speakers in the boat?

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 01-31-2005, 3:04 PM

2 channel is cheaper but will be running @ 2ohm (I'm assuming the speakers are 4ohm) 4ch is going to be pretty expensive for that kind of power per channel. If I were you and all your running is 4 speakers buy a 2 channel and run it in 2ohm. (make sure the amp is 2ohm stable) Overheating might be an issue during the summer. if your really cranking on them.

(jansen) · (jansen) **Join Date: Sep 2004** 01-31-2005, 3:42 PM

What is the RMS rating on the speakers?

(ladythump) · (ladythump) **Join Date: Jul 2004** 01-31-2005, 6:31 PM

50 watt rating
220 watt peak

(jansen) · (jansen) **Join Date: Sep 2004** 01-31-2005, 8:43 PM

Generally, you would match as close as possible the RMS rating of the speakers to the RMS rating on the amp.

Yes, you should get a 4 channel amp with a RMS rating between 50 and 75 watts per channel at 4 ohms.

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 02-01-2005, 6:09 AM

Sorry , I mis read, I thought it was 220 RMS. But you'll still be able to get into a decent 2-ch. for cheaper.

(ladythump) · (ladythump) **Join Date: Jul 2004** 02-01-2005, 8:03 AM

So, something like this should do the trick??

Number of Channels: 2
RMS Power (4 ohms): 50 watts x 2 chan.
RMS Power (2 ohms): 75 watts x 4 chan.
RMS Power (1 ohm): Not Stable
Bridged RMS Power: 150 watts x 1 chan.
Peak Power Output: Approx. 300 watts
Min. Impedance Unbridged: 2 ohms
Min. Impedance Bridged: 4 ohms
THD @ Rated RMS Power: 0.1%
Speaker Level Inputs: No
Amp Preamp Outputs: No

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 02-01-2005, 10:39 AM

your stats don't look right

"RMS Power (2 ohms): 75 watts x 4 chan."

its proba}bly just going to be 75 watts x 2 @ 2ohms. Remember you'll have to divide the wattage by 2 .

4 speakers will each see 37.5 continous watts, and that is @ 100%. I'm guessing your boat is not @ 14.4 volts? more like 13.5??? and the amp is rated @ 14.4 so you'll be seeing less clsoer to 25-30 RMS.

If it were me I'd get something a little bigger. something closer to 100-120 x2 RMS @ 2ohms

(ladythump) · (ladythump) **Join Date: Jul 2004** 02-01-2005, 11:18 AM

I'm just so confused. I was told to get a receiver with 5 volt preamps. I got a receiver with 4 volt preamps. Now I'm reading I should get an amp with the 4 volt output also otherwise the extra volts are not used. I can't seem to find that spec on the amps.

(acurtis_ttu) · (acurtis_ttu) **Join Date: May 2004** 02-01-2005, 12:43 PM

Amp w/ a 4 volt output??? An amp is not putting anything out through the RCA's unless its conected to another amp. You'll be fine w/ the 4 volt preamps out of the radio. The gain on the amp helps regualte the preamp voltage.

If your getting really confused, find a local stereo shop...most car audio nuts will talk you ear off.

(Message edited by acurtis_ttu on February 01, 2005)

(ladythump) · (ladythump) **Join Date: Jul 2004** 02-01-2005, 12:54 PM

I think it means I have to make sure the amp can handle the 4 volts. Do all amps handle 4 volts.
Adam, thanks, you've helped a lot.

(jklein) · (jklein) **Join Date: May 2001** 02-01-2005, 1:07 PM

When your boat is running you should be closer to 14.4, but just 12 with the motor off.

the pre-out voltage will not hurt the amp. The 4 volt will be just fine.

If you have RCA pre-outs for the front vs the rear speakers, then you should get a 4 channel amp that can do 50 to 75W RMS output at 4Ohms per channel.

If you have just 1 RCA pre-out, then you can't fade anyway, (you will have just left and right control) so get just a two channel amp with 75w RMS per channel at 2Ohms per channel.