View Full Version : Help choosing an amp

05-06-2011, 07:15 PM
Hey guys

I have a 700w peak 175w rms sub that I need an amp for. I can get a 2 x 60w rms amp bridgeable to 175rms and 350w peak or I could get a mono amp which is 200rms and 600 peak. I dont really understand why there is a difference in the gap between rms and peak for both amps so can't work out if the 175 amp will power it properly or if the 200 will be too much power.

05-06-2011, 11:13 PM
Both those amps would be fine to run that sub as long as they are setup correctly. I would choose the mono block because they are a cl*** D amp and like to put out low frequencies. The mono block would run more efficiently also.

06-06-2011, 02:18 PM
Thanks Timmy

It occurred to me that the 600 peak is probably at 2 ohms and is probably 400 peak at 4 ohms. I didn't go for the mono block in the end but decided on a broader solution which involved upgrading the amps for all speakers. I'll do up a thread on the install when it's all done.

07-06-2011, 03:49 PM
Sorry it is to late Simon.
Buy the biggest, cleanest amp you can afford, you can never have too much power.
I have run 50wrms speakers from 3000wrms amps before, many times with no problems. You can always turn the gain down on an amp, this will give you a very clean(No Distortion) output so you will never burn the speaker out, you can overdrive it though, but that can be done a lot easier with a small amp producing distorted output.
Amps are something you should buy once and do it right and then you will never have to buy another.
The more power you have, gives you more control of the speaker voice coil and cone, so more accurate sound output and less chance of damage.
Hope this helps!!!

07-06-2011, 03:58 PM
P.s. The difference in the outputs can be explained by the way they are tested.
At 400w it may have had a distortion of 5% and at 600w it may have had a distortion of 10%.
When looking at spec's make sure you are comparing apples with apples, The test should also be A weighted wich means it was tested with a full bandwidth 20hz to 20000hz, not just a 1000hz sign wave which is one way amp manufacturers cheat.

07-06-2011, 04:12 PM
Thanks for the info Gunsrunner.

I've bought some CEA rated amps with rms ratings spot on what the speaker manufacturers recommend so while they won't be overpowered, they should run nicely. I agree with the overpowering though, particularly with the sub. This all started because my Sub amp died after 10 years of abuse. it was a 2x400watt peak amp so maybe 300watt rms bridged. It ran my 175w rms sub beautifully but had to have the gain dialled back a bit. I've replaced it with a 180w rms amp so slightly more than recommended. I'm currently running it on a borrowed 120w rms amp and it's a touch under powered so I think the 180rms should be perfect.