Amp RMS: How much is too much?

Systems

I have a pair of Polk db650s (max 60w rms) up front and db525s (max 45w rms) in the back. I am currently powering them with an Alpine V-Drive headunit. Great unit, but the power just isn't there, in spite of what the V-Drive is supposed to offer. So I'm off to pick an amp.

When I asked Crutchfield how much RMS amp power I should use to drive these speakers, they were a bit vague. On the one hand, they said that pushing them with 60W RMS would be no problem. Then they said, "well, but if you want to follow polk's numbers, select something lower". Then they recommended a Rockford Fosgate P4004, which I've read puts out much more than the advertised 50w RMS (some folks claimed to be getting 70+). Would something like the P4004 cook these speakers, or would I be in the clear? Definitely a sweet looking unit, but I don't want to do anything...stupid! Thanks all.

exalted512

itll be fine
-Cody

Big10Fan

ya well, i just got my polk amps in, the 300.2 thats going to be powering my 125w rms mmc6500's is rated at 170x2 rms from the birth card, now that worries me, lol

MacLeod

Dont sweat it too much. As long as your sensible and set the gains properly, (i.e. before you hear distortion) you will be fine.

Systems

Thanks everyone. I'm going for it!

The P4004 is actually pretty long and is going under my seat, which will probably cause an occasional issue for the person who sits behind me.

Screw 'em!

Systems

Well, this will be interesting. I got my P4004, and the birth sheet shows 98W RMS!!!! Anyone have any tips on setting the gains, given that my fronts are rated for 60W and my rears for 45?

MacLeod

Her ya go.

Properly setting the gains will keep you from blowing your speakers.

Youll want your rear speakers to be set lower than your front speakers anyway to lessen the soundstage being pulled to the rear.

denim

rf, always underratted

Systems

Well, I got it all hooked up. It is definitely loud, that's for sure. No distortion and a fairly conservative gain adjustment.

I kind of hoped it would "pound" more than be just "loud", but I guess there's no substitute for a sub.

neomagus00

Originally posted by cmp
but I guess there's no substitute for a sub.

ya got that right

Systems

Well, of course I can't leave well enough alone. I'm loving this P4004, particularly since I now have the option to run my DBs in parallel and free up the rear channel to run......a sub....I must succomb....

As I'm reading the birth sheet, the P4004 says it makes '593 total watts RMS @2ohms all channels combined'.

A couple questions, if anyone has time:

Does this mean that half goes to the front, half to the rear, leaving 296w split up among the four DBs, and 296w for the sub?

In the case of the DBs, will they equally take on 1/4 of the 296w?

Given the addition of a sub to the amp (let's say a Polk MM2124, sealed enclosure), will my 5-gauge power feed still be adequate? As well, might I need to think about adding a cap?

And on it goes....I was so sure I was going no further than the head unit when this whole thing started....

MacLeod

That would be 2 speakers hooked up to each channel or a 2 ohms stereo load. So at 2 ohms front and back channels make about 300 each or 150x4 at 2 ohms stereo or 75-80x4 at 4 ohms stereo. Your DB's can easily handle the 80.

5 guage? Never heard of that. Sure its not 4 guage and you just hit the wrong key? If so then yes that will be fine.

You dont need a cap.

cmp

No it's 5 gauge, I swear. It's from a Scosche kit that I found at Wal-Mart. I went for "resourceful" on this install. I found $5.00 Monster interconnects on blowout at PepBoys, then picked up the amp kit for about $25.00. Hey, it's wire.

Thanks for the input. Did I not read somewhere on these boards that you were a proponent of a 10" sub vice a 12" for SUV applications (SUV...I have a Forester...I'd loosely call that an SUV, but anyhow)? You still maintaining that position?

MacLeod

Yup, but strictly from a SQ standpoint. If youre wanting sheer volume then the bigger the better.

But for a SUV or hatchback or something that puts the sub in the cabin with you, I think a 10 is a better match for SQ. A 12 may be too much. Im running an 8 now in my truck and its almost enough but Im going to upgrade to a 10.

1996blackmax

Originally posted by cmp
Well, of course I can't leave well enough alone. I'm loving this P4004, particularly since I now have the option to run my DBs in parallel and free up the rear channel to run......a sub....I must succomb....

:eek: :eek: :eek: :eek: :eek:
You will ruin your front stage with this. MacLeod had it right.



Your sound stage up front will cease to exist if you do this. If you really want a sub with this amp, leave the front speakers hooked up to the amp the sub bridged to the rear, and have the rear speakers connected to your head unit. This will sound better as you will still maintain your soundstage up front. You can play witht he gains or fader to get it just right after that.

cmp

Hmm. Well, I must admit I have always liked my stage a little behind me and not blasting square into my ears. That's just me.

More to come! As soon as I get to the bottom of this MM2104 vs. Infinity Perfect 10.1 internal debate, I'll be back with an update.

MacLeod

Originally posted by cmp
Hmm. Well, I must admit I have always liked my stage a little behind me and not blasting square into my ears. That's just me.

More to come! As soon as I get to the bottom of this MM2104 vs. Infinity Perfect 10.1 internal debate, I'll be back with an update.

The soundstage should be in front of you. When you go to a concert, the band is in front of you and ideally your system is supposed to be able to duplicate a live performance.

All the images in front of you about eye level with good depth and proper seperation of instruments and sounds.

1996blackmax

Originally posted by MacLeod
The soundstage should be in front of you. When you go to a concert, the band is in front of you and ideally your system is supposed to be able to duplicate a live performance.

All the images in front of you about eye level with good depth and proper seperation of instruments and sounds.

Exactly.

Hmm. Well, I must admit I have always liked my stage a little behind me and not blasting square into my ears. That's just me.

That would be like going to a concert with your back towards the performers .

TrappedUnder Ice

Denim...I dissagree....RF was not always under-rated in power. there was a 4yr period that thier amps (punch series) just flat out sucked. I have a 401s that is just aweful. and the ones right before that were not much better. Careful with what ya say

swerve

buy the polk sub... i'm tired of everyone buying infinity right now... all my friends are buying infinity perfect this and perfect that... so in conclusion... buy the polk.

denim

Originally posted by TrappedUnder Ice
Denim...I dissagree....RF was not always under-rated in power. there was a 4yr period that thier amps (punch series) just flat out sucked. I have a 401s that is just aweful. and the ones right before that were not much better. Careful with what ya say

I am careful, I have owned a large number of RF amplifers, all came with birthsheets, and all were underratted,

many friends and aquaintences have competed with RF, and all of their amplifers have been under ratted, I have not used every line from RF, but almost all, I still own a 250a2 and a 125a2, both are nearing 10 years old and both are 100+ watts under ratted, both seeing duty in family cars, if I had the extra loot I would order new RF amps in a heart beat, I know that RF has not always been perfect and I know that they have made some decisions that had made people upset or alienated some customers, but in my experience, all the RF amps I have played with, and that is a lot more than the average, have all been under ratted

exalted512

all of my RF amps are overrated. One is rated at 500 and puts out 846 watts at 14.4 V. Its a 2000 model. Ive especially never heard their old amps underrated...i think youre crazy
-Cody

denim

Originally posted by exalted512
all of my RF amps are overrated. One is rated at 500 and puts out 846 watts at 14.4 V. Its a 2000 model. Ive especially never heard their old amps underrated...i think youre crazy
-Cody

if your amp is putting out more power than ratted, it is underratted

I have installed more than my fair share of RF amps, and I always saw the birthsheet when the amplifer was taken out of the box,

RF, Orion, and Kicker are a few of the long standing companies that have a history of underratted amplifers

MacLeod

Originally posted by denim
I am careful, I have owned a large number of RF amplifers, all came with birthsheets, and all were underratted,

many friends and aquaintences have competed with RF, and all of their amplifers have been under ratted, I have not used every line from RF, but almost all, I still own a 250a2 and a 125a2, both are nearing 10 years old and both are 100+ watts under ratted, both seeing duty in family cars, if I had the extra loot I would order new RF amps in a heart beat, I know that RF has not always been perfect and I know that they have made some decisions that had made people upset or alienated some customers, but in my experience, all the RF amps I have played with, and that is a lot more than the average, have all been under ratted

Normally Im not the typo police, thats Austin's job. But for Gods sake man, its underraTed!

TrappedUnder Ice

I was talkiing about the last series of RF amps..and the ones right before that. Your 10yr old RF amps dont really fall into those...do they. Thats why I said what I said! Not all RF amps are what they appear to be. I have 3 generations of RF amps...and the 401s is of the worst...your a2 series are probably fine punch products....but those were not the ones I was talking about.

exalted512

Originally posted by denim
if your amp is putting out more power than ratted, it is underratted

I have installed more than my fair share of RF amps, and I always saw the birthsheet when the amplifer was taken out of the box,

RF, Orion, and Kicker are a few of the long standing companies that have a history of underratted amplifers

yea dont listen to me, im an idiot
-Cody

TrappedUnder Ice

Man....Am I holding my tounge!!!! hehe

exalted512

you know, with all this talk about how much is too much rms...i think i need some more caps, but dont get the lightening audio ones, theyre filled with sand to make them heavier, go with RF because theyre heavy because of all the liquid metal that retains energy to give to the amps for more bass.
i put a rf cap on my system and got a 3.6dB increase
-Cody

MacLeod

Originally posted by exalted512
you know, with all this talk about how much is too much rms...i think i need some more caps, but dont get the lightening audio ones, theyre filled with sand to make them heavier, go with RF because theyre heavy because of all the liquid metal that retains energy to give to the amps for more bass.
i put a rf cap on my system and got a 3.6dB increase
-Cody

LOLOLOL!!!!!

Thomas is probably turning blue right about now!

TrappedUnder Ice

Blue...yup.....hit my head on the table on my way too the floor from laughing so hard! Life in the Cap lane.....hehe

exalted512

Originally posted by TrappedUnder Ice
Life in the Cap lane.....

everything, all the time....life in the cap lane ummmhhmmmmmmmmm
-Cody