Help me choose an amplifier

[DGajre777]

I just bought 2 x Polk Momo MM2124 400 watts RMS subs and I have a receiver with 6 volt preamp output and low pass crossover.

I've been look at these 3 damn amplifiers for months and I can't decide which one to get. All of them are Class D Mono amplifiers, have an internal cooling fan and digital volt display I'll be getting it in about 2 weeks when I get my paycheck.

1) Alpine MRD-M605
600 RMS x 1 @ 2ohms - 2006 CEA compliant
60amp fuse
Up to 8 volt input
$ 250 shipped on ebay

2) Kenwood Excelon KAC-X812D
919 RMS x 1 @ 2ohms - 2006 CEA compliant
60 amp fuse
Up to 5 volt input
$212 shipped on ebay

3) Alpine MRD-M1005
1000 RMS x 1 @ 2ohms - 2006 CEA compliant
80 amp fuse
Up to 8 volt input
$430 shipped on ebay (this one is kinda out of my budget)

I can't find any reviews on the Kenwood amp but it seems like it is the best deal.

I like the M605 Alpine more, it puts out 600 RMS compared to 900 RMS but I can set it up to 6 volts from my receiver for a better signal.

Anyone have any input?

Note to moderators: I put this in the newbie forum because the interior forum is down.

Pic below - Alpine MRD-M605

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Pic below - Kenwood Excelon KAC-X812D

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Pic below - Alpine MRD-M1005

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[Addicted2DSM]

since your subs are 400watts RMS each you need a amp thats 800 watts RMS. What OHMS are the subs?

 

[jking29]

Out of the 3 choices I would go with the Alpine m605 if the 1005 is out of your price range. I would avoid the Kenwood, as I and also a couple of friends have had problems with the newer Kenwood amps. They are nothing like the older Kenwoods and also overated. The 605 should be fine though, as the Momos are fairly efficient. You also might check out some of the DEI class-d amps. They offer a lot of bang for the buck and can take a lot of abuse.

 

[Addicted2DSM]

Jking, the only problem with that choice is what ohms is the subs? have to make sure the ohm output are correct for the sub ohms

 

[jking29]

The Momos he listed are 4 ohm. Wired in parallel the amp will see a 2 ohm load which is what they are rated at.

 

[Addicted2DSM]

Ok another question, if the subs are 400rms why would he only want to send 300 watts each? Wouldnt that be under powering them?

 

[DGajre777]

The subs are rated for 75-400 Watts RMS. Below 75 RMS will be under powering them.

I prefer Alpine over Kenwood, but I'm not sure if 600 Watts RMS is enough power. My Alpine Type S front components and 6x9s are powered by the receiver and get 22 Watts RMS each, I don't get any distortion and the sound is very clear. But then again I think that 1000 RMS watts of bass might be too much for 22 x 4 RMS watts of mids and highs.

 

[larsenracing]

I would go with the Alpine M605 which would do the job great. My personal opinion I would go with an Memphis audio amps like this one http://memphiscaraudio.com/products/details.asp?id=25
Good luck though its been a while sence ive bought any audio stuff i still run my memphis d1000 watt amp that i bought more than 8 years ago with there cast basket 10" sub's (2).

 

[Addicted2DSM]

if you want to put a little more power into your front and rear speakers look into a 4 channel amp, they are not big amps but depending on the wattage needs of your speakers you can get them to sound to their full potential.

 

[DGajre777]

if you want to put a little more power into your front and rear speakers look into a 4 channel amp, they are not big amps but depending on the wattage needs of your speakers you can get them to sound to their full potential.

The speakers in my car have a high db rating which is probably why the sound so good and clear with very little power. I have no plans of running a 4 channel amp. The Pioneer Premier DEH-P860MP is a very good receiver.

 

[Addicted2DSM]

Hey man are you going with the Alpine amp?

 

[DGajre777]

Hey man are you going with the Alpine amp?

Yeah, the M605.

 

[drivemusicnow]

First of all, you cannot compare the power consumption of the subs to the front speakers and say "I'm concerned that 1000 watts to the subs will over power 22 watts to the speakers" It doesn't work like that. That would be somewhat equivelant to saying "oh well my t25 puts out 20psi, which would obviously be faster than your GT42 at 10 psi. "

the comparison is a fallacy and thus means nothing.

Also, Why do you want a digital voltmeter? why is this important to you?

the "up to XX volt input" means absolutely nothing. The gain on the amp controls the "percieved voltage" of the input. You set the gain (or at least you SHOULD) by taking it up to the point of distortion at 80% volume on a sin wave, and then backing it off a touch. this will ensure that your amp is well within its power range.

the "High dB rating" is a signal to noise ratio. higher is better, but it is not a rating of "clarity" at high volumes.
The type S's are a good "budget" speaker, and the pioneer head unit is a good unit all around. (other than pioneers focus on looks rather than audio features...) any QUALITY amp at about the 600-800 watts rating will serve your purpose. I would personally find something other than the alpine, however the 250$ ebay offering seems like a decent price. The only problem is I'm going to guess they're not an authorized dealer, and therefore you may not have a warranty. (even if it says they are, talk to alpine before you spend the money)

Make sure you DO NOT use the "polk/momo" enclosures. They suck. If you don't believe me, use them, then build a proper MDF box and listen to them. You will immediately notice a difference and be like "wow those polk/momo enclosures suck!".

Good luck with your audio decision.

 

[DGajre777]

Drivemusicnow - Thank you for the detailed post.

First of all, you cannot compare the power consumption of the subs to the front speakers and say "I'm concerned that 1000 watts to the subs will over power 22 watts to the speakers" It doesn't work like that. That would be somewhat equivelant to saying "oh well my t25 puts out 20psi, which would obviously be faster than your GT42 at 10 psi. "

the comparison is a fallacy and thus means nothing..

That's true. I didn't think about that even though I've seen all kinds of charts about low frequencies needing more amplification that mids and highs.

Also, Why do you want a digital voltmeter? why is this important to you?

I don't really care if it is there, I'm getting a volt gauge in a pod anyways. The cooling fan is something I want. My last amp kept overheating and shutting off when it was in the hatch of a 92 Eclipse.

the "up to XX volt input" means absolutely nothing. The gain on the amp controls the "percieved voltage" of the input. You set the gain (or at least you SHOULD) by taking it up to the point of distortion at 80% volume on a sin wave, and then backing it off a touch. this will ensure that your amp is well within its power range.

The Alpine V12 amps don't have a gain knob. The gain is set by selecting input voltage between 1volt and 8 volts. I know that a 6volt signal is better and clearer than a 2 volt signal and the amp has to work less with a clearer signal. The Kenwood goes up to 5volts and since my preamp output is 6volts, that 1 more volt of signal I can get if I go with the Alpine. Fell free to correct me if I'm wrong.

the "High dB rating" is a signal to noise ratio. higher is better, but it is not a rating of "clarity" at high volumes.
The type S's are a good "budget" speaker, and the pioneer head unit is a good unit all around. (other than pioneers focus on looks rather than audio features...)

Yes I know, DB is a measurement of one watt at one meter. And a 105db speaker is more efficient at making sound that a 98db speaker. And since my speakers are efficient they sound more clear, hence I mentioned clarity.

any QUALITY amp at about the 600-800 watts rating will serve your purpose. I would personally find something other than the alpine, however the 250$ ebay offering seems like a decent price. The only problem is I'm going to guess they're not an authorized dealer, and therefore you may not have a warranty. (even if it says they are, talk to alpine before you spend the money).

No they are not under factory warranty. Some vendors on ebay offer their own 1 year warranty or a 3 year replacement plan for a small fee. If I want warrany I can get them from Crutchfield for $399 but for that price I can get the M1005 from ebay.

Make sure you DO NOT use the "polk/momo" enclosures. They suck. If you don't believe me, use them, then build a proper MDF box and listen to them. You will immediately notice a difference and be like "wow those polk/momo enclosures suck!". .

I have a Dual 12" Q-Logic 1.0cu ft sealed box.

Good luck with your audio decision.

Thank you!

 

[drivemusicnow]

You are correct in saying that the Alpine does not have a gain "knob".

However it operates the same way. It is a "digital" adjustment from .1V to 8V. (i'm assuming it goes in increments of .1V) You adjust it in a simlar fashion to how I stated.

For instance, my amps are a 0-4V gain, my Alpine Headunit outputs 4V signals. I do NOT have my gain at 4V. (by the way .1V setting on the amp is the loudest... Do you understand why?) Currently My gain is set at approx 1.1 volts as to the testing method I stated above.


Lower frequencies inherently require more power to create. HOWEVER, there is a LARGE difference between efficiencies of speakers. There are subwoofers that have an RMS rating of 3000 watts that, on a dB meter, are no louder than a different sub with 900 watts.


True, Clarity at high volumes and efficiency TEND to correlate. But it is just that, a correlation, not a causation.

Yay for the Q-logic boxes... Your ears will appreciate them.

As for the warranty, thats one of those risks you need to decide. There used to be stores like "thezeb.com" and others that were authorized retailers and had amazing prices. There are still some out there, and you'd probably be able to find that amp for less than 300 with a warranty. Just thought I might bring it up. (can't think of any off hand, however I have a bunch bookmarked at home. PM me if you'd like me to send you the links)

 

[DGajre777]

You are correct in saying that the Alpine does not have a gain "knob".

However it operates the same way. It is a "digital" adjustment from .1V to 8V. (i'm assuming it goes in increments of .1V) You adjust it in a simlar fashion to how I stated.

For instance, my amps are a 0-4V gain, my Alpine Headunit outputs 4V signals. I do NOT have my gain at 4V. (by the way .1V setting on the amp is the loudest... Do you understand why?) Currently My gain is set at approx 1.1 volts as to the testing method I stated above.

How does this work? If an amp has a higher output input voltage it would get a clearer signal and put out a output sound with less distortion. If your gain is set to 1.1v, does the amp convert the 4v signal to a 1.1v signal and then process it? Or does it keep the 4v signal, thinks it is a 1v signal and amplifies the 4v signal x 4?

PM sent.

 

[NitroTalon]

alpine all the way... depending on how you are going to run them i say the Alpine MRD-M1005 would be the way to go... that way you can always just up the subs and not have to worry about the amp. again just make sure you have the proper guage wires depending on the amp you get

 

[DGajre777]

alpine all the way... depending on how you are going to run them i say the Alpine MRD-M1005 would be the way to go... that way you can always just up the subs and not have to worry about the amp. again just make sure you have the proper guage wires depending on the amp you get

The Polk Momos that I bought are 4 ohm SVC so they will be hooked up in a 2 ohm load. I have streetwires 4 gauge power and ground wires to be installed.

 

[2DaTrakNow]

since your subs are 400watts RMS each you need a amp thats 800 watts RMS. What OHMS are the subs?

NOOOOOOOOOOOOOOOOOOO.....thats all wrong.

First off, if you have 2 subs that are 400 watss RMS each, you do not NEED an amp that is 800 watts. There are so many confusing and hard to understand about systems, and alot of people completely ignore them, forget them, or just dont think about it. I dont even know where to start, but i will try to get a lot across.

First off, for beginners...Do not think that you can go into a store, and buy a 1000 watt amp for $140. The brand of the equipment you are buying, and the price that you pay says alot. For example, I have a friend who has 2 amps. He has a 1000 watt pyle, and a 250 watt MTX. His 250 watt MTX pushes my 2 15's, and yes they get loud, but obviously not as loud as their potential. His Pyle amp, when bridged WILL NOT even push one of my 15's. His amp will start to move the sub, then once you start to turn it up the amp shuts off because it cant handle it. The labels on "off-brand" stuff is not always correct. I dont care who you are, you will not buy a true 1000 watt amp for $140. I wouldnt be suprised if he hooked up his Pyle to a tester, and the results came back saying his amp could only send out 50 watts Max, and some of the subs that say "800 watts RMS" and "1600 watts max", like alot of what Audiobahn sells, could never ever ever ever take a true 800 watts for even a second. With systems, the labels are so incorrect it isnt even funny. You get what you pay for my friend.

Secondly, there are so many variables when buying/hooking up a system. As he stated above about if you have 400 watts rms to 2 subs, then you need an 800 watt rms amp to push them. That is so false that i cant even beleive somebody could think that, and no offense to Addicted2DSM. You have to look at what brand you have, what they reccomend, the ohms on your subs, the ohms on your amp, the channels on your amp, if your going to bridge it, just on and on and on. When the subs say "400 watts rms" that means you could feed 400 watts to them all day long and they wouldnt blow up. Does that mean you have to always feed 400 watts to them? of course not.....not even close. You could feed 200 watts to each sub, and as long as you didnt turn it up extremely loud you would be fine. Then for the 800 watt RMS amp....well....if you want an 800 watt RMS amp, you will pay $800 for it, and there are no ands, ifs, or buts about it. JL and Memphis are one of the few companies that have amps that will give you the power that they say that have. JL's price for amps is a 1:1 ratio. You pay $100 you get 100 true watts. You pay $500, you get 500 true watts. I used to have 2 15" clarion 600 watt RMS subs. I had a 720 watt max power accoustic amp pushing them. Now, according to Addicted2DSM, my amp could not not and would not power those subs. I pushed those subs so hard, my mirror couldnt stay facing up. Everything i turned up my system, and looked into my mirror, i would be looking almost straight down at the floor. Your telling me i need two of those amps to push my subs??? no way in hell. Even my friends tiny little 250 watt MTX amp was pushing my 15's, and pushing them pretty hard. I dont need 1200 watts to push 2 600 watt subs. He had 21% of the amp power that he needed and they sound great.

For one more example, i had a friend who had a 1000 JL amp. His dad bought it for him, and payed $1000 for it. He was pushing 8 subs with it. He had 4 12's, and 4 10's. For only being 1000 watts, that sure pushed 88 inches worth of subwoofers just fine. You really cant judge a system by how many watts it is, or what it is rated at or anything like that, and with a system you can never say "if you have this, you have to have this". You will always get what you pay for, and dont ever be mislead by the labels that say 3000 watts only $90.

 

[drivemusicnow]

NOOOOOOOOOOOOOOOOOOO.....thats all wrong.

First off, if you have 2 subs that are 400 watss RMS each, you do not NEED an amp that is 800 watts. There are so many confusing and hard to understand about systems, and alot of people completely ignore them, forget them, or just dont think about it. I dont even know where to start, but i will try to get a lot across.

yadda yadda yadda....
For one more example, i had a friend who had a 1000 JL amp. His dad bought it for him, and payed $1000 for it. He was pushing 8 subs with it. He had 4 12's, and 4 10's. For only being 1000 watts, that sure pushed 88 inches worth of subwoofers just fine. You really cant judge a system by how many watts it is, or what it is rated at or anything like that, and with a system you can never say "if you have this, you have to have this". You will always get what you pay for, and dont ever be mislead by the labels that say 3000 watts only $90.

I have to leave work soon so this is going to bo short.

First, the old 1$ 1watt thing IS NOT TRUE. It used to be very true and a good rule to follow, however with modern electronics this isn't true. I personally payed 400$ for my 1500watt amp. Guess what, tested it puts out 1610 watts at 1 ohm. Clean power as well.

He also stated that the subs are 4 ohm. he has 2 of them. You wire them in parallel and you will have 2 ohms resistance.

The amp is rated at 2 ohms resistance. Therefor the subs he mentioned CAN handle 800 watts from the amp he mentioned.

I know what you were saying about misinformation and such in amplifiers (and subwoofer) manufacturers. In this case it was misplaced. And no, you never "need" an amp rated at the maximum powerhandling of the subs, however why wouldn't you get one?


and for myth number 334 about car audio. You cannot damage speakers by underpowering them. You can damage them by having them play with distortion, which can happen if you're using a smaller amp with the gain cranked all the way.



Dgajre.. you're about right on the Gain thing. I'll type more in the PM to you, but I gotta run.

 

[DGajre777]

First, the old 1$ 1watt thing IS NOT TRUE. It used to be very true and a good rule to follow, however with modern electronics this isn't true. I personally payed 400$ for my 1500watt amp. Guess what, tested it puts out 1610 watts at 1 ohm. Clean power as well.

Agreed. The old $1 per watt is not completely true. There are amps that are now 1 ohm stable that you can get for a cheaper price than amps that put out the same wattage in 2 ohms. And yes underpowering subs doesn't kill it, distortion from low powered amps kill it. If you keep the gain down on a small amp where there is no distortion, you can play it all day long.

2DaTrakNow There are $400 amps out there that put out 400 RMS at 4 ohms, 800 RMS at 2 ohms and 1000 RMS at 1ohm. If you are talking about 4ohms, then yeah the $1 per watt, maybe be partially true.

If you noticed all my power ratings were in RMS and were 2006 CEA compliant. CEA is an independent company that tests amplifiers to a certain standard. If the amp meets the testing criteria they are CEA compliant and this testing is optional. No one forces Alpine, MTX and all other name brand companies to get the amps tested. It just means that they won't lie about their RMS rating. Ever wonder why Audiobahn and Pyramid amps and not CEA compliant?

Another issue is how the power rating is given. An amp rated at 600 Watts RMS at 14.4v is not the same at 600 Watts RMS at 12v, the 12v rated amp will have a higher output at 13.6v. An amp rated at 600 Watts RMS from 20-200hz is not the same as an amp rated at 600 Watts RMS at 100Hz, the 20-200Hz will have a higher output.

Most cheap amps never have their RMS rating in the owner's manual, the cover will have "1000 Watts", well that might be 250W RMS or 500W RMS, depending on who makes it and how they rate their amps. The best way to tell is the fuse rating. If you have a 1000 Watt amp with a 30 or 40 amp fuse on it, it is not 1000 Watts RMS.

 

[2DaTrakNow]

Agreed. The old $1 per watt is not completely true. There are amps that are now 1 ohm stable that you can get for a cheaper price than amps that put out the same wattage in 2 ohms. And yes underpowering subs doesn't kill it, distortion from low powered amps kill it. If you keep the gain down on a small amp where there is no distortion, you can play it all day long.

2DaTrakNow There are $400 amps out there that put out 400 RMS at 4 ohms, 800 RMS at 2 ohms and 1000 RMS at 1ohm. If you are talking about 4ohms, then yeah the $1 per watt, maybe be partially true.

If you noticed all my power ratings were in RMS and were 2006 CEA compliant. CEA is an independent company that tests amplifiers to a certain standard. If the amp meets the testing criteria they are CEA compliant and this testing is optional. No one forces Alpine, MTX and all other name brand companies to get the amps tested. It just means that they won't lie about their RMS rating. Ever wonder why Audiobahn and Pyramid amps and not CEA compliant?

Another issue is how the power rating is given. An amp rated at 600 Watts RMS at 14.4v is not the same at 600 Watts RMS at 12v, the 12v rated amp will have a higher output at 13.6v. An amp rated at 600 Watts RMS from 20-200hz is not the same as an amp rated at 600 Watts RMS at 100Hz, the 20-200Hz will have a higher output.

Most cheap amps never have their RMS rating in the owner's manual, the cover will have "1000 Watts", well that might be 250W RMS or 500W RMS, depending on who makes it and how they rate their amps. The best way to tell is the fuse rating. If you have a 1000 Watt amp with a 30 or 40 amp fuse on it, it is not 1000 Watts RMS.

i realize what you are saying, but my main point was that just because you have two subs that say 400 watts RMS, doesnt mean that you need an 800 watt rms amplifier.

 

[DGajre777]

i realize what you are saying, but my main point was that just because you have two subs that say 400 watts RMS, doesnt mean that you need an 800 watt rms amplifier.

Agreed. Many people think that just because a sub is rated at a RMS level, you need an amp to push that much power.

 

[kenamond]

Heh...I have a 13-year old Alpine v12 in a closet somewhere. They look cooler now. I also still have the HDP box with 2 10" Kickers collecting dust in my workshop corner, too. I think that my '86 Grand Am POS trunk was the perfect volume, because that thing was a helluva lot louder than the Phoenix Gold ZX500 powering the 2 10" XMax's in my 2g system now (damn, it's 9 years old now!).

Good luck...and don't fux up your hearing. It won't come back.

 

[DGajre777]

I hope I don't, It need my hearing for my FAA medical every 6 months.