Quality Amp

What would be a quality amp to power 4 sets of Polk mm651um speakers? They are 100 watts rms and I'm looking at a $400 Max. Thanks for the suggestions.

What about a PPI P900.4

225x4 at 2 ohms and 14.4V
150x4 at 2 ohms and 12v

Less than half your budget as well.

Polarbill love the suggestion and the fact that its a class d amp. Do you have this amp?

No, I just remember people mentioning it some a while back as being a very well priced amp. From what I remember it shares the same chasis as a couple other brands that might be more expensive. Crap, for under $200 it is worth the risk almost.

I have the PPI amp. It's been great so far. I run pair rev10's off of one and 8 exile 6.5's off the other.

PPI P900.4 ($190 shipped): http://www.sonicelectronix.com/item_...PI-P900.4.html

I have the Polk version of it, the D4000.4 ($250).

Both will be more amp than you need for those speakers. If you don't need fading capibility (if you are running towers off 2 channels and the in-boats off 2 channels), I would suggest running this at 2 ohm and saving even more money:

PPI P600.2 ($140 shipped): http://www.ebay.com/itm/NEW-PPI-Phan...-/190576553382

Still more amp than those speakers need for only $140. The Polk D2000.2 is the equivalent amp @ $160.

NVX also makes a version of these amps as well (at least the 4-channel); the JAD800.4 ($240): http://www.sonicelectronix.com/item_...-JAD800.4.html

If you need something to run your sub as well, you could go with the 5-channel version from NVX or Polk, the D5000.5 ($290) or JAD900.5 ($280). I have the 5000.5 running my in-boats (MM651...the 2.7ohm version of your speakers) and sub plus a D4000.4 running my four Exile surf speakers.

I just bought the polk pa d2000.2 running 2 pairs of wetsound xs650's and it does a damn good job. Its at running 2 ohms and it is getting warmer to the touch than i would have expected for a class d amp but nothing close to shutting down or hot yet. The real test will be in some 100 degree nor cal heat though. Sound wise its great for the money. The crossover is where you notice the difference. You end up setting it a little higher than you actually need to because its not as good as a higher quality amp. Its got plenty of power and does a great job keeping up with my rev 10's. I had the arc 300.2 amp hooked up to the same speakers for a day and didn't like it, it seemed to lack clarity compared to the polk and the jl hd600.4 i had prior. The total fuse ratings are the same on both, but the polk uses two of equal size vs ppi uses a larger and a smaller. I don't know if you could change them or not...

Thanks for all the suggestions. My question is which one of these amps will have the best sound quality? The Pd 4000.4 sounds interesting. Is worth the extra hundred bucks over the other brands that have been mentioned? It being $250 shipped is already a deal to me. Would the system be enhanced by keeping it all Polk or does that not matter?

Originally Posted by 22vdrive

Thanks for all the suggestions. My question is which one of these amps will have the best sound quality? The Pd 4000.4 sounds interesting. Is worth the extra hundred bucks over the other brands that have been mentioned? It being $250 shipped is already a deal to me. Would the system be enhanced by keeping it all Polk or does that not matter?

The Polk, PPI, and NVX are all the same basic amps. They should all sound and perform equally. The Polk is marine rated if that matters to you. I think the Polk and NVX look better than the PPI.

I'd still suggest going with one of the 2 channel amps for much less money unless you really need fader control for the in-boats. A lot less money than the 4 channel amps for similar performance.

Also, what is the rest of your boat's setup? Do you have a sub, and if so, what is powering it? Tower speakers? Running a head unit, head unit + EQ, or EQ only?

Nitrous, are you suggesting he run 4 pairs of polks off one 2 channel amp? Wouldn't that run it at 1 ohn or if there is a way to wire it only give each speaker 75 watts?

This is a guess, but I was assuming E was running 2 pairs of polks on the interior and another 2 pairs on the tower.

Right now the boat has 3 sets of skylon in boat speakers and a 10" Orion sub running off a 5 channel clarion amp. In my opinion the set up blows. I use to have all Kickers gear in my last boat and the sound was great. I hear the Polk's are built well and sound great so I'd like to give them a go. My sub will be the next thing to go. My goal is to have a clear and balanced sound in the boat. Like Johnny Cash I'll be getting it all one piece at a time.

So are you going install 4 interior pairs of speakers in the boat?

Ahh, you are running 4 pairs of speakers. I read it as 4 speakers total.

Scratch that 2-channel idea - it won't work.

But instead, since you have a sub, you might want to consider the Polk D5000.5. It won't give you the power of the 4-channel Polk/PPI/NVX but you will likely be happy with it. 100x4 @ 2ohm and 400x1 @ 2ohm for the sub. Just something else to consider @ $290. I just installed a D5000.5 in mine (haven't fired it up yet), but with the MM651's being 2.7ohm speakers, I should be seeing right around 90x4 to the in-boats.

Guess it depends on how loud you want the interiors.

do you have the mm651um's yet? Take a look on the magnet on the back.... mine were 3 ohm. In which case you're going to really be stressing a 4 channel amp by running all four channels in parallel at 1.5 ohms. I guess the nice thing about the ppi amps is they are cheap enough you can get two and stay within your stated budget of $400 and give each speaker its own channel.

Shawndoggy I haven't ordered them yet so I wouldn't be able to tell you what it says. Do all Polk 651 um's run at 3 ohms? So it would be less complicated to get two four channel amps to run this setup as opposed to one?

I had the Polks in my boat as well. While I called Polk and asked for their rating they assured me all of the UM were 4 ohms. However mine were stamped with 3 as well. I didn't understand it. I called 3 different times and asked 3 different tech guys. The one thing I didn't do was run an Ohm meter over them. That would have been the easiest.

Never got an explanation though why that was. I ran 2 pair off the front to channels of my Syn 4 and a Polk sub bridged off the rear. Never had any issues. Til the gear was stolen.


Heard great things about the ppi and Polk Onyx amps. Really good bang for your buck.

Originally Posted by xstarrider

I had the Polks in my boat as well. While I called Polk and asked for their rating they assured me all of the UM were 4 ohms. However mine were stamped with 3 as well. I didn't understand it. I called 3 different times and asked 3 different tech guys. The one thing I didn't do was run an Ohm meter over them. That would have been the easiest.

Never got an explanation though why that was. I ran 2 pair off the front to channels of my Syn 4 and a Polk sub bridged off the rear. Never had any issues. Til the gear was stolen.


Heard great things about the ppi and Polk Onyx amps. Really good bang for your buck.

How did you like the Polk's? What do you have now?

I have them, four pair, running off of a jl xd 600/6. They sound really nice. A touch bright on the trailer, but about perfect out on the water. Not quite as "rich" as the JL MX 650s which are a really smooth speaker, but purty darn good. I would not hesitate to run kickers again though either. The km6250s look nice and are pretty reasonably priced.

Shawndoggy which do you prefer the Polk's or Kickers?

I really like their(the Polk UM's) sound. They were a pretty well rounded sounding speaker in my opinion. Not too sharp on the highs, but they lacked a little bit on the low end compared to my original Polk Momo's(its a good thing in my eyes). I thought the UM's were a very good/ if not one of the best marine rated speakers at that price point. I liked them a bit more than my Momo's because they offered a more mid range and highs which helped ton in the open air for my liking of the speaker. I have a dedicated 12inch sub so appreciated the "higher" sounds of the UM's.

I cant give a comparison to the WS XS-650's just yet. I just ordered those to replace the UM's because they were gangstared out of my ride. I was really torn between the WS and the JL MX650's. WS won strictly because of my local dealer support.

In regards to the Kicker vs Polk for me each of those brands in the boats I have heard..........the Kickers always seem to have a sharper "higher" sounding tone. Obviously it depends on the model, but in general for me from what I have heard in stock mfg's boats with each brand, the kickers are always a bit bright for me.

Thanks for all the advice I'm set on the ppi 900.4. I have a new question. What is the difference between a 4ohm and a 2 ohm subwoofer with a dual voice coil? Which one would be a better buy? I'm looking at a 10" re audio sex10d. Thanks again for the help.

Dual 4 ohm can be wired to 2 ohm or 8 ohm

Dual 2 ohm can be wired to 1 ohm or 4 ohm

If your amp is a 1 ohm stable amp buy the dual 2. If its only stable down to 2 ohm buy the dual 4 ohm. This is if your only running 1 subwoofer..

Brad I want to run one woofer I have yet to choose an amp for it because I wanted to make sure I get the correct one for the woofer. Which would be easier to work with 2 ohm or 4 ohm?

Would I be better off with a monoblock amp with a variable bass controller or would it be fine with a two channel? I'm leaning towards another ppi phantom amp for the woofer. Is it better to run at 4, 2, or 1 ohm?

I would just run the PPI 1000.1 and run it at 1 ohm. So you would wanna get the dual 2 ohm RE audio sex subwoofer.

Originally Posted by BradM07SS

I would just run the PPI 1000.1 and run it at 1 ohm. So you would wanna get the dual 2 ohm RE audio sex subwoofer.

Wouldn't that be to much power? That's 1000 watts rms and the speaker is rated for 600 watts rms.

I have a PPI600.2 running a pair of MB8's & the PPI900.4 bridged runing my Pro 80's. My tower is loud as hell! I am waiting on the PPI900.5 which is supposed to be out end of month for my interior.

It will handle it fine. I had the same woofer on a kicker zx1000 for a couple years. Just be sure not to send a clipping signal to the woofer. Set gains with a DMM or o-scope.