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Discussion Starter #1
My system consists of the following:
2005 Nissan Altima SE-R:
Source: Kenwood Excelon DNX9960
Line Driver: Tru Tech SSLD6i
Front: Dynaudio System 360
Front Amp: Pioneer GM-X1022
Rear doors: Blaupunkt 8" Triaxial in rear doors
Rear Deck: 10" Pioneer TS-W253F Diamond plates (2)
Rear/Sub amp: Massive NX5 powering rear doors and subs.

So I got one of the NX4's because I thought it would be perfect for my wifes car in terms of power output and size. I was right about the size. I also have had an NX5 for quite some time.

First and foremost the NX5 - The sub section isn't bad, I've got it running at 2 ohms on a pair of 10's IB. Obviously they don't need that much power to get going, so that is the caveat to that. The 4 channel section of that amp is overrated IMO. in bridged mode it should be putting out 240 rms, but my 100x2 rms amp up front (Pioneer GM-X1022) blows it away in output. I expected more, much more. I was at some point considering going with just that one amp, but quickly decided against that after having run it a while. Also the output from the rear door triaxials is pretty muddy. I would not run one of these amps on a front stage where clarity is the focus. This amp will stay in my car for 3 reasons, size, sub power is adequate for my needs, no cash to replace it, though I may stick a pdx 4.150 and pdx1.1000 in place of it to see how it turns out.

Wifes Car - 2009 Toyota Corolla:
Source: Pioneer AVIC-Z110bt
Front: Eclipse SC8365 3-way comps with midrange and tweet in A pillars
Front Amp: (Was NX4) Now PDX-5
Rear Deck: DLS OA8's pair in rear deck
Rear/Sub amp: (Was NX4) Now PDX-5


Next the NX4. This amp, IMO is extremely overrated as well, and here's why. The amp should be able to do 100x2 rms and 400x1 rms bridged when run in 3 channel mode. Great! Well the output on the components in my wifes car up front was, to say the least, very unnatural sounding. Overwhelming shrill output, and the amp seemed to put out quite a bit less power than I anticipated. (I'll give more reasons for my thinking this in a few lines down). I did not put the amps on the bench and I have no o'scope, so this is simply my ear telling me what I heard.

On the sub side, the amp REALLY disappointed me. The OA8's were the second set I owned, I had a pair in my Altima way back and they sounded very good. With the NX4 the subs were extremely dirty sounding with poor output. I had put the subs in and decided that if they didn't sound good I would replace them with something else (that's when I bought the eD 8's in the hot deals section). I just didn't like how dirty they sounded and how weak the output was for being rated at 400x1 rms, it sure didn't sound like it. Another thing I noticed with the NX4 was quite a high noise floor and alt whine.

So the next step was to either put in the eD's - which I waited on doing, and also put in a PDX-5 I had waiting in the wings that I just bought a couple weeks ago. I decided to start by putting in the PDX-5. Immediately the subs output was cleaner, clearer, and much much more intense. The front stage was a totally different animal off the PDX-5, it sounded much cleaner and clearer as well. The amp was initially installed with just channels 1 and 2 on the fronts, then I bridged it and was even more impressed. The PDX-5 does around 214x2 bridged (107x2 rms on birthsheet) and 458 rms on the sub. On both, the PDX-5 rips the NX4 apart. I was thoroughly impressed with the non bridged output, and again once I bridged the amp it was even better. The last thing I noted - alternator whine GONE and noise floor substantially lower, but still audible.


Here's my review summed up - Overrated, over-hyped, poor sound quality amps.

Disclaimer - these are my thoughts and experience with these products, yours may vary. I do not claim to be any kind of expert, I just rely on my past experience and product usage to arrive at these conclusions. This review is not intended to skew anyone away from buying this amp or not buying this amp. Solely my opinion and nothing more.
 

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Thanks for posting this review. I've been going back & forth on picking up that NX-5 for my girl's car, but I'm glad I waited it out.
 

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I haven't had the same experience as you have but here are a few things I can add.

First off the 2ohm or bridged rating on massive amps are pretty much peak power. From the PDF file of the bench test on the nx4 I posted(that came from massive audio), we can see that it won't make 400 bridged but instead 250. There should be a noticeable difference in output vis a vis the pdx5 sub channel, although not as dramatic as what your describe.

Also I am not sure if the massives are rated all channels driven or only one. If it's not "all" this would also lower output when used in your configuration. Soundmagus(build house for the nano's) rates their "nano" amps at 75 per channel. I don't know if there are tweaks between the models or if they are measured differently to account for the extra power from the massive branded ones, tuff to tell.

Presumably there should be an audible difference in power output between the nanos and PDX’s that would be apparent because of the differences in power output since there could be around a 3db difference.

You def have strong opinions on their "SQ" to which I have not experienced, and disagree with as I find they sound as they should :)
 

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Discussion Starter #5
I haven't had the same experience as you have but here are a few things I can add.

First off the 2ohm or bridged rating on massive amps are pretty much peak power. From the PDF file of the bench test on the nx4 I posted(that came from massive audio), we can see that it won't make 400 bridged but instead 250. There should be a noticeable difference in output vis a vis the pdx5 sub channel, although not as dramatic as what your describe. Of course the PDX’s sub output also has a bass boost (I think) and if used should def make a difference in perceived bass output VS the bridged nano.
Moot point, I don't use the bass boost, and in fact I don't think the PDX-5 has it, only the mono's do.

Also I am not sure if the massives are rated all channels driven or only one. If it's not "all" this would also lower output when used in your configuration. Soundmagus(build house for the nano's) rates their "nano" amps at 75 per channel. I don't know if there are tweaks between the models or if they are measured differently to account for the extra power from the massive branded ones, tuff to tell.
True, but that doesn't explain the difference between 240 rms and 214 rms, if all else is equal. Also the gains on the pdx-5 are very low, whereas on the massive they were about 1/2 way. Either way the performance of both my nx5 and nx4 are far less than what I am getting out of the PDX-5. Also the unbridged ratings are essentially the same 75x4 and 75x4, if you go by what the spec sheet says then it should be 100x4 vs 107x4, negligible difference.


Presumably there should be an audible difference in power output between the nanos and PDX’s that would be apparent because of the differences in power output since there could be around a 3db difference.
True.

You def have strong opinions on their "SQ" to which I have not experienced, and disagree with as I find they sound as they should :)
I certainly do, mostly because everything I've listened to out of them has been extremely muddy and pretty distorted sounding. The sub channel on the NX5 is definitely pretty strong though, just not sure how it would compare to a PDX-5 sub since I haven't had both in my vehicle.

Thanks for your comments.

What do you have your nano's powering?
 

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Most of my post doesn't make sense looking back as the pdx5 is 75watts per channel I kept thinking 150... so there sould be no difference when looking at power output accept for the scenario bridged nano vs sub output of the PDX.

I wanted to add, and you have been around for a long time and should know this :p , that gain location has nothing to do with output relative to other models.

I was running Ck components and some IB subs in the rear shelf. I didn't get much sub time.

I changed car and don't currently have a system installed.
 

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Discussion Starter #7
I know, but the voltage out does, the voltage out was about equal, I don't recall exactly where it was now, but the voltage on the dmm was the same/close.
 

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hehe you reply before I finish editing. I should re-read before posting.

on a diff subject
I do find it strange that the nx4 is rated at 100\ch and the nx5 and nx2 at 120\ch.
 

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A Russian car audio web site also tested the NX4 amplifier. These are some of the results:

Maximum (RMS) Output (14.4V, 1% THD): 65,8 watts 4ohm/107watts 2ohm
Input sensitivity: 0,17 — 4,0V
SNR: 93,6dB
Left-Right/Front-Rear stereo separation: 69/75dB
Frequency response (+0/-1dB): 15 — 27300

The whole article is here:

×åòûð¸õêàíàëüíûé óñèëèòåëü Massive Audio NX4 - avtozvuk.com

Their review is positive, but obviously amp's power rating is massively oversold it seems. Right now massive web site lists:

RMS Power 100 x 4
PEAK Power 800 x 2
[email protected] 200 x 4
Bridged RMS 400 x 2
 

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A Russian car audio web site also tested the NX4 amplifier. These are some of the results:

Maximum (RMS) Output (14.4V, 1% THD): 65,8 watts 4ohm/107watts 2ohm
Input sensitivity: 0,17 — 4,0V
SNR: 93,6dB
Left-Right/Front-Rear stereo separation: 69/75dB
Frequency response (+0/-1dB): 15 — 27300

The whole article is here:

×åòûð¸õêàíàëüíûé óñèëèòåëü Massive Audio NX4 - avtozvuk.com

Their review is positive, but obviously amp's power rating is massively oversold it seems. Right now massive web site lists:

RMS Power 100 x 4
PEAK Power 800 x 2
[email protected] 200 x 4
Bridged RMS 400 x 2
Not too surprised based on people's listening impressions!
 

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wow. glad I held out to try one of these Phantoms.

Something just kept me from buying these massives. I liked the looks but a/b in such a small package seemed a risk.
 

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the reason for massives ratings is they use a speaker apparently to rate their amps, end results is better ratings.

The interesting part is this is allowed by CEA2006...

In any case, one has to wonder who else does t his with their CEA rated amps.
 

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So how do the class D amps ratings come in? Are they closer to the published specs? Im running a N3 mono amp on a single 12 @ 2ohm (rated at 700 watts @ 2 ohm) and am quite happy with the results after moving from a Memphis 250 watt mono amp. Seemed stronger and more defined all the way around. Your mileage may vary, I am happy with the mileage I am getting though.
 

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Discussion Starter #18
Class D might be better, just not entirely sure. I hear that they are even potentially a little underrated, the 5th channel of the nx5 certainly was pretty strong, but the caveat to that is that I ran it only at 2 ohms and on IB subs.
 

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Bring back from the dead!!!! Nismo, Did you ever try the amp not bridged? It looks like both amps that you used (nx4 and nx5) you only used bridged. Massive's spec sheet shows that the the distortion is very high and that bridged they don't put out their ratings but ran stereo they have their rated power at a respectable thd. If not that could help explain why everything was muddy. Maybe you did try it unbridged,idk, I've just been curious to this review for awhile because it seems these amps were loved and after this review every1 got gun shy. I have 1 myself but I have not used it yet. I too was planning to run mine 3ch and add a nx2 for tweeters but after seeing the 2ohm thd and reading this review I'm thinking.... Is that the problem with these amps? It seems like most have loved them at 4ohms.
 

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To reinerate what I was trying to say.... Not all amps, well actually most amps don't double their power when bridged or lowered impedance but do increase distortion but.... unfortunately alot of companies claim the double in power on their marketing. It looks like with these amps their distortion goes up allot more than the power does when bridged. Now, correct me if I'm wrong but I think that the cea rating is for 4ohm only....

So is it possible that these amps are what everyone loved and what they claimed when run stereo 4ohm? Seems like they were top notch to most even when being compared to amps triple their price. I agree that if bridging them is what caused this terrible review then it is bad marketing on their part but I think it is safe to say that allot of companys do that especially companies on the lower end of the price scale. Either way I don't agree with that marketing and it hurts them more than it helps but no matter how you look at it 120x4 and 800x1 is a monster!
 
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