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nyryan2001

NVX 800.4 Amp Review

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nyryan2001

OK, in the never ending quest to get a clean 400w+ to ea REV10, i bought a NVX 800.4 for $225 shipped, to replace my Fosgate T600-4 I had powering them. I bought the Sonic Electronix 3yr service plan on it for an extra $25, i knew I'd be putting it thru its paces. I wanted more power to the Rev10s, but also wanted to do it more efficiently in the Class D, and also run cooler. Temps here are 110+ every summer, so you are at a disadvantage running ABs, eventually they will cut out on you when you push them hard.

Initial impressions: its a small amp which is great. I can easily fit 2 of them where my single T600-4 used to be. Makes me wanna get another set of Rev10s just because the amp would fit so nicely in there. :biggrin:

Performance: It IS better than the T600-4. I am happy, its good quality power. Sounds clean and it is an imporvement over what I had. Dont use the high pass filter, run it full range(i also installed the Exile ZLD ( :biggrin::):biggrin::rockon: :rockon: :biggrin: ), the ZLD may also be influincing my tower zone music quality some). If I had to guess, its around 320w at 12.5v ish and right at 410w at 14.4v. With 3 25A fuses 12vx75 divided by 80% efficient = is where I am getting these guesses on power ratings from. It does come with 4ga power inputs with a 1/0 ga adapter... I ran a real thick 4ga, more comparable to 2-3ga to power it. My 4ga would not fit into their 4ga inputs so I used the 1/0 adapter. Sturdy gear, does not feel cheaply made. Terminals are strong, well made. No hiss, or anything like that. I have my gains set at about between 4 of 10.

sidenote: f'n get your wiring diagram correct NVX! Bridged x 2 is the OUTER 2 speaker terminals for front and rear, not the inner 2. lost me 20 mins and 2 pounds of sweat in a full planking contorsionist position pulling the amp back off and rewiring it again and putting it back in there. if their directions were right I wouldnt have had to do that.

sidenote: the NVX DOES get hot. supposedly with the Class D, they are supposed to run much cooler, not the case here. It gets warm and stays warm just powering it up and light music. I ran it hard for about 5 mins (100degs outside), and was warm/hot to the touch. Not so hot you couldnt hold your hand on it, but it did suprise me it was hot. Never went into protect mode or anything. My 2500w Re Class D sub amp wired at 1 ohm stays ambient temps pretty much unless you was doing hairtricks with it, and was hoping for that. I ran it for about 2hrs at medium party cove volume, it did well. impied in this is if you install, use some spacers to get it off the carpeted amp board some so it can breath.

So all in all, I'd say its a great buy for $225. Could you find a better amp to deliver a little more power 400-500w range? Yes, but most of those are in the $500+ range. they pair nicely with the Rev10s and would suffice for 90%+ of folks at a huge discount compared to the other 400x2 class D's. It def got warm, but never cut out and I run my gear hard. I will repost if I ever get it to cut out this summer.

Edited by nyryan2001

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mk_deuce

Good to know. Looks like that discount is over on the NVX stuff. I have found the Polk counterpart to this amp for around $250 online. I read a review on the Polk that said it didnt really push the lows to the speakers very well. I would assume thats why you turned it to full range?

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Murphy8166

What made you decide to run the Rev 10's in full range versus high pass?

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nyryan2001

Murphy- its sounded so much better and fuller and they Revs could hadle it. Previously I had always ran them HPF set at around 50-80hz, no need here... and I prefaced that with that the ZLD may have had something to do with it, i donno. I am not tracking the ZLD has a crossover on the tower channels....not sure why, but they were not overly vibrating like subs on full pass.

On my T600 I used the HPF. Even up to max volume, they sounded good.

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Murphy8166

Ryan - it is a huge "no no" to run those speakers on full pass....they are not subs.

Yes, they sound good but you are severely limiting the life of those speakers.

Take my advice for what it's worth.

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nyryan2001

I'll crank them up for you this weekend, and you can tell me what you think. I think the ZLD has something to do with it.... as in being able to run them on full pass. It's almost as if the ZLD has an internal HPF set at the perfect point. . Whatever it is, it sounds good to me. I am looking forward to seeing all the different setups.

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cowwboy

ya'll going to texoma this weekend?

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Murphy8166

Hamm Creek.

Yes, the sound great on Full Pass....but you are sending those speakers some low frequencies that they are not designed to play - it is only a matter of time before you blow em. I would imagine that you would have a hard time warrantying them as well.

I'm just trying to help you out. Looking forward to meeting you.

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Murphy8166

Looks like it comes in around 350 watts at 12volts. A little bit under that advertised 400 but I doubt your ear can tell the difference.

Hard to beat for the price....that's for sure. These amp ratings are pretty subjective across the board.

Edited by Murphy8166

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shawndoggy

Looks like it comes in around 350 watts at 12volts. A little bit under that advertised 400 but I doubt your ear can tell the difference.

Hard to beat for the price....that's for sure. These amp ratings are pretty subjective across the board.

CEA compliant amps are measured at 14.4v.

Primary Output Power should, according to CEA2006, be measured with 14.4V DC supply, a 4-ohm load and with 1% or less total harmonic distortion in the output.

http://www.cea2006.com/howtomeasure.htm

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Murphy8166

Now that I looked at the 14.4v number - it looks like they pretty much took the average of the 12v and 14.4v which is right about at 400.

So I would imagine that it actually exerts 400 watts most of the time.

Either way - that is a lot of power for a little dollar!

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nyryan2001

Shawn, also know that CEA testing is done only at the easiest loads.... so on this amp it would be done at 4 channel mode, 4 ohms per channel to get whatever ratings they are publishing.

When you drop ohms or bridge the amp, as you would do in this case, to get the 400x2, the CEA ratings dont apply. They generally follow closely, but not exactly. Thats why I wish they would create a standard to test the amps thru all of their functions and rated impedances, both at 12.6v and 14.4v, with the exact guage wired spec'd at the terminals on the amp... pretty much test it how 90% of folks would use it.

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Deephaven

Good to know. Looks like that discount is over on the NVX stuff. I have found the Polk counterpart to this amp for around $250 online. I read a review on the Polk that said it didnt really push the lows to the speakers very well. I would assume thats why you turned it to full range?

Whomever said that has a misconception. I have 3 of the Polk's in my boat and compared them directly with my JL amps. There are no issues with the Polk. From the description above it sounds like they may have a better heatsink as well. Don't get me wrong I can get mine warm, but hot isn't how I'd describe them.

Looks like it comes in around 350 watts at 12volts. A little bit under that advertised 400 but I doubt your ear can tell the difference.

Your ear definitely cannot tell the difference. And it is still rather impressive in particular for the $. The Polk's are "Marine Certified" according to the box, lol.

And with no standards on the distortion nor uncertainties specified it is still a rather non-standard standard. Of course it's the mobile audio industry so it isn't like we'd expect honesty.

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Nitrousbird

I ordered the Polk version yesterday (Polk D4000.4). Seems there are several brands of this amp out there; PPI is the cheapest but on national backorder. NVX is now more expensive. Hertz and Nakamichi sell versions overseas but hard to find here. It's also rummored on some forums that Arc and Soundstream sell versions of this but I didn't see anything in their lineups that match. Polk ended up being the cheapest I could get ($243 new shipped; showed up 24 hours later too!).

Looking forwards to getting it going this weekend.

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nyryan2001

Nitrous-- great, very interested to hear if you have the same experiences:

bridged is the outter 2 terminals, not the inner 2--directions are wrong. test everything before you mount it to the amp board and save yourself some time.

its gets warm/hot

running full pass is the way to go

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Murphy8166

Ryan, you are running 10" mid bass driver with a much larger magnet that a 6.5" exile or any 6.5" speaker....Full pass will toast them. You need to be careful on that full pass advice. You are also running the Exile ZLD which you may have mentioned have a crossover setting mixed in.

NB - please do not run those speakers on full pass, they won't last. Talk to any audio professional out there. A 6.5 coax speaker need to be run in High Pass.

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Deephaven

Even with a 10 I wouldn't run full pass. Cross to blend with your sub. Doesn't mean you can't cross low, but both from a protection standpoint and an acoustic standpoint it'll be better not full pass.

That being said, I personally will never use amplifier crossovers so I'm doing that with a digital signal processor up stream.

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shawndoggy

what dsp are you using deephaven? And are you running active?

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nyryan2001

OK- lemme rephrase what I am trying to communicate here:

The NVX HPF sucks, even when I crossed it at the lowest freq, 20-30hz I think.. I didnt like it, made the music sound crappy. perhaps the polk has a better HPF than the NVX.

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Brianinpdx

Ryan - Just get it in the range. And use the adjustable freq control on the preamp EQ to fine tune as needed. It should give you plenty of room to make changes song by song. And remember in terms of setting a HP cover, thats establishing the corner point of the system 20-30hz is way to looooooooow (for HP). I think you know this. Just making double sure. Good talking with you the other day. Cheers!

-Brian

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NorrisMike

Sounds like the Polk might have a quirky crossover setup?

FWIW - the Precision Power amps have been great so far. Not sure when the next batch of p900.4 amps will be released but it is a great option at a great price. I can also vouch for the p600.2 - it rocks as well. Everyone that's heard my stereo has been thoroughly impressed and it was done on somewhat of a budget. I think it's really cool that there are inexpensive alternatives that perform awesome!

What is most impressive to me is the size of these new amps (Polk, Precision Power, SoundStream, Hertz, etc..)

Here is the p600.2

p6002.jpg

And here they are installed next to the stock Rockford 400.2

Amps.jpg

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Earmark Marine

Just to clarify, most EQs that have a sub lowpass filter do not contain a corresponding highpass filter. Even if they did, most EQs run a single stereo OP amp followed by a fader for both the front/in-boat and rear/tower zones. So even if they contained a highpass filter you couldn't adjust the in-boat and tower zones independently.

I agree that all tower speakers should be run highpass. For a number of reasons the midbass drivers in an HLCD speaker are designed very differently from that of a true woofer. Past a point, long excursions do not translate to more output, just more distortion. Trying to push a speaker below its natural resonance (which is high in a small pod) and against considerable internal resistance will really heat up the voice coil.

David

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nyryan2001

Norris, did your PPI's get hot pushing your rev10s at 400x2?

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Deephaven

what dsp are you using deephaven? And are you running active?

Not the amps :) Minidsp's, I wanted to just use a PC as a processor but a marinePC on a moored boat just didn't seem reliable. My challenge is always to incorporate my music collection to where I go and that requires a hard drive which a pc and touchscreen makes easy, but so does a Galaxy Tab and external HDD. No processing for multi-channel sound on the Tab so an off board proc was required. The lack of functionality on most 12v ones drives me nuts so I went with the mini's.

OK- lemme rephrase what I am trying to communicate here:

The NVX HPF sucks, even when I crossed it at the lowest freq, 20-30hz I think.. I didnt like it, made the music sound crappy. perhaps the polk has a better HPF than the NVX.

I can't clarify on the Polk, I refuse to use amp crossovers for anything. Obviously when they aren't defeatable you have no choice.

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