# JL Audio HD Amps



## ErinH

I currently am running (2) JL HD 600/4 and (1) JL HD750/1 for my entire system. One of the 4 channels is bridged for midbass.

I came from (2) Alpine PDX 4.150’s, and (1) PDX 1.1000. I had sold the PDX’s a while back because I had issues with the noise floor being too high and giving me ‘hiss’ that was clearly audible at interstate speeds. I sold the PDXs and went with Zapco DC Reference amps. I wound up dropping the Zapco’s simply because I preferred the Audison Bitone interface over the Zapco. These had nothing to do with processing itself; just the way the software and the interface worked. 

I’ve now had these JLs in for about a week, though I’ve owned the amps much longer. These review may not be as detailed as I’d like it to be, but frankly, there’s only so much you can say about these kind of thing.



*Initial Thoughts:*
Off the top... these thing is SMALL. About 1/2" shorter than the PDX, while being as small as the PDX in all other dimensions. Though, I believe the PDX might be a hair shorter in one of the geometries, but not enough for me to even notice at all. 

My absolute favorite thing is that these have *removable plugs* like the PDX, BUT they also have removable power/ground/turn-on plug which makes installation a snap. Imagine being able to build the amp rack out of the car including power/ground wires (assuming you use a distro block on your rack, too). Then you set the rack in the car, drop the JL in, and plug up the connectors and you're done. That's awesome. I can't tell you how awesome that is for me. And, going one step further, these amps don’t have the stupid 45* angle connectors that the PDX uses which makes the install much easier, too. Simply put, this feature is AWESOME! 


*Features:*
All the specs can be found on JLs site, so I won't list them. But, basically you have a defeatable x-over on both Front/Rear channels. The x-overs go from 50-500hz making these nice for some passive setups.

Balanced differential inputs. Wish I had a balanced output processor (damn you, Jorge!). 


*Power:*
The good stuff... the stuff we all came here for. 
Okay, the hd600/4 is rated 150wx4 @ 4ohms. 300x2 @ 4ohms bridged.
So, let's see...

Testing was done with a cheapo DMM from sears. An oscope I got from ebay. A 4 ohm PE dummy load and my Iota power supply which can totally keep up with an amp. I used a Samsung DVD unit to take the signal level constant (didn't have to worry about clipping at the source for the most part). I used a 1khz tone from the Audison test setup CD. 

Results:
1 channel driven: 152w @ 4 ohms. 

I didn’t test the 750/1 yet. But, I’m going to trust JL on their power specs.



*Heat:*
During bench testing, the 600/4 sat on the bench getting power for over an hour. The dummy load was hot as hell to the touch. The JL was very cool. Room temp at my house is ~76*F. The JL was not much warmer than this at all, to the touch. 
I spent most all of my Saturday this past weekend with these amps on. I mean from 11am to 5pm these amps had power. While I wasn’t sending music through them off and on for a while, they were powered up the WHOLE time. The amps were warm to the touch but never scalding hot. Just as you would expect (or hope). They never thermal’d down on me and keep in mind that during the RTA testing I was sending pink noise through these for at least 30 minutes at a time with the volume near max. For a 4 hour period I was doing intermittent pink noise listening and never had an issue with these amps. 


*Noise/Listening Test:*
Noise floor is essentially minimal with these puppies. I set the gains on EACH of the amps at no less than 1:00 on the dial when setting gains with a -10dB tone and had only a bit of hiss coming through. That’s a phenomenal step up from the PDXs I was running which gave me noise floor issues even with the gains set at 9 o’clock on the dial. Induced noise on the JL’s is MUCH lower. In fact, once I got everything level matched I had no noise issues due to the amps at all… now it’s all on the shoulders of the h701. 

Listening wise, I am very happy. I don’t have any issues at all. My ears aren’t golden, but I will say that I don’t have any qualms or concerns with these amps. The bottom line is that I don’t believe they color the sound, and there is plenty of low end out of these for me.



*Other things:*
- The plugs are hard as hell to remove once they're in. That can be good or bad. 

- Um, it's small. 

- Did I mention the plug style connectors and even for power/ground? Did I mention how awesome these is? 

- Fits 4 gauge no problem. I was using some old Rockford Fosgate 4g wiring for the oscope bench testing. Installed, I’m using knukonceptz and stinger 4 gauge wiring and it fits inside the terminals without an issue. Actually, 8 gauge is a bit too small in the connector. It'll hold... but 4 gauge would be the best fit for sure.

- Requires 3 different sized allen heads. That's kind of a pita. Especially if you're like me and always freaking forget where you put your tools.


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## ErinH

*Pictures:*

Random stuff:




















































































*1 Channel Test delivering 152w:*


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## ChiTownSQ

Thanks for the Review.. I have PDX now and have been looking for something with less noise in it around that size!

Joe


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## bmwproboi05

hahaha. i had a jl hd. an now im going into the big amps again xD. sure am gonna miss the little space required.


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## 98kugt

Glad to hear these are getting good reviews. I'm looking into the 900/5 and 600/4 for my system myself.


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## doitor

bikinpunk said:


> Balanced differential inputs. Wish I had a balanced output processor (damn you, Jorge!).


I love you too, buddy.
Great review.
Dont worry, I'll let you know how they sound with balanced inputs.

J.


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## ErinH

Thanks for rubbing it in.


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## DATCAT

Thanks for this review. I have been hearing a good bit about these amps. Can't wait untill you review how they sound.


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## ItalynStylion

Gahhh, makes me want the 900/5 even more now. I gotta hang tough and hold out a bit longer. Gotta save my money!


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## ErinH

DATCAT said:


> Thanks for this review. I have been hearing a good bit about these amps. Can't wait untill you review how they sound.


Frankly, I won’t be giving any sort of in depth review on how they sound. They sound like an amp to me. :/
I don’t notice any coloration or have any issues with distortion. The bottom line is that they do rated power and they do it very well. They stay cool, do not thermal after MANY hours of use in 90+ degree weather, and are small. So, in my opinion, they’re just what they should be and are as marketed. 



ItalynStylion said:


> Gahhh, makes me want the 900/5 even more now. I gotta hang tough and hold out a bit longer. Gotta save my money!


Yea, that 900/5 does look sweet. Would be a great amp for a 2-way + sub setup for sure.


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## ItalynStylion

bikinpunk said:


> Frankly, I won’t be giving any sort of in depth review on how they sound. They sound like an amp to me. :/
> I don’t notice any coloration or have any issues with distortion. The bottom line is that they do rated power and they do it very well. They stay cool, do not thermal after MANY hours of use in 90+ degree weather, and are small. So, in my opinion, they’re just what they should be and are as marketed.


_Brilliant! _


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## SoundChaser

I had the HD600/4 mounted on the back seat of a 2007 Honda civic. On really hot days it would go into thermal shutdown. If I drove with the backseat down (with no AC) it did not overheat. Maybe because with the seat up the amp was on a vertical slope and the heat traveling up accumulated more over the heat sensor. Dunno…


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## ErinH

^ likely.

Mine's under a false floor in the trunk of a black 2006 civic sedan. I live in Alabama. I park in direct sun. Truthfully, if anything can survive that environment, then I figure it's good for just about anyone else, too.


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## t3sn4f2

SoundChaser said:


> I had the HD600/4 mounted on the back seat of a 2007 Honda civic. On really hot days it would go into thermal shutdown. If I drove with the backseat down (with no AC) it did not overheat. Maybe because with the seat up the amp was on a vertical slope and the heat traveling up accumulated more over the heat sensor. Dunno…


CLIPPER!!!!!!!


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## SoundChaser

bikinpunk said:


> ^ likely.
> 
> Mine's under a false floor in the trunk of a black 2006 civic sedan. I live in Alabama. I park in direct sun. Truthfully, if anything can survive that environment, then I figure it's good for just about anyone else, too.


I would assume you use an external fan.


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## SoundChaser

t3sn4f2 said:


> CLIPPER!!!!!!!


Ummm... I don't get it?


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## t3sn4f2

SoundChaser said:


> Ummm... I don't get it?


If you set gains too high you, increase the average power that the amp need to produce (through clipping), which in turn makes it work harder then it was originally designed to.

You are not likely to here this clipping distortion until you ask the amp to produce 4! times its rated power. So you'll be there clipping along not hearing anything wrong and your amp is sweating balls lol. Now imagine if the songs you were playing were already of higher average power like a modern compressed clipped version.


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## ItalynStylion

^What a great picture.


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## SoundChaser

t3sn4f2 said:


> If you set gains too high you, increase the average power that the amp need to produce (through clipping), which in turn makes it work harder then it was originally designed to.
> 
> You are not likely to here this clipping distortion until you ask the amp to produce 4! times its rated power. So you'll be there clipping along not hearing anything wrong and your amp is sweating balls lol. Now imagine if the songs you were playing were already of higher average power like a modern compressed clipped version.


Yes, guilty of overdriving the amp. But I’d rather pull the seat down than turn the volume down.


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## ErinH

SoundChaser said:


> I would assume you use an external fan.


Nope. Never had on any amp setup I've ever had.


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## m3gunner

ItalynStylion said:


> ^What a great picture.


+ 100


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## Tonyguy

So what do these sound like compared to the Zapco's?


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## ItalynStylion

Tonyguy said:


> So what do these sound like compared to the Zapco's?


Sound like watts?


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## kyheng

Great review, Bikinpunk. Now I know that my buy on 750/1 is not a mistake. Guess the main -ve review on HD amps are the connector on the power section. Once plug in it is really hard to remove. I plug it wrongly when first I got it.


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## ErinH

yea, even when you plug it in right, they're a pita to remove.


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## falkenbd

when I saw this thread, I thought it was in the classified section...  after all you didn't put review in the title...

Well written... Are they there to stay?


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## kyheng

Well, the best method to remove it unscreww their side screws. This is how I remove mine.


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## SD757

Thanks for the review! I'm definitely getting the 900/5 now.


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## BlueAc

Hey Erin where did you get you HD's from? I got the itch to do some ugrades. I think my PDX's are gonna be the first to go.


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## ErinH

got 'em used from a forum member.

e-bay prices are pretty decent, fwiw.


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## BlueAc

bikinpunk said:


> got 'em used from a forum member.
> 
> e-bay prices are pretty decent, fwiw.


Thx man... eBay scares me for audio equipment. Hopefully some will pop up soon.


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## JayinMI

I plan to run these. Just watch the power plugs on the 750/1 and make sure you have fusing in the back.

Oh, and I didn't think to look over here before commenting on the lack of reviews in your build thread...so ignore me over there. 

Jay


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## ErinH

why do you say to watch the power plugs? ...

Yep, fusing is ~2' away via the distro block


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## JayinMI

One of the first ones our company installed overheated and caught the carpet on fire and totalled the truck. I've seen a couple since then with melted power plugs. JL Has recommened fuses near the amp to help combat this...IIRC, they said 80amps.

Jay


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## ErinH

wow. hadn't heard about that.

I have a 100a fuse next to mine. when I do another PE order I'm going to order some smaller fuses and I'll make sure to get one for the 750/1.


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## JayinMI

I'm hoping it was just a problem with the first run, and I imagine if you don't beat the piss out of them, they'll hold up fine...just something to keep an eye on.


Jay


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## doitor

Since Bikin*I*punk is my car audio role model (NOT) I just had to.










J


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## ErinH

yours are in better shape, I betcha.


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## doitor

bikinpunk said:


> yours are in better shape, I betcha.


BNIB gear tends to be in pretty good shape.
I'm still in shock about this little things.
I'll be getting more power using 1/3 of the real state and 1/3 of the weight.
Just check this out:










J.


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## ErinH

LOL!
I almost didn't even notice the HDs in that picture!

Yea, they are sweet little amps. Balls to the wall suckers, too!


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## doitor

bikinpunk said:


> ....Balls to the wall suckers, too!


You sure got a way with words, buddy.
LOL.

J.


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## ErinH

that's what she said. (she being the lady cop as she hauled me to jail)


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## ItalynStylion

doitor said:


> BNIB gear tends to be in pretty good shape.
> I'm still in shock about this little things.
> I'll be getting more power using 1/3 of the real state and 1/3 of the weight.
> Just check this out:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> J.


I'm going to send this picture to anyone who asks me why I just bought a JL HD900/5. Wow....just wow.


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## doitor

ItalynStylion said:


> I'm going to send this picture to anyone who asks me why I just bought a JL HD900/5. Wow....just wow.


And it gets better.
Total power:

With 5 Slash amps: 1,700 watts
With 3 HD amps: 1,950 amps

J.


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## ashlar

^^^I believe you meant to say 1,950 watts.


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## unpredictableacts

So the slashes should all be up for sale soon.....on the cheap I am sure.


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## kyheng

Looks like I have to ditch my 6 channel amp to get them....


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## doitor

ashlar said:


> ^^^I believe you meant to say 1,950 watts.


LOL.
True.



unpredictableacts said:


> So the slashes should all be up for sale soon.....on the cheap I am sure.


Yep.
All five of them.
Mint with original box, manuals, used with gains all the way down all the time.


J.


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## unpredictableacts

doitor said:


> Yep.
> All five of them.
> Mint with original box, manuals, used with gains all the way down all the time.
> $20 shipped and a huge from a large hairy man.
> 
> J.


Damn just a little over my budget.:laugh:


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## PGT FTW

anybody running the 900/5 yet? I've got a 10W6v2 and DLS Iridium 6.3i...I'm thinking it will fit the bill nicely.


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## lucas569

wow seeing them next to the othe jl amps really gives you an idea how small they really are... 

hate seeing pics like that, makes me start to plot out systems!


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## PGT FTW

No joke. I emailed Manville from JL over the weekend and asked about the 900/5. He told me it was a nice amp and used it himself but is currently running a 600/4 and 700/1 combo. DAMNIT!


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## P_4SPL

Could you post a pic of the amps while your holding one?> I'd like to see how compact they are.


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## t3sn4f2

P_4SPL said:


> Could you post a pic of the amps while your holding one?> I'd like to see how compact they are.


Here's a cool little trick. You cut a piece of paper to the dimensions of the amp and you look at it. Tadaaaaaaaaaaa!


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## snaimpally

BlueAc said:


> Thx man... eBay scares me for audio equipment. Hopefully some will pop up soon.


Troy of Axxis Audio, a forum sponsor, is an authorized JL dealer and has been giving some excellent deal on stuff to forum members. One of my friends got 3 Arc Audio amps from him and prices were as good or better than ebay.

JL is going to have a 1200 watt HD sub amp in the near future.


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## snaimpally

P_4SPL said:


> Could you post a pic of the amps while your holding one?> I'd like to see how compact they are.


Check Doitor's thread for pics compared to his old JL amps.


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## doitor

P_4SPL said:


> Could you post a pic of the amps while your holding one?> I'd like to see how compact they are.


 Here are some pics with common things to get a reference.





































J.


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## ANT

I run the following

(2) 750/1 - on 2 8w7
(1) 600/4 - sent to ultra subs componenets

I went with them becuase they are so small and produce the power I was looking for. Plenty of flexibility for me.


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## kvndoom

That is an incredible setup! One day I'll have the money...


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## hybridamp

Wow, those are sweet pics; the size of the HD amp is a very beautiful thing indeed.


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## omega48er

kvndoom said:


> That is an incredible setup! One day I'll have the money...


Same here buddy 


Sent from my Xoom using Tapatalk


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## ssc_wilson

i ve 2 hd600/4 on 2 10" eminence beta for midbass, 4 8" eminence beta midrange, 6 pyle pro tweeters high and a slash 1000v2 on 2 12w6v2, they rock everything in sight


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## THRASH

Great write up.


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## low2001gmc

900/5 SEEMS VERY NICE AMP IN A SMALL PACKAGE


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## adrenalinejunkie

i have been thinking of going with a new amp for my front stage and i've been thinking of going with this amp, but was thinking it wouldn't be a great choice since it was class d. So, this review has convinced me that this amp is built properly and does what an amp is suppose to do. I was thinking of getting this amp and bridging it so i can have more "head room" for a pair of passive HAT 6.5 Clarus would that be over kill or what? I do plan to do a 3 way active setup in the future once i'm ready for it. Great review Bikinpunk sorry for bringing this from the dead, but it's worth reading.


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## BuickGN

Which one?


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## adrenalinejunkie

BuickGN said:


> Which one?



HD600/4


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## BuickGN

I have one and love it. It seems to have more power than the 150w rating would have you to believe. Unbridged, it pushes my Dyns very well. In fact, I have the McIntosh which is rated at 100w on the tweeters and center and it does not come close to keeping up with the HD. The Mac is maxed out for all it's worth, the HD is no where close.


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## adrenalinejunkie

Great, this amp seems to be very strong. I bet it's the fact that it does rated power from 11-14v I'm assuming...


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## adrenalinejunkie

How much do authorized dealers normally sell these HD600/'s?


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## sq_guru

I'm going to try the new HD900/5 this go-around as a replacement for my existing 450/4 and 1000/1 Slash series amplifiers. I just can't afford to give up the space and stiffen the electrical system for the power-draw in my present car like I have in the past. I've heard great things about them, and I never would've imagined using a Class "D" for full range!

I need to sell these two amplifiers, first, though!


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## sjg5359

Going back and forth on HD750/1 + HD600/4 or HD900/5 to power HAT Clarus 2way front, HAT Imagines coax rear and single JL 13tw5 sub.


Leaning HD750/1 + HD600/4? any opinions.


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## tintbox

I'm running (3) Hd's right now. You gotta love head room.


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## tseng2394

Thinking about going with a 1000/1 for my w3's. I think I might go with it now. Thanks for the great reiew


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## mtnbkr

sweet jesus...


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## Blackandblu

looks tasty


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## nerofive4

low2001gmc said:


> 900/5 SEEMS VERY NICE AMP IN A SMALL PACKAGE


I just purchased and installed on and had it crap out on me after use, thank god I bought it from sonic electronics and not used from ebay like I was considering. 

I am kind of pissed that sonic is charging me for the return shipping, but thats my own issue.


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## nerofive4

bikinpunk said:


> yea, even when you plug it in right, they're a pita to remove.


+100 Hell yeah they are


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## ecbmxer

I decided that I'm gonna try and swap my massive NX5 and NX2 out for a 600/4 and 750/1 in the spring. I think it will fit my install better and not have a turn on pop like my massives. Do you feel that the 600/4 provides enough power for a stout set of 6.5" midbass drivers un-bridged? Right now I have the massive bridged to my midbasses, which gives me a good bit of headroom.


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## Schizm

ecbmxer said:


> I decided that I'm gonna try and swap my massive NX5 and NX2 out for a 600/4 and 750/1 in the spring. I think it will fit my install better and not have a turn on pop like my massives. Do you feel that the 600/4 provides enough power for a stout set of 6.5" midbass drivers un-bridged? Right now I have the massive bridged to my midbasses, which gives me a good bit of headroom.


Hey ecb, my N4 has no popping when turning on. or well ever. It may be something external from your amps causing your noise. Or your specific amps I suppose. 

Btw my darned stock system in this Peterbilt 387 has a pop in it though! Really makes me cringe when I hear it. Can't wait to put my amps and speakers in.


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