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I got mine installed yesterday. Writing a separate review given this and pasmag review would be quite redundant. Based on everything we know so far, it performs within manufacturer specifications, runs efficiently, and takes little space. Sonicelectronix has these on sale for $200, but even at 'normal' $230 price, these are a good value. Another thing I like about this amplifier is that you can turn off the filters completely. I prefer to set crossover between my speakers and subwoofer on my stereo, which should result in more precise settings and also in less phase shift issues.


Right now, it's running only a subwoofer with bridged channels. The subwoofer is Infinity Kappa 120.9w. I have set my gains by ear as usual. My head unit has 4V outs. The amplifier gain knob is a little below the middle position. The texture of bass sound _seems_ to become more robust, somewhat more detailed. However, it's not a fair comparison vs my old amplifier, since my previous sub amp was a cheap A/B amplifier that probably wouldn't even provide its rated 250watts. Moreover, I flipped the impedance switch on my subwoofer from 2ohm to 4ohms which should result in all three voice coils now wired in series. This later change could also affect the sound somewhat. Overall I am pretty happy. Right now I am looking for a good way to mount this amplifier on the back of my subwoofer box.

I see only a few minor negative issues so far:

1. 4 AWG wire barely fits.
2. Accessing screws for power, speakers, etc is a little uncomfortable. Those bars on sides get on the way.
3. The manual does not explain how to bridge channels. I had to infer this from the instructions for the 2-channel version and also from the manual of Polk D4000.4 (a closely related amplifier).
I was just looking at this amp on Sonix, thinking about a future single cab beater truck install (it's already inheriting my new Massive CK6V set that won't fit in my friggin doors on my car!!) It looks powerful enough to run a mild sub off channels 3 - 4, and the Massives off 1 - 2.
 
Since all of these amps are nearly identical (and very small) I think someone should design a docking cradle for them. You could pull the amp at night to prevent theft.
 
I was just looking at this amp on Sonix, thinking about a future single cab beater truck install (it's already inheriting my new Massive CK6V set that won't fit in my friggin doors on my car!!) It looks powerful enough to run a mild sub off channels 3 - 4, and the Massives off 1 - 2.
That's EXACTLY what I'm going to do! CK6V on the fronts and an IDMAX on the rears! Can't wait. I'll update this thread with my opinions once I get it installed!
 
2. Accessing screws for power, speakers, etc is a little uncomfortable. Those bars on sides get on the way.

The bars are removable. There are two screws on each one on the bottom of the amp. But you would have to make ne mounting tabs.


I just received my amp and have yet to install it but it seems to have a very solid weight and feel to it. The plan is to be running my fronts off ch 1-2 and my sub off of ch3 @ 2ohms and then ch-4 will run dedicated midbasses in each rear door. If I like this amp and the reviews suggest I should then I will get a 1000.1 to run the back stuff and use this 900.4 to go full active up front.


Question for you guys on this amp. This seems stupid to ask but I do not see a setting for LPF. Just HPF - fr - bp. I am assuming that you just use bandpass and set the hpf at 20hz then adjust the LPF to what ever it is I want. Is this correct or am I missing something?
 
I was wondering the same thing when I first got mine and was going to use the filters. I'll be using the MS-8 for filtering now.

I think you are correct in the settings, the HP essentially becomes your subsonic filter if using for a subwoofer.

Would be nice to remove the bars and have links/bridges to gang a few together. Hmmmm I'll have to look at that. Always liked the look of 2-3 amps appearing to be 1 big one.

Eric
 
R+ L-, its actually in the manual, just no pictures.:)
 
I was wondering the same thing when I first got mine and was going to use the filters. I'll be using the MS-8 for filtering now.

I think you are correct in the settings, the HP essentially becomes your subsonic filter if using for a subwoofer.

Would be nice to remove the bars and have links/bridges to gang a few together. Hmmmm I'll have to look at that. Always liked the look of 2-3 amps appearing to be 1 big one.

Eric
Going back and rereading the manual it is now even less clear :confused: Why can't they just give us this info in the manual. When looking at the manual on the first page for the 900.4 numbers 7 and 11 refer to the x-over switch. This is what it says verbatum : "Choose to activate the High Pass Crossover, Low Pass Crossover, or Band Pass Crossover. Band Pass Crossover uses the high pass and low pass simultaneously."

I notice that it does not mention the "Full" position for the switch but mentions Low Pass that does not exist for the switch.

So now I am even more confused. I am sure I will be able to figure it out but this is a negative in my book for this amp. I hope the authorized installers get better instructions for this amp. I Know PPI ONLY wants authorized dealers to do the installs as shown by the lack of warranty for those who install it themselves but c'mon. 90 days if I install but 2 years for a shop??? C'mon why not the typical 1 year or even atleast 6 months but 90 days? They can certainly tell if you had it turned up too high or installed it incorrectly. Besides even if a shop installs it that does not mean that the settings can't be adjusted by the end user. Or that the end user won't disconnect it for some reson and then reconnect it. That is negative number 2 for me but hey for the price I guess if it breaks just throw it away and by a new one lol. I bought the 3 year sq trade warranty for mine because of this so I should be good. Neither of these is a deal breaker and hopefully will be the only drawbacks/negatives for this amp.

On a side not my GF got mad at me for buying a brand new amp for my car while buying a used SoundStream Ref405 for hers. I showed her that I only get a 90 day warranty and she laughed. I then reminded her that the SoundStream was built in 1994 and is still working flawlessly. Only time will tell if this PPI can last so long.

How do you go about bridging 3/4 channels? There's no obvious marker on the amp.
Look at the instructions for the 600.2. It shows to use the R+ and L-. I would hope this is the same for both front and rear on our 900.4's. Someone earlier mentioned this so I am thinking it worked for them.
 
R+ L-, its actually in the manual, just no pictures.:)

HMMMM in my manual it is only PICTURED. It is on the 600.2 pic. I have not found a single instruction however, just the pic.
 
on the rear of the first page for the 900.4, item 1, it gives subwoofer wiring instruction, but manuals could have changed:) mine don't have page numbers:laugh:
 
on the rear of the first page for the 900.4, item 1, it gives subwoofer wiring instruction, but manuals could have changed:) mine don't have page numbers:laugh:
Mine will be delivered tomorrow, but I have read someone else's concern about this matter. Guess I should have just been patient and read the manual tomorrow night. ;)
 
Know what ya mean, read the polk audio manual before i got mine, he he:D
 
on the rear of the first page for the 900.4, item 1, it gives subwoofer wiring instruction, but manuals could have changed:) mine don't have page numbers:laugh:
Ahhh found it. I can be blind at times :laugh:.

I just finished hooking mine up. As to be expected it powers my comps very well. I am running it off of a factory head unit with a basic line out converter so the input signal is not very strong. That coupled with the use of a single brand new 8" sub in a (on the large side) sealed box made me have to turn the rear almost all the way up. I figure that once I get my aftermarket HU in and the sub breaks in and goes into it's perm ported box, I will be able to turn the gain down some.


As for the low pass I found it works only in the band pass mode. Someone correcet me if I am wrong again lol.
 
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