Incredible Sound Quality and Power, But a Tight Squeeze!
Written: Sep 23 '03
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Pros: Powerful, Perfectly Clear, Authoritative and Punchy- a Wonderfuly Amp
Cons: Too Damn Big! A bit Power Hungry, limited band-pass X-over, read details please
The Bottom Line: With its Superb construction and PPIs fanatical attention to detail and quality, the 4125 is among the best 4 channel power amps available.
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| nick1326's Full Review: PPI PCX-4125 Car Amp |
PPI has been a leader in mobile audio for generations. Undeniably, when you think of cloud-9 level car stereo products, PPI and Phoenix Gold are probably the first two that come to mind. Within this upper echelon of products, Precision Power amps are one of my favorite brand on power and purity alone, and the PCX-4125 is no exception. Versatile, tremendously powerful and obviously underrated (like virtually all PPI amplifiers) the PCX-4125, while rated at 125W x 4ch @ 4ohm, typically comes out of the box pushing closer to 180W x 4ch... I've seen the birth cirtificates come out over 200 in fact! On the short-and-sweet side of this review, I can say this: There is nothing negative about the sound or quality characteristics of this amplifier- PPI's are as true and uncolored as they come. However the problem with the 4125 is its ridiculous size...but we'll get to that. Typical street price on this beast is whithin the ballpark of 575-675 or so, though you can certainly find cheaper if you buy from a grey-market retailer who isn't a certified dealer...This is a risk that you may wish to take, but understand that your warranty is out the window. I recomend buying from a local certified shop when it comes to mobile electronics, since the environment is ever-changing and you never know what can happen...
The 4125 is a beast of an amp. Sitting on the proven PCX chassis design, the length is what sets this amp apart from the others in the line. While 10" wide and 2.5" deep, the chassis is a whopping 25" long! Fitment will surely be the biggest obstacle for anyone potentially looking to buy an amp of this magnitude- for if it were about half its length, PPI probably wouldn't be able to keep any on the shelves. Given the enormous chassis, the possible of mounting the amp underneath a seat is remote, at best. This is sad, because with a gorgeous 115+ dB signal to noise ratio (s/n) this is one of the most transparent and uncolored amplifiers on the market. That considered, I consider the 4125 to be a perfect choice as a front-stage amplifier for bi-ampable seperates... However In this application, It would be wonderful to have the ability to mount it closer to the front of the vehicle. Rated harmonic distortion is less than .02%- another nice on-paper spec, but even nicer in practice- again, we'll get to the sound characteristics of this amp shortly.
Spec Sheet a/p PPI:
" Channel: 4
4 ohm: 125
2 ohm: 250
Bridged: 500
Damping: >500
S/N Ratio: >115dB
Dimension: 2.375" x 10"
Length: 25"
THD: 02%
Power Input: 4 Guage
Freq. Resp.: 4.5-100k
I/P Sens.: .15-12V
X/O Slope: 12dB
X/O Freq.: 30Hz-4KHz
X/O Type: 2 way
Input Type: 12 vDC
Cooling Fan: yes
QBass: QBass™ Plus "
The 4125 does not have slats or fins to aid cooling- instead PPI has chosen to install cooling fans internally for ventilation and efficiency. Accordingly, the amp can be mounted sideways (upright) or inverted if the application calls for it. Installation if very straightforward, once you figure out a suitable location- this will probably be the most time-consuming aspect of this install, in fact! Once mounted, wiring goes quick and the PPI interface is industry standard, no funky connectors- it's a high powered amp and accomodates 12ga. wiring with ease and is designed for 4ga power/ground.
Aside from the obvious versatility of a 4 channel amp, the 4125 has an integrated cross-over network making it even more versatile. Both 1-2 and 3-4 channels can be set for variable x-over between 30hZ and 4Khz- user selectable hi-pass or low pass, or run full range without and crossover. The amp DOES have a band-pass feature, but it is inherently limiting, and I'll explain why. The band-pass feature is only usable of you send the hi-pass filter from channels 1-2 ON to 3-4, THEN select a low pass on 3-4 (this effectively makes 1-2 a hi pass and then makes 3-4 a low pass WITH a the hi-pass frequency selected by 1-2.) WHile this certainly functions as a band-pass, I would have rather seen TWO independent crossovers on channels 3-4, this way the user could select different hi-pass frequencies independently for 3-4 channels. The way PPI has chosen to do it, if you must band-pass (cross over hi and low for the same channel-pair) you are inherently stuck with the same hi-pass frequency as the 1-2 channel... Otherwise the amp features are standard, but power and sound purity are where the amp really shines:
At 12V input voltage, a healthy 125x4 is going to push a set of high-powered seperates quite nicely. The latest application I found for the PCX-4125 was in a BMW X5 which I did for a friend- we chose MB Quart PCE-216 2 way seperates (configured as coax for inaging purposes- tweet mounted atop woofer) and bi-amped using a 4125. THe amp's birth certificate indicated 197w x 4 rms @ 12.5 volts- quite a nice number to deal with. While this far exceeds what the PCE's ratings are, the sound is UNDISTORTED and UNCLIPPED even at high volumes. This means that despite the high wattage, you will not blows your speakers- you're much more likely to damage drivers by UNDERPOWERING them- as underpowering tends to yield clipped sound waves and highly destructive waves of distorted power- this is turn has a damning effect on your drivers. With PPI's superb clarity and none-clipping nature, you can power up the PCEs without worry of frying anything- just start with a low gain and take your time setting your levels. The PCEs absolutely SANG on PPI power- response with so crisp, using a few key reference discs (including Coldplay- Rush of Blood.. , Steely Dan's Greatest, Spyro Gyra's Breakout and Groove Collective) We did a through run-through on the front stage. The PCE's have their own passive cross-over networks, yet nevertheless, I usually like to hi-pass the woofers to protect against any kind of bounce at high SPL levels. The Quart woofs REALLY perform tremendously and produce smmooooth mid-bass down to about 55-60 Hz. I have the PPI's hi-pass filter set to just a bit over 60 and this worked really nicely- the mid-basses rolled off just in time to avoid bass-bounce on Groove Collective's Pounding "Jay Wrestles the Bari Constrictor" track- this is a great album to work-out your speakers- horns, piano, vocals, bass, WONDERFUL drums and rhythmz track, this album is like jungle of sound- I highly recomend this album to anyone's critical listening catalog ESPECIALLY for auditions and assessments of this nature. Using an Alpine 7940 head unit, the PPI didn't bat an eye- BUT, I will say, the amp is quite power hungry, and without a capacitor, you may notice punch-fade after bigger bass hits... Still, we ran the X5 without a cap and the fronts sounded brilliant.
To summarize, again, if you can get past the sheer size of this beast and don't need independent hi-pass frequency adjustment in a hi-pass/band-pass configuration, this one's a winner. I hate to offer comparative looks at amps like this, since it is so subjective- however I cannot help but share my love for a/d/s/ power-plate amps, especially older ones! While the current series run a very respectiable .03% THD and >95 s/n on paper, the older series was one of the only (if not THE only) amp I've ever known to run 120db s/n!!! And this is only on paper- in my opinion the a/d/s/ produced absolutely the SMOOTHEST yet authoritative response- wonderful amp isn't the word! Nothing will ever rival my trusty a/d/s/ 850- the amp is a monster and does everything. I also have a P640 in my commuter powering 3-way Bostons up front (brideg 1-2 / 3-4 to mid-basses and 5-6stereo to mids/tweets) and it does a lovely job. In comparison I'd say the PPI produces a noticably greater punch, and is equally linear, but the a/d/s/ just has more "IT" in terms of musicality according to my taste. Compared to the awesome JL amps, I still think PPI and a/d/s/ take the cake hands down- Phoenix Gold is right up there with the a/d/s/ PPI crowd too. When you are on this level, the best thing to do is listen listen listen and try to research as much as possible. Sadly, because of the install-to-listen nature of mobile audio, you really can't know anything until you buy- because you won't be able to return an amp like this most likely- but you will be able to sell it and get back most of not all of your money, if you don't like it for whatever reason. On the other hand, I can't see you not liking the 4125- either as a front-stage amp OR for 2 subs- Bridged power is 500W a side!!! You can easily drive 2 high-power subs in a bridged-mono configuration and rattle neighbor's home with it- the amp is a mobile earth-quake! Be ware, especially for bridge sub-work, the amp will DRAW POWER- a cap is pretty much bare-essentials, otherwise you will be able to see the lights dim every bass-hit! In terms if other possible configs, I've seen the Amp used in all stereo, 1-2 channels to front L-R seperates (single, not bi-amped) and channels 3-4 stereo into a 2ohm load, either bridged-mono in 2ohm to a dual voice coil sub in parralel (JL 12w6) OR to 2 seperate Boston pro 12.5 2ohm subs- While the amp is stable in 2ohm mono with no problem, the clarity is noticably better in stereo 2ohm to the bostons- Boston pros are phenomenal subs and the 4125 has enough juice to power 2 2ohmers with decent authority- remember, quality and musicality over simble boom- the PPI's PCX line is all about purity! Hell of an amp, despite its large size, the 4125 is a proven winner and well worth the money if top-notch is your heart's desire!
Recommended:
Yes
Amount Paid (US$): 475
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Epinions.com ID:
nick1326
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Location: Long Island, NY
Reviews written: 232
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Music, Motorcycles, Drumming, Surfing, the finest cigars and living life to its fullest...
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