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Alpine PDX-F6 Review (4 channel Car Amplifier)

amirm

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This is a review and detailed measurements of the Alpine PDX-F6 four channel car audio amplifier. It is on kind loan from a member. When new, it cost US $849 but is now discontinued.

Alpine PDX-F6 Review four channel Class D Car Amplifier.jpg


Not a fan of the plastic trim which are showing their age now. But otherwise, it is a nice looking unit. I especially liked the stout wiring terminals:

Alpine PDX-F6 Review Rear wiring terminals  four channel Class D Car Amplifier.jpg


The speaker terminals have deep shrouds to keep the wires from shorting out which is a wise move.

Alpine PDX-F6 Measurements
The unit became stable pretty quickly upon powering on:
Alpine PDX-F6 Measurements Warm up four channel Class D Car Amplifier.png


Don't mind the variations as I had not taken care of grounding it and it was picking up noise. With that in place, here is our dashboard:

Alpine PDX-F6 Measurements four channel Class D Car Amplifier.png


I was disappointed with the poor channel matching which persevered through the full range of the gain control (there is only one for each pair of channels so you can't fix this variation). On the other hand SINAD which summarizes noise and distortion is well above average for home amplifiers (79 dB) let alone car audio:

best four channel car audio amplifier review.png


Distortion in the FFT window is below 100 dB which is excellent. As is SNR:
Alpine PDX-F6 Measurements SNR four channel Class D Car Amplifier.png


Multitone test shows essentially no frequency dependency which again is very nice:

Alpine PDX-F6 Measurements Multitone four channel Class D Car Amplifier.png


Crosstalk is above average for even home amplifiers:


Alpine PDX-F6 Measurements Crosstalk four channel Class D Car Amplifier.png


Class D amplifiers have output filters that usually interact with the load to create varying frequency response in the audible band. Not so here:

Alpine PDX-F6 Measurements Frequency Response  four channel Class D Car Amplifier.png


There is good bit of power and near spec into 4 ohm:
Alpine PDX-F6 Measurements Power vs Distortion 4 ohm four channel Class D Car Amplifier.png


Alpine PDX-F6 Measurements Max and Peak Power vs Distortion 4 ohm four channel Class D Car Amp...png


One channel is lower due to channel imbalance mentioned before.

Switching to 8 ohm we still have decent amount of power:

Alpine PDX-F6 Measurements Power vs Distortion 8 ohm four channel Class D Car Amplifier.png


Varying the frequency again shows how the amplifier operates regardless of input frequency:


Alpine PDX-F6 Measurements Power vs Frequency 4 ohm four channel Class D Car Amplifier.png


Wideband spectrum analysis shows a switching frequency way above average:


Alpine PDX-F6 Measurements FFT four channel Class D Car Amplifier.png


This helps a lot with the filtering performance mentioned before.

Conclusions
Can you smell it? Try again. That is the smell of a well engineered amplifier! In every every measurement there is indication of care in design and optimization. This would be nice to see in a home amplifier but is even more impressive in car stereos where bigger "watt" number seems to be the only thing that sells. Cost is way up there though but at least you are getting increased performance for your money. The only hitch is that channel balance which seems to me to be an out of spec part or something like that.

It is my pleasure to recommend the Alpine PDX-F6. Not sure if they are easy to find on the used market. If so, they will be a very good buy. I am hoping Alpine has released newer models with similar excellent performance.

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KxDx

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Impressive!

I bought a PDX F4 (100x4) and M6 (600x1) right when that line was redesigned (the original ones were silver and had slightly different model numbers).

I sold the F4 when I stopped playing so loud in my car. Still have the M6 on sub duty though, to a JL 12”. Over 10 years and in at least 4 different cars. Good little piece of engineering.
 

KxDx

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There was a stacking kit you could buy that allowed you to stack the amps vertically.

No fan, no ventilation holes, and they still ran pretty cool to the touch after hours of hard use, and that’s into 4 ohm door speakers and 2 ohm subs.
 

pma

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On the other hand SINAD which summarizes noise and distortion is well above average for home amplifiers (79 dB) let alone car audio:
Maybe a typo, looks rather like 89 dB.
This is a well measuring amplifier.
 
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amirm

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ROOSKIE

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Wondering if car amps should be tested at 2 & 4 ohm? More typical than 8 ohm. Rarely does anyone use 8ohm rated car products in solo mode.
 

GWolfman

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Surprise surprise. Hopefully the channel imbalance is not common. The stereo balance should be able to correct if needed though, luckily.
 

capslock

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Tear down and power measurements on a sister model (PDX F4).

This is clearly class D and there seems to be quite a bit of post filter feedback. Any idea what technology was used? This seems to surpass the usual suspects of ICE-Power or IRF, maybe even UcD and was well before the advent of ncore.
 
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amirm

amirm

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Wondering if car amps should be tested at 2 & 4 ohm? More typical than 8 ohm. Rarely does anyone use 8ohm rated car products in solo mode.
Yeh, that is more typical but I don't have a 2 ohm dummy load. If we were going to do a lot more testing of them, I would build one but not sure it is worth the expense and effort right now.
 

Matias

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Very nice! I own the PDX-V9, which is the 5 channel version of this amp, including an extra 500W channel for the subwoofer, and it's still in production. End game, buy and forget, has been used daily for 7 years now. Love it!
 

capslock

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After some online reading, the F4 and F6 seem to be second generation. The first generation comprised models like the PDX-4.150 and according to unverified rumors used ICE-Power technology.
 

Matias

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Notice the multitone and various frequencies power x THD+N graphs how well behaved this amp is in higher frequencies. This is cleary a more sophisticated class D design, something like NCore of car audio.
 
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milosz

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I use an Alpine MRV-M500 amp driving a Dayton Audio RSS315HO-44 with it's voice coils in parallel in a 0.5 cu ft sealed enclosure in the trunk of my car, the amp works quite well and this setup provides the proper amount of tight bottom-octave support in my car, without sounding "subwoofery." The amp has worked really well for me in this application with a DSP crossover at about 50 Hz.
 

jannek

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Glad to see one of the best recent car audio amplifiers tested, proving that there is car audio beyond power levels and boomy subwoofers.
If a PDX F6 cannot be found, an Eton Mini 150.4 is a proper alternative still available. I don't know how common Eton is in north America, but this would definitely be worth a test (as well as the Eton Core A2 as a high end class AB design).
 
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PeteL

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I’ve never really so far been in tha market of replacing my car amp, the noisy environment make me feels that what I have stock is adequate and I don’t drive much, but thinking, it looks like a good amp, Is four clean 70 Watts channels for 850 bucks a price”way up there”? it appears reasonable no?
 

Jdunk54nl

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Thanks for measuring!

I paid $250 for this amp used a couple years ago.

I do know on the v9, after many years of being in a rough environment of camping and off-roading, the gain pots and switches sometimes need to be wiggled a little bit to clear the dust/dirt that has built up.

Maybe the f6 is similar.

Can’t wait for the v9 to be measured too!
 
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capslock

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The F4 and F6 seem to have been discontinued. The V9 is still available, as are some M models.

Any idea if the V9 uses the same technology? Are there multichannel successors to the F4 and F6 that have retained this technology? I know there are other cheaper multichannel Alpine models but I doubt they use this kind of tech.
 

Jdunk54nl

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My v9 is in Amir’s hands currently and should be measured today. So your question will be answered shortly.
But, as far as I know, the v9 is basically an f4 and a m6 combined into a single package, with a little less power to the m6 part due to sharing the power supply.
 

pseudoid

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Sad to witness this cottage industry (as with many others; like VHS rentals @Blockbusters) shriveling up and going away.
I must have owned about 14 new cars, 13 of them had their 'radio' systems de-gutted and upgraded to sound instead like 'audio' systems.
In the fourteenth one (2-Din head-unit on a '06 Goat), was so well integrated into the rest of the vehicle's electronics (including steering-wheel controls and funky amps hidden in weird places, etc.) that I decided to leave its 'radio' system as much OEM as possible (except; by adding an Aux input patch to the head-unit PCB).
The integration of the automotive audio-systems have become so complex and so well integrated w/i the vehicle electronics that even the simple task of swapping power-amps is near impossible for vehicles made in the 2020s!
RIP!
 
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