# Alpine PDX-F6 / Alpine PDX-M12



## Brian Steele (Jun 1, 2007)

This year I decided to give myself a Christmas present and replace both of the amplifiers (an old MTX-4160 driving the front and rear speakers, and a Pioneer GM-D510 driving the bass) with the Alpine PDX-F6 and the PDX-M12 combination. I received the amplifiers last week and installed them this weekend. The notes below are from installation and first tests. I still have some fine tuning to do, primarily because the LP filter option on the PDX-M12 is different to that on the GM-D510.

In the box:
Amp, adapters for stacking amps together, instructions, warranty and registration cards, various screws and two allen keys - a large one (for the power connector) and a small one (for everything else). Oh, and verification certificates - one for the PDX-F6 ([email protected] (0.39 dB of extra power)) and one for the PDX-M12 ([email protected] (0.36 dB of extra power). I think it would have been nice to see testing at a more realistic voltage level - for example my MTX-4160's certificate shows that it was tested at 12.5V, producing 54W per channel at that voltage.

Installation:
These amplifiers are tiny. Seriously, particularly considering their rated output capabilities. Smaller than the GM-D510 (a class D amp rated @500W into 2 ohms). Considerably smaller than the MTX-4160, which is rated at 30Wx4/4, but capable of 54Wx4/4. So small that I had to fabricate extra brackets to mount them in the usual locations below the front seats. So small that even with the brackets raising the amps by about 3/4 inch, there was still ample space for them below the seats. The image below should give a fairly good idea of its dimensions (that's the front seat area of my Hyundai Tucson)










The use of plugs instead of screw terminals for quick connection is generally a positive feature, though the speaker plugs tended to be difficult to remove once they were inserted. Unfortunately I had to cut off all of the power and speaker spade terminals I used to connect the cables to my previous amps, but I'm hoping this this is going to be a one-way change anyway . 

First Impressions:
I still have a bit of adjustments to make (gain settings, and x-over points), but I thought I'd give a few first impressions.

Concerning the PDX-F6, I think the upgrade was a generally positive one. It seems to have oodles of clear, clean power on tap, and as I kept turning the volume up the output remained clear until I had to turn it back down because it was too loud for my liking - this is the first amp install I've done where my ears gave out before the amplifier did. 

Concerning the PDX-M12, the performance improvement over the previous amplifier (the Pioneer GM-D510) was a lot less noticeable. In fact, in some ways I prefer the GM-D510. While the output seems to be there (the amp is capable of driving my Infinity 122.7W subs to their limits), the Pioneer seemed to be capable of a bit more low-end oomph (and yes, I ensured that the PDX-M12's subsonic filter was off).. It's possible that this may be caused by a x-over or gain setting though, so I'm reserving final judgment on this until I get those two things sorted out. 

Overall though, I'm quite happy with the purchase, and looking forward to even better results after I've completed the necessary tweaking.


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## Brian Steele (Jun 1, 2007)

One thing I forgot to mention - the PDX combo (particularly the PDX-F6) seems to run considerably warmer than my previous amps at idle. While class D amps are more efficient than their AB counterparts, perhaps the efficiency difference disappears at lower signal levels.


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## rytekproject (Feb 25, 2011)

Any updates on this? I was thinking of upgrading my M6 to a M12 but noticed the same thing you mentioned about low end omph. I though it was bc I was pushing the amp too hard


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## DirkDiggler87 (Feb 20, 2011)

Brian Steele said:


> Concerning the PDX-F6, I think the upgrade was a generally positive one. It seems to have oodles of clear, clean power on tap, and as I kept turning the volume up the output remained clear until I had to turn it back down because it was too loud for my liking - this is the first amp install I've done where my ears gave out before the amplifier did.
> 
> Concerning the PDX-M12, the performance improvement over the previous amplifier (the Pioneer GM-D510) was a lot less noticeable. In fact, in some ways I prefer the GM-D510. While the output seems to be there (the amp is capable of driving my Infinity 122.7W subs to their limits), the Pioneer seemed to be capable of a bit more low-end oomph (and yes, I ensured that the PDX-M12's subsonic filter was off).. It's possible that this may be caused by a x-over or gain setting though, so I'm reserving final judgment on this until I get those two things sorted out.


I am running the PDX-F4 and PDX-M12 and had pretty much the same experience.

The PDX-F4 sounds so clean, I love that amp and have nothing bad to say about it. 

Now on to the PDX-M12. The M12 replaced an amp with less power and I too feel like I lost some "oomph" in my sub stage. Even after some adjustments I still felt the loss of bass. 

I talked to a local shop and they told me I would see better results running the M12 @ 2ohms. Not sure if it's true or not because the M12 is supposed to do 1200 rms from 2-4ohms, but it does make sense.


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## umadamba (Oct 19, 2009)

Maybe because the M12 doesn't boost anything down low? I am just guessing here.
I mean, watts are watts, right?

Anyway, will report back on my own experience when it is installed to power a Ultimo 12 4 ohm.

Sent from my GT-P1000 using Tapatalk


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## Brian Steele (Jun 1, 2007)

DirkDiggler87 said:


> I talked to a local shop and they told me I would see better results running the M12 @ 2ohms. Not sure if it's true or not because the M12 is supposed to do 1200 rms from 2-4ohms, but it does make sense.


I'm running the M12 @ 2 Ohms (Two Infinity 122.7W subs, each configured for 4 ohm operation, then wired in parallel). There's definitely some difference in the low-end response (compared to my previous amp). I really haven't had a lot of time to do any serious testing though. Perhaps this weekend.


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## JJDu4 (Jun 8, 2011)

Well I'm glad I ran accross this post.....I just took delivery of my 2 PDX-M12's and I was gonna use them to replace my 2 PDX-M6's. I'm running 4-10W3's right now and the M12's are for my 4-Type R 10's I just got. Both setups will run each amp at 2ohm as I'm running 4ohm 10w3's and the Type R's are Dual 2's........anyway I'm curious as to what would cause this loss of low end umpth. Of course what is so cool about these new class D amps is these two amps are the exact same physical size and the M12 is twice the power......the M12 max draw is 100 amps and the M6 is 80 amps. Anyway I'm still a few weeks out on my swap so I'll watch this thread for any new info. One last thing I was gonna ask Brian was if you were from Grenada MS?


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## jp_over (Dec 21, 2011)

Brian Steele said:


> I'm running the M12 @ 2 Ohms (Two Infinity 122.7W subs, each configured for 4 ohm operation, then wired in parallel). There's definitely some difference in the low-end response (compared to my previous amp). I really haven't had a lot of time to do any serious testing though. Perhaps this weekend.


Enjoyed the write up; please keep us posted. I'm strongly considering a class d Alpine as well.


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## Brian Steele (Jun 1, 2007)

JJDu4 said:


> Well I'm glad I ran accross this post.....I just took delivery of my 2 PDX-M12's and I was gonna use them to replace my 2 PDX-M6's. I'm running 4-10W3's right now and the M12's are for my 4-Type R 10's I just got.


You should be able to do a direct swap between the M6 and the M12 amps in your setup. I suggest swapping them before you swap the subs. Any differences in performance that you notice will then be solely caused by the amps.




JJDu4 said:


> One last thing I was gonna ask Brian was if you were from Grenada MS?


I'm from the other "Grenada" - in the West Indies


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## Brian Steele (Jun 1, 2007)

umadamba said:


> Maybe because the M12 doesn't boost anything down low?


The Pioneer GM-D510M doesn't have any sort of bass boost either.


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## Brian Steele (Jun 1, 2007)

jp_over said:


> Enjoyed the write up; please keep us posted. I'm strongly considering a class d Alpine as well.


I think you'll likely be quite happy with it. I found some more time this weekend to so some more tweaking, which resulted in a bit of delay added to the sub channel and a different x-over point for the rear channel. I then loaded the USB stick up with some stuff like the Laidback Luke remix of Anjulie's "Brand New *****" and the Fedde Le Grand remix of Coldplay's "Paradise" and took the car out for a spin to see how the system performed with the volume up several clicks higher than I normally play it. 

The M12 delivered, and in spades, particularly considering that the Infinity 122.7Ws in my sealed box result in an Fb of around 30 Hz, which means that current draw at the typical "bass" frequencies (40~60 Hz) should be a bit higher than your typical car audio sealed box 12" . In fact, if I wanted any more output (I don't at this point), I'll either need more subs, or better subs. I'll also need serious work done to my car to track down and fix all of the rattles and buzzes that seemed to show up at the levels that the system is capable of achieving with the M12.

About two weeks ago, I was repairing some CV PSX-153 15" 3-way pro audio speakers for my brother (blown x-overs, most likely caused by a combination of too much power and questionable x-over design - a WT3 impedance measurement of one of the working speakers showed that impedance for the 8 ohm speaker dipped to just above two ohms between 100 to 300 Hz). I repaired the x-overs (and did a few minor mods to fix the impedance dip), and asked him to bring over an amp to test them at high power levels as my current 30Wx2 "house" amp was not going to cut it. Well, he brought over an old Crown Macro-Tech, a heavy beast of an amp that looked like it was all business, and boy, did it get down to business! After doing the power test on the fixed PSX-153s, I hooked up one of the subwoofers I had lying around and that Crown amp easily drove it to its limits with the bass remaining tight and clean for as loud as I could stand it. 

The Alpine M12 reminds me of that Crown Macro-Tech amp, only in a much smaller, lighter, quieter and easier to install car-friendly package .

One more thing I noticed - the voltage "dips" measured by the deck's built-in voltmeter during heavy bass passages seem to be less than I noticed when the Pioneer GM-D510M was hooked up. This is quite curious, as this suggest less power is being pulled from the car's supply, which is basically the stock alternator and battery. 

Work is likely going to have me very busy over the next week or two, but once I get the opportunity, I'll do some basic FR checks and have a closer look at that power question.


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## rytekproject (Feb 25, 2011)

Thanks for the update, I'll probably end up testing one of these out.


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## tyroneshoes (Mar 21, 2006)

Thanks for the review. Had the same thoughts on my m6. I swapped it out and put in one of those Krypt mono Ubuy G/h deals and the difference was night and day. The Krypt sounds better in all aspects though 180w less. Im done with PDX as I greatly disliked the first versions but decided to give the new versions a try. Nope. So far the only full range digital I liked were the Kenwood x4r but I particularly dislike the pdx monos, even with the rux knob to tune song by song, never sounded right. I just prefer a/b class (or g/h), subjectively, but over many years of trial.

I am curious about the jl xd or hd compares to a well built class a/b. Never tried JL's amps aside from slash


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## UNFORGIVEN (Sep 25, 2010)

I run a Alpine PDX-F6 and it's great for sound clarity with lots of power to back it.

Very nice amp


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## ZAKOH (Nov 26, 2010)

Wait until the amplifier is fully broken in ..


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## tyroneshoes (Mar 21, 2006)

ZAKOH said:


> Wait until the amplifier is fully broken in ..


What?


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## Brian Steele (Jun 1, 2007)

I just want to post a quick followup note: I'm pretty sure that the "lack of oomph" I initially noticed with the M12 is a gain adjustment issue. Some more fiddling I've done during the week suggests that this amp is pretty good at getting loud and low (and giving a stock electrical system a good workout) when called upon to do so. For my "normal" listening, the M12/F6 combo just sounds pretty good, and definitely a step up from my previous sub/main amp combo, and I think I actually may have had the gain a bit too high on my previous sub amp to compensate for an inferior midbass transition between the subs and the main speakers. 

This weekend, with multimeter and a frequency generator in hand, I'm going to be taking a closer look at the gain settings to see if my observations are a good match for what I think is going on.

I'm likely going to hardly ever be calling upon the M12 to deliver all of its rated 1.2kW, but it's nice to know that the power is there if I ever decide to turn the volume up a few extra notches. It's already generated some surprised looks from some observers, particularly when I invite them to play a game of "find the amp"


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## thomasluke (Jun 10, 2011)

ZAKOH said:


> Wait until the amplifier is fully broken in ..


:laugh: Unless your for reals then:surprised:


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## ZAKOH (Nov 26, 2010)

thomasluke said:


> :laugh: Unless your for reals then:surprised:


It wasn't for reals until I read the follow up review update!


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## fj60landcruiser (Oct 10, 2011)

Any new updates to report?


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## Brian Steele (Jun 1, 2007)

fj60landcruiser said:


> Any new updates to report?


Still very happy with my amps 

Note: Alpine released the PDX-V9 after I purchased the the PDX-F6 and PDX-M12. Given the choice now I'd be really tempted to purchase two PDX-V9s instead, which would give 8 full range channels and two subwoofer channels, compared to the 4 and 1 that I get with the F6/M12 combination. The extra channel flexibility would be worth more to me than the 200W I've giving up on the subwoofer feed.


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## tyroneshoes (Mar 21, 2006)

I found that most of my issues with this amp went away when I hooked up an AC matrix and the gain acted normally at the higher voltage section. 

You kinda really need a line driver on these because the gain setup is pretty poor.


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## robtr8 (Dec 6, 2011)

I'm in the middle of a build with 2 PRS-D800's for left/right active and I was having difficulties deciding on a mono-block for a 12" Vanadium in a PWK Designs box. I had settled on a PDX-M12 for aesthetically and wiring reasons. I was then vacillating between using a Zed RA or a RUX knob. After reading this thread I think I'm glad I stuck with the RA. Sounds like the M12 wants a hot line in.


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## matdotcom2000 (Aug 16, 2005)

Damn damn damn I am considering the m12 over my current space hogger jbl 1400.1.. I am gonna be running the rane on it, so I will have plenty of voltage... I wonder if that wil work.


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