Alpine PDX Class D amps - How is the SQ?

[o2 SENTRA 10+ year member]

I am now using the 4x100 instead of my f-450 due to the fact that I'm gettig ready to go to the new type-R- 6.5's.at the moment,I have the older type-R's,and for being a 'D' class amp powering my components,it sounds as good as my old a/b class amp.I'll post again when I'm finished with my upgrade.02 SENTRA.............

 

[BMW Sidewayz 10+ year member]

Here's the Down low

http://www.caraudiomag.com/0607_cae_alpine_pdx_4150_amplifier/

I was going to sell my JL Audio 450/4 and get the pdx4.150, but after reading the reviews, I'm not so sure, Im actually thinking on the RockFord t600-4.

 

[Audio1]

BMW Sidewayz,

The way I see it you can fit the PDX 1.600 and 2.150 in the same basic pysical space as the 450/4. I too have considered the Rockford t600-4. I really need more power for my sub so I am kind of deciding between these two. It seems overall the Alpine may be the way for me to go.

 

[Ignatowski 5,000+ posts]

I am considering switching to these I am really liking the small foot print

Most of todays amps are larger than they need to be anyways

hoprfully this is a trend and not just a one off brand thing

 

[Ekeko 10+ year member]

Anybody noticed any decrease in the midbass with the PDX's?

I was testing a PDX 4.100 side to side against a JL 300/4 and a Xtant 404M & can't get over how different the PDX's sound...not bad, I actually like the mids better but the ADS speakers on my bench end up sounding "thin" on the PDX...//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif

 

[Dozy_production 10+ year member]

I thought a watt was a watt?

 

[frzninvt 10+ year member]

To me Class D based amps sound quite different from their Class A/B counterparts and not in a good way.

Kind of stale, lifeless, and uninvolving. Fine for subwoofers where SQ is not as big a concern but never for a front stage - yuk!

If you think it sounds good on your front stage it's probably because you haven't heard better.

No, all watts are not created equal.

 

[T3mpest 10+ year member]

Wow, not even really going to bother to argue too much so I'll just say this. First off the pdx measured +/- 1db from 5hz to 35,000hz. You can't hear that type of variance at least not when it occurs ove such a large range and is most likely doing it at the 30,000hz plus mark. Secondly, damping factor is a useless measurement as is slew rate when it gets past a given point depending on power levels. The pdx does fine in both categories the amp wont' put out more than 400 watts when playing music, sorry, just won't happen.

Secondly to slightly attack the credibility of those posting how bad class d's are

1. If your running passive components your setup isnt' even close to good enough to determine the difference, the car's acoustics wrecks your setup, can't polish a turd.

2. Your music selection better involve lots of stuff from sheffield labs and no MP3's or modern compressed music.

 

[squeak9798 5,000+ posts]

To me Class D based amps sound quite different from their Class A/B counterparts and not in a good way.
Kind of stale, lifeless, and uninvolving. Fine for subwoofers where SQ is not as big a concern but never for a front stage - yuk!

If you think it sounds good on your front stage it's probably because you haven't heard better.

No, all watts are not created equal.

//content.invisioncic.com/y282845/emoticons/hilarious.gif.02a037aad04aa96f19982b298a3d70a8.gif

The issues been beaten to death.....but I still find these types of comments absolutely hilarious......

 

[Ekeko 10+ year member]

Wow, not even really going to bother to argue too much so I'll just say this. First off the pdx measured +/- 1db from 5hz to 35,000hz. You can't hear that type of variance at least not when it occurs ove such a large range and is most likely doing it at the 30,000hz plus mark. Secondly, damping factor is a useless measurement as is slew rate when it gets past a given point depending on power levels. The pdx does fine in both categories the amp wont' put out more than 400 watts when playing music, sorry, just won't happen.
Secondly to slightly attack the credibility of those posting how bad class d's are

1. If your running passive components your setup isnt' even close to good enough to determine the difference, the car's acoustics wrecks your setup, can't polish a turd.

2. Your music selection better involve lots of stuff from sheffield labs and no MP3's or modern compressed music.

I am using a well designed home audio monitor in a damped room to test the amps. A/D/S, 4 ohm, VERY flat. Actives in my car, but there is no reason why you couldn't design a passive crossover to get VERY close... Not using Sheffield labs anymore ( I have a couple)-I can only stand so much Pat Coil- I am actually using Sony-London, Telarc & Chesky. I am using SACD for a source, because that was what we used at ASUSA to test out tube amps. And if you are //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif::still looking at graphs to figure out how good something sounds, well...I guess then you are right, there is no point of disscusing it.

FYI most people that work in Audio design know that the plot of a static resistive load is not a set in stone indicator of behavior under real world, dynamic loads with other components such as inductance. There are so many more parameters that affect sound that is quite possible that an amp that measures well within range is doing something else affecting the sound...

PS-I actually like, very much, the sound of well designed class D amps. Alto Mobile makes an awesome example. I am no lover of transistor A/B amps and they are one of my least favorite topologies. But, for all the midrange clarity I get out of my class D amps they are still doing something wrong at the very upper end...it's just that we haven't caught up (completely, there is the 400 ripple that can be measured)with what the measurements are...this is an identical argument to that of tubes vs. transistors...remember that transistor amps started to get good when people rediscovered tubes...SA designers were force to reexamine the limitations of their designs, but only after years of fighting, name calling & graph showing...we learned to use both, brain & ears. At the end both, tube amps & transistor amps got better because we learned so much about what makes an amp sound good... //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

The future of car audio is probably in the class D amplification...but don't hurry it up because there is still catch up to be done. Things are going to get better if we keep the dialogue...

If we stick to absolutes...well, it almost spelled the end of High End Audio in the 80's...things got stagnant. Keep listening to both; discuss what you like and what you don't so we can figure out how to build a better mousetrap...don't get frustrated 'cause there is not ultimate amp the fun is in the search.

 

[Ignatowski 5,000+ posts]

I dig PDX's........

 

[kmanian 5,000+ posts]

i have a 4150 in my wifes car running some Rainbows, it actually sound pretty good.

 

[benzmansl65amg 10+ year member]

they sound great to me

 

[///M5 10+ year member]

I'm interested in the PDX-600.1.
I've honestly never been a fan at all of past Alpine amps (or their products in general). I'm just curious if they actually picked up the quality on the PDX amplifier line-up at all? Those things are super compact, how's the SQ?

You gotta be kidding me, what is the actual noise floor in your car??? WAY beyond that of the amp. As for the frequency response it is more than fine as well.

 

[Boulderguy 10+ year member]

I've tried them & wasn't too happy. The SQ just wasn't there for me. Compared to A/B amps, two big issues I had were a soft low end lacking impact (but EQ-able) and a less-realistic sound.

If you were around when CD's started outflanking vinyl & you ever got to hear a good turntable vs a CD player, it was like that. The vinyl was just more "real" sounding. The PDX amps are like the CD player in this analogy - clean and potent, but not quite good enough yet. I'd give 'em a few more years.