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Does the brand AMP really matter?

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  • Does the brand AMP really matter?

    I am slowly starting to build up my setup, but now I am really trying to budget everything. I was going to go for highend Amps and speakers, but now I really dont want to throw down the money. I am still going with the Alpine SPR-17C for all the speakers.

    I originally wanted to go with the Alpine PDX Series amps, but honestly do not want to spend $250 - $380 per amp. I then came across these that seem to have the same specs as the Alpine PDX, are also similar size, and are very very low in price. They are called STAX Amps. They of course are stackable like the PDX amps. The 4 channel amp is a class A/B, so it will run alittle hotter, and the Mono is a D class. Since I have so much cooling in my case, the extra heat isnt an issue. http://www.poweracoustik.com/pa2006/..._amp_stax.html Do you think these amps are any good? I havent heard anything bad about them. If these amps arent good, what do you recommend? The amps have to be compact, stackable, put out 100 RMS per channel for small speakers and 500 RMS for sub. Also has to be a good cheap price.

    What difference is there between the PDX series and the STAX series, besides the PDX being all class D.

    Thanx in advance!
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  • #2
    Those amps should work ok for door speakers. But I wouldn't rely on the specs from the website.

    100w from a Alpine PDX is probably the same power as ~300-600w from a Power Accoustic.

    Also I would not run that mono at 1 ohm, even though they claim its stable....

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    • #3
      Originally posted by jake789 View Post
      Those amps should work ok for door speakers. But I wouldn't rely on the specs from the website.

      100w from a Alpine PDX is probably the same power as ~300-600w from a Power Accoustic.

      Also I would not run that mono at 1 ohm, even though they claim its stable....
      I only look at RMS..... They say its 500 watts, but at 4 ohms its 100 watts rms per channel. I think the speaker I want to use is 2 ohms.
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      • #4
        RMS is the only worthwhile rating.
        Music Power as was sometimes called "peak" used to be double the RMS but not always.

        Any other Wattage can be anything - I have seen 2800W claimed for watt is (pun ha ha) probably 400-500WRMS. (It's a bit hard getting 2800W through 40A of fusing!)

        Brand name means nothing. It's like Kawasaki & Honda - both have 2 wheels, both are petrol. (Mind you, I would only ever admit to riding & owning the former!)
        (Alpine is considered good or "quality". It doesn't mean others aren't also. Maybe ask over at the12volt.com?)

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        • #5
          RMS means practically nothing. There are many tricks to provide exaggerated ratings.

          The brand name just lets you know how much to trust the ratings and overall quality. Better companies like Kicker, Alpine, etc generally are fair with their ratings. But the lower end amps like Pyle, Power Accoustic, etc are generally very overratted.

          I would bet a sum of money that an Apline PDX 100w rms amp would be more powerful than a Power Accoustic STAX 300w rms. Thats just a guess going from the companies reputations.

          Also cheaper amps that are rated to be 1 ohm stable generally are not.

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          • #6
            You've heard it all before, but they make a huge difference.

            I've tried finding a decent "100w RMS" amplifier for a while now for my speakers. It is very difficult to find properly rated ones these days. I went through Visonik, Power Acoustic, all those crappy brands while testing.

            I settled on a nice Kenwood unit that sounds wonderful. Same goes with the subwoofers. I stuck to a brand that I've heard good things about, MTX Audio, and although they aren't hooked up yet, I am confident that they will sound excellent and produce clean notes.

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            • #7
              Originally posted by jake789 View Post
              RMS means practically nothing.....
              I mostly disagree. Whilst here are many more factors than power output with relation to and loudness, quality etc, RMS is the best measure we have.

              It is also the most useful in general - ie, how much power is being consumed or required, how much heat etc.

              It is a simple formula that cannot be argued. It is RMS. It does not care about peaks or waveforms etc.
              It can be qualified - eg, 300W RMS between 20Hz & 20kHz.
              But it cannot be fudged using trickery.

              It can be misunderstood etc - eg, people multiplying voltages and currents at different frequencies, or confusing true-RMS voltage and current meters and readings with RMS power meters.
              But for DC, RMS power is V x A. For AC, use a resistor and measure the heat given off.


              It is other power figures that will mislead - peak, music, max, transient.

              To use an example - my car's engine outputs a peak of over 3,000HP, yet it is only a "67 HP" engine as measured on a dyno at max output (ie, RMS rating).
              Which figure do you think is the best to use?


              As to power (RMS) versus volume - that's a different issue.
              I rarely see amps advertised with an SPL output - most seem to go by power (Wattage).

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              • #8
                i have a late-model 4 channel kenwood amp and its outstanding. i run infinity kappa 5x7's all the way around, and they are 100w rms speakers. the amp drives them all nearly to their max, as it should (80w rms x 4 amp specs). crystal clear, one of the cleanest car amps ive heard.

                mine are also 2ohm speakers, and while i havent noticed that much more volume out of the amp, it is much nicer to have the gain set just over half way when with 4 ohm speakers you need to crank it past 3/4 way....

                the amp makes as big of a difference as the speakers do. you dont need to spend a lot, but something like $150 for an amp and $100 for a pair of speakers will get you into the quality stuff.

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                • #9
                  I'll say this and then I will shut up.

                  Don't get me started on power acoustic! I wish their company would die and burn in hell!

                  I'll leave it at that.
                  ATTENTION FELLOW CAR PC ENTHUSIASTS, POWER ACOUSTIC = CAR PC KRYPTONITE!!!! AVOID AT ALL COSTS!!!!

                  To my adoring fans, No my Toyota's gas pedal didn't get stuck! Instead I saw you crossing the street and decided to floor it! Unfortunately, I MISSED!!!

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                  • #10
                    Focus on RMS ratings, S/N ratios and impedance. They're probably the most useful specs you'll need for an amplifier.

                    Yes, generally the more expensive amps ARE better than the cheaper ones, but it's not quite an absolute rule (but is true in most cases).
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                    • #11
                      Thanx everyone for the comments and advice. I guess the one issue that limits me is the size of the amp. It has to be a certain size since I set it up to work with the PDX series amps. The PA STAX amps are the only other amp, that is within my price range, that will fit. A lot of the small amps are not powerful enough and usually have a 50 rms per channel, which will not power the speaker, since Alpine speakers are know to work like $h!+ if they dont get the RMS they are made for. It looks like I am being backed into a corner and may have to go with the PDX either way. Toyotatyrant has now scared me away from using PA products, although I have seen good comments on the Stax series. Is there a way to measure the amps RMS out put? Maybe I can buy a Stax Amp for testing and see if it can put out what it claims.
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                      • #12
                        I was actually looking at this amp myself when I was deciding on a 4 channel amp to run my stock speakers. I ended up going with the BAMF series from the same company for some reason. I believe they have the same specs, just a different casing. They sound pretty good; good enough that I ended up not upgrading my speakers until a later date. I'm not an audiophile nut in any way, but I do like my music to sound good.

                        Anyways, I believe the amp you're looking at is pretty small and sounds good enough. Also, for the price, you can't go wrong.

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                        • #13
                          one of the other things that i like to see is CEA certified power ratings-- while it is a non-enforced standard for car audio power ratings, some of the bigger companies like alpine(i know for sure alpine uses it, and i think jl audio is another one) have started using it, making it easier to judge what the amp will put out compared to other brands--it at least puts all the amps on equal ground, and eliminates some of the voltage variables that some of the less popular companies tend to use to boost ratings.

                          not sure if you have seen them, but last i went through the car audio shop, they were showing me these for a different option to getting a pdx, or a HD series amp:
                          http://www.kenwoodusa.com/Car_Entert...plifiers/XR-4S

                          they are very similar in size, and power to the pdx series, and a crutchfield is selling them refurbished for $270(so they gotta be somewhere else for around $200 ). all the guy could tell me about them was that they sold a lot of them, and they sounded great. but he was trying to sell me a amp, so take it with a grain of salt..

                          since alpine came out with the pdx series, the category for small amps has gotten huge--just thinking about it, almost every car audio company has since built their own version of them-- so just look around, compare the numbers, and if they only tell you about the peak wattage, run far away. the one that might get you stuck the quickest would be this one: generally, the higher s/n(signal-to-noise ratio) the better quality the audio is going to be coming out of the amp.

                          if you want to play with the big dogs, your gonna need to pony up. power ain't cheap.(and this is the reason that i still have the same setup from my last car, making it a 4 year old setup..)

                          Originally posted by toyotatyrant View Post
                          I'll say this and then I will shut up.

                          Don't get me started on power acoustic! I wish their company would die and burn in hell!

                          I'll leave it at that.
                          actually, i am kind of interested in why they are so horrible--i have seen their products here and there, i always thought it was nothing to write home about, but they always seemed to do decent for the cheap cost(cost being the biggest factor).
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                          • #14
                            I'm scratching thinking back to where and what century I read that "a good amp" should output double the power for halve the impedance (speaker Ohms).
                            And whether that included 12V amps etc.

                            But having relatively recently stated elsewhere that increasing speaker resistance could overheat an amp... (Sorry - wrong century. Or not audio amps.)

                            But I like the S/N ratio comment.... (Providing they don't use 1-uSec peak signal and normalised 1Hz "audible only" noise... Nah - it's a ratio, of RMS values?)

                            As to Amps RMS output - isn't that useless?
                            Don't you want power?

                            Or am I thinking electrical (socket/mains) AC power where (eg) [email protected] times [email protected] = 0 Watts (not 100x10=1,000W)?
                            Whereas in audio, the output current is the output voltage divided by the resistance (all at whatever frequency).

                            And now I don't know why I even bothered...

                            Yes - I like the S-N comment.
                            And the RMS output current merely needs a "true RMS" ammeter that covers the frequencies involved (as does true-RMS voltage).
                            True RMS power is the heat given off a resistor (or speaker core?)
                            (Sorry - it's 2:55AM.)

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                            • #15
                              Originally posted by soundman98 View Post

                              actually, i am kind of interested in why they are so horrible--i have seen their products here and there, i always thought it was nothing to write home about, but they always seemed to do decent for the cheap cost(cost being the biggest factor).
                              How about knobs, buttons, and controls not working on their products after about 3 to 6 months. LED indicators out in 3 months on brand new equipment. Sounds like a great buy to me huh? Yes, I've run into all of this with their products. Their customer support is terrible, not to mention the specs and claims are so overblown to the highest extremes to add insult to injury.

                              That stuff has some of the worst quality control I have ever seen out of anything! I'd honestly pay for Kraco or Pyramid before I would even consider donating a jar of my pee to Power Acoustik.

                              Do I sound hostile toward them. Absolutely, because people pay money for that s#!%. Despite that it is not top of the line gear, it could at least power up and work like it's supposed too. That stuff is 100% JUNK! And I would not do the crime of recommending anyone pay their hard earned money for any of it. I'm sorry, my feelings are that strong about their stuff.

                              Again, I hope there is a special place in hell for that company, and I mean it!
                              ATTENTION FELLOW CAR PC ENTHUSIASTS, POWER ACOUSTIC = CAR PC KRYPTONITE!!!! AVOID AT ALL COSTS!!!!

                              To my adoring fans, No my Toyota's gas pedal didn't get stuck! Instead I saw you crossing the street and decided to floor it! Unfortunately, I MISSED!!!

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