Is this amp any good?

Discussion in 'OT Technology' started by ACURA TL-S, Oct 9, 2002.

  1. ACURA TL-S

    ACURA TL-S OT Supporter

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    http://www.sounddomain.com/shop/item.pl?sku=BOSREV3000D&sidebar_type=&selected=

    It is for a friend this is what he wanted me to post

    im going to get a mono amp that is that one that will push 2200W by one channel at 2 ohmns and then wire it in parallel with two subs that are rated at 350W rms and 700 or 1000 W peak but i think inorder to give me the 2 ohm load that i want to get the hick in power i will have to have a dual voice coil and then how to i hook that up do i use each voice coil in parallel and then each speaker in parallel to the amp. will that work and is that best or do i take two 4 ohm subs and hook them up in parallel to get them to be at 2 ohms that way
     
  2. edrox

    edrox A good man, and thorough

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    about that amp...

    There is a lot to be said about amplifiers like this. If you read the manufacturer's "specs" closely, you will notice that the power listed (2200x1 RMS) carries no THD at that rating. My guess is that it is in the 10% range, if not higher. This rating is what we called ILS - If Lightning Strikes. Should you take a direct hit of lightning to the car, you might get 2200w out of it.

    In buying an apmilifer, you and millions of others, are falling victim to specs that are, essentially, meaningless.

    First off, current (amperage) is what moves your speakers, not wattage. Remember its called an AMPlifier, not a WATTifier. A 100w amp with 12a current will produce more clean, usable plower than a 1000w amp at 3a current. Think of it as a comparisson of horsepower and torque.

    The problem is that dealers and manufacturer's have pushed high wattage for so long, that many of them don't truly know the physics of sound and amplification. They are not intentionally misleading you, they just don't know any better.

    When shopping for an amp, read the ENTIRE spec sheet. If a piece of gear omits critical info, a buzzer should go off. you should see frequency response, thd, power, and headroom. Although most mid-line manufacturer's never quote headroom, they will quote RMS and peak power, essentially the same thing

    A properly stated spec sheet would tell you that the amp has, for example:

    continuous power - 100w, peak power - 300w, Frequency response 10Hz-30kHz THD<.05%

    Look out for an amp that rates its power and distortion at a specific frequency, as opposed to the full range. Some mfgs state it like this: power at 1kHz - 300w THD < .05%

    This means the the amp was fed a short burst, 1000 Hz test tone, and its reults measured. Which is fine if you drive around listening to snare drum taps and nothing else.

    All of this was a long-winded way of telling you there are better amps out there, for the same money. They may not claim 2200w, but the sound, build, quality, and usable power is much, much better.
     
  3. 04

    04 Guest

    Re: about that amp...


    Um, sorry but that is incorrect. Have you ever heard of Ohm's law? Into an 8ohm load the current produced by the amplifier at 100 watts is: P = V^2/R 100 = V^2/8 800 = V^2 V = ~28. Ok, now take a 1ohm load with a power of 100w is 10v. Do the math if you dont believe me. Now if your theory was correct, the 8ohm amplifier would not be putting out as much power as the 1ohm one. According to your theory the Boss amp would be more powerfull than an amplifier that could do 8kW into 16ohms. Yeah right... The voltage output at max sine power for the boss should be 49v and 24a and for the 8kW amplifier it is 358v at 22a. Tell me, since the Boss has more current output than the 8kW amplifier, it should produce more power, right? Therefore also making the speaker move more?

    Since you don't know, an AMPlifier is refering to a signal amplification, not AMPERAGE.

    Dear god man, now you say that the engineers building the amplifiers have no idea what they are doing? High wattage is what I want, not high voltage or amperage, AS THAT WILL BE DEPENDANT ON THE IMPEDENCE OF THE LOAD BEING DRIVEN!!!

    Frequency response is a moot point, since every modern day amplifier can do a flat 20hz to 20khz. Any modern amp has inaudible thd. Headroom is non existant in a car amplifier, because the power supply is a switching type, and will not allow for it. So basically every one of those specs you said should be a mandatory is useless. Also how the hell would an amplifier have a continous power output of 100w while it peaks at 300w? Either that peak or RMS power rating is incorrect. Peak power is 2x constant power, because the RMS voltage and RMS current is .707 x peak voltage/current. If your peak voltage is 10v then your RMS voltage is 7.07v and when multiplied by your RMS current of 7.07 you get 49.99w.

    As for your final statement of better amplifiers out there for the money, in some ways that is correct, and in others it is totally false. The sound quality before clipping will be identical on a bandwidth limited (we are talking class D here) frequency response to that of a super expensive amplifier. The usable power could very well be higher on a less expensive amplifier, because we all know Boss overrates all of its products. As for build quality, you are probably right there too.

    But none of those reasons make it a bad amplifier, you can just get better deals for the money.

    In short, just about every rating an amplifier manufacturer has can be fudged in some way or another. However, usually with decent brands they are pretty close, or even underrate the true power output.
     
    Last edited by a moderator: Oct 10, 2002
  4. BobG

    BobG Fuchs.

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    Re: Re: about that amp...

    Brotha-man just PREACHIN' the truth! :bigthumb:
     
  5. edrox

    edrox A good man, and thorough

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    Wow

    OL so I can see that we are going to need to get on the same page a lot.

    First off, I never saif engineers did not know what they are doing. I am referring to the salespeople we typically run across in your every day Best Buy or Circuit City. Enve then, those guys have a little more on the ball than others.

    Frequency response SHOULD be stated on a spec sheet as a clarification of testing methods and spec attainment. There is a lot of difference between specification quoted across the full range of sound as opposed to specs quoted at a single frequency. Granted, all amps will reeproduce better than 20-20, but when listed on a spec sheet, it is a companent of the overall test used to provide those specs. This is what i am referring to by saying you should look for the FR on the spec sheet.

    Since you are obvioously knowledgable and very well versed in audio, you know that the addition of lower frequencies demands more power from an amplifier. When that amp that was clean at 1000 Hz is asked to reproduce the entire specturm of sound, the load created by lower frequencies can cause more clipping and more distortion than the singular 1000 Hz tone would.

    Headroom is existant in any amplifirer. That is why there is a nominal and a peak. Headroom allows ffor instantaneous, short burts of higher power. You will not find, as I said, headroom quoted as a specification on car amps. You will find, in may cases, a continuous and peak power rating. If you want those peaks to be there, you need current as well as watttage. Your stiffening capacitors are not storing wattage. If headroom is, as you said, nonexistant, then when your amp is maxed out and a demanding passage comes in, you are going to get nothing but clipping and distortion. That is assuming the amp does not shut off completely.

    Given the choice between a 100w (manufacturer rated) Rockwood amplifier and a 100w Rockford Fosgate, which would you choose? which would sound better? Which would have the better, cleaner, power?

    And when you compare the spec sheets of those two amplifiers, you will find exactly what I am talking about here. One that has incomplete or, as you said it, "fudged" numbers, and one that lists exactly what I said.

    As for the physics behind ohm's law, sure that is 100% correct. But how stable is that "2200 watt" Boss going to be at that 2 ohm load? Will it stay there continuously? Myabe, but I would be skeptical.
     
  6. edrox

    edrox A good man, and thorough

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    ugh - just re-read my entry - forgive the typos its early
     
  7. 04

    04 Guest

    Ok, I realize the quoted power should be from 20hz to 20khz, as you are right, that is more accurate than quoting 1khz power, however this is more of an issue with home amplifiers than car ones.

    I never said that low frequencies are harder for an amplifier to reproduce.

    Regarding the headroom issue, it is nonexistant in a car amp. And yes if you are playing loudly and a demanding passage comes up, you will get clipping and distortion. Remember even with 3dB of headroom, that is only 2 times as much power as nominal. It shouldnt turn the amplifier off either, unless their is a problem with it.

    As for the Rockwood and Rockford Fosgate analogy, I obviously would want the Fosgate more, because it would actually put out 100w, while the Rockwood most likely wouldnt. The Fosgate would probably look better too.

    Just because a manufacturer does not state certain specs does not mean it cannot produce its rated wattage, but it is more unlikely that it does.

    I would actually bet that the Boss could stay at a 2ohm load just fine, but then again, I have never used one. I have heard from people that do use them that they work fine though...
     
  8. edrox

    edrox A good man, and thorough

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    042...

    Well sir, maybe you and I are not so far apart as it first appeared. I think we are on the same page, just saying things differently. Maybe you are better at putting it to writing than I am, who knows?

    As in the other thread, I will gladly admit that I have been out of 12V sound for a while. Maybe my memory is not as sharp as I thought, maybe things have changed.

    I sure hate being the old man in the rocker saying "Back in my day ..."

    I realize that you never said low frequencies are hard to reproduce. I was just trying, in my own ham-fisted way, to clarify my original post that started all of this.

    You obviously know your stuff, and I know a good bit (or at least did).

    The problem that I am at least attempting to illustrate is that while the engineers and builders know what they are doing, the box and the print material is done by the marketing department. They will always do their best to present the info in a way that looks best to them. That is why I approach specs like this with the attidue of "Where's the lie?"

    The over-riding problem with this entire situation is that there is no standardization, no governing body for the way the manufacturer's present this information. In the home audio industry, there is, so the information tends to be more apples-to-apples instead of what we have in 12v
     
  9. 04

    04 Guest

    Well, I agree with you 100%. The marketing department is usually full of crap and makes up BS quite often.

    I agree there should be some type of governing body, but even in the home audio governing is not as good as I think it should be.
     

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