Quality of Amps

[kronos98]

Like I mentioned in another post, I've been testing out various amps with my subs. I never knew exactly what was meant by a "poor quality amp" until I heard for myself.

The first amp that I had tried was a US Acoustics. I must say, it set a pretty high standard, because nothing I've tried so far has left quite an impression on me. After I apparently blew that one out by accident, I tried an MTX, Sony, Jensen, and finally a Profile. None of them have satisfied me as much as the US Acoustics did.

Instead of a manly pounding that the US Acoustics produced, the Sony, Jensen, and Profile all felt very limp. The bass replication was imperfect...very loose and ringy. The MTX certainly made my subs punchy, however, the bass was muddled, and not very clear.

Exactly what causes that? Why are some amps better than others? I'm not looking for an answer like..."price tag" or something like that. Does anyone know exactly what in the design/circuitry makes one amp so clean and crsip, while others struggle? I'm an engineering student, and the a technical answer is what I really long to hear.

Thanks all.

[Gunman]

For me to explain and for you to fully understand, I would have to send you to school for a year.

[kronos98]

lol. i'm a chemical engineer, and unfortunately, we don't learn anything at all that would help me with circuitry.

good to hear from you, again, gunman. haven't seen you around recently.

[Gunman]

been busy with a whole bunch of things going on and all, but basically like everything else, there are things that seperate components from the rest. The most important is the current draw which determins the power of the amps. I always get a kick out of amp that claims 1000 watts and only has a 20 amp current draw. If you know the math, you would understand thats impossible. If you apply ohms law, a 20amp power amplifier will only produce about 250 watts. What a lot of companies do is use a peak power rating. Thats all gonna change soon by the respectable companies, where they are gonna regulate themselves, by printing only true rms ratings. JL audio has done that from the get go, and are very good amps. Of course this is a basic summary, and its very possible to get more than 250 watts out of 20 amp draws, by using digital filters, regulated power supplies, more effecient heat transfer and different class types, but thats too far involved to get into. Bacically if you see some huge power 2000 watts amp for $199.00 be very wary.

[prophesized]

why are some amps better than others? the same reason bentley is better than kia.

better quality components, better filters, the craftsmanship involved, the engineering behind the amp to make it perform best, how long it will last, reliability etc are what make brax better than pyle.

[pro956]

i have a few us acoustics amps on hand, maybe i can replace your old one that u liked so much, what are you trying to power?

other quality amps- tru, arc audio, older clarions, older fosgates, jl, zapco, planet audio (much like us acoustics, made in the same factory--but us acoustics moved to a different manufacturer in asia for cheaper labor and so on, avoid newer us acoustic amps), linear power, brax, xtant, and umm, i'm know i'm missing a bunch but whatever

[Luc]

All amplifiers consist of 3 stages: input stage, gain stage, and output stage. On the gain stage, it depends on what the manufacturer chooses to use, whether it'd be a differential or complementary FET or BJT, or Darlington design. Much of the transistor design depends on the doping densities between the n- and p-substrates. FETs are used more widely since they are easier to design with and more efficient compared to BJT. Within the FET, there are MOSFET, JFET, GaAs, etc., thus different designs for different application. A good class to take is "Fundamental of Semiconductors", where it explains the intrinsic characteristics of transistors.

[Luc]

by using digital filters

Digital filters? In an analog circuit design? Unless there's a DSP or microprocessor in the amplifier design, there exist no such thing.

[swimshady906]

arent class d amps digital? isn't that why they are so efficeint for the most part?

[Gunman]

by using digital filters

Digital filters? In an analog circuit design? Unless there's a DSP or microprocessor in the amplifier design, there exist no such thing.

trying to use tems that he can understand, but the new alpine amps are all digital, the heat sinks are for cosmetic purpose since it is all digital, you can bury one of those amps and not worry about it overheat since it cant.

[Luc]

I hope you will all understand that there is NO such thing as a digital amplifier, that's just marketing terms, since digital implies better. Those mono-amps are all rated Class D and D does NOT equal digital. It's just a design parameter, where it's at least 80% efficient with limited bandwidth. Thus, they are perfect for subs, since you wouldn't want to feed something like 1-kHz to a sub anyway. Class A is the least efficient, but the cleanest, since current runs through the transistors even when the amplifiers are NOT on. Class B is more efficient, but doesn't produce the best quality, thus, Class A/B comes along, with designs from both, but only operating about 50% efficiency. Class A, B, and A/B all have full bandwidth support, thus, using them to run subs may be a waste of productivity and power. Class D uses a switching power supply, thus, doesn't require constant power consumption. Getting into more specifics would be too much to list, so these are just in generality. After studying all the different classes, FET/BJT types, etc., it tends to escape memory, unless of course you are a professor.

[swimshady906]

i understand gunmans backrounds in the audio eqp. (i think for the most part) but i dont know your's luc... care to share?

im not trying to be rude or sound like a smart ahh, im just curious.

[Luc]

BSEE, MSEE, MECP installer. How's that?

[ZapmanSQ]

quality amp! all i know AB class amp is the best for sound quality.

[Luc]

quality amp! all i know AB class amp is the best for sound quality.

If you have the money, try a Class A, that is the "best."