what makes a SQ amp so special?

[Desousa93]

Like i know an amp is you get what you pau for but whats an sq amp vs a normal amp? Might sound stupid but since for now i cant fot my L7''s in mu trunk i want to get my components to be loud and clear as possible

[AI James]

english?

[Ben Fultz]

I'm going to go out on a limb and say I think he's asking the difference between a class A/B (SQ amp) and a class D ( normal amp).

[Desousa93]

Sorry. I was typing on my phone keyboard.. i want.to make my component's scream and be clear as possible. Whats a SQ AMP?

[8ight]

Dynamic headroom, damping factor, low THD+N, slew rate...

Give my thread about amps (in general) a read http://www.stevemeadedesigns.com/board/topic/166008-whats-in-those-guts-8ights-amplifier-analysis-part-i/

Also check out these articles:

From the man behind Zapco and Arc Audio, Robert Zeff, a true genius http://www.caraudio-forum.com/forum/topic/4255-anatomy-of-the-power-amplifier-by-robert-zeff/

From QSC (they make a shit ton of AC-powered PA amps) http://www.qscaudio.com/support/library/papers/amptalk.pdf

Getting into actual design:

A little bit of fun http://www.electronics-tutorials.ws/amplifier/amp_5.html

Some more fun if you're up to it/still reading and cognitive http://www.diyaudio.com/forums/solid-state/60918-explendid-amplifier-designed-michael-bittner-our-mikeb.html

It doesn't help to explain what makes a great SQ amp, you must learn what makes a good amp in general. If you're really interested feel free to PM me anytime, even if you just wanna shoot it about amps for a while.

[AI James]

you can have the best amp in the world and not know how to hook it up/tune it and it sound like crap still. Also, not all speakers are created equal on frequency response.

[Desousa93]

Thank you 8ight

[8ight]

you can have the best amp in the world and not know how to hook it up/tune it and it sound like crap still. Also, not all speakers are created equal on frequency response.

Straight shooting. Also be sure the signal making it to your amps is as clean as possible. For a baseline it helps to set a flat EQ, turn all loudness / bass boost / presets OFF, roll with a conservative gain setting if you don't have a scope/DD-1, and use the highest quality source material you can find. Uncompressed music makes a huge difference in quality as well as how you play it back. Hint: headphone jacks suck, most devices outputting audio to a mini TRS jack have a noisy internal amp you cannot bypass that is driving the jack. Best results with a CD or USB drive.

[trumpet1]

Sometimes you need to ignore the manufacturers' claims and marketing lingo and trust your ears. Not all amplifiers sound the same, but you don't have to spend a lot of money to get a good sounding, reliable amplifier. When not run at the limits, one good amplifier should sound very similar next to another good amplifier when the levels are matched close enough that the perceived loudness is the same. It's certainly not as simple as Class AB = SQ and Class D = the rest.

[Johnny2Bad]

Well, you are opening a can of worms here ...it's not really possible to answer your question in one, or maybe even a hundred, forum posts. I will try to lay out some basics but to be honest the ultimate answer takes years of experience because critical listening is a learning process, and without that, it's impossible to judge Sound Quality (SQ) in a system. The amplifier is only one part of the System, although it's an important part.

First of all, specifications are not where you find SQ. It is entirely possible to build an amplifier that tests with very impressive numbers but sounds bad, and it's reasonably common for an amp with a SQ reputation to have so-so numbers. Without taking too much on the subject, I will give an example.

Negative Feedback is a circuit feature common in almost all amps today. In layman's terms, NF takes a little piece of the overall output signal, and compares it to the (original, unamplified) input signal, and then corrects the output signal so it most closely resembles the input. It does this dynamically (all the time).

The details are not important, really, but if you switch polarities of a signal you can create a cancelling signal, and if that cancelling signal is correlated to the distortion component of the output you reduce distortion.

But, there is a time smearing when you do this. It's very small, but not zero. It simply takes a bit longer to go from output back to input and then back to output again. Sp your correction signal is always slightly out of sync with what it's trying to correct. Because electricity travels at near the speed of light in a circuit, and we are only concerned with much lower frequencies (audio band) the timing is pretty close, though.

You can "crank the NF dial" up or down when you design an amp. Use lots of NF and measured Total Harmonic Distortion (THD) goes way down ... numbers like 0.005% are hardly difficult. You can use less NF and maybe your amp measures 0.1% THD; you can use no NF and probably you will measure best THD numbers of 1% or even higher.

So, this is an option, a choice, the designer has in his toolkit when building an amp. And given the example of the three choices above, when used in essentially the same amp design, all three will sound different to a critical ear, and the units with higher overall THD may well sound the best. They have less time smearing of the signal, and will probably have advantages in certain distortion characteristics where timing issues show up (transient response, Intermodulation distortion (where two signals interact, THD measures the amp with a single frequency tone), and so on.

I don't want to make too much of the above; the take-away of all that is its just an example where an amp designer may make a design choice based on listening, rather than measuring. The designer of a modern amp must make **some choice** of NF and that includes not using any. There are many opportunities to make such choices when designing a circuit.

What you want is a designer who makes the choice based on listening to his circuit; what you don't want is a designer who makes the choice based on his measurements alone and fundamentally believes "all amps sound the same". Such a designer has no critical listening skill and believes listening to a circuit is a waste of his time. Buying his products is a waste of your money.

Younger designers tend to build circuits based entirely on what they learned in Electrical Engineering classes. Older designers tend to use their experience where a "perfect circuit" from EE class doesn't sound all that perfect to their ears. The difference is fairly easy to understand when you realize that EE classes are all about theory and typically assume "perfect" components (all electronic design software also assumes perfect components); the real world is all about practical application and experience which shows that nothing ever is perfect ... the resistor (or whatever) in a circuit does not behave exactly the way the theory suggests. If you are into SQ, you don't want the Young EE's amp. It probably measures beautifully, though.

There is more ... a LOT more ... to your question. But I will leave it for now, awaiting comments.

EDIT: corrected a typo: "of1%" changed to "of 1%"