A/B vs. D

[genxx 10+ year member]

You guys with golden ears need to sign on for the $10,000 amp challenge. Hell I would put my paycheck on it that in a double blind test you will not hear the difference. This has been debated and is like beating a dead horse really.

I will leave you guys that have golden ears to fight this one out.

This is just my opinion as well.

I competed in IASCA and USAC years ago with class D and no one ever new the difference. Not one judge or anyone that listen to the car or truck ever commented on if I ran class AB I would improve my sound stage, imaging or anything else. I did switch to class AB 1/2 way through a season and my score sheets stayed the same. I run class AB now because the amp manufactures I like produce AB, if they made class D I would run that. Like Zapco DC, ARC and Audison. I still have some class D amps and still cannot hear the difference.

 

[michaelsil1 10+ year member]

This is what I read: Class D Amplifiers have higher distortion @2 KHz and above; (whether it's noticeable to the human ear I couldn’t say); another issue is the four channel Amps have crosstalk how much I don't know. I was using the Alpine PDX 4x150 full range I wasn't that happy with the top end I'm not sure if it was crosstalk, distortion or both (no meters). I'm now using the PDX Bridged for Mid Bass and an A/B Amp for Tweeters; I like this setup much better.

 

[squeak9798 5,000+ posts]

i believe its an a/b. go to maxxsonics.com and check
1000 watts wont be very significant either way. about 20 amp draw difference.

I would disagree.

The difference very easily could be significant, especially on a stock charging system.

Depending on various factors, the difference in current draw at full power and/or 1/3 power (closer to where an amplifier will typically be operating) could be anywhere from 40A - 60A

 

[squeak9798 5,000+ posts]

Eric Stevens of Image Dynamics can tell a difference. Well, he suggests class a/b amps or higher quality class d amps, but there is definately a difference for him. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

No one has ever proven they can hear a difference in amplifier topology.

I'll leave it at that.

 

[NeoNot 10+ year member]

You guys with golden ears need to sign on for the $10,000 amp challenge. Hell I would put my paycheck on it that in a double blind test you will not hear the difference. This has been debated and is like beating a dead horse really.

I dont believe the amp challenge is comparing Class D to Class A/B. If memory serves me correctly it is comparing the 1Watt is 1Watt no matter what amplifier it is playing on.

In this reguard I would agree with you. If you have two devices setup to run at the same level with no additional filtering on either amp they should sound the same.

The issue that I see between the A/B and D amps is the power supply. I dont know what speed the D class amps power supply pulses at so I have no idea if you can hear it or not. I would however have to believe that at some given point in a song the power supply will pulse and cut off a note since the output stage have no power. This in turn could create a problem. The key is how quick it pulses. If the pulse is quicker than the human ear can detect then it would most likely not be noticable.

Again I say check both amps out and see which sounds the best to you. That is the amp I would purchase, if it was me purchasing the amp.

 

[squeak9798 5,000+ posts]

I dont believe the amp challenge is comparing Class D to Class A/B. If memory serves me correctly it is comparing the 1Watt is 1Watt no matter what amplifier it is playing on.

The premise of the amplifier challenge is that the "sonics" of an amplifier are completely characterized by the measurements of frequency response, power, gain, noise and distortion and generally identifies limits regarding what differences in these measurements are audible.

What does this mean? That if the above 5 measurements above are within inaudible tolerances, the two amplifiers will "sound" identical regardless of the amplifier topology.

 

[FoxPro5 5,000+ posts]

Class A usually sounds Awesome, everyone knows that.

Class D usually sound Dirty.

They are named for how they sound, can't believe you guys don't know this.

 

[helotaxi 5,000+ posts]

The issue that I see between the A/B and D amps is the power supply. I dont know what speed the D class amps power supply pulses at so I have no idea if you can hear it or not. I would however have to believe that at some given point in a song the power supply will pulse and cut off a note since the output stage have no power. This in turn could create a problem. The key is how quick it pulses. If the pulse is quicker than the human ear can detect then it would most likely not be noticable.

Most A/B amps use a pulse width modulated power supply. Class A/B and Class D refer to the output topology, not the power supply. Class A/B uses a linear(ish) push-pull transistor arrangement where the output device will vary from fully on to fully off and all the range in between. A Class D is a switchmode amp where the output devices are either fully on or fully off but never in between. The Switching of the outputs when filtered through an inductor creates a very good approximation of signal. The linearity and efficiency of the amp is based on the switching freq as you somewhat get. There is a tradeoff in efficiency to get better linearity. For a full range Class D linearity is more important and some efficiency is sacrificed. For limited bandwidth dedicated sub amps, efficiency is more important and linearity suffers a small bit; however, because of the nature of the filters used, the effect of a low switching speed on the linearity of the amp is very small at low frequencies.

Based on your statement above it is quite apparent that you don't fully understand how a Class D amp operates and your conclusion about the relative sound quality capabilities of the different amplifier classes is based on uneducated speculation rather than educated reason. Digital audio uses a switching algorithm to convert analog sound into a digital data stream. It is generally not considered to have a negative effect on the quality of the sound. Why then would a properly designed switching amp?

 

[hoodkid 10+ year member]

Before I got my Kx2500.1 fixed, i was just playing around and hooked my type r up to my 4-channel amp, and bridged it, It was getting about 500 watts from that amp, and when I finally got my Kicker hooked up and installed I noticed a difference, the 4-channel amp seemed to be more musical, and the low end was better, idk it was wierd, musically at lower volumes the 4-channel amp sounded better, but of course when I cranked the kicker it killed it in output, but at lower levels around the same watts as my other amp, the 4-channel one sounded better.

 

[dB-SPL 10+ year member]

Before I got my Kx2500.1 fixed, i was just playing around and hooked my type r up to my 4-channel amp, and bridged it, It was getting about 500 watts from that amp, and when I finally got my Kicker hooked up and installed I noticed a difference, the 4-channel amp seemed to be more musical, and the low end was better, idk it was wierd, musically at lower volumes the 4-channel amp sounded better, but of course when I cranked the kicker it killed it in output, but at lower levels around the same watts as my other amp, the 4-channel one sounded better.

I'm not sure the comparison of a 500W amp and a 2500W amp would even be fair enough to state that amplifier class alone would cause sound quality to vary.

-Bill-

 

[helotaxi 5,000+ posts]

around the same watts as my other amp, the 4-channel one sounded better.

Same watts based on what? Your guess? Differences in setup not amp topology.

 

[audiowizard 10+ year member]

my amps D class it sounds amazing

 

[hoodkid 10+ year member]

when I installed my KX everything was stock with 4 gauge so I didnt crank it up till the next week when I had my electrical upgraded, So I had the kicker amp gains set very low, I didnt use a DMM but I was guessing it was putting out around the same power as my other amp, they were both equally loud, but the 4-channel amp just sounded better than my kicker amp, when i had it set relatively low, all im trying to say it when I had my 4-channel amp at full tilt, and then hooked the kicker amp up and set the gains really low, the output was very similar but I could tell a difference in the way both amps sounded.

 

[helotaxi 5,000+ posts]

I didnt use a DMM but I was guessing

This

I could tell a difference in the way both amps sounded.

Completely explains this. Totally nonscientific, biased and invalid.

For a comparison like this to be valid you would have to match the outputs and keep the power level within the usable range of both amps as well as the speakers they are hooked to. You would then have to be in the dark as to which amp was playing at any given time to keep your preconceived notions from biasing your listening. Doing any less is going to yield a totally worthless opinion.

 

[joetama 5,000+ posts]

Years ago the assumptions that Class D didn't hold a candle A/B or pure A was true...

HOWEVER, with todays transistors and circuit technology a Class D is just as good as a A/B for most intents and purposes.

Class D is great because it is a VERY efficient circuit output method.

I honestly wouldn't ever use a A/B or A in a car on a subwoofer. They are just too inefficient for this use, and generate A LOT of heat from wasted energy.

Home is a different story and High Frequency is a different story in a car. But, Class D is great for car use, Low Frequency and High Frequency...

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