Do Class D amplifiers sound a lot better than Class AB Amps?

[MacLeod1592]

Im one of the extremely few audio nuts that believes there is no audible difference between different types of amps. Tubes are the one exception because of their resistance, they roll off the top end of the frequency spectrum which gives you a "warm" sound. A class AB could do the same with an EQ.

An amps only job is to take the source signal, amplify it and transfer it out to the speakers without changing anything from the original signal. It doesnt take a big fancy bunch of circuitry to do this. You can look at frequency response graphs when amps are tested, theyre ruler flat from 20-20KHz.

If you think about it, why would you want an amp that changes the sound? You wouldnt.

The thing about class D amps is that theyre much more efficient so youll get more output power with less input draw. Theyre also smaller and run cooler usually. But theyre also much more expensive. Class D amps are best for subwoofer applications because those need a lot of power and the D's efficiency helps out a lot with this. I prefer AB for mids and highs because the amps are cheaper.

 

[HeXen]

Pure class A wins. Class AB is very good. Class D varies greatly, you could include Class T, G/H...etc since their apparently all basically class D topology.
Remember class D can produce lots of interference effecting radio stations too. Some are designed to prevent that, Some sound better than others...i guess the old saying about getting what you pay for can be more appreciated with this particular Topology.

Truth is most people won't notice a difference, others wont care and only a few who will and do care.

Point is, not all Class D amps are the same. you mostly look at other spec features to determine your needs.

 

[sam013]

Hello,
I want to replace my Receiver that has excessive noise or distortion at loud volume levels can be unlistenable. I prefer audio recievers with a low distortion level than a more powerful amplifier with high distortion levels.My personal choice is Denon AVR 1911,to buy this product An additional factor is the ability of a receiver to output its full power continuously. Recomend me any online store which describe all technical specifications about the Denon AVR 1911.:whiste:

 

[alcoholbob]

Wow, I thought outsourced salespeople only went to post on cesspool message boards like [H]ardforum. But anandtech too?

 

[ericlp]

Bi-wiring is when you take one wire from the amp output and split it into two at the speaker inputs. Perhaps you are thinking of bi-amping? In which case you need an active equalizer and crossover management, such as getting a set of Behringer DCX and DEQ2496. That would put you back at least $500 and this is considered one of the least expensive ways to bi-amp. You're better off spending your money elsewhere.



Not everyone has 95.5db sensitive speakers. A cursory scan of Amazon shows most speakers are closer to 89db. Take a typically seating distance of 10 feet and you have 79db @ 1W. Reference levels are 95db with 105db peaks. This would require 37W RMS and 370W for peaks.

My living room theater's sitting distance is 19 feet from my screen and I've got a pair of NHT Classic 4s, with 86db sensitivity, giving me 71db@ 1W. This requires 134W RMS and 1340W peaks to hit reference levels. My Yamaha RX-Z11 receiver only has a 1000VA transformer so it's unlikely to pull this off.

And even going by your example of a 95.5db sensitive speakers, you'd still need 45W to hit reference peaks at 10 feet.

I don't think its necessary to have 105db peaks...

[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]With a sensitivity of 95.5dB, impedance of 8 ohms and frequency response of 39 - 23,000Hz +/- 3 dB and boasting a front-ported bass reflex, the Synergy F2 is one amplifier-friendly and easy-to-place speaker. Most importantly, it matched the TA-10 perfectly. Since the F2 is bi-wirable, I used two TA-10s, one per channel. I started with the Restek CD player as source hooking up the amps directly through a pair of Y-adapters. I turned the Alps volume control on the back of the Restek to maximum and maintained the TA-10s in integrated amp mode so that I could balance the left channel and right channel volume which I find very important for some classical recordings. I never had to dial up the volume beyond 10 o'clock to get life-like sound pressure and presence. That allowed the Tripath chips to work comfortably within their low distortion range. The bass was powerful and clean cut thanks to the dual 6.5" woofers on each speaker. And the mid and high frequencies are airy and liquid smooth thanks to the 1" aluminium dome tweeter coupled with Klipsch patented 5" Tractrix square horn.

I know the trends is a bit of an old amp already. But, I believe you can bi-wire using 2 amps per channel using a pair of Y adapters per speaker you can double the watts as the above. Take it what it's worth even tho you could build your own custom hi pass filter for the paranoid.
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[Howard]

I don't think its necessary to have 105db peaks...

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Depends on how used to live music you are and what your general preferences are.

 

[Specop 007]

Im one of the extremely few audio nuts that believes there is no audible difference between different types of amps. Tubes are the one exception because of their resistance, they roll off the top end of the frequency spectrum which gives you a "warm" sound. A class AB could do the same with an EQ.

An amps only job is to take the source signal, amplify it and transfer it out to the speakers without changing anything from the original signal. It doesnt take a big fancy bunch of circuitry to do this. You can look at frequency response graphs when amps are tested, theyre ruler flat from 20-20KHz.

If you think about it, why would you want an amp that changes the sound? You wouldnt.

The thing about class D amps is that theyre much more efficient so youll get more output power with less input draw. Theyre also smaller and run cooler usually. But theyre also much more expensive. Class D amps are best for subwoofer applications because those need a lot of power and the D's efficiency helps out a lot with this. I prefer AB for mids and highs because the amps are cheaper.

There isnt when levels are matched, equipment is ran within spec and sound processing is turned off. In fact another individual was so convinced of it he put up $10,000 to anyone who could identify a difference between amplifiers in a blind listening test.

10 grand. NO ONE passed it over the years the challenge stood and many tried.

Thats pretty telling. Now of course this was in a controlled lab setting, and even the author of the test Richard Clark will admit amplifiers do sound different in the real world.

http://www.tom-morrow-land.com/tests/ampchall/index.htm

 

[MacLeod1592]

Totally agree. Clark put that up ages ago and it still stands.

You're also right that its not that we're saying all amps sound the same, cause that's not the case. Better quality amps will have no noise, bigger amps will have more power and be more dynamic, feature rich amps will have lots of processing and so on. What we're saying is that one type of amp or circuitry has a different sound than another if it's functioning properly and that you buy an amp for power and features and not for "cleaner highs and tighter midbass". Those are characteristics of speakersb not amps. Same goes for cables and power cords and other snake oil that gets sold to people.

My favorite is the Signal Cable Magic Power Cord. That's really the name and its a $60 extension cord about 3' long that claims all kinds of ridiculous improvements to your sound. Never mind the fact that the juice has already travelled they a bunch of miles thru standard cable, they transformers and regulators and then thru basic cables they your house, fuse boxes and everything but those magic 3 will make a dramatic difference? The best part of all is that the AC power that is magically running thru your cord is turned into DC by the amps power supply anyway so all that magic is lost before it ever actually gets to the amp itself!

 

[Fallen Kell]

My first thought is that a class D would have less audible harmonics. In Class AB you have actual audio coming through the entire amp, where in D its converted to a PWM signal at some point. With an AB on the outputs you have audio frequencies moving around directly, where in D the thing is turning on and off thousands of times per second. No chance for an even harmonic if the output device is running at 4 times or more then the highest audible frequency right?

Just a thought.

Which is all a moot point unless you are playing back vinyl from an analog player (not the newer digital players) and the pre-amp/receiver does not do anything like "room correction", or "dynamic eq", etc., in which it does a analog to digital conversion which will then lose all the harmonics past the sample rate used by the converters...

 

[ericlp]

What we're saying is that one type of amp or circuitry has a different sound than another if it's functioning properly and that you buy an amp for power and features and not for "cleaner highs and tighter midbass".

Well, I guess..... But why even put a label THD on amps if your not going to buy one for clean sound?

I agree on cables. As long as the cable is a at least 16 gauge and pure copper maybe even add oxygen free copper (makes it more pure so they say)... I'm all for it as being great sounding ...

I use to think amps didn't make much of a difference ... till I read a review @ 6moons on the sonic T-amp and so I bought one for 30 bucks. I was looking for new computer speakers anyway, so 30 bucks plus I had some cheap speakers. Damn! 6moons was totally right....

Next thing you know I'm bringing my reference speakers in to my computer room to hook up to the crappy ass spring clips that I hate so much... UNBELIEVABLE ... I went out and bought a trends t-amp for the living room as my expensive onkyo sounded like crap ... good for movies but crap for music. Anyway.....

If your happy with your setup that's all that matters and if it sounds good to YOU then who cares...

Happy listening!

 

[gevorg]

Class D is ideal for car audio.

For home/desktop use, a good Class AB is better than a so-so Class A, and so on. Choose what sounds good to you, not how specs say it *should* sound.

 

[HeXen]

Class D is ideal for car audio.

For home/desktop use, a good Class AB is better than a so-so Class A, and so on. Choose what sounds good to you, not how specs say it *should* sound.

not really. the same applies to both. Actually if you went to a Caraudio forum and said that, you would be short from banned and called a troll.

Car audio enthusiasts are much more sensitive, their literally nuts. If your not using Helix pure class A or some oldschool PPI, your screwed. more or less speaking. Use mainstream brands and your screwed too...go figure, but they really seem to hate China.

That said, and as i mentioned before, a good class D amp can be as good sounding as Class A/b. But its more expensive to develop and many other factors get involved.
Unless you know your specs, class D should be avoided for both HOme and car audio, cause its a technical nightmare and every manufacturer tries to pull on the marketing gimmicks.

 

[gevorg]

not really. the same applies to both. Actually if you went to a Caraudio forum and said that, you would be short from banned and called a troll.

Car audio enthusiasts are much more sensitive, their literally nuts. If your not using Helix pure class A or some oldschool PPI, your screwed. more or less speaking. Use mainstream brands and your screwed too...go figure, but they really seem to hate China.

More sensitive than home audio? Car is one of the worst environments for audio, how can you be more sensitive in it when there are so much reflections/etc going on. And I was pretty much talking about general car audio enthusiasts that upgrade crappy stock speakers to some nice Polks and Alpines. No comment on those niche and self-proclaimed audiophiles with their "golden" ears.

That said, and as i mentioned before, a good class D amp can be as good sounding as Class A/b. But its more expensive to develop and many other factors get involved.
Unless you know your specs, class D should be avoided for both HOme and car audio, cause its a technical nightmare and every manufacturer tries to pull on the marketing gimmicks.

Troll!

 

[HeXen]

More sensitive than home audio? Car is one of the worst environments for audio, how can you be more sensitive in it when there are so much reflections/etc going on. And I was pretty much talking about general car audio enthusiasts that upgrade crappy stock speakers to some nice Polks and Alpines. No comment on those niche and self-proclaimed audiophiles with their "golden" ears.
Troll!

you read wrong. sensitive as in defensive and technical. You have to be more technically knowledgeable with car audio because as you said, its a harsher environment to produce quality audio. golden ear or not, it can be a pain and expensive to get good, spacious sound.
You don't just go in to those forums talking about your new Rockford Fosgate speakers and Sony amp without harsh criticism.
like i said, most of them are nuts. well all audiophiles are nutty imo.:sneaky:

my comment about class D is valid. If you don't know much about technical specs and what to look for and your looking for high quality sound, then you should avoid it. A quality sounding class D amp can be more expensive than equivalant sounding class A/B. Cause its harder to design a Class D amp than a Class A or A/b for that matter. And marketing gimmicks get out of hand with Class D..including its derivitives Class g/h, class T...etc.
not saying Class D itself should be avoided. OP asked if one sounds better than the other and i say no to the higher end products, possibly to mid level and likely to low end.
but we all listen differently and SQ itself is subjective imo.

 

[alcoholbob]

Class D gives you a lot of power, it's just takes a hell of a lot of power to clean it up. Same thing as magnesium speaker drivers, they can be really damn good in a fixed performance band, but need a hell of a lot of work to push down the resonances.

 

[alcoholbob]

double post

 

[MacLeod1592]

Well, I guess..... But why even put a label THD on amps if your not going to buy one for clean sound?

THD doesnt mean how clean an amp is or isnt necessarily. Its a rating of how hard an amp is being pushed at its rated power. Its kinda like how they tell you the RPM when they tell you the horsepower of a car, so you know how hard the engine has to rev to get that number. An amp that makes 1% THD at say 100 watts, would maybe make .5% at 50 watts (just hypothetical numbers).

The human ear cant hear anything below 1% anyway, so seeing a rating of .005% THD only means the amp isnt being pushed very hard to make that rated power so if you have one amp rated at 100x2 @ .005% THD and another rated 100x2 but at 1% THD, you know the former is a more powerful amp cause it doesnt need to be pushed as had to get that power.

 

[Howard]

THD doesnt mean how clean an amp is or isnt necessarily. Its a rating of how hard an amp is being pushed at its rated power. Its kinda like how they tell you the RPM when they tell you the horsepower of a car, so you know how hard the engine has to rev to get that number. An amp that makes 1% THD at say 100 watts, would maybe make .5% at 50 watts (just hypothetical numbers).

The human ear cant hear anything below 1% anyway, so seeing a rating of .005% THD only means the amp isnt being pushed very hard to make that rated power so if you have one amp rated at 100x2 @ .005% THD and another rated 100x2 but at 1% THD, you know the former is a more powerful amp cause it doesnt need to be pushed as had to get that power.

We don't fully understand how much, or what type, of harmonic distortion is audible yet. You say 1% THD is only beginning to be heard but I would say that 0.9% 5th harmonic (say, at 600 Hz fundamental) would be exceeding painful to listen to.

 

[alcoholbob]

The order of the harmonics is very important. A much lower amplitude is audible at higher, odd orders. Otherwise people wouldn't be complaining so much about low level ringing.

 

[joetekubi]

I don't have golden ears - for years I've thought that there was no real difference in amplifiers beyond "high current" designs like HK or NAD. I hang out with a bunch of high-end audio guys into DIY speakers, and suddenly many of them are going to Class D amps because they sound a lot better to them. Some of the DIY Class D kits are pretty reasonably priced, so I'm going to try it out myself.

 

[HeXen]

the only thing that bothers me with the cheaper class d amps personally, is how...well at least the ones i've experienced, how they interfere with FM stations. i have one in particular where i can't hardly pick up anything, some seem worse than others. But i suppose i need to come off the wallet for Sirius radio.
I found it hard to tell from specs, unless its specifically noted, if its going to cause interference or not...but i think its something to do with the damping factor? but i believe the source of the issue itself is the power switching supply

 

[Howard]

the only thing that bothers me with the cheaper class d amps personally, is how...well at least the ones i've experienced, how they interfere with FM stations. i have one in particular where i can't hardly pick up anything, some seem worse than others. But i suppose i need to come off the wallet for Sirius radio.
I found it hard to tell, unless its specifically noted, if its going to cause interference or not...but i think its something to do with the damping factor?

Nope. RFI, obviously. A poorly-designed amp will produce significant amounts of it.

 

[HeXen]

i found the technical explanation. but its not about poor design itself, its about cost.
in other words, its the switching power supply....i believe if its designed a certain way, i guess higher damping? it can fix the issue, but costs more of course.

the reverse recovery charge of the MOSFET body diode flowing from the top rail to the bottom, similar to the shoot-through current. During the dead-time inserted to prevent shoot through current, the inductor current in the output LPF turns on the body diode. In the next phase when the other side of the MOSFET starts to turn on at the end of the dead-time, the body diode stays in a conducting state unless the stored minority carrier is fully discharged. This reverse recovery current tends to have a sharp spiky shape and leads to unwanted ringing from stray inductances in PCB traces and the package.

 

[Howard]

i found the technical explanation. but its not about poor design itself, its about cost.
in other words, its the switching power supply....i believe if its designed a certain way, i guess higher damping? it can fix the issue, but costs more of course.

Which parts are skimped on so that this is caused?

By the way, damping factor has nothing to do with RFI.

 

[HeXen]

cause its cheaper to just produce a more simple half bridge class d amp i suppose. They can be a lot more complicated than class A/B designs.
Class D amps will generally have a high RFI/EMI. Most all of the amps that i've seen advertised for low RFI were in the higher end range. Like the Gilmore amps for example.
but i guess it depends on your definition of high and low end too.
In car amps, all the sub $200 amps have high RFI, you get into $400 range and you can find some that have lower RFI.
of course i never claimed to be an audio engineer in the least. But i've purchased quite a few amps in the last 8 years, recently getting a Sony class D which was cheaper and resulted in poor FM reception still.
For my car i did break down and buy an MTX elite which doesnt interfere compared to my MTX thunder XD which has horrible RFI.