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amp classes??????


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#1 of 25 OFFLINE   Lyden

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Posted January 09 2003 - 10:31 AM

Hi All ok ive been hearing about amp classes like some subs have class a/b amp and so on what is the differance?? and what type should a reciver have?? i think mine has class H or something is that good??? please any explination would be a great help to understanding this thank you.
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#2 of 25 OFFLINE   Yogi

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Posted January 10 2003 - 01:38 AM

Class A - output devices always fully turned on. The full waveform is amplified by each output device. Very high transient response. Very low distortion. Very inefficient (typically less than 25%). High heat dissipation at idle. Most preferred by audiophiles. Only the most high-end single ended amps use this.

Class B - Push pull type . output devices amplify opposite signs of the waveform in complimentry push pull style (one pushes one pulls). Cross over distorion when the signal crossesover from one device to the other. Low heat, better efficiency (typically around 70%).

Class AB - Class A upto a certian point (watts) and then switches to Class B. Most amps and receivers fall into this category. Best compromise between the two types.

Class C - I dont knowPosted Image

Class D - Digital switching type. Use switching power supplies. Very efficient (more than 95%). Low power consumption low heat. Used mostly in PA systems and sub amps. There is some swithing noise but with the advent of modern high speed swithing devices the noise is pushed out into the extreme ultrasound which cant be perceived by human ear.

Class H - Hybrid type. Two rail voltages one for low output and one for high output. Efficient design. Good at extreme ends of the volume range. Mid volume rail crossover distortion. Mostly used in Technics and some other receivers.

Class G - I dont know.

Also I dont know if there are some other types. Someone might be able to fill me in on that.
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#3 of 25 OFFLINE   Rob Rodier

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Posted January 10 2003 - 02:43 AM

I think that their is also an "h" class that isn used on lower end ss deigns. Technics uses "H" I think. Lyden, this is not the kind of thing you should worry about. As long a the manf is competant, they can find a way to make all of these designs sing. PS Audios new digital amp for example. Sounds great. Impressive rundown Yogi -rob

#4 of 25 OFFLINE   Yogi

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Posted January 10 2003 - 04:11 AM

[quote] As long a the manf is competant, they can find a way to make all of these designs sing. PS Audios new digital amp for example. Sounds great. [quote]

I agree to that. As long as it sounds good to your ears thats all that matters.
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#5 of 25 OFFLINE   Brian Vaughan

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Posted January 10 2003 - 06:09 AM

If you're interested, here is a great article from the PS Audio site discussing the history of digital amplication and their current design. BTW, I have the HCA-2 and could not be happier. It makes my 804s sound amazing.

http://www.psaudio.c...ticles/sdat.asp

Cheers, Brian
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#6 of 25 OFFLINE   Kevin_R_H

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Posted January 10 2003 - 07:18 AM

Yogi gave a lot of good information. However, my monoblocks are Pure Class A, and they are NOT Single-Ended. They are Push-Pull / 100W Triode. I'm sure there are others... Kevin

#7 of 25 OFFLINE   Yogi

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Posted January 10 2003 - 07:33 AM

[quote] However, my monoblocks are Pure Class A, and they are NOT Single-Ended. They are Push-Pull / 100W Triode. I'm sure there are others... [quote]

Sorry my mistake. For some reason only SET's came to mind when I was thinking of Class A amps. Class A can also be push pull. Thanks for correcting me Kevin.
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#8 of 25 OFFLINE   Greg_R

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Posted January 10 2003 - 10:06 AM

Some additional areas for confusion: - Amplifier classes have nothing to do with Stereophile equipment recommended component ratings (Class A, B, or C rating). - Classé (pronounced 'class-ae') is an audio equipment manufacturer (who make various classes of amplifiers).

#9 of 25 OFFLINE   Jim Garbern

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Posted January 20 2003 - 03:07 PM

There's a nice article here.

#10 of 25 OFFLINE   ShaneH

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Posted January 20 2003 - 03:48 PM

As far as I know class C amps are used only in RF communications, and modulation of the data/audio signal, and are not used in audio applications where the signal is not being transmitted. Just thought I would add this if anyone was interested.

#11 of 25 OFFLINE   Larry B

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Posted January 21 2003 - 01:45 AM

Yogi:

[quote] Only the most high-end single ended amps use this. [quote]
Actually, VAC amps are pure class A, P/P. Read about them here

Larry

#12 of 25 OFFLINE   DonJ

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Posted January 21 2003 - 04:50 PM

So which call would an H/K AVR320 be in? I know that they are a 'High Current Amp' Which puts out the same amount of power at all volumes. But I wonder what the difference is between 'High Current' and Class A?
I'm still typing with a broke hand and it sucks.

#13 of 25 OFFLINE   Rob Rodier

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Posted January 22 2003 - 04:12 AM

[quote] So which call would an H/K AVR320 be in [quote]


I am sure it operates in class a/b. Class A for the first watt or two then switching to the more efficient class b.

-rob

#14 of 25 OFFLINE   Tom Grooms

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Posted January 22 2003 - 04:20 AM

'High Current' is not a amplifier design , it a marketing term....

#15 of 25 OFFLINE   Rob Rodier

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Posted January 22 2003 - 07:36 AM

[quote] it a marketing term [quote]

Lets not open up that can of worms!Posted Image

-rob

#16 of 25 OFFLINE   Chris Eriksen

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Posted January 22 2003 - 03:37 PM

[quote] Class H - Hybrid type. Two rail voltages one for low output and one for high output. Efficient design. Good at extreme ends of the volume range. Mid volume rail crossover distortion. Mostly used in Technics and some other receivers. [quote]
I think this is actually a Class G amplifier. From my understanding, the rail voltage tracks the input signal in a Class H design.

BTW, HERE is an excellent reference on amplifier classes.

#17 of 25 OFFLINE   DonJ

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Posted January 23 2003 - 07:10 PM

Rob-
[quote] Lets not open up that can of worms! [quote]

Well I need to know so I'm gunna have to.Posted Image

So what do you mean by just a marketing term, from what i understand is that High current means you are putting out the same amount of watts whether you are at min volume all the way to max. By doing this you have a cleaner sound through the volume range of the amp(imaging and detail) stay the same even to there limits without distorting, with the standard receiver(typical $100.00 Sony that claims 100 watts per channel) has peaks and valleys in out-put and you might achieve the wattage claim for a second and then drop again. Now when I was testing receivers the ones that say they have 'high current amps' did sound better through the whole range the ones that didn't. I could crank the H/K 520 to max volume and it wouldn't blare or strain to put the sound out, but when listening to the standard Pioneer VSX-810 it really started to strain,shout, and blare like it couldn't keep up with the music, it became unmusical at that point which was 3/4 to max,and when you got the max volume you could even recognize what you were listing to it was that distorted. The H/K remained musical at it's limits but it wasn't as loud.

Please if you could explain more.
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#18 of 25 OFFLINE   Yogi

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Posted January 24 2003 - 01:56 AM

[quote] from what i understand is that High current means you are putting out the same amount of watts whether you are at min volume all the way to max. [quote]

With all due respect I would like to correct you. The term high-current means that the amps current delivery increases linearly with a drop in impedance. So if your amp puts out 100W@8 ohms it will put out 200W@4 ohms and so forth. In reality no amps can do this given the dispersion characteristics of the internal components and wiring. Most good amps will come close to this. For example the Proceed Amp2 is rated for 125W@8 ohms and 250W@4 ohms when in reality it delivers something close to 150W@8 and 250@4, not a true doubling of power with halving of impedance. The manufacturer will usually understate the higher impedance rating to make it seem like the amp is doubling its output when the impedance drops to half.

No amp gives the same amount of output for all volume levels. if that were the case there would be no use for the volume pot.

The term high-current is a real phenomenon and well designed amplifiers do deliver high amounts of current to the drivers and thats what gives them their superior control and damping characteristics. However this term in the spec sheet often is a marketing gimmick. For example like I pointed out in another thread about HK's specs of a receiver with +/-85 amp high current delivery. Now no one and not even the HK tech service people (according to another poster who called them about this ambiguous term) know if this rating if for all channels combined or is for a single channel, if it is a peak to peak rating or a rating in absolute sense, if its a rating for 1 micro second or if it is a rating for a few seconds, etc, etc. It is clearly meant to misguide the ordinary consumer who would look at this spec and say 'oh my God 85 amps is a lot of current and if my vaccuum cleaner rated for 15 amps can hold a bowling ball on its end then surely this sucker can start my truck on a cold winter morning'. So IMHO the term 'high-current' can be interpreted either way. It could mean a good amplifier design (althoug I usually dont see the term used in the spec sheets of very high end gear like Krell, ML, ARC etc) and could mean a marketing gimmic in the case of HK. This by no means is an insult on HK who I think makes one of the best and most musical receivers in their price range.

My 2 cents.
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#19 of 25 OFFLINE   Lyden

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Posted January 24 2003 - 03:03 AM

well heres the reall killer question about "high current" recivers. what is better a reciver with high current capability or just taking my 810s and getting some expensive amps for the pre outs?? more expensive but IMO since all u'll be using the reciver is decoding .. you coudl just use any decent reciver with all chanel pre outs and strap nice amps and get better sound then a "HC" capeable reciver.. do tell if im wrong here
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#20 of 25 OFFLINE   Lyden

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Posted January 24 2003 - 03:11 AM

im curious .. i have acess to a few PA system amps kid says they are like 1000 watts each .. would one of those for the main chanels be better then getting other amps?... i'd never run 1000watt amps with my speakers ... just curious if i was to some how have a set up like that would it be betetr then buying say an onkyo 2 chanel amp ... .. i wonder if just turning my system on with that setup would the cones on my towers just shoot out of their frames or whatever the "technical" term is for them is .. hmm would be kinda funny ... mostlikely the coils would melt and ither triger safety system or kill the amps and make a perdy fire correct? ..... thanks keep responding im learning so much here Posted Image ... anyone know how to build a 50 watt amp? i need a 2 chanel 50 watt amp for some computer speakersi made
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