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Class A, A/B endangered species?

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TrevC

Well-known member
Jun 12, 2013
248
87
18,870
andyjm said:
manix said:
Alberich said:
nopiano said:
busb said:
Alberich said:
Benedict_Arnold said:
I shall consider buying a Class D amp. Until then it's Class A or no class at all. My little hi-fi isn't going to kill the planet. After all, the brats almost certainly burn more juice leaving the pantry light on than I shall ever use listening to my stereo.
I suppose I'm trying to gauge what is the level of likelihood that future fans of class A will be deprived that choice. Future generations of audiophiles may have their hands tied on this. In 100 years from now audiophiles may not have the luxury to choose class A, and for better or for worse, class D and no doubt other topologies, will be the mainstay. Class A will become something uttererd only by ageing audiophiles and connoisseurs of vintage kit and ultimately resigned to history.

Look at the EU energy commissions ruling on vacuum cleaners for precedence. Who knows what regulations will have to imposed in the future. Some may find this tone alarmist in nature but be warned lovers of the pure current, the end is near!
The power consumed by vaccuum cleaners is vast compared to the few remaining Hi Fi systems so don't be too surprised if Hi Fi remains completely under the radar of commissioners!
Hopefully they are too stupid to realise that cleaners are used for a few minutes but hifis can be left on for hours! Soon we'll be heating kettles with candles...
Some systems spend their lives powered up indefinitely. Not talking standby mode either. I suspect it's the minority though.
It's a great way to shorten the life of your amps.
Strangely, no.

Most components fail because of mechanical reasons, and it is the thermal shock and inrush current at switch on that causes them to fail. Electrolytics are an exception and will dry out quicker in a warm environment, so if you have a class A toaster, it would make sense to keep it off when not in use.
Mechanical reasons????
 

Infiniteloop

Well-known member
Jul 23, 2010
48
4
18,545
TrevC said:
Infiniteloop said:
TrevC said:
"Your comment is about as accurate as saying that Fettucine al Fredo is what we used to eat before the advent of superior Pot Noodle".

I expect you think a vintage Ford Popular is superior to a modern Ford Focus, but that doesn't make you right. The ultimate hifi is all solid state. Much lower distortion, better damping factor, less noise, the valve is an also ran in every department. The valves in otherwise SS equipment are there for audiophool marketing purposes. Add a couple of pointless valves to a CD player and double the price, the audiophool will buy it and claim it sounds better.
Yet the sound that some pure class A Valve Amps produce is sublime. - Funny that.
They produce the asymmetric distortion that pleases you for some peculiar reason. Of course it can sound good on non-demanding music.
All Amplifiers distort the sound to some degree.

You might find this educational:

http://spectrum.ieee.org/consumer-electronics/audiovideo/the-cool-sound-of-tubes/3
 

iQ Speakers

New member
Feb 24, 2013
129
1
0
The review Electro mentioned in HiFiWigwam was carried out by a £8K Audionote valve amp owner. He know owns a Class D Nord Class D amp paid at full price, a summer amp. I think he still prefers the Audionote but its very close then they were considerably less to buy.

I dont think you should choose a Class D amp purely on it efficency, its primary use is to engage and make you happy which Hypex based amps certainly do and then some. But they ae not for everybody which is fine.
 

manix

New member
May 31, 2016
7
0
0
andyjm said:
manix said:
Alberich said:
nopiano said:
busb said:
Alberich said:
Benedict_Arnold said:
I shall consider buying a Class D amp. Until then it's Class A or no class at all. My little hi-fi isn't going to kill the planet. After all, the brats almost certainly burn more juice leaving the pantry light on than I shall ever use listening to my stereo.
I suppose I'm trying to gauge what is the level of likelihood that future fans of class A will be deprived that choice. Future generations of audiophiles may have their hands tied on this. In 100 years from now audiophiles may not have the luxury to choose class A, and for better or for worse, class D and no doubt other topologies, will be the mainstay. Class A will become something uttererd only by ageing audiophiles and connoisseurs of vintage kit and ultimately resigned to history.

Look at the EU energy commissions ruling on vacuum cleaners for precedence. Who knows what regulations will have to imposed in the future. Some may find this tone alarmist in nature but be warned lovers of the pure current, the end is near!
The power consumed by vaccuum cleaners is vast compared to the few remaining Hi Fi systems so don't be too surprised if Hi Fi remains completely under the radar of commissioners!
Hopefully they are too stupid to realise that cleaners are used for a few minutes but hifis can be left on for hours! Soon we'll be heating kettles with candles...
Some systems spend their lives powered up indefinitely. Not talking standby mode either. I suspect it's the minority though.
It's a great way to shorten the life of your amps.
Strangely, no.

Most components fail because of mechanical reasons, and it is the thermal shock and inrush current at switch on that causes them to fail. Electrolytics are an exception and will dry out quicker in a warm environment, so if you have a class A toaster, it would make sense to keep it off when not in use.
I agree turning on and off has it's own penalty but doing that once a day is better than leaving a amp on for 24 hours.

Obviously stanby is different though even then it depends on what standby exactly is on the particular unit and how well it is designed. Lets not forget those Kef subwoofers that if left on standby failed within 2-3 years. Turning them on and off after use extend the life massively before needing to open them up.
 

TrevC

Well-known member
Jun 12, 2013
248
87
18,870
Infiniteloop said:
TrevC said:
Infiniteloop said:
TrevC said:
"Your comment is about as accurate as saying that Fettucine al Fredo is what we used to eat before the advent of superior Pot Noodle".

I expect you think a vintage Ford Popular is superior to a modern Ford Focus, but that doesn't make you right. The ultimate hifi is all solid state. Much lower distortion, better damping factor, less noise, the valve is an also ran in every department. The valves in otherwise SS equipment are there for audiophool marketing purposes. Add a couple of pointless valves to a CD player and double the price, the audiophool will buy it and claim it sounds better.
Yet the sound that some pure class A Valve Amps produce is sublime. - Funny that.
They produce the asymmetric distortion that pleases you for some peculiar reason. Of course it can sound good on non-demanding music.
All Amplifiers distort the sound to some degree.

You might find this educational:

http://spectrum.ieee.org/consumer-electronics/audiovideo/the-cool-sound-...

Shame about the utter nonsense about crossover distortion, that simply isn't present in a correctly biased AB amplifier. Of course there will be crossover distortion in a class B amplifier, even a portable radio was never class B. All have forward bias of some description that makes them class AB. It also fails to mention that the distortion caused by an adequately powered modern SS hifi amplifier isn't audible.

If you want the ultimate it will be SS. Biased nonsense isn't all that educational.
 

Infiniteloop

Well-known member
Jul 23, 2010
48
4
18,545
lindsayt said:
I think is. You think it isn't, TrevC.

If you think it isn't then SS is the way to go for you.

If anyone thinks that distortion (in the broadest sense of the term) is audible in modern SS amps then valves might be the best solution for them.

No big deal. It's not as if the difference between a good valve amp and a good solid state amp is as big as the difference between two good speakers of different genres.
Quite. Although there are differences to be enjoyed - that's why I maintain and listen to both.
 

lindsayt

New member
Apr 8, 2011
16
2
0
I think it is. You think it isn't, TrevC.

If you think it isn't then SS is the way to go for you.

If anyone thinks that distortion (in the broadest sense of the term) is audible in modern SS amps then valves might be the best solution for them.

No big deal. It's not as if the difference between a good valve amp and a good solid state amp is as big as the difference between two good speakers of different genres.
 

Alberich

New member
Mar 15, 2016
11
0
0
Exactly. I've never understood this stance to fervently denounce one topology in order to champion the other.
Valves have their place, SS has its place, Class A, A/B, and D have their place.

On the other hand if we all agreed on everything , audio forums would be excruciatingly boring places.
 

TrevC

Well-known member
Jun 12, 2013
248
87
18,870
Alberich said:
Exactly. I've never understood this stance to fervently denounce one topology in order to champion the other. Valves have their place, SS has its place, Class A, A/B, and D have their place.

On the other hand if we all agreed on everything , audio forums would be excruciatingly boring places.
Nothing fervent about it, it's simply a fact. The ultimate amplification will be solid state. I like valves, i built a 6L6 stereo one in the 60s.

Would it be especially fervent to denounce 78s in favour of LPs?
 

Al ears

Moderator
TrevC said:
Alberich said:
Exactly. I've never understood this stance to fervently denounce one topology in order to champion the other. Valves have their place, SS has its place, Class A, A/B, and D have their place.

On the other hand if we all agreed on everything , audio forums would be excruciatingly boring places.
Nothing fervent about it, it's simply a fact. The ultimate amplification will be solid state. I like valves, i built a 6L6 stereo one in the 60s.

Would it be especially fervent to denounce 78s in favour of LPs?
The last time I looked 78's were LPs, at least by most definitions. Perhaps 33.3 RPM's might read better.
 
May 28, 2013
33
0
0
Only heard a few class Ds outside of AV amps, so not realy qualified to comment. But see the Hypex Ncores have found favour with none other than Ken Ishiwata as the forthcoming Marantz flagship £6500 PM10 appears to feature that Dutch technology.
 

TrevC

Well-known member
Jun 12, 2013
248
87
18,870
Al ears said:
TrevC said:
Alberich said:
Exactly. I've never understood this stance to fervently denounce one topology in order to champion the other. Valves have their place, SS has its place, Class A, A/B, and D have their place.

On the other hand if we all agreed on everything , audio forums would be excruciatingly boring places.
Nothing fervent about it, it's simply a fact. The ultimate amplification will be solid state. I like valves, i built a 6L6 stereo one in the 60s.

Would it be especially fervent to denounce 78s in favour of LPs?
The last time I looked 78's were LPs, at least by most definitions. Perhaps 33.3 RPM's might read better.
No, what I wrote was correct.
 

Gazzip

New member
Jan 15, 2011
88
0
0
...back to the OP:

I would say that A/B might have its days numbered. It was afterall developed to make pure class B work without audible distortion during the push/pull transition, which in turn enabled manufacturers to make products which could get close to pure Class A performance at a fraction of the cost/power consumption. Class D is a (kind of - I await TrevC's input) development of Class A/B which is smaller, cheaper and more efficient, so I believe it will ultimately supersede A/B...

Class A will however always have a place because:

1) It is theoretically the most linear sound possible, which will ALWAYS be sought after by the purist with deep pockets.

2) It is the audiophile snobs weapon of choice. Better or worse is irrelevant. There will always be a demand for it.
 

Gazzip

New member
Jan 15, 2011
88
0
0
TrevC said:
Gazzip said:
...back to the OP:

I would say that A/B might have its days numbered. It was afterall developed to make pure class B work without audible distortion during the push/pull transition, which in turn enabled manufacturers to make products which could get close to pure Class A performance at a fraction of the cost/power consumption. Class D is a (kind of - I await TrevC's input) development of Class A/B which is smaller, cheaper and more efficient, so I believe it will ultimately supersede A/B...

Class A will however always have a place because:

1) It is theoretically the most linear sound possible, which will ALWAYS be sought after by the purist with deep pockets.

2) It is the audiophile snobs weapon of choice. Better or worse is irrelevant. There will always be a demand for it.
My dad's old Alba radiogram had a decidedly non-linear class A single ended valve amplifier. If only he was still alive I could have told him that it was the best possible topology according to a clueless person. Class D uses pulse width modulation that requires filtering and there is no evidence it will supercede class AB, or is in any way superior apart from a very slight energy efficiency point of view. When you consider that all Class AB amplifiers are class A at low volume there's little point in wasteful class A biasing in a hifi amp.
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency. These amps also generate virtually no heat which is as you know the enemy of all things electronic.

This is why it will supersede Class A/B. There is also plenty of evidence that this is beginning to happen, with Devialet blazing the trail. I personally think you are wrong on this one TrevC, but only time will tell. I hope you are right as it goes because I like my big, heavy, hot lumps of amplification.
 

andyjm

New member
Jul 20, 2012
15
0
0
Gazzip said:
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency. These amps also generate virtually no heat which is as you know the enemy of all things electronic.
Gazzip, I have no idea what you are going on about.

The difference between A/B and D is that in the case of A/B the output stages are operating in their linear mode, where as in class D the output is a switch - either on or off.
 

Gazzip

New member
Jan 15, 2011
88
0
0
andyjm said:
Gazzip said:
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency. These amps also generate virtually no heat which is as you know the enemy of all things electronic.
Gazzip, I have no idea what you are going on about.

The difference between A/B and D is that in the case of A/B the output stages are operating in their linear mode, where as in class D the output is a switch - either on or off.
I am describing the pulses.
 

andyjm

New member
Jul 20, 2012
15
0
0
Gazzip said:
andyjm said:
Gazzip said:
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency. These amps also generate virtually no heat which is as you know the enemy of all things electronic.
Gazzip, I have no idea what you are going on about.

The difference between A/B and D is that in the case of A/B the output stages are operating in their linear mode, where as in class D the output is a switch - either on or off.
I am describing the pulses.
Oh. Thank you. I am afraid I still have no idea what you are going on about.

There is lots on the web about class D amplifiers, theory, application and so on. The wikipedia article is good start. Might be worth having a read around the subject.

Just a 'for what its worth', the number of class D amps now dwarfs all other topologies. Phones, TVs, car radios - you name it, it is now class D. Small, high power, efficient, little heat, whats not to like?

The hifi world is slowly getting there - most subs already have class D amps, the streaming speaker brigade (Sonos and similar) are class D - in fact, apart from hifi separates, the rest of the world has generally moved on.
 

NSA_watch_my_toilet

New member
Aug 24, 2013
7
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0
Mesure and distorsion of a Ayon Orion tube amplifier :


Mesure and distortion for a Unison Simply Italy tube amplifier :


Mesure and distortion of an Accuphase E-213 transitor amplifier (A/B) :


Distorsion of a Sugden Masterclass IA4 (A)


Credits : All mesures are property of Stereoplay, Tom Klasing Verlag. Use is only for eductional purpose.
 

Al ears

Moderator
NSA_watch_my_toilet said:
Mesure and distorsion of a Ayon Orion tube amplifier :

Mesure and distortion for a Unison Simply Italy tube amplifier :

Mesure and distortion of an Accuphase E-213 transitor amplifier (A/B) :

Distorsion of a Sugden Masterclass IA4 (A)

Credits : All mesures are property of Stereoplay, Tom Klasing Verlag. Use is only for eductional purpose.
And your point is?? Oh, it's measure by the way ;-)
 

Gazzip

New member
Jan 15, 2011
88
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0
andyjm said:
Gazzip said:
andyjm said:
Gazzip said:
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency. These amps also generate virtually no heat which is as you know the enemy of all things electronic.
Gazzip, I have no idea what you are going on about.

The difference between A/B and D is that in the case of A/B the output stages are operating in their linear mode, where as in class D the output is a switch - either on or off.
I am describing the pulses.
Oh. Thank you. I am afraid I still have no idea what you are going on about.

There is lots on the web about class D amplifiers, theory, application and so on. The wikipedia article is good start. Might be worth having a read around the subject.

Just a 'for what its worth', the number of class D amps now dwarfs all other topologies. Phones, TVs, car radios - you name it, it is now class D. Small, high power, efficient, little heat, whats not to like?

The hifi world is slowly getting there - most subs already have class D amps, the streaming speaker brigade (Sonos and similar) are class D - in fact, apart from hifi separates, the rest of the world has generally moved on.
The description I gave accurately (and simply) describes the waveform a Class D amplifier generates. Not sure why you consider this to be gobbledygook?

Class A/B will almost certainly be superseded by Class D, but audio Class A is a keeper because the hifi enthusiast will demand it to be so.
 

andyjm

New member
Jul 20, 2012
15
0
0
Gazzip said:
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency.

The description I gave accurately (and simply) describes the waveform a Class D amplifier generates. Not sure why you consider this to be gobbledygook.
Sorry Gazzip, don't want to be confrontational, but I am afraid your description makes no sense to me.

Anyone else get it?
 

Gazzip

New member
Jan 15, 2011
88
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0
andyjm said:
Gazzip said:
There’s still the same kind of positive-negative waveform treatment going on in a Class D amplifier, except that the negative portion is now basically made up of unused high frequency signals. So in theory, by interpreting half the wave form as a Class B or Class A/B does as the full wave form, and using what is in essence a “dummy” circuit to complete the cycle between positive and inaudible negative, you’d theoretically get the best of both worlds—clean, linear sound and efficiency.

The description I gave accurately (and simply) describes the waveform a Class D amplifier generates. Not sure why you consider this to be gobbledygook.
Sorry Gazzip, don't want to be confrontational, but I am afraid your description makes no sense to me.

Anyone else get it?
I don't take it as confrontational at all.

Put another way the pulses track an incoming analogue waveform around an HF frequency carrier, intersecting it and creating a square wave representation of the original.

The carrier is the unused HF frequency and the square wave representation is the waveform treatment to which I refer.

Each of these intersected "slices" is then amplified by high current on/off switching.

I left this bit out because I was talking waveforms, but I concede that this may have been confusing seeing as this is the actual amplification!!

Finally the unused HF frequency is removed through a low pass filter.

This is the dummy circuit to which I refer.

Does this make more sense? I refer to Class D as linear because in a way it is.
 

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