| BrianEno |
Nice to have a special forum for a amplifierbrand. It will create a solid base of followers.
First of all I´m not a technician or audiodesigner. Just a customer of highend audiogear for the last 20 years.
Had the privilige to own several poweramplifier designs from Colangelo (ML-3), Agostino (KSA-100, KMA-200´s), Jeff Rowland (model 7 Series II, IV and model 8T) and Nelson Pass (S/300 and S/1000´s).
In the eighties Class A was the buzzword in highend and hifi world. John Curl designed for Levinson the ML-2 a 25 watt amp which consumed 400 watts at all times. Saw a lot of ML2´s with there heatsinks in time turned purple or even gold because of the heat. Krell was king in that area though. They specialized in copiing the designs of Levinson but make it even more outrageous with a designs like the KRS200 and six piece KRS-1. The more "modest" designs like the KMA-200´s drew a constant 1150 Watts from the outlet to retain the magical 200 watt Class A. It needed two noisy fans to cool it down. Threshold started with a original concept to tackle the constant draw of current with the dynamically biased 800A which at idling only consumed about 200 watts. In 1980 came the Stasis 1 (still the most sought after amplifier from Pass, also for it´s gorgeous looks, never superseded again in my opinion, probably thanks to Rene Besnee) with a completely new operating concept. From the accompanying brochure at that time: "Threshold Stasis amplifiers move beyond "class" designations through achievement of a completely new operating concept." In the accompanying tecnical paper (extremely readable though) a few years later with the introduction of the S/150 - 1000 series Nelson Pass stated that "While Class A operation was capable of reducing this effect (current variations in the gain devices) by swamping it with a large idle current, a method of reducing the current fluctuations would tackle the problem more directly. If one could envision a tandem arrangement of gain devices where current fluctuations were surpressed instead of voltage fluctuations as in cascode operation, this effect would be achived. Out of this concept came the STASIS amplifier.
So obviously there was no need anymore for that thermally stressing, power consuming ecologically unfriendly and in the summer to hot Class A biasing. Problem solved case closed! But then came the SA series after that the Aleph and now the XA series with a behemoth XA-200 of 80 kilograms idling just under the Krell and not even behaving as a voltage source because 200 Watts is the maximum you can get out of it according to the designer. The meter won´t move either than I suppose it just shows you the constant currentdraw from your pocket.
Krell (after abandoning the forced cooling and ridiculous large protruding sharp coolingfins (KSA-200 for example) and Levinson (always the more refined anyway of the two) got sensible and are now deploying plateaubiasing. Jeff Rowland has taken the real bold move to dispense with heat alltogether with his Icepower designs wich is the way of the future. He should only remove the heatsinks from his 300 series because there´s no need for it anymore just like the meter on the XA series.
So why is perspective with the other manufacturers of highend audio/amplifications has Nelson Pass revert back to energy wasting solutions from the past. Why is he back to square one in that parameter?
PS Found a series of photographs from the seventies of Threshold in www.passlabs.com/threshold One portrayed a Mark who later became president of MLAS. Is this Mark Levinson or Mark Glazier or just a stupid question. |
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| Babowana |
Maybe Papa doesn't know how to make good AB . . . ?
:scratch1: |
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| badman |
:dodgy:
What's your motivation here? It sounds as if you're looking to bash a skilled designer for his design decisions. The advantages/disadvantages of Class A have been discussed to death in various forums, perhaps a few searches are in order before you call energy efficiency progress with no consideration of any other issues. |
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| Netlist |
Bad badman. :nownow: :)
I really think Brian's question has merit and not only from an energy efficiency point of view.
/Hugo |
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| Jeb-D. |
| It does seem wastefull and excellent results can be had with other approches. However, by opperation no class is as pure as class A. The signal is never cut in half like in a AB or B amplifier nor is it ever hacked up then re-assembled like in a class D. As I said you can make an excellent AB,B,D,G ect. Amp, But for some people absolute pure, un-defiled audio is all that matters. |
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| BrianEno |
| quote: | Originally posted by badman
:dodgy:
What's your motivation here? It sounds as if you're looking to bash a skilled designer for his design decisions. |
Certainly not! Have fond memories of the Threshold S/300 and S/1000 mono's in my system one of the most musical products I encountered. Love the NFB designs from Nelson Pass and Jeff Rowland. I'm seriously interested why the designer which skills I cannot and will not dispute has chosen for designs that waste so much power. That is a valid and legitimite question I backed up with the context I provided. Jeff Rowland stated it very elegant in one of his discussions he published named "A technical discussion With Jeff Rowland" subtitle: The Myth of "Class A" Operation"
last paragraph: "Most modern power amplifiers are quite inefficient and forwardthinking audio designers must become more ecological responsible by designing equipment which consumes less yet giver more." That's an opinion too made in the beginning of the nineties. Nelson Pass himself mentioned in his literature Stasis as the solution of all Class wars. He spoke over achieving linearity (his central topic in all of his discussions en designs) by swamping the circuit with biascurrent and propagated his Stasis solution as a less cruder and efficient way. I think it is in no way offensive to question/ask why a designer chooses to develop designs which waste so much power while he claimed in the eighties the end of the Class wars with his Stasis concept. You as a citizen of a country that in his First Amendment guarentees the freedom of speech shouldn't curtail me by saying I'm bashing a designer. Let's have a open discussion, I'm curious aren't you? Or is he a God... |
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| jacco vermeulen |
The pic is Mark L, NP posted it when we had a talk overhere on Mr Levinson.
Small world, isn't it.
I've heard Mr Rowland's new age power amps.
Great design, but look and sound like refrigerators imo.
The pool in the backyard wastes a whole lot more, i kinda fancied nukes in a weird way too though. |
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| el`Ol |
| I heard several powerful amps at the Highend in Munich this year and the (class A) Electrocompaniet Nemo had so much more soul than what I heard from Mark Levinson, Jeff Roland and (worst of all) MBL. I have my doubts this will ever change. |
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| Netlist |
You will want to read this old post from Nelson on the subject:
http://www.diyaudio.com/forums/show...8173#post558173
While it is true that the best power is the not-consumed one in terms of efficiency, I replaced a bunch of old light bulbs in the house with low-power ones. It turns out that I can enjoy many more hours of ClassA sound with an equal yearly electricity bill. ;)
/Hugo |
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| BrianEno |
| quote: | Originally posted by jacco vermeulen
The pic is Mark L, NP posted it when we had a talk overhere on Mr Levinson.
Small world, isn't it.
I've heard Mr Rowland's new age power amps.
Great design, but look and sound like refrigerators imo.
The pool in the backyard wastes a whole lot more, i kinda fancied nukes in a weird way too though. |
Thanks for the info on that picture.
Do you favour any particurly nuclear design? Fission or fusion Thermo-nuclear?
It's not the waste of energy only I pointed out. It cost you money the design is thermally stressed and the parts like the big toroids, heatsinks and so forth are costly items making the amp expensive.
The model 201 & 501 do look anything but not as a refrigerator. Though my refrigerator weighs less then a X-1000.5 or XA200.
How does a fridge sound anyway (don't say cold;) |
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| jacco vermeulen |
Chilly ?
It is an interesting question though, as Mr Pass is not the only pro audio designer reverting to full class A.
There was a lengthy and heated chat about Mr Curl's Blowtorch pre-amp on diyA last year, Mr Curl certainly hasn't straightened out.
Nice timing, btw=>HEAT Me |
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| GRollins |
| quote: | Originally posted by BrianEno
...not even behaving as a voltage source because 200 Watts is the maximum you can get out of it according to the designer.
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Two quick comments before I run off to feed the boys...
1) You'll need to do a little homework before you say that the XA isn't a voltage source, simply because it tops out at 200W. It is a voltage source. That it doesn't increase wattage into low impedances is due to limitations on the bias current. The bias can easily be increased in that topology (something that would be anathema to you, apparently) and that would allow for full power into any arbitrarily low impedance that you might desire. The problem is that the amplifier would run hotter, require more power supply and heatsinking...and cost more. As a practical matter, designers have to stop somewhere.
2) You're spending far too much time reading, and vesting far too much emotion in sales literature. In case you haven't noticed, every new model from every manufacturer is lauded as a technological breakthrough of immense proportions. In direct consequence, they always claim to have rendered obsolete any and all pre-existing designs by any manufacturer...including themselves. Don't read too much into such claims, except for cynical entertainment value.
In passing: Your statement that class A subjects output devices to undue heat stress is poorly thought out. While it's obviously true that class A circuits run hot, each power cycle represents one heat cycle for the output devices; they get hot, stay hot, then cool down when the amplifier is turned off. Less aggressively biased amplifiers turn on, then get hotter/cooler/hotter/cooler/hotter/cooler...according to the demands of the music. This leads to many heat cycles every time the amplifier is turned on. Incidentally, this is one of many reasons that class A amplifiers are superior--the operating conditions for the devices are more consistent and distortion is inherently lower.
No one contests that class A amplifiers are more power hungry. That's simply the nature of the beast. Just how big a problem this is in terms of the environment is a matter of perspective.
Grey |
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| BrianEno |
| quote: | Originally posted by GRollins
[B]
1) You'll need to do a little homework before you say that the XA isn't a voltage source, simply because it tops out at 200W. It is a voltage source. That it doesn't increase wattage into low impedances is due to limitations on the bias current. The bias can easily be increased in that topology (something that would be anathema to you, apparently) and that would allow for full power into any arbitrarily low impedance that you might desire. The problem is that the amplifier would run hotter, require more power supply and heatsinking...and cost more. As a practical matter, designers have to stop somewhere.
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Thought that the perfect voltagesource has to double it's currentrating when the impedence halved to keep his voltage up like in Ohm's law. Now it turns out I'm wrong about that.
So what your saying that it could do that but the designer choose to do otherwise to keep the cost in balance. That must be a joke, you can't lift the XA200 by yourself and it costs a small fortune anyway with the restraints you mention. In fact you agree with me because as you say yourself: more bias requires an amplifier that would run hotter, require more power supply and heatsinking...and cost more| quote: |
2) You're spending far too much time reading, and vesting far too much emotion in sales literature. In case you haven't noticed, every new model from every manufacturer is lauded as a technological breakthrough of immense proportions. In direct consequence, they always claim to have rendered obsolete any and all pre-existing designs by any manufacturer...including themselves. Don't read too much into such claims, except for cynical entertainment value.
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Maybe that's not only truth for the sales literature but also for the products themselves. Class A has a magical ringing and when there's a market for it you tap in on that opportunity.
Apart from washingdetergent blahblah in the sales literature of even Nelson Pass products I take his technical exercitions in his technical papers somewhat more seriously then the brochures.
| quote: | | In passing: Your statement that class A subjects output devices to undue heat stress is poorly thought out. While it's obviously true that class A circuits run hot, each power cycle represents one heat cycle for the output devices; they get hot, stay hot, then cool down when the amplifier is turned off. Less aggressively biased amplifiers turn on, then get hotter/cooler/hotter/cooler/hotter/cooler...according to the demands of the music. This leads to many heat cycles every time the amplifier is turned on. Incidentally, this is one of many reasons that class A amplifiers are superior--the operating conditions for the devices are more consistent and distortion is inherently lower. |
I have a Levinson ML-3 amplifier that is moderately biased for Class A and probably 90% of the listening is in that region and that will be the case for most of the Class AB designs. My other ML-3 operated for almost 30 years without problems.
I'm also not only taking in account conductors but also about electrolytics (saw some Sprague curves for them with diminishing life-expectancy by rising ambient temperatures) and soldering joints that crystalize.
Nice though to have a serious reaction on my questions.
Thanks |
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| Christer |
| quote: | Originally posted by BrianEno
Thought that the perfect voltagesource has to double it's currentrating when the impedence halved to keep his voltage up like in Ohm's law. Now it turns out I'm wrong about that. |
You are right about perfect voltage sources. But they are theoretical constructs that don't exist in reality. No amp is a perfect voltage source, whether it is class A, class B, class D or whatever. Neither is you mains outlet in the wall a perfect voltage sorce. Neither is a nuclear power plant. Anything in reality must have some limitations. However, within the limitations, we may consider amplifiers as approximating perfect voltage sources. But we must draw a limit somewhere. What about pluggin in a U-shaped copper bar instead of the speaker cable? Would you require the amp to keep up the voltage, just as a perfect voltage source would |
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| john65b |
| quote: | Do you favour any particurly nuclear design? Fission or fusion Thermo-nuclear?
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I prefer a recent PWR over antiquated BWR nuclear power plant design, but then again, who wouldn't?
OMG, I actually made a knowledgeble contribution to this site. Too bad it has nothing to do with Audio Equipment. |
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| Audio_se |
Now be careful! We don't want any politician to come up with an idea of having CO2-taxes on class A amps :bawling:
You say that you have using highend gear for 20 years. How do you rate sound quality on these amplifiers compared to others? |
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| GRollins |
BrianEno,
If your intent is to rail again common practice in the audio industry, please be aware that there have been numerous threads over the years that took one or another (or all) manufacturers to task for advertising excess. We surely don't need another; it's all been said, ad infinitum, ad nauseum. Advertising is what it is. If you don't like it, don't read it. If you choose to read it, take it for what it is--mildly entertaining fiction, nothing more. Viewed objectively, it's no worse than the advertising for cars, cameras, or vacation hot spots.
If your intent is to ask technical questions as to why class A continues to be the class of choice, even after all these years of 'death-of-class A' pronouncements, you would do well to moderate your tone. At present, you sound more like you're spewing than asking serious questions. Bear in mind that the answers to may not suit you. Physics is implacable. Certain things are not open to negotiation. Mother Nature will allow certain work-arounds, some of the time, but don't think for an instant that there's an operating class that sounds as good as class A but uses only enough bias to power a flashlight.
Regardless of what the sales literature says.
Remember the "Have you searched?" button that you tagged in the process of starting this thread?
It's clear you didn't.
Grey |
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| jacco vermeulen |
| quote: | Originally posted by BrianEno
I have |
I have a Krell-50 copy that shells out 700 Joules every second a few hours a day and it pleases me a lot more than the micro-wave.
The Mrs has been bugging me for a week to repair the Siemens wash-dryer, i told her we need energy awareness.
My kind of nuke, the best looking whale on the block : Astute |
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| Nelson Pass |
It's a legitimate question, nevertheless. Wasting power is
indeed something of the past.
Of course that depends on your definition of waste, and as I
pointed out before, the consumption of power is to be weighed
against the value it gives.
When I need to go somewhere, I give little thought to the
many kilowatt hours I have to use to accomplish it. When it's
particularly hot or cold, I will again spend kilowatt hours to be
comfortable. No Class A amplifier I ever built competes with
that consumption.
If you care enough about the sonic difference, then the energy
expenditure of the equivalent of a big plasma screen is worth it.
Clearly there is a small market segment for audio amplifiers
which consume high power, and that is why they exist. but there
are so few high end audiophiles running big Class A amplifiers
that it is not much of a target for those concerned about the
ecology.
If you are concerned about the environment and still want Class
A, the best thing to do is get some efficient loudspeakers and
buy or build little Class A amplifiers. In fact I recommend that
approach anyway, and between the Zens and First Watt, I
have made it easier for you....
:cool: |
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| mpmarino |
| quote: | Originally posted by jacco vermeulen
My kind of nuke, the best looking whale on the block : Astute |
Do they take MasterCard? Where's the order form?
I always say - it's recreation. You could go for a drive in the country, you could hop on a plane for a vacation, you could listen to your class A amp, or you perhaps could sit at home in the cold with the lights off. However you choose to spend your time/money/energy is up to you. I choose class A 'cause me likes :devilr: |
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| badman |
| quote: | Originally posted by Netlist
Bad badman. :nownow: :)
I really think Brian's question has merit and not only from an energy efficiency point of view.
/Hugo |
| quote: | Originally posted by BrianEno
Certainly not! Have fond memories of the Threshold S/300 and S/1000 mono's in my system one of the most musical products I encountered. Love the NFB designs from Nelson Pass and Jeff Rowland. I'm seriously interested why the designer which skills I cannot and will not dispute has chosen for designs that waste so much power. That is a valid and legitimite question I backed up with the context I provided. Jeff Rowland stated it very elegant in one of his discussions he published named "A technical discussion With Jeff Rowland" subtitle: The Myth of "Class A" Operation"
last paragraph: "Most modern power amplifiers are quite inefficient and forwardthinking audio designers must become more ecological responsible by designing equipment which consumes less yet giver more." That's an opinion too made in the beginning of the nineties. Nelson Pass himself mentioned in his literature Stasis as the solution of all Class wars. He spoke over achieving linearity (his central topic in all of his discussions en designs) by swamping the circuit with biascurrent and propagated his Stasis solution as a less cruder and efficient way. I think it is in no way offensive to question/ask why a designer chooses to develop designs which waste so much power while he claimed in the eighties the end of the Class wars with his Stasis concept. You as a citizen of a country that in his First Amendment guarentees the freedom of speech shouldn't curtail me by saying I'm bashing a designer. Let's have a open discussion, I'm curious aren't you? Or is he a God... |
Hm. Seems to me I asked a question and stated an impression, no accusations.... I'm not one to curtail legitimate questions, but your phrasing was pretty negative on class A- and it sounds as if your 'question' (which contained quite a few statements) operates on the presumption of Class A as archaic technology.
Short version: it read to me as follows:
"Class A is old. Everyone else in the industry has moved on. Why does Pass continue making products with outdated technology?"
Hugo, not exactly seeing what I did or said that warrants a wagging finger....
FWIW I don't use and haven't built any Pass gear (or pass style), and I use a variety of amps in my various playback chains (office, bedroom, 'big rig') from class D to SE OTL, so I'm not here to call Nelson a "God" (Though I do respect him from what I know)
Perhaps if you had kept the question shorter there'd be less motivation read into it- negative comparisons with the more 'modern' companies, etc, really bias your post towards negativity. This might have worked better:
"With most designs moving to more efficient topologies, why does Pass stay with Class A? Nelson even said "blahblahblah" about it." |
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| BrianEno |
| quote: | Originally posted by GRollins
If your intent is to ask technical questions as to why class A continues to be the class of choice, even after all these years of 'death-of-class A' pronouncements, you would do well to moderate your tone. At present, you sound more like you're spewing than asking serious questions. Bear in mind that the answers to may not suit you. Physics is implacable. Certain things are not open to negotiation. Mother Nature will allow certain work-arounds, some of the time, but don't think for an instant that there's an operating class that sounds as good as class A but uses only enough bias to power a flashlight.
Grey |
Moderate my tone? Euphemism for shut up.
My question is valid and legitimate. This is supposed to be a Forum like in Webster definition: "a public meeting place for open discussion". You remark about the supremacy of Class A is rather absolute. Mother Nature (you dragged her in!) would not prefer a solution that wastes so much resources for achieving a certain goal. As in the Origin of Species from Charles D. those designs will be phased out. I had several Class A amps and they didn't sound good just because they were biased for that point of operation. It's just a parameter of a total conceptual structure. But it has severe consequences for the construction of the amplifier and it's environment. Maybe a valid answer could be that there's a solid marketdemand in this niche or the designer balances the pro's and contra's and concludes it's all worth it.
Just powered up my old ML-3 drawing 180 watts from the line for a max of 6.5 watts Class A power. 'Smooth operator' from Sade is on. Miss the comfy warm illumenated meters from the S/1000. |
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| R-K Rønningstad |
I think NP himself put it well down:
"Clearly there is a small market segment for audio amplifiers
which consume high power, and that is why they exist. but there
are so few high end audiophiles running big Class A amplifiers
that it is not much of a target for those concerned about the
ecology.
If you are concerned about the environment and still want Class
A, the best thing to do is get some efficient loudspeakers and
buy or build little Class A amplifiers. In fact I recommend that
approach anyway, and between the Zens and First Watt, I
have made it easier for you...."
Quoting P. Klipsch (from memory): "What the world needs is a good 2 W amp".
Class A, B or D, the world could really do with more efficient loudspeakers.
Also, if smallish F3 type amplifiers gives enough power, I cannot see their power consumption as outrageous.
One should see this in some perspective. The world is filled with factories producing all kinds of unneccessary "vampires" that consumes power by themselves - some Watts here, some Watts there. And quite a few of them produced in at factories getting their power from very dirty coal powered power plants.
On perfect voltage sources: Yes, in class A these would use infinite bias current. I once owned ML-2s. Class A into everything between 8 ohms and your big toe. Uneccessary. Only suitable for the old Quad electrostatic. So I sold them. So why mentioning these monsters? Well, they were "perfect" voltage sources (within their limit ;-) ). Is really a perfect voltage source necessary? Electrostatic speakers are best driven by voltage sources. But the common so-called dynamic speaker is really not, because the good old formula F=B*I*L does not mention voltage at all, but rather the current through the voice coil.
An interesting question is then should we really design our amplifiers quite different?
Maybe I de-railed the discussion to some degree. But I think NP has answered for his part, and we should go on discussing something more interresting.
Regds
Rolv-Karsten |
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| BrianEno |
| quote: | Originally posted by Nelson Pass
[B]
When I need to go somewhere, I give little thought to the
many kilowatt hours I have to use to accomplish it. When it's
particularly hot or cold, I will again spend kilowatt hours to be
comfortable. No Class A amplifier I ever built competes with
that consumption.
If you care enough about the sonic difference, then the energy
expenditure of the equivalent of a big plasma screen is worth it.
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Sure I prefer a Plasma screen over a LCD one, a Chevy big block V8 over a Volkswagen Lupo engine etc... Maybe in the end it sums up to a significant quantity.
But that's the consumer's point of view. As a designer you could have an other perspective on this matter. It's not a case of moralizing you but rather a case of curiousity why you choose for a solution that consumes (if you like that better then waste) so much resources. | quote: |
Clearly there is a small market segment for audio amplifiers
which consume high power, and that is why they exist. but there
are so few high end audiophiles running big Class A amplifiers
that it is not much of a target for those concerned about the
ecology.
|
Isn't it the other way around? Because those designs are so expensive that only a few people can afford them?
No it's not gonna save the world if we prohibit Class A amps but that's not the issue here. The issue is of it is still necessary today to waste so much resources for achieving that linearity, that musical goal while other designers claim the same performance (and I don't mean the middle of the road designs) but collagues of you like Jeff Rowland or Thomas Colangelo, Levinson and Krell design teams with designs that are much more efficient. Shouldn't it be designgoal in itself to produce efficient working gear? If you say as a designer it's absolute necessary to achieve the best sounding amplifiying device, at that biasing point, I have no choice then to take that for an answer. If you say it's a marketdriven solution because there's a demand for it then that's a business decision. The truth could be somewhere in the middle.
I don't think there was a demand for your elegant Stasis solution. You just put it on the market as a visionair and your sales boomed as never before I understood. I hope you understand the subtle difference between the two.
| quote: |
If you are concerned about the environment and still want Class
A, the best thing to do is get some efficient loudspeakers and
buy or build little Class A amplifiers. In fact I recommend that
approach anyway, and between the Zens and First Watt, I
have made it easier for you....
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Just like you I think because that's were we have to live in.
I have full range Acoustats that do not excel in efficiency but most of the time I stay in the Class A operating area with my ML-3 or Rowland model 8T. So now and then I like to play a louder and then due to the logarithmic operation of my ears I need a lot of power more. Thanks for your reply. |
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| dsavitsk |
| quote: | Originally posted by Nelson Pass
If you are concerned about the environment and still want Class
A, the best thing to do is get some efficient loudspeakers and
buy or build little Class A amplifiers. In fact I recommend that
approach anyway, and between the Zens and First Watt, I
have made it easier for you.... |
I think this is a great point. There are tons of low power class A amps, and it does seem that efficient speakers is a better sonic solution than class B amps.
Moreover, at least in the winter, the heat from an amplifier is more efficient than the heat from the heater in your basement as the amp heat is not lost in the pipes on the way up. So, run your amps hard in the winter and turn the heater down a bit :) |
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| vdi_nenna |
| How funny would this look on a high-end amp? I think Jacco is rubbing off on me!!:D :D |
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| BrianEno |
This another European one.
Which Class would the XA-200 fall in do you think? |
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| jacco vermeulen |
Eeh, not sure, i've got the 400hp Chevy V-8.
According to Hugo's link i need a 280.000W model from NP.
Colangelo's Viola power amp runs in AB2, at 400 watts rms in 8 me thinks it's a hot babe.
Vince,
send me the tag, i'll stick it on the sub. Someone has been smoking cheese again, and it wasn't me this time
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| GRollins |
BrianEno,
The very title of the thread is a question: 'Why class A?' That's fine as far as it goes (though it's been done to death if you'd only take the time to look at some of the older threads). You assume a hostile stance from the outset, ask a question you don't really want answered, then profess not to understand why no one wants to play your game.
You say that you don't have a technical background. You resist answers that in any way lean towards the technical. Well, duh! If you reject technical explanations for class A, naturally you're going to think that it's an advertising phenomenon.
My advice is simple, although I doubt you'll take it: Unlearn the advertising fluff. Learn some electronics. Learn how bias influences the performance of the gain devices (Nelson recently posted a graph in another thread shows distortion vs. bias--although there's more to it than simple distortion). At that point, you will be in a position to understand why people might choose class A, even though it is relatively inefficient.
You seem to think that there's a magic bullet topology that will let you have it all--something akin to the fabled 100MPG carburetor that has supposedly been suppressed for the last fifty years. Ain't so. Yes, there are distortion canceling schemes, ranging from negative feedback to clever topologies. The funny thing is that if you take a given circuit and crank up the bias...it works better still. It's not that difficult an experiment to perform.
Or if, as I suspect, you simply want to be argumentative, you will find that folks here tend to tire of that sort of behavior rather quickly.
Grey
P.S.: Do you also intend to become a member of websites dedicated to electric toothbrushes? After all, they waste electricity doing something that can be done just as easily by hand. Oh, and electric watches! Don't forget them! Golly, get a stem-winder and save the power. Light bulbs, too...you'll need to become a member of every light bulb site and take a stand for the newer, more efficient florescent bulbs!
No?
I didn't think so.
You're just posturing, and it's annoying. C'mon...show us you're serious. Learn a bit about what you're talking about. |
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| BrianEno |
| quote: | | You assume a hostile stance from the outset, ask a question you don't really want answered, then profess not to understand why no one wants to play your game. |
Who's hostile here?
| quote: | | You say that you don't have a technical background. You resist answers that in any way lean towards the technical. Well, duh! If you reject technical explanations for class A, naturally you're going to think that it's an advertising phenomenon. |
I know the benefits of Class A biasing to keep a transistor in it's lineair operation region away from it's cutof point. I know what crossover distortion is in a complementary design.
But even if I had now tecnical understanding at all I would still be entitled to pose a question why a designer of some of the best audio gear around chooses for a design solution given the context I supplied in my initial posting. If you find that offending so be it. This is a Pass Labs forum that deals about products from Pass and I find it totally appropriate to wonder why the design is what it is. If you start to question my motivation in a earlier posting don't you think I've the right to argument my question.
If you don't like an argument because you know you're just right all the time then there's no cause for a Forum.
| quote: | | Do you also intend to become a member of websites dedicated to electric toothbrushes? After all, they waste electricity doing something that can be done just as easily by hand. Oh, and electric watches! Don't forget them! Golly, get a stem-winder and save the power. Light bulbs, too...you'll need to become a member of every light bulb site and take a stand for the newer, more efficient florescent bulbs! |
Ridiculizing your conversationpartner is not a nice/strong way of changing arguments. I treat you with respect don't I? |
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| Nelson Pass |
| quote: | Originally posted by BrianEno
Is this Mark Levinson or Mark Glazier or just a stupid question. |
Mark Glazier.
:cool: |
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| MikeBettinger |
| quote: | Originally posted by el`Ol
I heard several powerful amps at the Highend in Munich this year and the (class A) Electrocompaniet Nemo had so much more soul than what I heard from Mark Levinson, Jeff Roland and (worst of all) MBL. I have my doubts this will ever change. |
Innaresting observation. But then what is soul when the specs on the rest tell all.
Regards, Mike. |
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| BrianEno |
| quote: | Originally posted by Nelson Pass
Mark Glazier.
:cool: |
Thanks I could not envision that it was Levinson cause he started his operation back in 1972.
Lot of people (here) do not want to generalize, must be cautious, I seem to be very popular here with my annoying questions about Class A)) think that you ment Mark Levinson in this photograph.
They all were curly designs, I mean Levinson himself, Colangelo end Glazier.
;) |
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| GRollins |
| quote: | Originally posted by BrianEno
I know the benefits of Class A biasing to keep a transistor in it's lineair operation region away from it's cutof point. I know what crossover distortion is in a complementary design.
|
You either do or do not understand what you wrote...you can't have it both ways. If you do understand, then you've answered your own question and negated your stated purpose in starting this thread. If you don't understand, then you should consider learning a bit of electronics. Your question would then answer itself.
Or, since you seem to prefer it in business/marketing terms: Every product has a natural life span in the market place. Some flop on introduction. Some last for years, perhaps decades. Yet they all reach a point where they're no longer adding enough to the bottom line to make it worth keeping them in the product line. Once the decision is made to terminate the product, a replacement product is needed. That product must be differentiated from its predecessor or it will not sell. So--in the case of audio--a new model appears, sometimes with a new topology, sometimes a 'rediscovery' of some operating class or another. Now, most manufacturers don't really change their product much. If you look at schematics for successive models, the actual guts of the circuit are almost identical. Nelson has a handful of patents and can combine and recombine them in various ways. Not varied enough? Stick in another idea; he is willing to do unconventional things and has more imagination than most. It's more effort than most manufacturers put into their product lines, which is why I spend most of my time in the Pass Labs Forum rather than any of the others. It's simply more interesting.
Why class A?
Indeed.
Because it sounds better, all things being equal. What? You thought class A got its reputation by accident? Or simply because some advertising maven pulled the term "class A" out of a hat? Not so. Had you done your homework, you would have found that class A was the default technology, over a century ago. After all, there weren't any "P" tubes, hence no complementary circuits. Class AB, B, and C (class C is really only of use for radio, but is of historical interest) came along later. If it was all a matter of advertising malarkey, AB and B would be the "latest and greatest." In fact they do have the lion's share of the market, but then the majority of the market is low and mid-fi, isn't it?
Are there people who buy things based on hype and advertising? Obviously. But that's not true for everyone. Some people actually listen, which is where class A comes in. In spite of the fact that it's a dinosaur, both in terms of age and size, class A is still a contender. Why? Because it sounds better.
Take any standard three-stage solid state amp. There's not as much difference between them as as the advertising would have you believe. Set the output stage bias to class B and listen. Then set it to class AB and listen. Then set it to class A and listen. If you can't hear a difference, then go forth and buy the cheapest, most efficient amplifier you can find and be happy. If you can hear a difference, then you have learned something. If it's a project amplifier that you built, then there's no advertising involved. Again, you have learned something. If you conclude that maybe, just maybe, class A does indeed improve the sound, then you reach the point where you can sit down and weigh the sound quality against the consequences for the environment. How you decide that question is up to you.
In the case of the Threshold Stasis amplifiers--incidentally, I own two S-500s--they run class AB. The topology is interesting and produces decent distortion specifications as it stands. That's not to say the amps can't sound better. Increasing the bias does yield some benefit, but the power supply and heat sinking preclude full class A bias. The amps are good, but not world beaters by current standards. They sound hazy. I use them for my subs and woofer panels. They do well in the low frequencies.
I repeat: If you want to actually ask questions and learn, you'll find that you're welcome here. If you persist in your current tone, don't be surprised if you find people avoiding you. Please note that there have already been several posts wherein the posters attempted to answer your question and/or expressed frustration with your attitude. You're not off to a good start.
Grey |
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| tubewade |
'Why class A?'
It is the simplest way to the cleanest possible sound.
'Wasting energy is a thing of the past.'
Not really. Loudspeakers still do it all the time. Many people consider 92dB 1W/1M to be pretty efficient. That's only 1% efficiency, which by my standards is pretty low. Automobiles and incandescent light bulbs are horrible offenders as well. Since I ride a bicycle to work every day and use exclusively fluorescent lighting, I don't feel bad in the least for enjoying music through class A amplifiers. Further, in the winter, any heat not generated by my amplifiers has to be generated by my furnace. |
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| john65b |
I don't get this whole thread. Why all the rumblings about Class A being inefficient? Of course it is, just like all else in this universe. Your car is no more than 10-15% thermally efficient.
Besides, wouldn't a theoretically, fully 100% efficient amp also be reversible, allowing you to input music and get heat and electricity at the output? I would love one of those in my shower.
Where is Carnot when you need him? |
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| Cloth Ears |
| quote: | Originally posted by BrianEno
So why is perspective with the other manufacturers of highend audio/amplifications has Nelson Pass revert back to energy wasting solutions from the past. Why is he back to square one in that parameter? |
I didn't think that Pass Labs had reverted to Class A at all. I believe they've been producing Class A amps since inception (were the Alephs the first series?). Class AB also, but always Class A.
Wasting power is another thing. If you're listening to your class-whatever amp, then you're "wasting power", as most of the power is given off as heat (very few current speakers are more than 1% efficient).
If you want to save power, try installing some solar panels; unplug all those "wall-wart" power supplies that are used for telephones/chargers/lights/portable units (as they're always on); turn off one or two lights (one porch light turned off would "pay" for 2 hours of Class A listening).
By the way, are you Brian Eno, or have you just borrowed the moniker? |
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| john65b |
If you are Brian Eno (as in Brian Eno /John Cale - Wrong Way Up - one of my favorite CDs), glad to meet you. Love your music.
Even if it sounds inefficient on my Magnepans |
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| audiorob |
| quote: | Originally posted by BrianEno
<snip>
I have full range Acoustats that do not excel in efficiency
<snip>
|
The irony of disparaging inefficient amplifiers while using
inefficient speakers is making me giggle. ;)
It is a fact that there are lots of speaker systems that are
FAR more efficient than Acoustats. I assume you have a
reason for squandering so much power in such inefficient
devices. Maybe, just maybe, this reason is similar to why
others choose to build and listen to Class A amps...
Just a thought.
Robert |
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| MEGA-amp |
I listen to my Class A in pitch black, with the lady of course. So I guess i'm doing my part to conserve energy, but at the same time expending it........YEAHHAAA:devilr:
Happy 4th!!! |
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| jacco vermeulen |
The motivation for all this holy war obsession about the ecological Class A malice still illudes me.
This whining has been going on for a quarter of a century, there's a vegamite guru scheduled to jump out of the woods every six months for a Class A swearing session.
Looks like it is legit to have a monster 500 watter Class AB, but anyone with the urge to shack with a 60 watt SE Class A cuty is a tresspasser.
The impression Mr Pass has given me over a lengthy period is that he would be bored out of his skull if he was stuck to the same old trick for the Harry Harlow peanut.
Criticising him for having the talent and skills to merchandise the offspring of his mental flaws, instead of acknowledging there's a structural demand from the audio git market for these amplifiers, denies the laws of economy.
The first Pass labs product was not the biggest waster steroid on the cat walk, Rowland Research's M7 and the largest Perreaux power amp model outclassed the Nulls in weight and excess heat.
The Aleph-0 was considered an oddball at first, with the proper loudspeaker the only competitors in 92/93 were bulky true environmental unfriendly triode tube amps.
After plus 25 years, it's finally dawning there's no easy way out to reach for heaven with a mosfet amplifier.
There's blindness for you, all it takes it to listen, but listening is not allowed by AB tweakers.
Not a week goes by without me hearing an automobile with a engine/tranny itch pass by.
Nowadays it's a jolly flash knowing that the car will be hauled to a mechanics shop within a week or two, 25 years ago it annoyed me every single time that people can be so deaf and dumb. :clown:
(thanks for the Glazier versus Levinson clarification, i wondered how Mr Levinson changed his image to the man-in-black that fast)
PS: i don't have a helicopter, yet. |
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| analog_sa |
| quote: | Originally posted by john65b
If you are Brian Eno (as in Brian Eno /John Cale - Wrong Way Up - one of my favorite CDs), glad to meet you. Love your music.
Even if it sounds inefficient on my Magnepans |
I somehow doubt that the real Brian Eno listens to Sade :) |
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| BrianEno |
| quote: | | You either do or do not understand what you wrote...you can't have it both ways. If you do understand, then you've answered your own question and negated your stated purpose in starting this thread. If you don't understand, then you should consider learning a bit of electronics. Your question would then answer itself. |
Just had a good continental nightrest.
| quote: | | Are there people who buy things based on hype and advertising? Obviously. But that's not true for everyone. Some people actually listen, which is where class A comes in. In spite of the fact that it's a dinosaur, both in terms of age and size, class A is still a contender. Why? Because it sounds better. |
You know what 's gonna happen with dinosaurs, don't you?
Can't compete with your black & white world.
Had several Class A amps from Krell and Threshold (the S/1000 was converted from a bridged topology to a massive parallel configuration, by the German distributor WBS for Threshold in that era, like in the SA/1. After consulting with Nelson Pass about the presetting of the heatsinktemperature I played around with the biastrimmer and lowered the quiescent current quite a bit. Did not really notice any declining in musicallity.
Had several incarnations of the model 7 from Rowland and the Model 8T. Would love an amplifier with the punch of the big Krells or Levinson ML-3 combined with the delicacy of the Threshold SA/1 or model 8T.
I'm always open for a new learning curve. What I learned from you is that Class A is the best and I can have a opinion after I built a Class A amp myself and then weigh the pro's and cons.
| quote: | | Please note that there have already been several posts wherein the posters attempted to answer your question and/or expressed frustration with your attitude. You're not off to a good start. |
Maybe you should ralley some support for a ban. That's how you should deal with dissedents.
:angel: |
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| BrianEno |
| quote: | Originally posted by john65b
If you are Brian Eno (as in Brian Eno /John Cale - Wrong Way Up - one of my favorite CDs), glad to meet you. Love your music.
Even if it sounds inefficient on my Magnepans |
I'm sorry I'm NOT the man. Was just a name that sprung up. Do like his music though and his tigeroutfit in the beginning with Roxy Music. ;) |
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| Netlist |
Guys, leave the personal allegations out of this thread. Email is a wonderful medium for distant fights, not this forum.
/Hugo :cop: |
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| vitalstates |
| deleted - missed the last page!!! |
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| stefanobilliani |
| quote: | Originally posted by BrianEno
You know what 's gonna happen with dinosaurs, don't you?
|
There are nice answers and theme variations in " the ice age 2 - the meltdown " LOL | quote: | Originally posted by BrianEno
I played around with the biastrimmer and lowered the quiescent current quite a bit. Did not really notice any declining in musicallity.
|
Many people that didnt know Class A and SE talk about musicality . The same thing for the CD era . Many people that didnt know LP s at all talks about musicality . Nothing "personal " , but I cant Image why .
Also many reviews , doesnt talk at all about stereophony , how is the sound of a bass drum - how do you enjoy that note throug that amplifier and so on. What is doing music to them . Oh yeah , they dont talk about the importance of being biased .... :)
What are the " effects " on your personal experience ... lowering the bias . |
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| jacco vermeulen |
Knock Knock, who's there ?
It's Thomas Jefferson, it's July 4th, can i come in now ?
Get out of here, you dinausor. |
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| BrianEno |
| quote: | | Criticising him for having the talent and skills to merchandise the offspring of his mental flaws, instead of acknowledging there's a structural demand from the audio git market for these amplifiers, denies the laws of economy. |
I did acknowledge that. There's also a market for 425 cubic inches, 427 BHP big block Chevy V8 engines but the marketdemand alone is not reason that you cannot question it's fuelconsumption related to it's performance in a particular chassis.
Love the sound of those engines though;)
| quote: |
audiorob:
The irony of disparaging inefficient amplifiers while using
inefficient speakers is making me giggle.
It is a fact that there are lots of speaker systems that are
FAR more efficient than Acoustats. I assume you have a
reason for squandering so much power in such inefficient
devices. Maybe, just maybe, this reason is similar to why
others choose to build and listen to Class A amps...
Just a thought.
Robert
|
Bought this speaker new back in 1989 and I'm really font of it.
To compensate for it's inefficiency I do not permit myself to operate a full Class A biased amp. ;)
Even with a SPL of approx. 80dB/1 watt@1 meter I seldom need more then a few Watts of power for acceptable soundlevels.
I receive a lot of reactions that compare the current designs of Pass with other activities that consume the same or even more plasma screen or turning up the heater or airco to feel comfy, Pass himself) getting a vacation with a plane and so forth but there in themselves no reason or argument to not wonder why a designer should choose to apply a technique that wastes at least 75 % of it's currentintake in heat while at his maximum outputcapability and beneath that point the efficiency only diminishes.
The answer from Pass in a nutshell was clear:
There's a market for those amps, it's a small one (nothing to be alarmed about) and the benefits of lineair operation under all conditions outweighs the penalties you have to pay for it.
Member Grey (Grollie I believe) even stated it very forcefully:
Class A is simply the best and there are customers that want the best.
My opinion/experience is that a specific Class of operation is just
one (important) parameter in a total concept but one that can have serious consequences for the final design of a poweramplifier. That's why people invent sliding bias amps like the 800A, Stasis topology, plateau biasing AB1, AB2 ... |
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| h_a |
| quote: | | Maybe you should ralley some support for a ban. That's how you should deal with dissedents. |
Your continuing ignorance of Grey's explanation (and others) is the reason why I didn't even bother to reply to you since I knew from the beginning it would be useless. You showed right from the beginning that you're not interested in a technical discussion; you just want to repeat product advertisments.
Well do so.
However I really care about above statement.
I highly respect Grey and I'm fully confident that he has in no way such inferior inclinations as to ban you.
Besides, don't start thinking anybody raises a finger to remove you from the board - you are not worth the effort, really. Further, the guys here are very liberal.
In a couple of weeks you're gone anyway or you finally learned something and pose your questions differently.
Cheers, Hannes
PS: how's it possible you admit lack of technical knowledge and at the same time refuse to understand replies from people who have it? |
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| Circlotron |
| quote: | Originally posted by dsavitsk
Moreover, at least in the winter, the heat from an amplifier is more efficient than the heat from the heater in your basement as the amp heat is not lost in the pipes on the way up. |
Not exactly. Don't forget the power station wastes fully 60% of it's energy up the chimney, and a further 10% in distribution. Only 30% gets to you. Your domestic heater is something like 70% efficient. |
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| AndrewT |
Hi,
two days on the Forum and what a rumpus.:devily:
Even I was not that bad (well in my somewhat blinkered view).:o
Can we get any agreement?:grouphug: |
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| AndrewT |
| quote: | | Your domestic heater is something like 70% efficient |
my domestic heater is a lot better than that.
I use a ClassA amplifier and ALL the energy input ultimately comes out as heat.
In my book that is 100% efficient (and no added water vapour to cloud the calculations).
Just great for three seasons in the Scottish year.
So the BIG question becomes:-
would Brian rather watch a three bar electric fire (radiator) or use a ClassA amplifier and get some real enjoyment?
You all know my preference.;) |
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| ROVSING |
| quote: | Originally posted by Circlotron
Not exactly. Don't forget the power station wastes fully 60% of it's energy up the chimney, and a further 10% in distribution. Only 30% gets to you. Your domestic heater is something like 70% efficient. |
Don't forget that "household animals" cows, pigs. etc. contributes with allmost 20% to the global heating each cow dissipates 600 liters of metan gass each day !
They pollutes more than cars and aeroplanes!
A little scary to think about - but i still like a good steak.... |
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| BrianEno |
| quote: | h_a
I highly respect Grey and I'm fully confident that he has in no way such inferior inclinations as to ban you.
Besides, don't start thinking anybody raises a finger to remove you from the board - you are not worth the effort, really. Further, the guys here are very liberal. |
You seem to know the "guys" here very well within 202 posts in six months.
Be carefull with the word 'liberal' in your statements, some people in the US at this forum could find that offensive.
You did not bother to read my remarks on the comments of Grey that's obvious. I do acknowledge the merits of full Class A biasing but I really wonder if it's worth to go the whole way.
Nelson Pass himself said that my questions were indeed valid and legitimate(now you can speculate that he was just polite to me, or did I was not really wort the effort just like you) nad he did answer them. Few people like you took my question as offensive or even provocative against a skilled designer. I did not start this personal quarrel and although I feel I have the right to defend myself against such accusations I will stop to react against these kind of personal attacks.
Cheers to you also mate! |
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| Zen Mod |
seems hat nobody mention shunt regs.........
especially when used for A class output amp
:devilr: |
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| h_a |
| quote: | | You seem to know the "guys" here very well within 202 posts in six months. |
What an amazing argument.
I've not written any books on electronics, but I've read some. So I'm not qualified to post here ;-)) ?
Forgive me my use of 'liberal', I'm not a native english speaker, but I hope you got what I wanted to say.
Interestingly you never comment on the real criticism, like mine:
| quote: | | PS: how's it possible you admit lack of technical knowledge and at the same time refuse to understand replies from people who have it? |
Well, at least I know the people here that contributed knowledge and/or schematics and it would be better if you would do as well.
You can always try the search button ;-))
If there was any offence in my previous post, I apologize.
Cheers, Hannes
PS: I'm going to stop posting to this thread, since I think everything was said. Maybe this is the reason I don't have 1000+ postings? But maybe you would call that spamming then? All what is possible to come now is further personal attacks or repeating statements.
PPS: if you want to give smallish Class-A a try, you're welcome to participate in the F3 group buy , I would say an excellent opportunity to find out what this is all about! |
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| BrianEno |
| quote: | | I'm going to stop posting to this thread, since I think everything was said. Maybe this is the reason I don't have 1000+ postings? But maybe you would call that spamming then? All what is possible to come now is further personal attacks or repeating statements. |
Your right there!
I just repaired the biascircuit of one of my Levinson ML-3's, hope it's stays stable and are now in the progress of repairing the rushincurrent limiting circuit of my other ML-3. I have a JRDG model 8T too to care for, so though tempting your F3 project I'll pass that offer.
Succes with the F3 project and let's agree on the fact that Nelson Pass is a hell of a guy sharing his knowledge for DIY projects and that he's always prepared to answer any questions about his current line of electronics or his former ones.
No hard feelings anymore? |
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| lohk |
I call my Class-A amps "my winter amplifiers" - they help to heat up the room, like any other device. Thats nothing more than good. And ecologically as correct or not as any other electric heater.
In summer I listen on cool days only - cause on hot days I am in the garden or at the lake (for the other occasions I have my Chipamps...)
:)
(So many devices in all homes run permantenly "on standby" which uses a lot more energy than the ClassA amps working hours... :( ) |
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| ssmith |
Seems the above 'discussion' can be summarised thus:
Q: Why Class-A? It's an old concept and not very eco friendly!
A: Because it sounds better.
:D
Anyway, the only thing I can contribute to this thread is from a very newcomer perspective. I've dabbled with Tripath (though not UCD), Gainclones, other chipamp designs, which all have their strong points, but my limited experience with Class A left me liking the sound more. Having close to zero technical knowldege, I cannot explain why. But I'm currently building Mini-Alephs.
:smash: |
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| lumanauw |
A couple of weeks ago, I had a table dinner with designers of Hertz loudspeaker (subsidiary of Audison, Italy) when they visit Bandung. (Eating satay and lontong, Jacco :D)
I don't know whether what they said is right or wrong, but if it is right, then there should be something (other than classA amps) that should be more of a concern. Loudspeakers.
If I'm not hearing wrong, 90% (or is it 95%?) energy that comes to a loudspeaker is actually turned into heat, and only 10% (or 5%?) that is becoming sound energy. The usage of loudspeakers should banned first before classA amps :D |
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| h_a |
| quote: | | No hard feelings anymore? |
Never had, really. Hannes |
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| janneman |
| quote: | Originally posted by lumanauw
[snip]The usage of loudspeakers should banned first before classA amps :D |
Spot on!:D
Jan Didden |
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| Kashmire |
Time to toss in my 2 cents ...
Ecological responsibility is increasingly urgent, but one must pay attention to the mathematics of scale. The aggregate energy consumption of my amplifiers is dwarfed by the energy consumed by my lights and HVAC system. Sure, I've endeavored to minimize consumption with CFL bulbs (more on this, see footnote), tankless water heater, and high-SEER air conditioner. I can prioritize and address the high consumers in my energy budget according to magnitude, and my amplifier's contribution to my consumption rate is very low on the list (especially if I include my car).
I also exchanged my AMD Opteron computer for a Intel Core Duo, which slashed power consumption by more than 50%. This change saves about 1kwh per day (100W for 10 hours vs. 200W for 10 hours), which easily compensates for running my amplifiers a few hours each night. I also got an Antec Earthwatts power supply, which also boosts efficiency and power factor.
That being said, I also prioritize my consumption based on personal value of enjoyment. I like my amplifiers, I like how they sound, and I like my music. I'm lucky in this regard: my vices for class-A amplifiers result in energy consumption less than my neighbor's porch light, which stays on all the time.
Now, some efficiencies can be addressed. A choke-regulated power supply (LC filter) will dramatically smooth the peak currents through the transformer and filter capacitors, and increase power factor. You can also have a switchable bias current (for example, 0.5A and 2.0A), depending on how critically you are listening. Casual listening can suffice with 0.5A bias current. Better power factor increases the efficiency of the entire power grid. Sure, a couple hundred watts is really small in this regard, but it gains a few percent of efficiency overall. The switchable bias current would divide power consumption by a factor of 4 during non-critical listening sessions.
Overall, I can clean up my consumption lifestyle considerably before my sins of an energy-consuming class-A amplifier becomes hypocritical. I can only hope the efficiencies of lighting, HVAC, automobiles, and computers get so good, that the worst thing I need to worry about is my amplifier.
PS: Note about CFL bulbs. You may want to carefully consider buying and using these bulbs, because of environmental problems.
http://www.newstarget.com/021916.html
PSS: According to Berkeley EETD, computers accounted for 2% of the total energy consumption in the USA at 74 TWh in 1999. The US Energy Department accounted for 3% in 2000. This number is undoubtedly larger in 2007, which places computers as being major energy consumers in the league with HVAC and lighting. |
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| jacco vermeulen |
| quote: | Originally posted by Kashmire
mathematics of scale |
Then you're gonna love this :
The global containership capacity in 2006 was 10.6 million TEU.(equivalent of a twenty foot container)
A 5000 TEU containership has about 70.000KW installed diesel engine power.
Suppose an average fuel consumption figure of 125 gr/KW/hr, 50% energy efficiency, and 280 days at sea.
The 50% heat that this fleet puts out in the air on a yearly basis is the equivalent of 1.25 Billion Aleph-5 amp owners who use their 400 watt heaters for 4 hours on a daily basis.
In reality, the average container vessel capacity is much less than half of 5000 TEU, requiring more horsepower per TEU, the average fuel efficiency is lower too.
More likely that every home in the world could listen through an Aleph-5 amp four hours a day if we sunk every containership.
Nelson should love that. :clown:
(the latest gasturbine engine developments lead to higher than 60% fuel efficiency, ecologist food)
Over the last couple of years we(me) have reduced our electricity consumption by 6000KWh per year, despite my awkward hobby. |
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| janneman |
... or if we dump every class-A on the planet we would have the containerships for free...:xeye:
Perspective if everything!
Jan Didden |
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| Nelson Pass |
It looks like everyone agrees why we would use Class A. The
issue is to waste less power. There are some good avenues
for this that don't require any re-design of products.
1) Use efficient loudspeaker drivers. They often sound better
anyway, and the 87 dB/watt speaker that requires 200 watts
Class A dissipation puts out the same amount of sound as the
97 dB/watt at 20 watt dissipation.
2) Turn the amps off when you aren't using them. I know, this
is heresy to a portion of the audiophiles, but if you only listen
an hour a day, you are wasting 96% of the energy.
I personally warm the amps up for an hour before critical
listening, and find that quite adequate, and unless there is a
specific test being conducted, I shut them off when I'm done.
3) Turn the bias down or use a chip amp or Class D amp for
noncritical listening. I use Class AB for my television.
4) As mentioned before, use Class A amps in the winter, and
if you use them in the summer, try to not use air conditioning
at the same time, which would constitute a double sin.
:cool: |
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| BrianEno |
Although some people found my initial posting on this subject offensive (I grant it was a bit provocative but never ment to stirr up a discussion just for the sake of argumenting) and questioned my motives I learned that to attain the best sound possible from an amplifier is a full biased device. I was not very impressed with lectures about other gear that would waste a lot of energy because with that argument there's never a incentive to design any efficient running gear because you can always point out a other offender.
Still it remains a fact that other high regarded designers of Highend audio products with the same goal in mind as Nelson Pass, that is to design amplifiing devices that keep the lowlevel inputsignal as much intact as possible, and a mean that in every parameter, before passing it with a greater amplitude to the ouputconnectors, do come up with different solutions.
My dentist is also a professional loudspeaker designer : URL http://www.mc-systems.com/ He mentioned to me that he heard PassLabs the other day and was very impressed with the performance of it. Do not know what Class it was.
Greetings and thanks |
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| Zen Mod |
| quote: | Originally posted by BrianEno
Although ................. |
no harm feelings............ ;)
just go and spend few hundreds on new software for your Aclass or no Aclass based system and enjoy..........
who cares about classes ...........
ya remember one preamp which have "volume" knob labeled as "listening pleasure" ............. or something like that;
that's certainly adequate attitude ........... |
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| steenoe |
| Come on, you cant be such an A##:D Class A rules, sounds mucho better and is generally the best listening experience you can get:D Ya mean to make fun of us?? I am sure you do....He-he I didnt bother reading through the thread since it would obviously be a dedicated waste of time:D Since I hate to waste time...... There you go:smash: |
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| Ed LaFontaine |
| quote: | | I'm sorry I'm NOT the man. Was just a name that sprung up. Do like his music though and his tigeroutfit in the beginning with Roxy Music. |
Brian Eno -> "Music For Airports"
Brian Ferry -> Roxy Music :whazzat: |
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| BrianEno |
| quote: | Ed: Brian Eno -> "Music For Airports"
Brian Ferry -> Roxy Music |
That's only partially true. On the first two records of Roxy Music in the beginning of the seventies Brian Eno participated as a full bandmember. He got a quarrel with the other Bryan over the direction of the band musically (that's how you spell his Christian name) and left the band.
Just something trivial hope that littel piece of information will not stirr up a other discussion;) |
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| Magura |
| quote: | Originally posted by Zen Mod
ya remember one preamp which have "volume" knob labeled as "listening pleasure" ............. or something like that;
that's certainly adequate attitude ........... |
Hmm, you mean pleasure control right? ;)
http://www.dartzeel.com/
Magura :) |
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| Zen Mod |
:clown:
your preamp certainly need large font for that knob
:devilr: |
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| Magura |
| quote: | Originally posted by Zen Mod
:clown:
your preamp certainly need large font for that knob
:devilr: |
I have taken the consequence of this issue, and emplyed NKT (no knob technology) :devilr:
Magura :) |
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| Zen Mod |
| quote: | Originally posted by Magura
I have taken the consequence of this issue, and emplyed NKT (no knob technology) :devilr:
Magura :) |
ha ..........
so- your preamp is wasting 5W/ch and your NKT circ is wasting 50W.......luckily- just in moments when you operate it ;)
edit:
look - we are on topic here!! |
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| Magura |
| quote: | Originally posted by Zen Mod
ha ..........
so- your preamp is wasting 5W/ch and your NKT circ is wasting 50W.......luckily- just in moments when you operate it ;)
edit:
look - we are on topic here!! |
Naah, I guess the pre's are wasting somewhat more, and there are 4 of them, though switching power between them as the need for the different inputs arise :angel: ....but no input selector switch in the signal path :cool:
And as for the NKT....I don't think 50W is adequate.....the stepper alone eats like 20W or so :hot: as it's got a big rotary switch to turn....remember ?
Magura :)
Edit: NKT, now also in red ;)
http://www.briangt.com/gallery/magura-40stepattenuator
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| john65b |
| quote: | | He got a quarrel with the other Bryan over the direction of the band musically (that's how you spell his Christian name) and left the band. |
Must have been a spat over Jerry Hall. Oh, whoops that was Ferry and Sir Mick.
Eno was in Roxy Music. But only because he had a reel to reel deck. |
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| GRollins |
The whole thing would be a no-brainer if class A didn't sound good. I mean, really, why would anyone choose class A? It's expensive, it's hot, it's heavy, it's bulky...absolutely everything weighs against it. Except for the sound quality.
I seem to recall having mentioned this before, but even class A amps can sound better. I built a couple of Aleph 2s (tip of the hat to Nelson for making the schematics available). Now, the Aleph 2 is a class A amp to begin with and sounds fairly good, but being unable to leave well enough alone, I spent a few days playing with the bias. The results: Lowered bias (but still class A) caused the amps to sound thinner, more hi-fi. Stock bias (~3A overall bias) filled out the sound and gave a better image. Increasing bias above stock improved the image further and gave even better sound quality. I compromised at about 10% over stock bias due to the fact I was using TO-220 output devices and didn't want to cook them. Enough people here have Aleph variants that this should be easy to replicate. It's even easier on a "normal" amp with a bias pot--just watch the heat dissipation.
Those who do not hear any benefit to class A are, as I said earlier, welcome to buy the cheapest, most efficient amp available. If it meets your needs, then be happy and go on to the next thing.
The topic of "sliding" bias circuits always comes up at some point. On the surface, they seem like such an elegant solution that it's hard not to be seduced by the idea. The devil, as always, is in the details. Bias changes a lot of things. Take heat, the very thing you're trying to get under control. As the temperature increases, so does the gain of the device. And if the gain changes, then everything changes, and not for the better. In operation the amp changes behavior depending on how loud you play it. Worse yet, it changes with the dynamics of the music. Then there's the circuit required to change the bias. No matter how fast it tries to change the bias, it is always a step behind. This takes on a literal interpretation when you see circuits that maintain a higher bias after a signal peak in the hopes of 'being ready for the next peak.' The idea works in the sense that music comes out, but it's a flawed solution.
Class D? Well, music comes out, I suppose you can say that for it. 'Nuff said.
The idea of using a small high quality amp in conjunction with a larger lower quality amp (Quad current dumping/Threshold Stasis) would seem to have promise, but the brute force amp always seems to impose more character on the signal than you'd like.
Negative feedback--long touted as the panacea for all ills--usually plays a supporting role in most efficiency schemes. This leads to some (e.g. Self/Slone) claiming that a class B amp with enough feedback can give both efficiency and sound quality. Enough has been said about the effects of excess feedback elsewhere that it's not worth wasting pixels here. Note that NFB alone isn't an energy-saver. It's used as a band-aid to repair the damage wrought by sundry efficiency schemes. Unfortunately, it's not without blame(less...er, sorry, shameless joke) in the sonic department.
Etc. etc. etc.
For every measure devised in an attempt to get class A sound quality out of a less power-hungry circuit, a new set of ills is unleashed on the world. Needless to say, the sales literature never mentions the problems, only the benefits. It's the next generation that admits, if only by implication, that there was anything amiss. Otherwise how could the new product be "New and Improved" if its predecessor was, in fact, already perfect.
And so it's left to class A to thunder across the landscape, scattering lesser designs before it. Dinosaur it may be, but it's still king.
Make fun of dinosaurs at your peril. They had a much longer and more successful reign than we puny humans have managed so far.
Grey |
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| Zen Mod |
| quote: | Originally posted by Magura
Naah, I guess the pre's are wasting somewhat more, and there are 4 of them, though switching power between them as the need for the different inputs arise :angel: ....but no input selector switch in the signal path :cool:
And as for the NKT....I don't think 50W is adequate.....the stepper alone eats like 20W or so :hot: as it's got a big rotary switch to turn....remember ?
Magura :)
Edit: NKT, now also in red ;)
http://www.briangt.com/gallery/magura-40stepattenuator
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yup I remember......but I'm little disappointed that you stay with that liliputan one.........even if I like this pic:
http://www.briangt.com/gallery/magu...PICT0092?full=1 |
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| Magura |
| quote: | Originally posted by Zen Mod
yup I remember......but I'm little disappointed that you stay with that liliputan one |
Now could you do me a favour and tell my GF that :D
Magura :) |
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