0.01% THD is -80dB ref the signal. -40dB ref the signal is 1% THD.
(edit
I see that post25 has already addressed this error).
-40dB = 1% THD is monstrous and typical of no global feedback valve amplifiers set up subjectively for "nice sound".
If you like your set up, then don't change it.
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If it is solely H2 (and perhaps H3) you'll have a hard time to detect it with music material (NOT sine waves or pink/white noise, who listens to that anyway) in those controlled DBT's which are so "en vogue" here.
Well, beyond measurements and with respect to objectivity and reproducibility, these are the only thing that really counts. At least more than 'feelings' and, even worse, 'alternative facts'.
Best regards!
Hi Andrew, Yes sorry for my error
Not enough coffee that day and too much snow here In post #29 I did admit my mathematical error. I agree 1% is monstrous for today's standards but for some reason nobody here cares. I swap amps out all the time and nobody seems to say a word unless there is something drastically wrong with an amp. I am in the camp that speakers are far more important than amps with crazy specs. I enjoy making things especially valve amps so I mainly make them and use them. I have very low distortion SS and tube Class AB amps but I hardly use them. I am happy with my "nice sound" but that doesn't mean I won't change things, I like to build and listen to everything, but I do prefer valves in general. In the future I do plan to build an F4 or something from the Pass family of amps.
So let's assume most listening is at slightly above "background level" or even a bit higher than that. Does it make sense to have the "headroom" of a higher wattage amp to improve the dynamics/bass at these low to mid listening levels? (I'm making an assumption here)...
Put another way, do some amps (or which) play well at lower listening levels?
you can make them with vodka and call them caipiroska! Similar flavour, same result!! The recipe is to make them very strong, very sweet and with lots of lime!! Take it from someone who made thousands of them!!
uh-oh, I'll have to disagree very strongly here. No vodka has the organic aroma of sugar cane like a good cachaça has.
They aren't interchangeable at all.
..even if the emphasis is of "TODAY" i do not think the question is answerable. Generational gap comes into the picture. I was born in the silicon age, obviously i will root for an ss amp topology.
Another thing was, this is a DIY forum, we are obviously subdivided into groups, the copy build group, the copy mod group, the designer analyst group, the writer/academic group and whatever group that you can think of. I do however think that there exists a "DEFINITIVE" amplifier topology. By definitive I mean popular by example.
In my opinion, more power does not do anything for you. I'll attack this from a few different points.
Most people will sit 8-10 feet from their speakers setup in a stereo triangle (measure your current setup, I bet I'm close ;D ). Worse case scenario for "average" commercial speaker sensitivity is 84dB/1M/2.83V that I've seen for the average well reviewed speakers that most people will end up buying. 2.83V is actually 2W at 4 Ohms, which most commercial speakers will be, but this easily translates into 84dB/1M/1W because we have 2x the acoustic radiators vs a single speaker.
83-85dB at the listening position is what most people consider "loud enough/ Perfect" and will set their listening volume at, without actually knowing what they are doing. Most music is also mastered at this volume level, as it's what most people prefer and it's a safe listening level for pretty extended periods of time.
With the "average worst case" 84dB efficient stereo speakers above, we need 4 watts to get to 85.5dB at a listening position of 3 meters (approx 10 feet). Each doubling of power ( 8 watts, 16 watts, 32 watts, ect) will gain you 3dB in output in theory, but you will run into "power compression" at larger wattages, where the voice coil heats up and loses some efficiency of turning power into sound.
Now the worst case ambient noise floor in the average living room in a first world country is 55dB. Most likely your noise floor is lower, from 40dB-50dB or lower if you're lucky.
Now given that we need 4 watts to achieve 85.5dB at the 3 meter listening position, we subtract the noise floor of 55dB and find we have a dynamic range of 30.5dB. That's far in excess of the dynamic range present in 99% of music. Only classical music will have that dynamic range, and will most likely not exceed 30dB of dynamic range.
I hope this answers your question! Somebody let me know if any of my math is wrong
If we get into the absolute details of what type of amplifier is best for "low" listening levels, I'd debate Class-A. Just because Class A's THD increases with power, while most amplifiers of other topologies decrease THD with power, up to a point ofcourse. A well designed Class A amplifier will also have a simple harmonic family that makes up it's THD, which most argue that is more "pleasant" but I argue is actually perceptually masked by the brain as hearing-mechanism-distortions (our ears create quite a lot of distortion on their own, but the brain filters this out). Long story short, a single-ended Class A triode or some silicon, such as Nelson Pass' SIT-2, creates the type of THD that I believe is most similar to what is created by the ear, and thus filtered out by the brain easily.
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You originally clarified that 'best' meant 'best sounding' which is a subjective appraisal. So given tastes in sound vary you're not likely to get much of a consensus.
Yet I believe there are more and less transparent amplifiers and that the 'best' sounding amp is the most transparent one when the source is music (emphatically not a sinewave). This is just a belief (hypothesis really) I don't know how to test this hypothesis yet
Hi Famous,
Actually I started a (nearly completely ignored!) thread here a few days back with a solid state SE class-A amp that does quite a bit better than that. Though it's "no-feedback" only in marketing-speak (as are all "no-feedback" amps when you get down to it). The output is a follower and each stage is a Sziklai pair, so there are several very short local-feedback loops. But doing it with tubes would be tough, I imagine.
Bill
An accurate magnification of the input I'd suggest.
Do please set out your reasoning taking into full account the practical implementation details of negative feedback.
OK, I have to correct myself this time. The amp does just about 0.01% at 1W, not 'quite a bit better'. Guess I'm also having trouble with the quick log calculations I guess.
clipping performance is going to matter
if you follow the last few bad examples to size your amps, select speaker sensitivity
Cordell has fast peak measurements of clipping a 200W amp "at realistic, yet listenable, levels in ordinary-sized rooms"
and we do have standards:
if you follow the last few bad examples to size your amps, select speaker sensitivity
Cordell has fast peak measurements of clipping a 200W amp "at realistic, yet listenable, levels in ordinary-sized rooms"
and we do have standards:
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Well lets see now....
I don't suppose I was averse to stirring some controversy with the OP...
Not sure I knew it would be to this degree though..
I did think some controversy would be illuminating, and it HAS!!!
Much of the "illumination" lays "between the lines"....
I also sorta expected the "there is no best" answers.... it did remind me about what every audio salesman in the 70s said as you walked in
through the doors.... basically, work your way back from the speakers....
Though I had kind of hoped that, with all the progress of decades... there might be one thing, that might be good for the vast majority of (non exotic) speakers, as well as the vast generality of tastes...
(or at least one that measures SO well, that everybody HAS to like how it sounds)....
Xaborus's post was most satisfying to me... in terms of what I was getting at with the OP..
(though I did figure some open debate would reveal a lot via long form)..
He cited various different "categories" as well as practicality and "more "normal" and versatile".
Equally valuable to hashing it out long-form via debate/discussion....
Blippo also sensed one of the root ideas I was getting at..
"where things are" with the current state of amp tech "..
On and on...
Thanks for attempting to quantify it though...
admittedly not a very funny one..
I couldn't disagree with this more!
Facts are facts! IF there exists an alternative set of facts, its only because some were omitted in the first instance....
As much as I agree about feelings in the general arena,
Music is ONLY... EXCLUSIVELY about feelings!!!!!!!!!!
You'll note that the name of the forum is diyAudio...
Not diyLaboratory-instrument....
Music, (unless we're talking about the reproduction of train-whistles and the like) exists only to evoke emotion.. feelings.............
So the only consensus so far, is that its purely subjective but its not at all subjective?!?!?!
(there needs to be a pot-stir emoticon)
There's another criteria which I'm aware of, as I've discovered it for myself...
That of "musical involvement"... Being involved in the music... or, a playback system that you find draws you into the music... as opposed to finding your mind wandering while listening............
Hate to say it, but... I've often had that experience with SS equipment.
Especially in this sterile/harsh/dry digital recording/source world we live in TODAY.....
HUGE learning, so Thank you!
I shall keep reading.. and learing.....
I don't suppose I was averse to stirring some controversy with the OP...
Not sure I knew it would be to this degree though..
I did think some controversy would be illuminating, and it HAS!!!
Much of the "illumination" lays "between the lines"....
I also sorta expected the "there is no best" answers.... it did remind me about what every audio salesman in the 70s said as you walked in
through the doors.... basically, work your way back from the speakers....
Though I had kind of hoped that, with all the progress of decades... there might be one thing, that might be good for the vast majority of (non exotic) speakers, as well as the vast generality of tastes...
(or at least one that measures SO well, that everybody HAS to like how it sounds)....
Xaborus's post was most satisfying to me... in terms of what I was getting at with the OP..
(though I did figure some open debate would reveal a lot via long form)..
He cited various different "categories" as well as practicality and "more "normal" and versatile".
Equally valuable to hashing it out long-form via debate/discussion....
Blippo also sensed one of the root ideas I was getting at..
"where things are" with the current state of amp tech "..
On and on...
Well how do I know you aren't???
Thanks for attempting to quantify it though...
This was actually intended as something of a joke...
admittedly not a very funny one..
As much as I like Kay... (and his cocktails)
I couldn't disagree with this more!
Facts are facts! IF there exists an alternative set of facts, its only because some were omitted in the first instance....
As much as I agree about feelings in the general arena,
Music is ONLY... EXCLUSIVELY about feelings!!!!!!!!!!
You'll note that the name of the forum is diyAudio...
Not diyLaboratory-instrument....
Music, (unless we're talking about the reproduction of train-whistles and the like) exists only to evoke emotion.. feelings.............
So the only consensus so far, is that its purely subjective but its not at all subjective?!?!?!
(there needs to be a pot-stir emoticon)
There's another criteria which I'm aware of, as I've discovered it for myself...
That of "musical involvement"... Being involved in the music... or, a playback system that you find draws you into the music... as opposed to finding your mind wandering while listening............
Hate to say it, but... I've often had that experience with SS equipment.
Especially in this sterile/harsh/dry digital recording/source world we live in TODAY.....
HUGE learning, so Thank you!
I shall keep reading.. and learing.....
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