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Can amplifier speed and resolution be measured?

mansr

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When the holistic benefits of wideband amplifiers were implemented, but with a blocking cap on the outputs of the RIAA stage and the preamplifier output itself, the following stages could be direct coupled. I have a number of power amps with FET direct coupled (capacitorless) front ends like this:

What's that schematic? Something Sony?
 

restorer-john

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What's that schematic? Something Sony?
Yes. Sony. They are easy to spot huh? :)

TAN77es/TAN80es. 1987/8 and 1989/90. I have two of the TAN77es amplifiers here:

(not my pics, from the internet courtesy Vincei)
1556146885804.png


1556145200793.png


TAN-80. Same basic amplifier, no meters.
1556145305622.png
 
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restorer-john

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It's a distinctive style.
Beautifully done multicolour schematics with precisely placed voltages. A lot of care went into Sony's schematics.

Some other brands are simply dreadful. Luxman is one of the bad ones. Sansui were always full of errors. Pioneer were also very good, arguably almost as good as Sony, but the print was really small, even on original A2/3 foldouts.
 
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Lately, the JDS Labs Atom has been making headlines due to its wonderful measurements (and yes I still have yet to receive mine... it's being brought to me by usps...).

Yet, many of those who "reviewed it" through subjective impressions did appreciate the performance "for the price", but have been quick to dismiss it as having quite a "lack of speed and resolution" compared to their other much fancier products (perhaps in an attempt to prevent buyers remorse from their audience or in statement of true facts).

Which sparks some curiosities in me:
1- Can amplifier speed and resolution be measured?
2- If so, by what metric?
3- Would this metric be quite audibly noticeable within lenient and strict threshold?

Thank you!
Currently I possess a JDS Labs atom (that im trying to sell), Rupert Neve amp, Schiit Asgard 2 and thx 789. The most enjoyable amp is the asgard 2 because of how warm it compared to the rest of my amps. None of my amps come close to the thx 789s resolution, yet its not the most enjoyable and not a first choice in my book.

Imagine people measuring vinyl records and concluded that because of its audible hiss, crackle and pop that it was inferior to digital. People within this forum jack it hard to measurements, and wet their bed when they see a bad measurement at -150db.. yet listen to and prefer vinyl.

Imagine you aren't a chef and buy the best ingredients to make a burger and the end results is garbo.. maybe this is a good analogy, is it not?


TL:DR

Use your ears. For gods sake use your ears. Notice the measurements, but dont buy strictly using the measurements. Your favorite ice cream flavor might not be someone else's favorite :)
 

DKT88

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Currently I possess a JDS Labs atom (that im trying to sell), Rupert Neve amp, Schiit Asgard 2 and thx 789. The most enjoyable amp is the asgard 2 because of how warm it compared to the rest of my amps. None of my amps come close to the thx 789s resolution, yet its not the most enjoyable and not a first choice in my book.

Imagine people measuring vinyl records and concluded that because of its audible hiss, crackle and pop that it was inferior to digital. People within this forum jack it hard to measurements, and wet their bed when they see a bad measurement at -150db.. yet listen to and prefer vinyl.

Imagine you aren't a chef and buy the best ingredients to make a burger and the end results is garbo.. maybe this is a good analogy, is it not?


TL:DR

Use your ears. For gods sake use your ears. Notice the measurements, but dont buy strictly using the measurements. Your favorite ice cream flavor might not be someone else's favorite :)
 
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Sorry, I am a newbe to this forum, and I will introduce myself @the respective Thread a little later.

For this Thread the initial question was "Can amplifier speed and resolution be measured?".
When looking into the last postings I am a little bit puzzled.

Has this question been answered, and if so, what was the answer, that made it through 14 pages of postings?

kr, sepp2gl
 

Jimbob54

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Sorry, I am a newbe to this forum, and I will introduce myself @the respective Thread a little later.

For this Thread the initial question was "Can amplifier speed and resolution be measured?".
When looking into the last postings I am a little bit puzzled.

Has this question been answered, and if so, what was the answer, that made it through 14 pages of postings?

kr, sepp2gl
I think the first 10 or so replies very adequately answer the question.
 

Killingbeans

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True. Threads like these usually give you all the info you need in the first handful of postings. Then they steer off to different off-topic technical discussions mixed with funny anecdotes, and eventually turn into talks about pineapple or pizza or pineapple on pizza. Then at some point somebody comes along and claims that his/(her... who am I kidding?) superhuman hearing is more than enough to dispute whatever was made clear in the first few pages... and the thread gets bloated with a varying amount of postings trying to do damage control, until the talk turns back to pizza, or a new superhuman pops in to make things go around in circles :D
 

solderdude

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For this Thread the initial question was "Can amplifier speed and resolution be measured?".
When looking into the last postings I am a little bit puzzled.
It depends on what one means with 'speed' and 'resolution'.
The meaning of these words appear to have a different meaning for technical and music loving people.

The technical aspect is easily measured. Correlation with subjectively found meanings of 'speed' and 'resolution' is not easy to find.
 

Wes

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Speed and resolution, like pace and timing or musicality are meaningless words used by sloppy subjective reviewers.

Speed, as in Slew rate, can be easily measured and ANY amplifier of hifi pretentions can comfortably perform adequately. Resolution similarly, if meaning signal to noise ratio, is more than adequate in every amplifier, but neither slew rate nor S/N ratio are what reviewers mean, it's an airy-fairy armwaving concept only they understand, and therefore of no validity whatsoever.

S

How often is slew rate measured when the amp is driving a difficult speaker load?
 

sergeauckland

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How often is slew rate measured when the amp is driving a difficult speaker load?
Slew rate is Volts/uS when driving whatever the amplifier's rated load. If the load exceeds the amplifier's specification, then, just like clipping, it's not a relevant measure.

In any event, all amplifiers of hifi pretentions far exceed any slew rate requirement for reproducing speech or music programme material.

S
 

KaiserSoze

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It depends on what one means with 'speed' and 'resolution'.
The meaning of these words appear to have a different meaning for technical and music loving people.

The technical aspect is easily measured. Correlation with subjectively found meanings of 'speed' and 'resolution' is not easy to find.
Uh-oh. Look out. Run for cover. If I were to make up a word and use it in a sentence, and you weren't able to know what I was trying to say, it would not be reasonable for me to say that it has a "subjectively found meaning" and to pretend that on that basis I had actually said anything. It is entirely the same if you use a word that has well-defined meanings but the way you use it is not precisely in accord with one of its well-defined meanings. Were you to do this, no purpose would be served by your telling yourself that it isn't meaningless because you had used the word according to a "subjectively found meaning". Whatever it is exactly that anyone is wanting to say when using the words "speed" and "resolution", the meanings need to be well-defined. It is self-evident that in order for words such as these to be well-defined, they need to be defined quantitatively. Which is what some people are alluding to when they say "objective".

On the other hand, if you want to say that people sometimes use these words in a qualitative sense, I suppose that would be different. But, there is still something that just isn't right when words that are naturally suggestive of quantitative meanings are used in a way that isn't quantitative.

Technical people and music-loving people are not two disjoint groups of people. Technical people are lovers of music just the same as non-technical people. Music-loving people are probably more likely to be technical than people who don't love music.
 

DonH56

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Any slew-rate limiting would exhibit as poor distortion and reduced full-power bandwidth. Achieving low distortion and flat response to 20 kHz requires bandwidth, and thus slew rates, far beyond the audio range. For example, achieving -1 dB at 20 kHz with a simple one-pole response (desirable for stability in the audio band, may roll off faster well over the audio band) requires about 40 kHz bandwidth and the slew rate to support it. Assuming I did the math right; it's late and it was a quick scratchpad calculation.

-1 dB = 20*log10(1/sqrt(1+(20 kHz/fp)^2)) -- solve for fp, the pole (HF corner) frequency
 

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