• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Can amplifier speed and resolution be measured?

pwjazz

Active Member
Joined
Sep 21, 2018
Messages
168
Likes
168
That's a fair point. I don't think it would be significant in this case since we're already talking about levels much higher than any sensible person would listen at, plus there isn't a huge difference between 300 and 500 Ohm, but in general it's something to take into consideration.
The thing about these impedance peaks is that they usually coincide with driver resonances, so while the impedance increases so does the efficiency and the overall power requirement stays basically the same. If it didn't, we would see major dips in the frequency response at those impedance peaks. So I think that as long as the amplifier isn't voltage limited at those peaks there shouldn't be a problem.

Someone who actually knows what they're taking about could probably explain this better than I
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,251
Likes
2,298
Location
Riverview, FL
I should think the amplifier would be taxed (more current demand) at the impedance dips instead of the peaks.

Phase angle plays a part in it too,
 

andreasmaaan

Major Contributor
Patreon Donor
Joined
Jun 19, 2018
Messages
2,630
Likes
1,719
The thing about these impedance peaks is that they usually coincide with driver resonances, so while the impedance increases so does the efficiency and the overall power requirement stays basically the same. If it didn't, we would see major dips in the frequency response at those impedance peaks. So I think that as long as the amplifier isn't voltage limited at those peaks there shouldn't be a problem.

Someone who actually knows what they're taking about could probably explain this better than I
That’s right. As long as the amp can deliver sufficient voltage, these peaks are nothing to worry about.

Having said that, in a case like this (ie into a high impedance load), it’s more likely to be voltage rather than current that limits the amp’s output.
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,251
Likes
2,298
Location
Riverview, FL
Having said that, in a case like this (ie into a high impedance load), it’s more likely to be voltage rather than current that limits the amp’s output.
The impedance peak doesn't demand any more voltage than the dips do, the voltage to be delivered is controlled by the signal. The high impedance ranges will "demand" less current, though.

You may be conflating high impedance headphones, which overall, might require a higher voltage than a low impedance 'phone, to deliver the power necessary to move the driver.

If the current flow into the speaker exceeds the ability of the amplifier to deliver, as could occur in the low impedance dips, then the amplifier will be unable to maintain the voltage output requested by the signal (clipping).

The high impedance ranges of the speaker would be "easy on the amplifier".
 
Last edited:

Frank Dernie

Major Contributor
Patreon Donor
Joined
Mar 24, 2016
Messages
1,181
Likes
1,177
Location
Oxfordshire
I can assure its much harder to make - totally and absurdly contrary to normally seen practices.
I am therefore mystified as to why you would bother making it then.
A conventional competently engineered preamplifier is not a limiting component in a Hi-Fi system and pretty well all of them are transparent.
 

andreasmaaan

Major Contributor
Patreon Donor
Joined
Jun 19, 2018
Messages
2,630
Likes
1,719
The impedance peak doesn't demand any more voltage than the dips do, the voltage to be delivered is controlled by the signal. The high impedance ranges will "demand" less current, though.

You may be conflating high impedance headphones, which overall, might require a higher voltage than a low impedance 'phone, to deliver the power necessary to move the driver.
I think you misread my post. I didn't say that the impedance peaks would "demand" more voltage, I actually said:

Having said that, in a case like this (ie into a high impedance load), it’s more likely to be voltage rather than current that limits the amp’s output.
Which is exactly what you just said, I believe? ;)
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,251
Likes
2,298
Location
Riverview, FL
Joined
Dec 31, 2018
Messages
14
Likes
15
I realized today that I’ve been wrong. Amplifier speed can be measured...

... wait for it...

If it’s in a moving object and there is suitable frame of reference of course... :-D

... unless it is so small that Heisenberg’s uncertainty principle takes over. ;-)
 

solderdude

Addicted to Fun and Learning
Joined
Jul 21, 2018
Messages
929
Likes
1,454
Location
The Neverlands
It is more complicated to measure its speed when it is dropped off a high building.
 

stereo coffee

Member
Manufacturer
Joined
Jan 2, 2019
Messages
36
Likes
16
I think what is mean't (so the topic remains relevant )

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!
- is there may be a grey area where measurements contradict what is heard. The Art of Sound Forum ( Marco ) in the UK provides a
viewpoint on this grey area by saying at Post 5 https://theartofsound.net/forum/showthread.php?17-The-basics-of-Ethos

"We would gladly use science automatically as the benchmark to judge all things hi-fi, if we felt that it provided all the answers necessary. It would certainly be much easier having an 'undisputable reference' as one's basis for judgement. But it's the grey areas that bother us.

Quite clearly, science can't currently provide all the answers in audio, certainly as far as measuring how equipment and its associated ancillaries treats music signals, and ascertaining how humans process recorded musical information, via our ears and brain. Therefore grey areas exist because we are not robots, and so when listening to music, our brains aren't programmed to respond in a specific way to known audio measurement parameters... The fact is, we do not listen to music in the same way as scientific apparatus measures sound waves.

If such apparatus could measure how we as humans listen to and appreciate music, then measurements would be truly meaningful and embraced wholeheartedly by music enthusiasts and audiophiles alike. That is why audio/music enthusiasts, like those on AOS, will always trust their ears more than any scientific tests or measurements, because what can currently be measured scientifically just doesn't tell the whole story.

Until the day comes when tests and measurements unequivocally provide all the answers, we will happily continue using our discerning ears which for us are infinitely more accurate and reliable in ascertaining what really matters in hi-fi (and subsequently in our enjoyment of music), especially in those all-important grey areas... It's often the small details or 'grey areas' that make the most significant difference, and thus are ultimately of most significance!

Marco"

My viewpoint is that it is possible to strip the essence of music from a piece of equipment by using electronic circuit techniques that make audio amplification or for that matter also attenuation sterile - yet at the same time the equipment might measure very well. Perhaps there are key measurements that also detect sterility in circuitry?
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
17,436
Likes
14,922
Location
Seattle Area
Quite clearly, science can't currently provide all the answers in audio, certainly as far as measuring how equipment and its associated ancillaries treats music signals, and ascertaining how humans process recorded musical information, via our ears and brain. Therefore grey areas exist because we are not robots, and so when listening to music, our brains aren't programmed to respond in a specific way to known audio measurement parameters... The fact is, we do not listen to music in the same way as scientific apparatus measures sound waves.
Such lay and incorrect opinions don't have any value in this forum. If he has not studied audio science, naturally he doesn't know what it knows and what it doesn't....
 

svart-hvitt

Major Contributor
Joined
Aug 31, 2017
Messages
2,018
Likes
900
In a previous post (#30) @amirm wrote:

«On speed, I think this is one of those random terms people use because they can't explain what they like better and just use that term. Again, this is a perception thing that goes away in controlled testing».

Have we come further? Has @amirm been proven wrong? Is there more to say of substance?

My experience with «speed» is that it infects the brain. On another forum, one highly esteemed user, a professional musician, talks a lot about «speed», or derivatives of thereof (transient detail etc.). So I challenged him to define what he really meant so as to track down this effect he writes so much about. It ended badly because my asking was seen as pedantic, little fruitful etc.

The problem is, people read this stuff, and take it seriously because it’s written by people they hold in high esteem. Infected in the brain by «speed» they go out buying new gear, new speakers, to realize that they are still chasing a (someone else’s !?) tail.

It seems to me that those who talk with more passion about «speed» never want to separate the discussion into «is it the room?» or «is it the gear?». Or even «is It speaker directivity?» or related problem.

So I found familiarity with my own anecdotal observation of audiophile behaviour in @amirm ’s post #30. Does anyone have anything more of substance to say about this matter?
 

SIY

Major Contributor
Technical Expert
Joined
Apr 6, 2018
Messages
1,495
Likes
2,146
Location
Phoenix, AZ
Such lay and incorrect opinions don't have any value in this forum. If he has not studied audio science, naturally he doesn't know what it knows and what it doesn't....
I clicked the link and quickly regretted it. There's a lot of derp packed into one page. The overall message is, "We're having fun playing make-believe, don't harsh our buzz." A perfect venue for peddlers of nonsense for fun and profit.
 

Frank Dernie

Major Contributor
Patreon Donor
Joined
Mar 24, 2016
Messages
1,181
Likes
1,177
Location
Oxfordshire
I think what is mean't (so the topic remains relevant )



- is there may be a grey area where measurements contradict what is heard. The Art of Sound Forum ( Marco ) in the UK provides a
viewpoint on this grey area by saying at Post 5 https://theartofsound.net/forum/showthread.php?17-The-basics-of-Ethos

"We would gladly use science automatically as the benchmark to judge all things hi-fi, if we felt that it provided all the answers necessary. It would certainly be much easier having an 'undisputable reference' as one's basis for judgement. But it's the grey areas that bother us.

Quite clearly, science can't currently provide all the answers in audio, certainly as far as measuring how equipment and its associated ancillaries treats music signals, and ascertaining how humans process recorded musical information, via our ears and brain. Therefore grey areas exist because we are not robots, and so when listening to music, our brains aren't programmed to respond in a specific way to known audio measurement parameters... The fact is, we do not listen to music in the same way as scientific apparatus measures sound waves.

If such apparatus could measure how we as humans listen to and appreciate music, then measurements would be truly meaningful and embraced wholeheartedly by music enthusiasts and audiophiles alike. That is why audio/music enthusiasts, like those on AOS, will always trust their ears more than any scientific tests or measurements, because what can currently be measured scientifically just doesn't tell the whole story.

Until the day comes when tests and measurements unequivocally provide all the answers, we will happily continue using our discerning ears which for us are infinitely more accurate and reliable in ascertaining what really matters in hi-fi (and subsequently in our enjoyment of music), especially in those all-important grey areas... It's often the small details or 'grey areas' that make the most significant difference, and thus are ultimately of most significance!

Marco"

My viewpoint is that it is possible to strip the essence of music from a piece of equipment by using electronic circuit techniques that make audio amplification or for that matter also attenuation sterile - yet at the same time the equipment might measure very well. Perhaps there are key measurements that also detect sterility in circuitry?
I know Marco, and he is a nice guy, but his opinions on matters hifi are completely at variance with mine and my experience.
I don't go on his site any more.
What you quote there is exactly where he is mistaken. Mind you there are a lot of non-technically minded enthusiasts who are easily convinced by this sort of thing, and there are plenty of "hifi" web forums catering to this (clearly erroneous IME) point of view.

This is not one of them and I am happy to say that what I read from the experts here is almost always completely matches my experience.
There are loads of hifi enthusiasts who prefer kit with distortion to kit which is clean and transparent, listening tests only give personal preference not fact.
 

RayDunzl

Major Contributor
Central Scrutinizer
Joined
Mar 9, 2016
Messages
6,251
Likes
2,298
Location
Riverview, FL

Similar threads

Top Bottom