Hi Guys
RN Marsh's comments regarding THD threshold are dead on!
I know from my own experience dealing with equipment of known THD levels and characteristics that the audible threshold is variable, but on average, much lower than what the popularly regurgitated rhetoric states. Does that sound judgemental? Just because a lot of people say something is true does not make it so. There was one guy who said the earth is round, then a few more, then more, now most people recognise the fact.
More important than THD is IM. Self makes little discussion of IM in his buy-the-same-material-again books. However, any measure taken to reduce THD also reduces IM, so IM does not generally have to be addresses separately. IM is much worse a distortion form and much more audible as it is nonmusical, and thus fatiguing.
Despite the fact that power amps generally contribute a very tiny portion to system distortion, changes made in them are generally audible even in the single and tens parts per million range. Bryston's products measure and perform in that range, yet when small improvements are made (and not announced, as they are part of continual improvement), customers report back about the sonic changes. Some people may be fooling themselves, but others have trained their ear to hear these things simply by learning about the equipment they use and getting used to what accurate sound is actually like.
Michael, I would amend your statement to be "No one should subject themselves to 0.1% THD". It is dreadful.
Have fun
Kevin O'Connor
RN Marsh's comments regarding THD threshold are dead on!
I know from my own experience dealing with equipment of known THD levels and characteristics that the audible threshold is variable, but on average, much lower than what the popularly regurgitated rhetoric states. Does that sound judgemental? Just because a lot of people say something is true does not make it so. There was one guy who said the earth is round, then a few more, then more, now most people recognise the fact.
More important than THD is IM. Self makes little discussion of IM in his buy-the-same-material-again books. However, any measure taken to reduce THD also reduces IM, so IM does not generally have to be addresses separately. IM is much worse a distortion form and much more audible as it is nonmusical, and thus fatiguing.
Despite the fact that power amps generally contribute a very tiny portion to system distortion, changes made in them are generally audible even in the single and tens parts per million range. Bryston's products measure and perform in that range, yet when small improvements are made (and not announced, as they are part of continual improvement), customers report back about the sonic changes. Some people may be fooling themselves, but others have trained their ear to hear these things simply by learning about the equipment they use and getting used to what accurate sound is actually like.
Michael, I would amend your statement to be "No one should subject themselves to 0.1% THD". It is dreadful.
Have fun
Kevin O'Connor
Quad ESL 57 I feel started the trend to think about this. D T N Williamson I believe was involved with their design . Often stated by Julian Vereker as being one of the few speakers with a 60 dB dynamic range . When I questioned him about that he said 0.1 % THD is 60 dB . I think I would challenge him on that now but would say he was much more right than wrong . So a C47 or whatever microphone , Williamson amp and ESL 57's would be as yet not surpassed by another however good hi fi if TSD ( total system distortion ) is being discussed . Some will say digital is a challenge to some amplifiers . Against a live feed is it ? A challenge to beleive it is working properly might often be more true , great spec and not much like real music . I cringe when people say OK for old fashioned analogue . Most speakers struggle to get down to 1 % THD .
If we can hear 0.01% I can only think it is an indication of well being of the amplifier and not a sceintific quality of 0.01% . Nothing I know about hearing says we can . Now what might be true is we need 0.01% at 10 watts to ensure 0.1% at 1 mW . If you say that I will beleive it as I find 1 mW louder than anyone might imagine in a quiet room . I always study 1 mW to 1 watt as my big concern . Either-net over mains is a big problem to ruin this range . The Williamson was very good at 1 mW . Proper Williamson's do not sound like valve designs . BTW , I am mostly someone who dislikes valves . Much as I am someone who dislikes sweet wine made from remarkable grapes . Dry Riesling exists , Luxembourg has fine ones .
One German engineer I asked about specs relating to the RIAA curve said . We should try to get right the things we can . That is correct up to a point . I said 0.2 dB is the error I have and it is done with remarkably few components . He shrugged his shoulders and smiled . He was right but not in the big picture of things .
5 watts is about universally where these things start not to matter . Almost universally people choose speakers that set a loud listening level at 5 watts . Why is not easy to say . 82 dB per watt in a small room ( LS3/5A ) 105 dB per watt in a large room . Above 5 watts if so we have about 30 % THD . Only at perhaps 0.1 watt do we challenge the equipment in our own abilities . Mr Self wrote to me once saying listening fatigue is unlikely . If true we would get visual fatigue . After much thought and agreeing I came to the conclusion we use very little brain power for listening . The visual is perhaps equivalent to 10 MHz bandwidth . I doubt we process more than 5 kHz audio with such precision ( 500 Hz to 5500 ? ) . After that just hints of things . I suspect the Quad 57's best quality is it's ability to produce reasonable square waves . That I am sure prevents the fatigue ( due to lack of brain power of humans to love phase distortion , organ music suggests to me it matters , too long to say why , about beats or hetrodynes of real music , organ looks like pure sine waves ) . One only has to listen to Caruso to know chillingly real sound is not a great in bandwidth . Sure it isn't hi fi . Fantastic is the word I would use . 300 Hz to 2 kHz on a good day ? If so why does it have impressions of dynamics and sparkle ( resonance no doubt ) ? Equally bandwidth limiting an amp at 30 kHz sounds dull ! Crazy .
Enrico Caruso - Tu ca nun chiagne - YouTube
If we can hear 0.01% I can only think it is an indication of well being of the amplifier and not a sceintific quality of 0.01% . Nothing I know about hearing says we can . Now what might be true is we need 0.01% at 10 watts to ensure 0.1% at 1 mW . If you say that I will beleive it as I find 1 mW louder than anyone might imagine in a quiet room . I always study 1 mW to 1 watt as my big concern . Either-net over mains is a big problem to ruin this range . The Williamson was very good at 1 mW . Proper Williamson's do not sound like valve designs . BTW , I am mostly someone who dislikes valves . Much as I am someone who dislikes sweet wine made from remarkable grapes . Dry Riesling exists , Luxembourg has fine ones .
One German engineer I asked about specs relating to the RIAA curve said . We should try to get right the things we can . That is correct up to a point . I said 0.2 dB is the error I have and it is done with remarkably few components . He shrugged his shoulders and smiled . He was right but not in the big picture of things .
5 watts is about universally where these things start not to matter . Almost universally people choose speakers that set a loud listening level at 5 watts . Why is not easy to say . 82 dB per watt in a small room ( LS3/5A ) 105 dB per watt in a large room . Above 5 watts if so we have about 30 % THD . Only at perhaps 0.1 watt do we challenge the equipment in our own abilities . Mr Self wrote to me once saying listening fatigue is unlikely . If true we would get visual fatigue . After much thought and agreeing I came to the conclusion we use very little brain power for listening . The visual is perhaps equivalent to 10 MHz bandwidth . I doubt we process more than 5 kHz audio with such precision ( 500 Hz to 5500 ? ) . After that just hints of things . I suspect the Quad 57's best quality is it's ability to produce reasonable square waves . That I am sure prevents the fatigue ( due to lack of brain power of humans to love phase distortion , organ music suggests to me it matters , too long to say why , about beats or hetrodynes of real music , organ looks like pure sine waves ) . One only has to listen to Caruso to know chillingly real sound is not a great in bandwidth . Sure it isn't hi fi . Fantastic is the word I would use . 300 Hz to 2 kHz on a good day ? If so why does it have impressions of dynamics and sparkle ( resonance no doubt ) ? Equally bandwidth limiting an amp at 30 kHz sounds dull ! Crazy .
Enrico Caruso - Tu ca nun chiagne - YouTube
Ad 1.
Not always, but in some cases I did hear a slight difference between carbon and metal film resistors. Admittedly, between standard carbon and Dale metal film.
Ad 2.
I have no idea what the distortion difference is between carbon and metal film resistors. Care to enlighten me? (Just curious, I use metal film by default)
Ad 3.
This is not a question for me, but for Mr Self.
No.
Please let's not start talking about resistors used at 1/2 rated power and extrapolating to source resistors at amplifier inputs at micro-watts again.
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Hi Guys
The sonic difference between carbon resistors and metal film is like night and day. Carbon adds a lot of H2 and other distortions. MF does not.
So, if you are used to amps built with carbons you will find an identical circuit with MF to be cold or harsh.
Similarly, if you are used to MF, carbon sounds warm or muddy.
Scott, your avatar is very negative. So is your comment. Is there a connection?
Have fun
Kevin O'Connor
The sonic difference between carbon resistors and metal film is like night and day. Carbon adds a lot of H2 and other distortions. MF does not.
So, if you are used to amps built with carbons you will find an identical circuit with MF to be cold or harsh.
Similarly, if you are used to MF, carbon sounds warm or muddy.
Scott, your avatar is very negative. So is your comment. Is there a connection?
Have fun
Kevin O'Connor
No?
So Scott, what would you say to a guy who wrote tha he can hear the difference in the color of the same capacitor, as originally say black to the same in say red?
I couldn't tell him anything, as I don't know a good shrink.
Hi Guys
Scott, my speakers are not "magic", but I do suspect the gnomes who built them might be. Are there gnomes in Japan?
My experience is obviously different than yours. I don't claim golden ears, but I have protected my hearing from as much abuse as I can over the years because I value creating and enjoying music and wish to continue to do so. To that end, I find that 90db is intolerable in my living space - 80db maybe for when you go wild with a music video. More usually 60-70db range. My speakers are 90db/1W at 1m, so for normal listening I only need milliwatts; only a couple of watts total for blasting.
As Nigel suggested, the full-power THD can be a reflection of the low-power THD inasmuch as there is a semi-linear relationship: as power reduces, THD number reduces as it is a ratio. The noise floor ultimately limits dynamic range but even THD artifacts buried in the noise can be perceived. You are welcome to choose to believe other things, but you owe it to yourself to keep an open mind.
My mind is generally open... oh, a bird just flew in...
Have fun
Kevin O'Connor
Scott, my speakers are not "magic", but I do suspect the gnomes who built them might be. Are there gnomes in Japan?
My experience is obviously different than yours. I don't claim golden ears, but I have protected my hearing from as much abuse as I can over the years because I value creating and enjoying music and wish to continue to do so. To that end, I find that 90db is intolerable in my living space - 80db maybe for when you go wild with a music video. More usually 60-70db range. My speakers are 90db/1W at 1m, so for normal listening I only need milliwatts; only a couple of watts total for blasting.
As Nigel suggested, the full-power THD can be a reflection of the low-power THD inasmuch as there is a semi-linear relationship: as power reduces, THD number reduces as it is a ratio. The noise floor ultimately limits dynamic range but even THD artifacts buried in the noise can be perceived. You are welcome to choose to believe other things, but you owe it to yourself to keep an open mind.
My mind is generally open... oh, a bird just flew in...
Have fun
Kevin O'Connor
Scott,
You are getting it backwards. The distortion is measured at 1/4 power and the claim is that there is a difference at even lower levels. So if one can hear the distortion at a micro-watt level then one possible implication is that THD is heard at astoundingly low levels.
Now my experience is that .25 db frequency response change in a parametric filter in a large scale sound system does produce a difference. I also know from adjusting crossover bias by listening to high frequencies in a headphone that .07% THD is very easily noted. (But there are also other issues there...)
Now most of the large loudspeakers I use do have less than 1% THD at the normal operating level. Now some folks when they get a new sound system find that their old source material is no longer adequate.
So I will design for what you would consider extraordinarily low levels because I can.
And on diode noise turn on and turn off occur with each cycle of rectification of the AC, not at power on and off!
Attachments
Nobody can hear 0.1% distortion. Nobody. Period.
It is ghosts in the machine . Make something absurdly good and a seldom considered parameters might get a Golf Medal also . To say you heard that as a result of 0.01% distortion is impossible as best as I understand things . That you heard something I 100 % beleive . Correct label is all that matters . It is like Homeopathy . I want to beleive but... placebo is possible and lack of toxicity helps . Also most medicines are not required . I think the French consume 4 times more medications than we Brits . Health outcomes about the same . To say placebos don't have their place is not to understand humans . Most health is time and not pill influenced . The remarkable and provable fact is for those illness the placebo for sceintific reasons is superior . Because it does nothing and nothing was the right treatment . A pharmacist told me there are 13 dreadful illnesses . Any doctor or pharmacist should be able to spot them . As luck would have it they all have obvious symptoms . Apart from that doctors refer to hospital or check for the 13 . When in a country that runs like Las Vegus see the pharmacist , often they are 100 % right . It is their duty to send you to a doctor if they think you are really ill and will . The family does this stuff if asking . In France or Belgium take wild mushrooms to a pharmacists . For no money he must identify them by law . I have had such meals with my ex father in law , he knows his mushrooms . Most medicine is plant based even now . Aspirin loosely speaking is ( Willow ) , modern is digital version if you like or made from prehistoric one ( coal ) . Aspirin is the Caruso of Medicines .
Slewing . That is rubbish although I am sure high slew rate amps can sound better . IM distortion isn't . They go together surely ? ESP says second harmonic distortion is not a friend . Brave for him to say that . I would say if we could have 3 rd onwards in exponential decay he might be right . In digital I guess we could ? I love digital , it isn't easy stuff .
Put carbon comp in MC input . Then measure noise with a real MC device . Apart from foil types it is low . Then take MC away . It looks bad . Do the maths . It still looks wrong metal film is not beating it . Listen to Tyco foil , fantastic . Metal films ( MRS 25 ) , like a dirty stylus . CC , dull but OK . No measurements says why . Ghosts in the machine . Forced to use MRS 25 for a dear friend I reverse inductively coupled from the same batch ( use rings to say reverse inductance and wrap like a fly for fishing ) . That I feel was a good compromise . Like a placebo I might be fooling myself . For less than a $10 a a product it is worth the risk .
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Well a simple No is a negative. It is pretty easy to build a line level preamp and keep all the resistors in the signal path at a few percent of rated power. In this case I would take deference to your night and day comment. BTW without DC there is no HD2 from self heating so many negative comments are holdovers from tube days where there were large DC biases, large voltage swings and resistors typically used at an appriciable fraction of their ratings. In fact usually the carbon resistors I find these days are carbon film and I have had a hard time finding NOS comp ones to easily demonstrate their short comings like excess noise to younger folk.
It is funny these things turning up in a D. Self thread. Yes, have fun don't let me intrude.
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Anyone got some measurements at 10 and 0.001 watt ? I seem to get 0.1% and up to 50 kHz in stuff I do at 0.001 watt . I look for things like it getting worse at 0.3 watt . FET amps will often do that . What do I do ? I go for 0.001 % if I can at 80 watts . Seems to iron out the real area of concern . Hitachi had great graphs for the FET amps . Look carefully they stop at 2 watts ! In truth the amps are great and they never needed to do that . Goldmund was a great version .
I want to build an Audio Precision type clone using a sound card . My company has a real one about 1000 miles away . A friend also in Austria . Anyone game for this ? I am totally stupid with things like this so don't expect me to be the lead . Surely this is a great use of our talents . Cheap , easy and not bad is what I need . 100 db reliable range and 120 db OK range .
Carbon Comp is used for pulse lasers and was used for CRT . They are often the device of choice . I use carbon film often and like them . Metal film I have doubts about . No idea why . In noise critical or temperature critical application I don't . I hope to try some thick film soon ( non inductive ) . They might be OK . The round SMD metal films are great . Some components are magnetic . Often they are OK !!!!!!! Sometimes steel , copper , silver is used as in RF cables ( 75 ohm coax ) . Soviet silver wired from USSR are wonderful ( metal film ) . Got some as a bulk buy and treasure them .
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Nigel,
Here is a link that RNMarsh put up on a professional discussion board recently. This may be something that you can use.
Steven
QA Blog - QuantAsylum Home Page
Here is a link that RNMarsh put up on a professional discussion board recently. This may be something that you can use.
Steven
QA Blog - QuantAsylum Home Page
Bingo Steven and RN. I think my boss needs to know about that . Very good . That's oh so close to excellent .
Thanks .
Many years ago, 5% carbon compound resistors were the cheap version, with a 350 ppm thermal. 1% metal film were 50 ppm and were the de luxe version.
But these days, even carbon are film resistors. I don't know the current ppm values, but I would be surprised to find out they haven't improved that as well.
So, is it the material inside, or the construction method as film based?
On the other side of the scale, metal film resistors almost never satisfy the 1% tolerance criteria they were advertised for until you get to Dale and such like. The average metal film resistors, from unnamed sources (probably from China and The Far East) are more like 2 or even 3% tolerance, although they are dirt cheap.
For critical applications, generally around the input stage, one must specifically order say German made metal film resistors to get the real deal, of course, at a higher price.
But these days, even carbon are film resistors. I don't know the current ppm values, but I would be surprised to find out they haven't improved that as well.
So, is it the material inside, or the construction method as film based?
On the other side of the scale, metal film resistors almost never satisfy the 1% tolerance criteria they were advertised for until you get to Dale and such like. The average metal film resistors, from unnamed sources (probably from China and The Far East) are more like 2 or even 3% tolerance, although they are dirt cheap.
For critical applications, generally around the input stage, one must specifically order say German made metal film resistors to get the real deal, of course, at a higher price.
Nobody can hear 0.1% distortion. Nobody. Period.
I agree completely.
This is flat-out untrue. Metal film resistors are in my not-unextensive experience always well within the stated tolerance. This includes reputable Chinese sources.
I have myself measured 100 1k resistors (I know, way too much time on my hands) that were 1% tolerance MF from Yageo. (Chinese)
The mean value was 997.66 Ohms (0.23% low) and the standard deviation was 2.10 Ohms. All the resistors were within 0.7% of nominal, and almost all within 0.5%.
This is a typical result.
Would you like me to send you a batch to retest again?
You live in a country with a highly developed market system; well over 70% of humanity doesn't. You take various market mechanisms, the protection of the customer being an important one, for granted. Wrong!
BTW, because I know that many nominally 1% resistors are off by more than that, I make it a point to measure each and every one of them before I solder them in.
Even in case of German made Beyschlag resistors, which have never yet failed me.
A friend, who owns a very much High End audio company and exports 99% of his production, recently received two bags with 200 pcs each full of very expensive output trannies, from the manufacturer's own European head office. They proved to be duds and died at 50V, even if rated for 230V. The manufacturer was fair and made good the returned packs with the real deal trannies.
This shows that the dummy business is so big and lucrative that they found ways to compromise even nominally clean and clear stocks. With an attitude and a situation like that, do you really think resistors will always be what they are supposed to be?
If you still haven't run into problems like that, you should consider yourself very lucky indeed.
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