Ok, so is there a way to lower the "FM distortions" (whatever that is) without affecting the "AM distortions" (whatever that is)?
If you think of PIM, then the source of this (modulating the loop gain by the circuit nonlinearities) is creating as much other intermodulation products, not only PIM.
Since this was discussed before, am I wasting my time here?
Sorry, let me clarify Gerhard: cartridge is DC coupled, not later stages.
Source resistor is 11 ohms, all active feedback. en total around 70nV 20 Hz to 20 kHz. Lower noise is possible with passive EQ but there are other issues then.
Source resistor is 11 ohms, all active feedback. en total around 70nV 20 Hz to 20 kHz. Lower noise is possible with passive EQ but there are other issues then.
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Better double check your numbers, 70nV in 20KHz is 0.5nV/rtHz. The source resistor has little over 0.4nV/rtHz, so your jfet results having 0.3nV/rtHz. I don't buy it.
I have no beef with either IC opamp, fully discrete, or a mix of both.
There's also no need for me to post something original, suffices to repeat the words of others :
- Mr. Curl also designs with opamps, in a league where all-discrete is unable to compete
- 99.8 percent of the world population will never be able to afford Constellation gear, nor capable to DIY something comparable, which makes it completely irrevelant whether opamps can challenge the best of discrete designs or not
- There are quite a few commercial audio companies which successfully manufacture and sell opamp based amplifiers in an exclusive price range. Whether aficionados of discrete-only circuitry approve or not, the market place says opamps have earned their ticket.
- The designers of those brands do not use a single opamp number, but pick a specific opamp for a specific task, obviously they too agree that not all opamps result in an identical sound (minus Mr. Self)
ESL2905, I've been a 63er since my early 20s. +100W full class A monaurals, 2-case all-discrete preamplifier with 0.1dB left/right accurate attenuation. (+ Thorens top model TT, 2-case programmable pre-pre that accepts 4 TT's, CD transport with Phili cd-pro2 full metal jacket, DAC with quad D/A converters. It's all balanced in, balanced out. My preferences/priorities for sound clearly differ from yours)
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Still going to be hard getting a 0.3 nV/rtHz, even with parallel. I think that's the point being made--even with 8 of them.
Hard to say if your preferences and mine for sound are similar or not, certainly not without each of us hearing the others system!
I like the idea of the quad D/A. Balanced has certain benefits, I do agree on that. Note that we are both using class A amplification. I have various amplifiers that can be pressed into service. Other interesting speaker systems too... more than one vector is available here.
So at least there is some agreement that opamps - even the ultra low distortion types - do not all sound the same and/or may be dependent upon application.
However, this still begs the question of how one might choose between two similar spec'd opamps that have been selected based on either engineering principles and/or empirical tests after that?? More than that, why ought they not sound essentially indistinguishable? And, importantly, is there any measurement or simulation, engineering basis for deciding which will sound best/correct/right/superior.
Personally, I don't have a big problem with the idea that you have to listen to know, but that appears to be seen as "questionable" by quite a few.
Sorry, your story still doesn't hold water.
Set aside it is heroic to get 0.3nV/rtHz from paralleled BF862's (you would need at least 10-15 pcs) using these with a 11ohm source resistor is stupid. Why paralleling so many jfets, then throwing away the low noise with such a large resistor?
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Yes, and they note that a two-tone IMD test can readily shake this out. And opamps do very well on two-tone tests.
But the previous post bringing up FM distortion spoke of it as if it was something that could be measured or seen with test equipment.
It's been awhile and I haven't double checked this, but I will take a rough shot at describing what I think they may be talking about. Again, roughly speaking, from memory:
They seem to talking about heterodyning type FM such as is done intentionally to make something like an FM radio broadcast station. It is just a specialized case of what is more generally referred to as intermodulation, which is what happens when 2 or more frequencies are subject to a non-linear process, such as multiplication, or nonlinear amplification. It produces sum and difference frequencies, which can then be filtered or processed to remove some of the resulting frequencies leaving an FM waveform.
Regarding hearing aids, some of them do funny things that would not normally be done with Hi-Fi. Multiband compression, combined with EQ, etc. Sometimes if more basic measures fail to work for someone with very impaired hearing, some hearing aids can pass through mid-band frequencies unaltered while frequency shifting higher frequencies that carry sibilance information down to a lower frequencies that can then be heard via more normal processing. Of course, at first the frequency shifting doesn't sound right at all, but some people can learn to make out spoken language this way, given time and practice.
Obviously, given all the specialized processing, some unusual distortion mechanisms can be involved.
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Actually, thinking about it some more I am may be mis-remembering some things about making FM signals, and I know I have forgotten other things about it altogether. So, I'll go check into it some more and get back here a little later.
What I said about hearing aids, I still believe to be correct.
What I said about hearing aids, I still believe to be correct.
In Engineering?
You are right.
In fact, for practical designs, 90% precision (meaning 10% variables spread) is usually acceptable .
Inside DIY Audio?
99.999999% precision meaning 0.000001% error (distortion of any kind) seems to be easily perceived by Golden Ears, even if unmeasurable at any Lab, and proven impossible to detect by tons of Acoustical research, and is cause of endless bitterly arguing threads.
Oh well, it´s dark, cold and windy outside and I bet it beats watching Gilligan Island´s reruns on late TV. 😀
Attached is an old text describing FM radio, including mechanisms of inadvertent FM. Also, Loudspeaker FM distortion article here: http://www.elpee.info/Documenten/KlipschVervorming.pdf
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There's nothing heroic about it. The 11 ohm resistor dominates the noise, but it's a single active EQ stage rather than split sections or passive which is the more usual approach when JFETs are involved.
The total input referred noise is shaped by the RIAA EQ.
Cheating, Distortion Variaty and Source
=======On Cheating and Psychology=======
That's what I'm talking about. Since I was a kid, I have shown a lot of good records regarding what people refer to as "intelligence". Of course, my IQ score has always been at the top every time it is measured with a group of people, BUT since high school, I always feel that I have something special, better than what is likely measured by the IQ test...
It is a psychology thing, which I know you are interested with, or even is the area of your expertise.
There is "logic" in the word psychological. Actually, it is about drawing logical relation between information points. But it is not part of intelligence that is measured by IQ test. Some researchers say that it is "right brain" but not much study has been done about what it is exactly.
========On Distortions and Symptoms=========
John Curl mentioned about FM distortions and AM distortions. Imo, almost all distortions that can be perceived by people are of AM types. How about non-AM distortion? Better not discuss this at all if you believe that nobody has sensitive ears sufficient to perceive such distortions...
There are so many types of "distortion" in sound/music. Each of them shows different "symptom" in sound perception. In blind test, it will take a lot of time to identify the existence of any of these symptoms, to ensure that blind test will be performed successfully...
Often, distortion is measured at non critical SPL. In blind test, we have to check music segment which produces high SPL and see if there is audibility there. In Norah clip previously posted, I used the lyrics "Come away with me" to perceive SPL differences. Go check with your software, you will see that the "away" is at high SPL. (Many blind test clips have shown how vocals are highly distorted when producing high SPL! which might be just a mistake during clip recording and not the mistake of the DUT).
In the same Norah album, I'm familiar with the high-SPL piano D6/D6# key tone around 1k2Hz. I wasn't successful in using this tone to detect 0.2dB SPL difference, but this tone is high SPL, in a sensitive (Fletcher-Munson) frequency and is a frequency that often produces fatiguing sound. I have successfully used this tone/segment to perceive fatigue.
There are soo many different kinds of distortion with their unique audible symptoms, but I will stop here, and proceed with how opamps with its superior measured performance may produce audible differences...
=======On Origin of the Distortion Perceived "In" Opamps========
Opamps have superior measured performance. Two questions. (1) Which performance instead of the "overall performance" that is critical to individual listener? There are more than one distortions and these have unequal acceptability thresholds. (2) Is the opamp measured exclusive from imperfect surroundings? "Sound of opamps" as reported by people, is perceived through speaker and unique varied imperfect surroundings (it is not just the opamp itself)...
I don't want to discuss the first question which will require a human with super hearing ability 😛
There is a critical point brought forward by several members (such as Dave S)... IME, effect of power supply is very unique in opamps performance. Dave S even think that there is some kind of "paradox"...
From my experience listening to fatigue in audio system, it is always related to very high frequency (HF tends to be more fatiguing than LF). This HF tone can be just fatiguing or modify the tone or timbre of the sound/music...
The HF garbage (which is fatiguing or can modulate other frequency to produce fatiguing tone) can intrude into the amplifiers from other than the input (e.g. power supply), or from the input but independence of the input signal in the noise test...
When I recognized (empirically) how critical the power supply was, I started to listen to SY who often promoted the very importance of amplifier PSRR. I thought, "Wow! Judging from how dangerous a power supply is in bringing in 'fatiguing tone', SY must have been onto something and the PSRR must be of a major criteria!"...
But then I found out (empirical of course), that no matter high the PSRR of an amplifier, it cannot protect the amplifier from not amplifying the garbage!
Measurements had been done on power supply noises. Nothing is found there. But I trust my ears (unfortunately I don't own such measurement devices)...
So regarding opamps audibility, I will also advice people to see how typical opamp circuits behave in relation to its power supply (or other possible entry points).
=======On Cheating and Psychology=======
That's what I'm talking about. Since I was a kid, I have shown a lot of good records regarding what people refer to as "intelligence". Of course, my IQ score has always been at the top every time it is measured with a group of people, BUT since high school, I always feel that I have something special, better than what is likely measured by the IQ test...
It is a psychology thing, which I know you are interested with, or even is the area of your expertise.
There is "logic" in the word psychological. Actually, it is about drawing logical relation between information points. But it is not part of intelligence that is measured by IQ test. Some researchers say that it is "right brain" but not much study has been done about what it is exactly.
========On Distortions and Symptoms=========
John Curl mentioned about FM distortions and AM distortions. Imo, almost all distortions that can be perceived by people are of AM types. How about non-AM distortion? Better not discuss this at all if you believe that nobody has sensitive ears sufficient to perceive such distortions...
There are so many types of "distortion" in sound/music. Each of them shows different "symptom" in sound perception. In blind test, it will take a lot of time to identify the existence of any of these symptoms, to ensure that blind test will be performed successfully...
Often, distortion is measured at non critical SPL. In blind test, we have to check music segment which produces high SPL and see if there is audibility there. In Norah clip previously posted, I used the lyrics "Come away with me" to perceive SPL differences. Go check with your software, you will see that the "away" is at high SPL. (Many blind test clips have shown how vocals are highly distorted when producing high SPL! which might be just a mistake during clip recording and not the mistake of the DUT).
In the same Norah album, I'm familiar with the high-SPL piano D6/D6# key tone around 1k2Hz. I wasn't successful in using this tone to detect 0.2dB SPL difference, but this tone is high SPL, in a sensitive (Fletcher-Munson) frequency and is a frequency that often produces fatiguing sound. I have successfully used this tone/segment to perceive fatigue.
There are soo many different kinds of distortion with their unique audible symptoms, but I will stop here, and proceed with how opamps with its superior measured performance may produce audible differences...
=======On Origin of the Distortion Perceived "In" Opamps========
Opamps have superior measured performance. Two questions. (1) Which performance instead of the "overall performance" that is critical to individual listener? There are more than one distortions and these have unequal acceptability thresholds. (2) Is the opamp measured exclusive from imperfect surroundings? "Sound of opamps" as reported by people, is perceived through speaker and unique varied imperfect surroundings (it is not just the opamp itself)...
I don't want to discuss the first question which will require a human with super hearing ability 😛
There is a critical point brought forward by several members (such as Dave S)... IME, effect of power supply is very unique in opamps performance. Dave S even think that there is some kind of "paradox"...
From my experience listening to fatigue in audio system, it is always related to very high frequency (HF tends to be more fatiguing than LF). This HF tone can be just fatiguing or modify the tone or timbre of the sound/music...
The HF garbage (which is fatiguing or can modulate other frequency to produce fatiguing tone) can intrude into the amplifiers from other than the input (e.g. power supply), or from the input but independence of the input signal in the noise test...
When I recognized (empirically) how critical the power supply was, I started to listen to SY who often promoted the very importance of amplifier PSRR. I thought, "Wow! Judging from how dangerous a power supply is in bringing in 'fatiguing tone', SY must have been onto something and the PSRR must be of a major criteria!"...
But then I found out (empirical of course), that no matter high the PSRR of an amplifier, it cannot protect the amplifier from not amplifying the garbage!
Measurements had been done on power supply noises. Nothing is found there. But I trust my ears (unfortunately I don't own such measurement devices)...
So regarding opamps audibility, I will also advice people to see how typical opamp circuits behave in relation to its power supply (or other possible entry points).
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Jay, it's quite common now to have opamps with 100 dB PSRR at 20 kHz and 20 times better at LF.
Feed them from a 7815 regulator and the real input referred noise emanating from noise on the supply rails is pico volts.
Feed them from a 7815 regulator and the real input referred noise emanating from noise on the supply rails is pico volts.
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