| SY |
| Controlled testing is the single most powerful tool in all of perceptual research; why throw it away or dismiss what it tells you? |
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| fdegrove |
Hi,
Geez, I'm having a field day...
| quote: | | you would be unable to tell with better than chance probability whether the two amps sounded identical or not, assuming the resistors had the same value and similarly low C and L parasitic impedances. |
Assuming that those are the only factors...in real life more is at work here...
Fred, it seems you're right, we really have to put in one little detail after the other...
Within a few months I hope to discuss quantum physics/mechanics and see how far we can push that...
In the mean time we all have to live with a null.
Cheers, ;) |
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| nw_avphile |
| quote: | Originally posted by Peter Daniel
One possible answer could be that measurements are done in two dimentional environment and we perceive music in three dimentional environment so it doesn't correlate well (if I can say so;))
It is actually better to do resistors test in one amp, because you can never position two amps in the same space in exactly same way. Both may be affected by different resonant modes and this cause the test to be invalid. Having two different amps involves two different sets of wiring and this is an additional variable. |
Sorry, but electrical signals are electrical signals. They don't care if we live in seven dimensions. The electrons pumped from your amp to your speakers are all those resistors have a chance to influence in this world.
As for your other concern, if both amps sounded the same would you be happy the resistors sounded the same? Or are you suggesting that somehow the resonances from mechanical vibration will, against all imaginable odds, exactly cancel out the electrical changes made by the resistors? |
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| SY |
| quote: | | that measurements are done in two dimentional environment and we perceive music in three dimentional environment so it doesn't correlate well |
I'm not quite sure what the mantra part means (measurements are done in however many dimensions an experiment calls for), but as to correlation, quite the opposite is true. If a box of gain has an output that's a scalar multiple of the input for any given test signal to within 16 bits over the audio band, that measurement will near-guarantee you that you won't be able to distinguish one from the other in a blind listening test, short term or long. |
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| Peter Daniel |
| quote: | Originally posted by SY
Controlled testing is the single most powerful tool in all of perceptual research; why throw it away or dismiss what it tells you? |
I'm not dismissing it and I would be really interested to see how it goes since I never took part in one.
I can only rely on my own experiments so far, yet not being completely retarted I cannot put away everything I learned and experienced so far and throw myself into realms of new religion.;)
I'm too old for that, but not scheptical yet. It's quite possible that I might take different POV if it would make sense. Things would be much simpler too, no $28 resistors to buy (I didn't tell you, but I'm getting them at substantial discount);) |
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| SY |
| quote: | | I hope to discuss quantum physics/mechanics |
There ought to be a corollary to Godwin's Law. |
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| fdegrove |
Hi,
| quote: | | Sorry, but electrical signals are electrical signals. They don't care if we live in seven dimensions. The electrons pumped from your amp to your speakers are all those resistors have a chance to influence in this world. |
Not true.
And maybe one day I'll explain...
Under attack I'm worse than Fred....Can't stand ignorance...
Do your homework.;) I won't be smiling for too long. |
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| Peter Daniel |
| quote: | Originally posted by SY
I'm not quite sure what the mantra part means (measurements are done in however many dimensions an experiment calls for |
The mantra, being spoken in very simple terms, meant that we might be missing something that could be measured, yet we currently don't have the necessary equipment to perform that task. You agree that this is possibility? |
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| nw_avphile |
| quote: | Originally posted by Peter Daniel
I'm not dismissing it and I would be really interested to see how it goes since I never took part in one.
I can only rely on my own experiments so far, yet not being completely retarted I cannot put away everything I learned and experienced so far and throw myself into realms of new religion.;)
I'm too old for that, but not scheptical yet. It's quite possible that I might take different POV if it would make sense. Things would be much simpler too, no $28 resistors to buy (I didn't tell you, but I'm getting them at substantial discount);) |
I stand corrected... you might be more open minded than I originally gave you credit for :)
Have you ever done any measuring on your gainclone (frequency response, power output, distortion, etc)? What other amps do you have available to you? Apparently some Aleph clones? Any commercial amps? |
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| nw_avphile |
| quote: | Originally posted by Peter Daniel
The mantra, being spoken in very simple terms, meant that we might be missing something that could be measured, yet we currently don't have the necessary equipment to perform that task. You agree that this is possibility? |
Well there's always some remote possibility of most anything. But in this case, Out - In = Distortion seems pretty darn hard to refute--especially when the input signal is limited to the audio band (which pretty much anything from CD is). |
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| Peter Daniel |
| quote: | Originally posted by SY
If a box of gain has an output that's a scalar multiple of the input for any given test signal to within 16 bits over the audio band, that measurement will near-guarantee you that you won't be able to distinguish one from the other in a blind listening test, short term or long. |
You are not advocating here the term: 'perfect sound forever 'and claiming that all CDP sound the same? |
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| Peter Daniel |
| quote: | Originally posted by nw_avphile
Well there's always some remote possibility of most anything. But in this case, Out - In = Distortion seems pretty darn hard to refute--especially when the input signal is limited to the audio band (which pretty much anything from CD is). |
You mentioned before microphonics, so you accept their existance. What do you think they cause to the parts so they start to sound different when subjected to vibrations? |
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| fdegrove |
Hi,
| quote: | | You mentioned before microphonics, so you accept their existance. What do you think they cause to the parts so they start to sound different when subjected to vibrations? |
Peter, with al due respect, I am sure you can figure that out for yourself.
Think along source isolation and amp isolation the viberations, ;) , then diff it , something must show up...:cool:
Ciao,;) |
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| SY |
| quote: | | You are not advocating here the term: 'perfect sound forever 'and claiming that all CDP sound the same? |
I specifically said "box of gain."
| quote: | | The mantra, being spoken in very simple terms, meant that we might be missing something that could be measured, yet we currently don't have the necessary equipment to perform that task. You agree that this is possibility? |
Speaking STRICTLY in the realm of boxes of gain, I think it's highly unlikely. If someone shows in a controlled test that a box of gain with the usual measurable criteria in these arguments (flat response, high input Z, low output Z, low offset, no overloading, etc, etc, etc) can be audibly distinguished, I'd certainly change my opinion. I'm someone who used to regularly hear all kinds of wonderful things, suddenly going (apparently) deaf the day I started putting my beliefs to a valid test. It's commendable that you're open-minded enough and curious enough (very important, that!) to try to do the same thing. |
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| Peter Daniel |
| I don't have an opinion on that. I just wanted to hear how they can comment this. |
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| Peter Daniel |
| quote: | Originally posted by SY
I'm someone who used to regularly hear all kinds of wonderful things, suddenly going (apparently) deaf the day I started putting my beliefs to a valid test. It's commendable that you're open-minded enough and curious enough (very important, that!) to try to do the same thing. |
Does that mean that you don't have a preference for any particular equipment (beside the convenience aspect only )?
Is it possible that after going through such test it is psychological now that suddenly you stopped hearing those things? Doesn't it bother you now that you possibly lost some of your previous abilities?? |
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| nw_avphile |
| quote: | Originally posted by Peter Daniel
You mentioned before microphonics, so you accept their existance. What do you think they cause to the parts so they start to sound different when subjected to vibrations? |
Well... this is sort off topic, but you asked so I'll answer.
Microphonics are a known issue with tubes. Tube phono (and mic) pre-amps, especially, are prone to picking up vibrations. The elements delicately suspended in some tubes are prone to moving around, and because of the very high gain in those circuits, their tiny modulations get amplified to an audible level.
I'm open minded enough to think vibrations can possibly have an effect on other components as well, but I've never encountered it that I'm aware of. The amount of overall gain in a power amp is roughly 2 orders of magnitude less than in a phono pre-amp. So any tiny effects from microphonics would be much less likely to have an audible effect.
Now if you're talking about mechanical things, like a CD transport (or, obviously, a turntable) vibrations can play a BIG role in the sound.
Looking at the pics of your amp, I can see you've put a ton of effort into turning it into a very non-resonant block. Your craftsmanship is very admirable! But as I pointed out earlier, null testing might be a really good guide as to just how much of that sort of thing is necessary on future projects. That way you might decide you can focus more of your efforts on the outside of the enclosure where they can be more readily appreciated by others (compared to the inside).
Regardless of the sonic benefits of the construction methods you used, the "cool factor" remains very high! It reminds me of elaborate inlaid wood projects that defy description. :) |
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| SY |
| quote: | | Does that mean that you don't have a preference for any particular equipment (beside the convenience aspect only )? |
Quite the opposite. I build tube stuff.
| quote: | | Is it possible that after going through such test it is psychological now that suddenly you stopped hearing those things? Doesn't it bother you now that you possibly lost some of your previous abilities?? |
In the sense that I lost my ability to believe in the tooth fairy when I caught my mom slipping a quarter under my pillow. |
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| Peter Daniel |
| Tubes, turnables and CD players have moving parts and resonance issues can be simply explained there. My main concern however is the influence of vibrations on static active and not active parts (ICs, resisstors, caps etc). I just noticed that using different insulating pad on my gainclone chip, changes the tonal character of the amp. And it is only my observation but a friend was surprised when I told him it's the same amp. So somehow the pad was acting as a barrier between chip and chassis and Kapton provided more damping than aluminum oxide which is more brittle. I still didn't figure out how vibrations affect the chip inside to change its sound. Do they modulate it somehow, if yes, what exactly and can it be measured? And this is still on topic. |
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| SY |
| I'd expect that differences in bolt torque will be more imortant to the resonant signature. But since it's the power amp part, it's an easy thing to check. With your ear near the speaker, tap on the IC with a hard, light object. Hear anything from the speaker? Repeat the test with soft music or test tones running through. Hear anything? |
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| nw_avphile |
| quote: | Originally posted by Peter Daniel
Tubes, turnables and CD players have moving parts and resonance issues can be simply explained there. My main concern however is the influence of vibrations on static active and not active parts (ICs, resisstors, caps etc). I just noticed that using different insulating pad on my gainclone chip, changes the tonal character of the amp. And it is only my observation but a friend was surprised when I told him it's the same amp. So somehow the pad was acting as a barrier between chip and chassis and Kapton provided more damping than aluminum oxide which is more brittle. I still didn't figure out how vibrations affect the chip inside to change its sound. Do they modulate it somehow, if yes, what exactly and can it be measured? And this is still on topic. |
Well you know what my advice is... if at all possible start doing blind testing or at least null testing and go from there.
As for comparing notes with someone else and coming up with similar descriptions for a given tweak, there are many possible explanations for that. Sometimes they heard or read about it (or something like it) elsewhere so they were biased in the same direction as you.
Sometimes one friend tips the other off with a "leading" conversation (i.e. "didn't it make the sound warmer in your system?" is an obvious one). These tips can be subtle but are often there in one form or another (i.e. in previous conversations, etc.). Often one person forgets or doesn't realize they lead the other person's conclusions in some way.
Sometimes people hear what they expect to hear based on just intuition from other common factors--in this case the aluminum oxide was hard so you both perhaps expected it to sound hard or harsh compared to a soft insulator (granted this may not be the best example, but this sort of thing comes up all the time in the audiophile world). The mind works in funny ways.
Finally, it's not that hard for pure random luck to cause many comments to align in the audiophile world. You don't have to put very many people in the same room for two of them to often have the same birthday. The often used "audiophile adjectives" (in any given year) number much less than less than 365 (the number of possible birthdays). So, it's more likely than you might think for people discussing the same piece of equipment or tweak to use some of the same descriptions to describe it--even if they're all random.
Of course, there's also the possibility you both heard the same thing because it really IS audible and repeatable. In that case, it should show up in a blind test! |
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| nw_avphile |
| quote: | Originally posted by SY
I's expect that differences in bolt torque will be more imortant to the resonant signature. But since it's the power amp part, it's an easy thing to check. With your ear near the speaker, tap on the IC with a hard, light object. Hear anything from the speaker? Repeat the test with soft music or test tones running through. Hear anything? |
That would work even better if the speaker was in one room and the amp in another with someone else doing the tapping. If they're next to each other, done by one person, it might be hard to hear any effects over the physical noise of the tapping coming from the amplifier itself. |
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| haldor |
| quote: | Originally posted by Peter Daniel
Tubes, turnables and CD players have moving parts and resonance issues can be simply explained there. My main concern however is the influence of vibrations on static active and not active parts (ICs, resisstors, caps etc). I just noticed that using different insulating pad on my gainclone chip, changes the tonal character of the amp. And it is only my observation but a friend was surprised when I told him it's the same amp. So somehow the pad was acting as a barrier between chip and chassis and Kapton provided more damping than aluminum oxide which is more brittle. I still didn't figure out how vibrations affect the chip inside to change its sound. Do they modulate it somehow, if yes, what exactly and can it be measured? And this is still on topic. |
That's really interesting Peter. Have you tried swapping the insulating pads between two identical amps to see if the effects follow (to avoid any other change)?
Pure speculation now, but reading this also brought other possible mechanisms for what you heard to mind. Is there a significant difference in the thermal conductivity between the Kapton and the aluminum oxide pads? I have heard the effects of power compression in a speaker (heating of the voice coil increases impedance which causes the power delivered to the speaker to drop) . Perhaps something similar is happening to the dynamic response of the amp? These chip amps have some interesting thermal protective circuitry inside them. Perhaps thermal spikes are causing the chip protection to engage for an instant?
Phil |
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| Peter Daniel |
Those amps when not pushed to the limits are running rather cold and my findings were observed in first half hour of operation so the chip was not even warm. So the thermal issues shouldn't be really influential here.
I noticed that the amp is very sensitive to the way it is placed on a shelf (shelf or platform material and the feet beeing used) Depending on a setup it was better with the spikes, but sometimes only one spike in front and two acrylic feet at the back was preffered. The chassiss is very compact and the chip is mounted directly to the rear panel. If the chassiss pics up any vibration , the chip as well, the only thing separating them is thermal pad. The screw shouldn't be much issue, because of plastic washer under. And my sonic impressions were in line with a properties of material constituting a pad. With double coated kapton the sound was kind of mellow and flat, with aluminum oxide washer it got more vibrancy and life. Also at the time I was experiencing it, I wasn't even considering a pad as something contributing to the sound. I came to it later. |
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| Steve Eddy |
Sorry, I missed this one originally.
| quote: | Originally posted by mikek
On the contrary, a single-frequency sinusoid is anything but 'static'....this is only true of pure D.C. |
Yes, "static" was a poor choice of words on my part. Steady state would have been more appropriate.
| quote: | | Despite a huge variety of 'new' test signal concocted by many to approximate real music signals, (surely an impossible task!), no evidence has been presented anywhere, (and this includes the learned A.E.S), that these demonstrate deficiencies in power amps. that cannot be revealed with cosinusoidal stimuli.... |
Yeah?
Tell me, how would you evaluate an amplifier's impulse response with a single steady state sinusoid?
Also, why do you say "cosinusoidal"? When you're talking about a single steady state sinusoid, the difference between a sine and cosine is irrelevant.
se |
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| traderbam |
It's sort of funny that people are happy to apply logic to digital circuits but logic sometimes goes out the window when it comes to analogue circuits. :clown:
Test:
Earlier someone said that a real music signal can be represented as an infinite collection of sinewaves (hence Fourrier transforms). Then they reasoned that if music is a collection of sinewaves a single sinewave is an adequate representation of music for the purposes of analysing distortion in an amplifier. What is wrong with this reasoning? |
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| traderbam |
| quote: | | mikek wrote: The overwhelming bulk of audio technology as known today, is due to such pioneering members of the AES as T. Holman, (THX fame), Dolby, D. Self (currently at audiolab), G. Stanley, (at Crown), E. Benjamin, Sondermeyer, Dennis bohn of Rane,...etc...etc......People who posess more experiance more audio design experiance in each of their finger nails than you're ever likely to accumulate in your lifetime....dear...dear... |
I think you'll find it's "experience" that is the desirable attribute. :cheeky:
You are compelling me to take sides with Fred because he talks about results and you talk about publicists and then insult Fred. I know you are a confident, budding designer who is getting air-time in an electronics publication and so you are naturally inclined to have the greatest respect for other publicists who preceeded you.
But before you drop names everywhere to back your arguments and plagiarize those who've published tombs, remember that a designer is only as good as his last design, regardless of how you quantify experience. Consider the best sounding amps in the world, who designed them? Are any of them on your list? |
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| pinkmouse |
| quote: | Originally posted by traderbam
Earlier someone said that a real music signal can be represented as an infinite collection of sinewaves (hence Fourrier transforms). Then they reasoned that if music is a collection of sinewaves a single sinewave is an adequate representation of music for the purposes of analysing distortion in an amplifier. What is wrong with this reasoning? |
Simply that music is not a steady state signal like a sinewave, imagine for instance a snare hit. this contains a huge number of frequencies, all with a particular attack/decay, and for any test to be viable it has to cope with this transient change in amplitude, as well as correctly reproducing the individual frquencies of the sound.
BTW the development of this discussion virtually parrallels that of discussions on testing such phenomena as ESP and dowsing:devily:, and in cases such as those that seem to have a particular ability in these subjects, no matter how highly their scoring starts, it always tends to average out over time... |
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| mikek |
| quote: | Originally posted by Steve Eddy
Sorry, I missed this one originally.
Yes, "static" was a poor choice of words on my part. Steady state would have been more appropriate.
Yeah?
Tell me, how would you evaluate an amplifier's impulse response with a single steady state sinusoid?
Also, why do you say "cosinusoidal"? When you're talking about a single steady state sinusoid, the difference between a sine and cosine is irrelevant.
se |
In analogue signal processing, it is more usefull to consider such excitations as a complex voltage, Ve^(jwt)=(Vcoswt+jVsinwt). This aids the determination of steady state response of a network to a sinusoid, because the complex exponential time waveform, e^(jwt) remains in the same form after differentiation or integration. This vastly simplfies analysis...as the real part of the applied voltage, which is cosinusoidal, (Vcoswt), is then used to solve of other quantities such as phase, fourier components, currents, etc..without the inelegant tedium of resorting to trignometric identities...
....you just try to solve for the curent in a simple L-R series circuit resulting from applied excitation Vcos(wt)....(assuming zero initial conditions for simplicity), using trig. identities....tedious...tedious..... |
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| mikek |
| quote: | Originally posted by traderbam
I think you'll find it's "experience" that is the desirable attribute. :cheeky:
You are compelling me to take sides with Fred because he talks about results and you talk about publicists and then insult Fred. I know you are a confident, budding designer who is getting air-time in an electronics publication and so you are naturally inclined to have the greatest respect for other publicists who preceeded you.
But before you drop names everywhere to back your arguments and plagiarize those who've published tombs, remember that a designer is only as good as his last design, regardless of how you quantify experience. Consider the best sounding amps in the world, who designed them? Are any of them on your list? |
Hi traderbam...
No...i did not insult Fred......with respect, i suggest the bulk of cutting edge audio today is designed by AES members...eg Robert stuart of Boothroyd- stuart Meridian, who uguably design and manufacture the best all-round, and technically advanced HI-Fi in the world here in the UK.....:)
However i confess, i do find your accusation of 'plagarism' insulting...indeed defamatory....you of course are incapable of adducing any evidence to back up such an unprovoked piece of scurilous nonsense?
:(
...and as for
'I know you are a confident, budding designer who is getting air-time in an electronics publication and so you are naturally inclined to have the greatest respect for other publicists who preceeded you.
.......please desist from patronising me, as you do not know me at all.....and me you for that matter...
cheers. |
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| mefinnis |
| quote: | | So it was actually a bit of disappointment to see it was greeted with a hostile response from some members under a false premise that I try to advertise it here. ..... |
Not meant to be hostile Peter, if it was interpreted that way, my apology. My concern (primarily) was the thread was being taken away from it's original intent - which I think is an important topic. Your "meander from the path", however pales into insignificance as I read the last 48 hours worth :(
Re the "advertising" bit, I just thought we need to be consistent. Remember poor old AKSA (Hugh) coped a beating around the ears when he first appeared for a lesser indiscretion.
Regards
mark |
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| Fred Dieckmann |
| quote: | Originally posted by mikek
....you just try to solve for the curent in a simple L-R series circuit resulting from applied excitation Vcos(wt)....(assuming zero initial conditions for simplicity), using trig. identities....tedious...tedious..... |
Hmmmmmmm....... I believe that is why they invented Spice modeling,which is far from tedious and is easy..... easy..... easy.
Nobody's written about it in the AES journal? |
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| Christer |
| quote: | Originally posted by Fred Dieckmann
Hmmmmmmm....... I believe that is why they invented Spice modeling,which is far from tedious and is easy..... easy..... easy.
Nobody's written about it in the AES journal? |
Except that a Spice simulation is not the same thing as solving
the equations. Spice does a numerical simulation for particular
component values and does not give a symbolic solution, and
being a numerical simulation, a Spice result can never be
trusted unless an error analysis is done.
That said, I agree that Spice is an extremely useful tool. Being
a computer scientist, I do however find a lot of shortcomings
that make it quite tedious to use. That should be possible to
fix, though, by adding an abstraction layer on top of the Spice
engine. |
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| Christer |
| quote: | Originally posted by Peter Daniel
You don't know me, then. I like to be practical and this is a simple setup for resistors sound comparison. It takes only few seconds to change resistor so you still have the memory of the sound of the previous one. Of course some will argue that this is not valid setup, because I don't solder resistors and it's outside of the amp so all kind of interferences come in effect. Yet it allowed me to hear repeted and consistant difference with few types of resistors and it was perfectly in line with other forum members. If you will continue to claim that resistors don't have specific sonic signature I simply refuse taking seriously anything you say.;)
And BTW, I never use inductive resistors. |
I think your setup is reasonable, but to make any experiments
valid you must have somebody else to do the resistor swapping
for you, and this person must try to emulate a random
behaviour, sometimes swapping resistors, sometimes just putting
back the resistors he/she just removed. Preferrably, this person
should also not be visible for you, but if he/she is well aware of
the potential problems when visible, I think it is not necessary. |
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| Christer |
SY,
since I think it is relevant to this thread, has anything happened
to the experiment you and dorkus were planning before
Christmas? |
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| mefinnis |
I thought you guys had been busy a couple of days ago when I checked back in to see what was happening........ WOW!
For raising this topic in this forum, I recall referring to NW as borderline insane and blessed his naive & deluded socks! (Stated in a standard "taking the ****-out" kind of speak, given I'm from Oz, ie no offence intended:))
Well, I was right ....... and we now have 20+ pages of proof (for those who like that sort of thing).
I'm not in a position to even remotely argue the "null-test" bit and actually this appears to have received some rational/educated debate.
The discussions around DBRCTs however have departed the realm of all rational scientific thought.
I have NOT stated any of the golden-eared ones will not be able to ascertain a difference between A & B. They may, they may not. However, failure to accept that phychological factors do alter perception seriously undermines the position taken by a number of people.
I am sure there are components which are better (or I certainly bloody hope so!). Reproducibly better and we should define these scientifically, so we may all be confident about what we are talking (and about to spend money on!).
People are (rightly or wrongly) perceiving this statement as an attack on their personal ability (hearing), their system, or their love of HiFi. The resulting slanging matches create images of 4yo children in a sand-pit.
cheers
mark
PS: That was a 2 glass of wine read ..... and opposed to those who say ETOH diminishes the appreciation of Hifi, I say ..... so be it, but it enhances the appreciation of the music ;) |
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| Fred Dieckmann |
| quote: | Originally posted by nw_avphile
Well... this is sort off topic, but you asked so I'll answer.
I'm open minded enough to think vibrations can possibly have an effect on other components as well, but I've never encountered it that I'm aware of. The amount of overall gain in a power amp is roughly 2 orders of magnitude less than in a phono pre-amp. So any tiny effects from microphonics would be much less likely to have an audible effect.
|
Yes unless they effected the differential pair that can cause gain variations outside the influence of the negative feedback loop. Before everybody decides that vibration effects in ICs are impossible, consider that silicon dioxide is commonly used as a passivation layer. The piezoelectric properties are known and put to use in crystal oscillators. Vibration could create noise voltages that are coupled into the semiconductors inside the IC. perhaps even the semiconductor material could have piezoelectric properties
http://www.wikipedia.org/wiki/Piezoelectric_effect
http://www.wikipedia.org/wiki/Quartz
http://www.batnet.com/enigmatics/se...properties.html
As for resistors, many of the ones recommended for delusional audiophiles have very low temperature coefficients and voltage coefficients. As the voltage signal changes across a resistor the power dissipated (V squared divided by R) changes the temperature and by proportion to the temperature coefficient; the resistor value. That is the resistor value is changing as a function of signal. This is also related to the thermal mass and thermal time constant of the resistor. A similar effect exist for the voltage coefficient.
It seems that two amplifiers identical expect for the resistors tempco will differ in output as a function of these resistor values dynamically changing with signal. Steady state sine waves are probably poor test signals to demonstrate this with and most of the test discussed may have insufficient resolution to test this effect. The mechanism for distortion is there and who is to say that we cannot hear it in a system of sufficient resolution and listeners with sufficient experience. I guess the guys at the AES have investigated all these effects though.
As for the Crown amp sounding wonderful, you must not have had the levels matched since we know it should sound no better than any other competently designed amp. |
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| SY |
Christer, no, nothing has moved much. The last I heard, there were some buffers that I was supposed to receive, but haven't yet. I've located and procured a rather massive multiposition switch for the box. If the "golden ears" think that something like a BUF-03 is an acceptable unit, I do have a few of those laying about which I'd donate to the cause.
I invite the participation of anyone who wants to help out. Specifically, I'm looking for the donation of some "approved" fashion plugs, resistors, and caps (they can even be painted with Tube-O-Later!); besides the switch and the box, I'll happily provide the Radio Shack grade comparison parts. |
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| Fred Dieckmann |
| quote: | Originally posted by mefinnis
I have NOT stated any of the golden-eared ones will not be able to ascertain a difference between A & B. They may, they may not. However, failure to accept that phychological factors do alter perception seriously undermines the position taken by a number of people.
cheers
mark
|
I absolutely accept that psychological factors do alter perception!
This is a two edged sword that may cut even more sharply in the other direction.
Consider the factors that effect the converse stand.
1. Reliance on the viewpoints of someone whose experience, motivation, listening skills and test methods I have incomplete knowledge. Some of these factors can influence testing measurements even outside situations with subjective factors.
2. Design of a test who's particular outcome is desired to prove an existing exception This should be the biggest red flag for any objective test.
3. Anxiety, time pressure, social pressure, and unfamiliarity with system under test for the test precipitants.
4. Design and resolution of the test system.
I don't understand the assumption that audiophiles are presumed to expect improvements for a given change and that the results of these changes are always assume to be improvements. Doing R and D on audio designs will just as often result in the converse, i.e. It sound worse, it sounds different, it sounds the same. Many of these depend on break-in time, power line conditions and RFI background (very time of day dependent by the way and discussed in non audio literature), source material, add variations in equipment set up, cable and component interactions, and a number of other factors. Almost all of these have scientific and engineering principles behind them.
My biggest problem with a lot of these discussions are the cynical presumptions made about the methodology, motivations, techical abilities, and experience of those who claim to hear differences based on factors outside of mainsteam audio engineering . There are any number of even sharper engineers from other disiplines outside the audio community. I know it is hard to believe, but many other engineering fields even more challenging that audio design. There are contributions from other fields that will advance the art. Siegfried Linkwitz's background at H.P. designing RF and microwave test equipment and its influence on crossover and spearker design is a perfect example. John Dunlevy had a background in antenna design as another example. I believe there are many contributions from areas of science and engineering outside the audio engineering disipline that can make contridutions to the advancement of the art. |
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| Peter Daniel |
| quote: | [i]Originally posted by mefinnis [i]
I have NOT stated any of the golden-eared ones will not be able to ascertain a difference
between A & B. They may, they may not. However, failure to accept that phychological
factors do alter perception seriously undermines the position taken by a number of
people.
cheers
mark
|
This indeed cand be two edge sword.
Let's assume that somebody takes part in one of those blind tests, yet for some reason it is not performed properly and the individual under test cannot identify the amps. This carries out a psychological effect on him and he starts to believe that all amps should sound the same (and indeed sound the same to him) and spreads the news to everybody he has a chance to. Most people are always on a look out for most convenient belief and this may appeal to many.
I mentioned it yesterday and this is certainly a possibility we cannot deny. |
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| SY |
I suspect that Sig Linkwitz isn't spending too much time painting goop on knobs or freezing his CDs!
In any case, Fred, the factors you name are well-known in sensory research. Yes, people sometimes do design tests badly- that's why it's silly to take the null results of one test and generalize from it. But when test after test after test, done by various people using various control methodologies, keep piling up one null result after another, at a certain point, one has to say that when it comes to boxes of gain, there don't seem to be any factors lying outside of conventional engineering which can be audibly distinguished.
A question for you; you mentioned the possibility of piezoelectric effects from SiO2 passivations in chips. I'm curious if there's any experimental evidence of that; as far as I'm aware, the lack of symmetry in the amorphous form (which is what results from passivation and CVD) would exclude this as a possibility.
Could that SiO2 somehow crystallize in normal processing and use? Quoting from one of your links:
"Unlike e.g. amorphous silicon, amorphous silicon dioxide will not crystallize upon annealing at normal temperatures. ("Devitrification" -- that is, crystallization -- of quartz furnace tubes used for high-temperature oxidation is sometimes observed after thousands of hours of use at temperatures exceeding 1200 C.) " |
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| Fred Dieckmann |
"A question for you; you mentioned the possibility of piezoelectric effects from SiO2 passivations in chips. I'm curious if there's any experimental evidence of that; as far as I'm aware, the lack of symmetry in the amorphous form (which is what results from passivation and CVD) would exclude this as a possibility.
From:
http://www.azom.com/details.asp?Art..._Piezoelectrics
Quartz has this property as it has a complicated crystal structure with a low degree of symmetry.
I don't know. I would think it would certainly be much less piezoelectric than crystalline form which exhibits a high degree of piezoelectric effect evidenced by it's use crystal oscillators.
Fred
Dieckmann /not a semiconductor physicist and doesn't even play one on the web |
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| nw_avphile |
| quote: | Originally posted by Fred Dieckmann
Yes unless they effected the differential pair that can cause gain variations outside the influence of the negative feedback loop. Before everybody decides that vibration effects in ICs are impossible, consider that silicon dioxide is commonly used as a passivation layer. The piezoelectric properties are known |
You bring up a good point. As I said, I haven't ruled it out and both SY and I suggested Peter test it.
| quote: | Originally posted by Fred Dieckmann
As the voltage signal changes across a resistor the power dissipated (V squared divided by R) changes the temperature and by proportion to the temperature coefficient; the resistor value. That is the resistor value is changing as a function of signal. This is also related to the thermal mass and thermal time constant of the resistor. A similar effect exist for the voltage coefficient.
It seems that two amplifiers identical expect for the resistors tempco will differ in output as a function of these resistor values dynamically changing with signal. Steady state sine waves are probably poor test signals to demonstrate this with and most of the test discussed may have insufficient resolution to test this effect. The mechanism for distortion is there and who is to say that we cannot hear it in a system of sufficient resolution and listeners with sufficient experience. |
And who's to say a pilot of a 747 cannot detect some bird droppings on the wing from the way the plane handles? I'm sorry, someone needs to do the math to demonstrate this is anything but a red herring. It's really hard to imagine that the tempco effects (which are really tiny to begin with) combined with any dynamic heating effects (which are going to be small to non-existant depending on how the resistor is sized and its location in the circuit), combined with the effect a change in that resistor's value actually has on the amplifier after feedback, won't be anything but a percentage so small that gamma rays from another galaxy probably have a greater effect on the amplifier. But, if you can come up with some real-world math to show me otherwise, I'll try to keep an open mind. |
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| Steve Eddy |
| quote: | Originally posted by mikek
In analogue signal processing, it is more usefull to consider such excitations as a complex voltage, Ve^(jwt)=(Vcoswt+jVsinwt). This aids the determination of steady state response of a network to a sinusoid, because the complex exponential time waveform, e^(jwt) remains in the same form after differentiation or integration. This vastly simplfies analysis...as the real part of the applied voltage, which is cosinusoidal, (Vcoswt), is then used to solve of other quantities such as phase, fourier components, currents, etc..without the inelegant tedium of resorting to trignometric identities... |
So? All you're saying here is that an impulse can be described mathematically. Which has never been in dispute as far as I'm aware.
The question, again, is how do you evaluate an amplifier's impulse response using a single, steady state sinusoid as the stimulus?
se |
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| nw_avphile |
| quote: | Originally posted by SY
I invite the participation of anyone who wants to help out. Specifically, I'm looking for the donation of some "approved" fashion plugs, resistors, and caps (they can even be painted with Tube-O-Later!); besides the switch and the box, I'll happily provide the Radio Shack grade comparison parts. |
Can someone tell me if there's a thread on this topic somewhere? It sounds interesting! |
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| mikek |
| quote: | Originally posted by Fred Dieckmann
Hmmmmmmm....... I believe that is why they invented Spice modeling,which is far from tedious and is easy..... easy..... easy.
Nobody's written about it in the AES journal? |
....using pspice without understanding its limitations, the underlaying circuit theory, how it arrives at results, and real world ramifications of its short comings amounts to cooking with a blindfold.... |
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| mikek |
| quote: | Originally posted by Fred Dieckmann
Hmmmmmmm....... I believe that is why they invented Spice modeling,which is far from tedious and is easy..... easy..... easy.
Nobody's written about it in the AES journal? |
..... we are yet to have arbitrary waveform generation in pspice......? |
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| nw_avphile |
Fred, thanks for providing some constructive points that can be addressed.
| quote: | Originally posted by Fred Dieckmann
I absolutely accept that psychological factors do alter perception! |
Well that's good to hear at least.
| quote: | Originally posted by Fred Dieckmann
1. Reliance on the viewpoints of someone whose experience, motivation, listening skills and test methods I have incomplete knowledge. Some of these factors can influence testing measurements even outside situations with subjective factors.
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Who's asking you (or anyone else) to do that? If you're saying you don't trust someone else to set up the test properly, that's a pretty weak argument--especially when you're welcome to set up the test yourself in your own system. You only need another person to assist with the blind switching and record keeping. If you don't trust them, have someone supervise them if you'd like? If I misunderstood the question, please let me know.
| quote: | Originally posted by Fred Dieckmann
2. Design of a test who's particular outcome is desired to prove an existing exception This should be the biggest red flag for any objective test. |
I'm not proposing that. I'm proposing that people design the test to determine if differences exist between two pieces of gear (or capacitors, or whatever). The outcome can go either way. I'm suggesting people use their own systems, their own music, etc. The number of variables changed from how you normally listen now are minimal.
| quote: | Originally posted by Fred Dieckmann
3. Anxiety, time pressure, social pressure, and unfamiliarity with system under test for the test precipitants. |
Well see above relative to the system, as to anxiety, etc, it needn't be much greater than any other non-blind critical listening test. And again, I have to say if the differences or so subtle that having someone else in the room causes you not to hear them, how significant are they? For more on the above, and the issue of time, I quote from post #15 in this thread by Steve Eddy:
Tom Nousaine has set up a number of self-professed golden-eared audiophiles with an ABX comparator in their own home using their own system and allowed to run tests at their own leisure over periods of months or more.
So far, none have been able to statistically discern any differences once basic issues such as distortion, frequency response and level matching have been addressed.
| quote: | Originally posted by Fred Dieckmann
4. Design and resolution of the test system. |
See the answer to point number 2 above. I'm suggesting people do these tests in their own systems. If they can or cannot hear a difference in their own system, with their own ears, with their own music, isn't that what matters most?
| quote: | Originally posted by Fred Dieckmann
It sound worse, it sounds different, it sounds the same. Many of these depend on break-in time, power line conditions and RFI background (very time of day dependent by the way and discussed in non audio literature). |
Well here's where the null test can be really useful. If you can show different null test results at different times of the day, then I'll conceed some of the above MIGHT have an audible effect. But I've run lots of comparison null tests and they never seem to vary by time of day. Our EARS certainly change by time of day and that is a much more likely explanation.
| quote: | Originally posted by Fred Dieckmann
My biggest problem with a lot of these discussions are the cynical presumptions made about the methodology, motivations, techical abilities, and experience of those who claim to hear differences based on factors outside of mainsteam audio engineering. |
I can't speak for everyone, but all I'm suggesting is this: If things people hear cannot continue to be heard when they don't know what they're listening to, they're VERY LIKELY caused by those psychological factors you agreed exist at the top of the post.
If you agree psychological factors are an issue, how do you suggest they be removed for accurate comparisons? If you tell me you have superhuman control of your mind and can ignore them, it will be my turn to laugh.
You appear frustrated by what you call "cynical presumptions" by folks who want objective evidence. I'm frustrated by subjective folks, who against all the objective evidence, against even common sense, insist they can hear things that have been shown time and time again, in a variety of ways, don't exist. Or, in a more general sense, they insist they're somehow exempt from well documented psychological behavior. Worse, they often refuse to participate in a blind test--at least one that can be verified by an unbiased third party. I wonder why?
I'm NOT criticizing your listening skills--I have no idea how skilled you are in that area. I've particpated in blind tests where one listener can pick out a piece of gear with 100% accuracy and someone else in the exact same session cannot manage better than random. Interestingly, this seems especially true with perceptual encoding (i.e. MP3, MD, etc.). Some people are sensitive to throwing away part of the audio signal, and some aren't. But none of this invalidates blind testing. It only matters what YOU can hear (assuming you're building/buying for yourself).
If you're designing a piece of gear to be sold or enjoyed by many, then it makes sense to have many listen to it during the development process. This is true for blind or non-blind listening tests. The blind ones are just much more likely to produce accurate results. |
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| nw_avphile |
| quote: | Originally posted by Peter Daniel
Let's assume that somebody takes part in one of those blind tests, yet for some reason it is not performed properly and the individual under test cannot identify the amps. This carries out a psychological effect on him and he starts to believe that all amps should sound the same (and indeed sound the same to him) and spreads the news to everybody he has a chance to. |
Well this isn't any different than all the people running around claiming to hear differences that have no objective basis in fact. And the way blind testing works, if you really can't hear anything, for that person at least in that system, it probably means the things being compared really ARE similar enough to be considered to sound identical (in other words a "false null result" would be rare).
If you want to talk about people running around sharing their knowledge, what about all the people who claim to evaluate an amplifier having only heard it in an unknown system? I run into that all the time. For example:
"Yeah, I stopped into Snake Oil Audio for the first time yesterday and listened to the new XA3000 Pass amp and MAN did it sound good!"
How rational is that? Yeah, the SYSTEM they heard may have sounded really good, but HOW ON EARTH did they attribute the good sound to the amplifier??? What about the speakers, do they know exactly how those sound (and when was the last time they heard them)? What about the room? What about the source material? Even most audiophiles will agree all those things are likely to make a much bigger difference than the amplifier.
The above can seemingly only be explained by audiophiles believing they're listening skills are SO superhuman, they're able to somehow exclude the speakers, room, source material, etc. and magically evaluate the sound of the amplifier in the above situation. I'm not saying they all do this, but it happens so often it amazes me. |
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| SY |
| quote: | | I don't know. I would think it would certainly be much less piezoelectric than crystalline form which exhibits a high degree of piezoelectric effect evidenced by it's use crystal oscillators. |
OK, I'll put you out of your misery- it's not piezoelectric at all. That's a good thing, too, since my cats are often perched near my window while I'm playing music and I'd hate to see them electrocuted by the rattling.
SY/ Formerly a semiconductor physicist/chemist |
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| SY |
| quote: | | The above can seemingly only be explained by audiophiles believing they're listening skills are SO superhuman, they're able to somehow exclude the speakers, room, source material, etc. and magically evaluate the sound of the amplifier in the above situation. I'm not saying they all do this, but it happens so often it amazes me. |
That's exactly what motivated me to test my own beliefs. I was quite certain of my own extraordinary skills. So were my audio geek buddies, who stopped talking to me afterwards.
I caveat this with the statement that guys like Fred or Frank or Peter are much too smart (seriously) to say silly things like that. |
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| nw_avphile |
| quote: | Originally posted by SY
That's exactly what motivated me to test my own beliefs. I was quite certain of my own extraordinary skills. So were my audio geek buddies, who stopped talking to me afterwards. |
It sounds like you and I are coming from a very similar place. We used to believe in the subjectivist's mantra, and now we're a bit more objective and rational (and subsequently at odds with much of the golden-ear crowd). It's amazing what participating in a few blind tests will do, isn't it?
Peter raised the concern that someone could somehow have a "false null" result from a blind test and run around telling everyone that all amplifiers sound the same. I think a much greater sin has been (and still is being) committed by all the people running around claiming differences that are based on pure psychological perceptions. That many subjectivists claim to know how an amplifier sounds, in a system unknown to them, is just one of the most obvious examples. |
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| Tube_Dude |
[QUOTE]Originally posted by Fred Dieckmann
[B]
Yes unless they effected the differential pair that can cause gain variations outside the influence of the negative feedback loop. Before everybody decides that vibration effects in ICs are impossible,[QUOTE]
Not in the case of Peter Daniel amp, as it is a inverting (gainclone) amp, in this case the diferencial pair is inside a overall feedback loop!! |
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| SY |
Peter's take is... novel.
I really hope that he takes the time to run some blind tests on his own. |
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| Fred Dieckmann |
| quote: | Originally posted by mikek
....using pspice without understanding its limitations, the underlaying circuit theory, how it arrives at results, and real world ramifications of its short comings amounts to cooking with a blindfold.... |
Duh........ I have expressed this view here on many occasions.
I don't advocate it for distortion analysis. Ask around.
Having used it since 1976. The first serious class project was to analyze the was to design see if a given set of performance goals could be met with a stated
topology and transistor choice. Yes, it could, if the Hfe was within a certain range that did not include the full Hfe variation for that part as show on the data sheet. I would have had to do lot of testing on the bench to find that out and have transistors with a large Hfe spread. I got an A on the project.
I guess might have a little experience with it. It has been incredibly useful on countless occasions for filter design, signal integrity, and stability simulations.
I have also seen how poor most of the op amp models are. If you want to see some limitations, go look at IBIS models for signal integrity analysis. We owned a $100,000 from Mentor graphics. It was still a very powerful tool and analysis of large boards and backplanes would be very time consuming. Time to market is very important constraint in the real world.
Spice is to supplement and not to supplant design testing on the bench. I suggest designing without it might be like cooking without a cookbook. I would still taste what I was cooking before subjecting other to the results. I still don't know why your asking if Spice can use arbitrary waveforms. If you are really trying describe a waveform from a description by the equations and find the task so tedious may I recommend MathCad. Spice does have a piece-wise linear input model, but it may not suit your needs. Surely you were suggesting modeling distortion with a complicated input waveform in Spice?
http://newton.ex.ac.uk/teaching/CDH...c3.html#3.2.1.4
I am curious how long you have been using Spice. I am also a little curious if you were even born yet in 1976. |
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| SY |
| quote: | Originally posted by Fred Dieckmann
I am also a little curious if you were even born yet in 1976. |
That's just plain old depressing. |
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| Fred Dieckmann |
| quote: | Originally posted by SY
That's exactly what motivated me to test my own beliefs. I was quite certain of my own extraordinary skills. So were my audio geek buddies, who stopped talking to me afterwards.
I caveat this with the statement that guys like Fred or Frank or Peter are much too smart (seriously) to say silly things like that. |
Perhaps you can't postulate a hypothesis then, Since I have heard the effect damping material applied to ICs. Much against my expectations and to my chagrin; and with blind testing no less.
Nobody wants to discuss tempco effects in resistors then? |
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| nw_avphile |
| quote: | Originally posted by SY
That's just plain old depressing. |
Yeah, and we're wandering off topic again. Fred seems bent on touting his vast experience, and/or discrediting the abilities of others, rather than debating the issues at hand although we're making some progress on the thread topics. |
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| traderbam |
| quote: | | Not in the case of Peter Daniel amp, as it is a inverting (gainclone) amp, in this case the diferencial pair is inside a overall feedback loop!! |
I'm not sure I understand, Jorge. Is the diff amp not always within the feedback loop whether in inverting or non-inverting config as the diff amp is just that - a difference between one input and the other. No matter which input you use for the source signal, the current fed back will be related to the difference between the inputs. |
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| nw_avphile |
| quote: | Originally posted by Fred Dieckmann
Perhaps you can't postulate a hypothesis then, Since I have heard the effect damping material applied to ICs. Much against my expectations and to my chagrin; and with blind testing no less.
Nobody wants to discuss tempco effects in resistors then? |
BLIND TESTING???? I thought you were OPPOSED to blind testing? All you've done is say bad things about it and the people who advocate it. Why were you using it yourself if it's so flawed in your eyes?
As to tempco, I already commented, you must have missed it. |
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| SY |
Tempco in resistors is (relatively) unimportant in box of gain circuits (as opposed to timing or precision DC circuits), unless it's so great that operating points drift; that's just bad design. The idea of some sort of thermal modulation of signal lacks experimental support (AFAIK) and makes little sense when considering thermal mass and time constants.
If you've got experimental data on thermal modulation of real-world resistors by signals which contradicts this, don't hold back. |
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| Fred Dieckmann |
| Gee, I thought I was trying to discuss things from an engineering perspective. The reputation and experience of some of said audio experts seems to be a major point, but no one seems to want to talk about engineers (not myself) with sterling credentials who still listen. Are Erno Borbely, John Curl and Nelson Pass just delusional audiophile hacks. I would think the patents, commercial successes, and over 25 years a piece might have some credibility. I guess it is MUCH easier to take pot shots at me. You and a few others have been remarkably silent about your background. We don't even know your names. The discussions of the physics and electronic effects behind the subject at hand seems to be absent from most of these post as well. |
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| Tube_Dude |
| quote: | | I'm not sure I understand, Jorge. Is the diff amp not always within the feedback loop whether in inverting or non-inverting config as the diff amp is just that - a difference between one input and the other. No matter which input you use for the source signal, the current fed back will be related to the difference between the inputs. |
In the noninverting configuration the voltage of the base of the LTP transistor conected to the input is compared with the voltage of the base of the LTP transitor conected to the feedback resistor...so the substraction is not direct...if any diference existe in the BE voltages of the 2 transistores ...the feedback can't do nothing to correct this...
In the inverting configuration...the input resistor curent and the output resistor current nulled in the - input of the amp...so the feedback become only dependent of this resistors...and there are no active elements in the process!
I hope i make myself clear....:)
If it was in Portuguese!!!;) |
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| planet10 |
| quote: | Originally posted by traderbam
Earlier someone said that a real music signal can be represented as an infinite collection of sinewaves (hence Fourrier transforms). Then they reasoned that if music is a collection of sinewaves a single sinewave is an adequate representation of music for the purposes of analysing distortion in an amplifier. What is wrong with this reasoning? |
When Sony & Philips were 1st introducing the CD i was taking a math course on Fourier Analysis -- discussions on this subject lead me to my conclusions of the inherent flaws (too low a sampling frequency) of CDs, and how far you could realistically apply FFT to audio signals...
This Conversation with Mr. Fourier is a pretty good summary.
dave |
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| SY |
| quote: | Originally posted by Fred Dieckmann
Gee, I thought I was trying to discuss things from an engineering perspective. ..
I guess it is MUCH easier to take pot shots at me. You and a few others have been remarkably silent about your background. We don't even know your names. The discussions of the physics and electronic effects behind the subject at hand seems to be absent from most of these post as well. |
Um, Fred, I've specifically taked about physics and electronic effects. And methods of sensory research. A few minutes getting personal info off my (non-audio related) web site and googling me (or running a search at USPTO with my name) will give you all the info on my background you want. |
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| Steve Eddy |
| quote: | Originally posted by Fred Dieckmann
I would think the patents, commercial successes, and over 25 years a piece might have some credibility. |
Credibility in terms of what exactly?
I don't see where patents or commercial success play any particular role in the area of credibility. You can patent perpetual motion machines and Eminem is a commercial success. So what?
The truth doesn't stand or fall based on patents or credentials. The truth either is or it isn't.
se |
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| nw_avphile |
| quote: | Originally posted by Steve Eddy
The truth doesn't stand or fall based on patents or credentials. The truth either is or it isn't. |
Well said! And, as even Fred has seemingly admited, psychological factors do alter perception. And it follows they can get in the way of truth when it comes to evaluating audio gear.
Again, at the risk of being obvious, the issues at hand here are the validity of:
1 - Blind Listening Tests (as compared to non-blind listening)
2 - Null Difference Testing of amplifiers (that is subtracting the input from the output and evaluating what's left)
If folks want to debate other controversial things that may affect amplifier sound (i.e. microphonics), that's great. But it would be nice if we could leave people's age and other personal issues out of the discussion.
There are obviously some contributors to this thread with strong knowledge in particular areas. While one may know the nuances of semiconductor physics, another may know human psychology, another may bring valid outside references to the discussion, and still others may have first hand experience with blind listening sessions of amplifiers. ALL of their opinions and contributions towards the topics at hand are equally welcome and valid IMHO. |
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| Fred Dieckmann |
I'll resist the temptation to tell you to put a cork in it (gentle humor that SY will understand) And if I ever need to know anything about plastic, your the man.
I can't agree with all the assumptions concerning resistor tempcos. I do not believe that the conclusions on time constant and thermal mass are insignificant. I was involved in the design of protection circuits for lightning (short time constants) and power cross (60 Hz) While this is on the macro rather than micro end of scale the consideration of time constants was a factor.
There is too much correlation between the best sounding resistors and the fact that they tend to have the lost temperature coefficient. I just don't believe this is a coincidence, way too much experience listening to resistors and amplifiers and preamplifiers with the best resistors.
To the rest of you:
I really think this all boils down to the motivation and effort put to investigating these issues. Those of you that hear these differences don't believe all the claims made, but unwilling to write it off to delusion, or think that it can always be heard in a double blind test. Test often full of variables that the adherents of, seem willing to overlook. It is not scientific rigor that I object to, but scientific rigor mortis. There are widely held opinions that the distortion measurements don't correlate completely with what we hear. Maybe we are not measuring the right thing. Maybe the resolution what we measure is not sufficient. I have run into these problems troubleshooting telecom circuits that were a lot simpler that the task at hand. Science's understanding of the brain and sensory perception is rapidly increasing. Instrumentation and computers get better at a dizzying pace. I don't think we have begun to exhaust the possibilities of testing in audio circuits, and I won't write off what people hear as delusion and sloppy science. Amateur speaker builders use FFT analysis, Spice modeling, and, speaker design software and these are just the motivated amateurs. I expect the real engineers and scientist to work on figuring out why we hear this things
and improve their testing until it is able to resolve this differences. What are the Double Blind proponents offering us in return, a way to go backwards in audio design? High End audio is designed to take us further into the music not to take everything to a level playing field or the status quo. Early solid state and digital design took us backwards, all in the name of better measurement numbers. the first time my wife heard a CD player she turned around and asked me if it was broken.
I have no problem with double blind testing seeking to quantify difference in amplifiers and try to make sure the differences we hear not just easily understood things like level, frequency response differences, and gross distortion. When the intent of the test is to make to different sounding amps sound the same, what is the point? Is the state of the art fine now? Is there some augment about some real danger or public disservice in making sound it better. Is it the new crack cocaine? Are people going to rob, murder, or prostitute themselves for a better stereo? Is building our own amplifier with good parts going to cost more than mid fi? What are you "double blind, sounds the same, just measure it" people saving as from? I think a much more interesting question is what are you trying to save yourselves from?
Arthur C. Clarke said "any sufficiently advanced technology is indistinguishable from magic." Maybe some of you should stop writing this all off as belief in magic and go do some investigation into sufficiently advanced technology.......
I propose a new testing strategy called the deaf dumb blind test or DDB test for short.
Don't hear differences in amplifiers that can't be explained by double blind testing. Don't even try.
Don't see what others are attempting to do to explore these differences, or look at your test method to see any limitations.
Believe in the pronouncements of a few self proclaimed experts and ignore the reports of hundreds of motivated curious people. |
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| nw_avphile |
| quote: | Originally posted by planet10
When Sony & Philips were 1st introducing the CD i was taking a math course on Fourier Analysis -- discussions on this subject lead me to my conclusions of the inherent flaws (too low a sampling frequency) of CDs, and how far you could realistically apply FFT to audio signals... |
I'm, for one, am not suggesting CDs (or the technologies behind them) are perfect, but the fact is, they're what the majority of us listen to most of the time. So in that sense, I argue they're a valid test signal. As to the debate of representing music with sine waves, I'm going to stay out of that one except to mention the following:
Interestingly, in amplifier null difference testing, you DO get a considerably higher average difference value using music than you do with a single sine wave. But if you were to do null testing with multiple sine waves, weighted for roughly the energy content of the music, at some large number of frquencies across the audio spectrum, would the RMS difference results sum up to the same value you get with music? I don't know.
Besides sine waves and music, bandwidth limited pink noise also makes a useful source for null testing. It's random in nature, somewhat approximates the spectrum of music, contains all audible frequencies and is easier to measure with. But, for the die-hards in the crowd, it's harder to argue the validity of a null test if you use your favorite, most reavealing, evaluation CD as the source signal. |
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| nw_avphile |
| quote: | Originally posted by Fred Dieckmann
What are you "double blind, sounds the same, just measure it" people saving as from? I think a much more interesting question is what are you trying to save yourselves from? |
I've only stated the answer to the above a half dozen or so times but I'll state it again: I'm only trying to "save" people from spending more money on things that don't make an HONEST audible difference in their system. If blind testing shows they're just as happy listening to $0.50 capacitors, why spend $75 on them?
If some of you want to spend $75 on capacitors because they make you feel good, or help you sleep better at night, or you just don't want to bother with any objective testing, THAT'S FINE! But, for those who prefer to focus on the things that matter, perhaps those with limited budgets, I'm just trying to present some tools to determine what things will really make a difference to them in their system.
I'm willing to let the subjectivists spend all the money they want on their own systems. But it bothers me when they fly in the face of all the objective evidence and try to convince everyone just because they hear something, under heavy psychological bias, it must be real.
If Fred or Peter or anyone else here was saying "I buy/build really high-end esoteric stuff because it makes me feel good and it sounds better to me" I'd say GREAT! But many of you are trying to argue the differences you hear, under very subjective biased conditions, are REAL and of potential benefit to others.
Some of you are even going so far as to come up with technical reasons why you hear what you hear that stretch credibility beyond belief. Instead of saying, "Yeah, it may be only psychological bias, but whatever the reason, I like the sound of my exotic resistors." You're trying to come up with incredibly weak technical explanations as to justify your biased listening results. Further, you're at a loss to explain away all the objective evidence that opposes you.
I ask folks bothering to read this far to consider which of the two is more likely and passes the test of common sense:
1 - Psychological bias, a well proven human phenomena, is likely responsible for the things people claim to hear when they know what they're listening to but disappear when they don't.
2 - If a person hears a difference, even though they're biased by knowing what they're listening to, and that difference disappears during a blind test, the blind test must somehow be flawed. Further, when we try to measure for any differences, even using extremely sensitive tests like the null difference test, no objective differences can be found. In this case, the blind tests and all of the objective tests must be in error as that person must be correct in what they hear--biased or not. |
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| fdegrove |
Hi,
| quote: | | I'm willing to let the subjectivists spend all the money they want on their own systems. But it bothers me when they fly in the face of all the objective evidence and try to convince everyone just because they hear something, under heavy psychological bias, it must be real. |
Ah, so we are subjectivists...you automatically assume we do not measure our stuff, you're wrong.
What objective evidence are you talking about?Now that bothers me...
Who is trying to convince who here? You certainly haven't convinced me and quite likely you never will.
If we, and together with us other people hear, repeatedly, differences we have no means of measuring does that mean the differences aren't there?
Heavy psychological bias? Biased towards what exactly?
Yes, it is real.
Naturally it makes life a lot easier dismissing audible yet unmeasurable differences claiming that if they can't be measured it therefore follows they're just not there.
I find that approach errrr, rather medieval.
I find this kind of attitude rather disturbing and if people keep that up nothing will ever change, well, not for the better anyway.
Fred mentioned tempco in resistors, he could no doubt add a myriad of other factors that influence sound...never, ever forget that music is dynamic and very complex in its content.
Oh, and capacitors are an even more difficult model to control in case you haven't noticed.
Note that these are just passive components, active components are nothing more than a complex series of passive brought to live under tension.
If you want to, and I hasten to add I don't know if it's the case in the U.S. of A, you can actually get a lot of help of the universities if you're a company...you'd be surprised to learn it doesn't cost you a dime.
Anyway, you seem to have your rigid beliefs...me I learned to be a tad more flexible over the years.
Cheers,;) |
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| Steve Eddy |
| quote: | Originally posted by Fred Dieckmann
There is too much correlation between the best sounding resistors and the fact that they tend to have the lost temperature coefficient. I just don't believe this is a coincidence, way too much experience listening to resistors and amplifiers and preamplifiers with the best resistors. |
I don't think that correlation is terribly meaningful.
I've only noticed such a correlation among those who are already of the belief that the best objective performance gives the best subjective result. So they're always going after resistors with the lowest tempco, dielectrics with the lowest dielectric constant, conductors with the highest purity and fewest crystals, etc.
And invariably whenever they can come up with some improvement, no matter how microscoically small and insignificant (such as the difference between 99.999% pure copper and 99.9999% pure copper), they invariably perceive it to be subjectively better.
I think if there's any meaningful correlation here, it's that our subjective perceptions tend to mirror our pre-existing beleifs. The correlation you offer here is akin to saying there's a correlation among Christians about the divinitiy of Christ.
You say the correlation is so significant that you don't believe it's due to coincidence, well, I don't necessarily think it's a coincidence either.
We're constantly being inundated with the notion that better objective quality ipso facto translates into better subjective quality. Not just through marketing, but also through peer pressure. And not just in audio, but in many other aspects of our daily lives as well. And when you look at the objectively better equals subjectively better correlation in this light, it's not surprising at all.
Now, when you look at those who don't hold such pre-existing beliefs to a significant degree, suddenly there isn't the same sort of correlation with objective criteria.
We're all victims of "group think" to one degree or another. We're basically insecure and we tend to feel more comfortable when we're part of a group of like-minded individuals.
Sometimes an intrepid, independent soul decides to see what's out there beyond the current group and sometimes they find something which may be completely at odds with the prevailing wisdom of the group but ultimately it gives them greater satisfaction.
Sometimes these individuals remain as outcasts. But other times, other members of the group start to wander off as well and discover these new thoughts and sensations and eventually the group think paradigm changes completely.
So again, I don't think the correlation you offer here is terribly meaningful.
se |
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| Steve Eddy |
| quote: | Originally posted by fdegrove
Ah, so we are subjectivists...you automatically assume we do not measure our stuff, you're wrong. |
Why would a subjectivist want to measure their stuff?
se |
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