This came up in the FM Thread, but I made no comment.
For a Faraday cage to work, the cage must completely enclose the circuit/device.
If one side of the cage is missing then the attenuation effect of the cage is destroyed.
First question:- How much is destroyed? Some, or all, or a little, or a very big amount?
Second question:- what effect on the attenuation of the cage does the direction of the radiation interference have in relation to the "hole" in the cage?
Third question, somewhat rhetorical:- Why does a radio receiver work inside a car/van/truck/warehouse/railway station where the "holey" cage nearly encloses the receiver?
Fourth question. If the enclosing can is not earthed and has a hole that consists as a complete cylindrical end missing, then how can it be regarded as a Faraday cage?
For a Faraday cage to work, the cage must completely enclose the circuit/device.
If one side of the cage is missing then the attenuation effect of the cage is destroyed.
First question:- How much is destroyed? Some, or all, or a little, or a very big amount?
Second question:- what effect on the attenuation of the cage does the direction of the radiation interference have in relation to the "hole" in the cage?
Third question, somewhat rhetorical:- Why does a radio receiver work inside a car/van/truck/warehouse/railway station where the "holey" cage nearly encloses the receiver?
Fourth question. If the enclosing can is not earthed and has a hole that consists as a complete cylindrical end missing, then how can it be regarded as a Faraday cage?
Obviously its not going to work close to a perfect faraday cage because it has wires through the base. But even a reduction in the RF being conducted to the chip could result in an improvement of sound quality.
Just a hypothesis anyway, it would be possible to test for this by providing a screening cage around the plastic parts and listening to see if the sound improved.
Just a hypothesis anyway, it would be possible to test for this by providing a screening cage around the plastic parts and listening to see if the sound improved.
Thickness is essential for magnetic shielding, not so much for electrical one.
All is pointless, because of the fact that the die size is a couple mm. The wavelenght of the RF signals that surrounds it is way bigger than that, so basically all the RF picked up will be minor and common-mode for the whole die. Plus, ground plane is substrate - that's the best screening. There will be not signifiant pick-up to inside circuits that are so close to the substrate (micrometers) because the wavelenght that would be capable to get in "between" is probably in IR light range. The outside pins (longer antennas) are connected either to low impedance or shorted to ground via decoupling capacitors.
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Give me some real answers. Like how much.
I think I disagree on your last re grounding of the screen (Faraday cage).
The grounding applies irrespective of whether it is a transmitter or a receiver that is inside or outside the screen.
Can you bring your comments outside the quoted section?
I think I disagree on your last re grounding of the screen (Faraday cage).
The grounding applies irrespective of whether it is a transmitter or a receiver that is inside or outside the screen.
Can you bring your comments outside the quoted section?
I think the plastic is as good for screening as the metallic can.
This is because in fact the die substrate itself (conductive) is providing the shielding. Even if is only on one side, is practically a Faraday cage for wavelengts of RF up to GHz, because the circuit itself is so close of it:
About Faraday cage and why grounding is used for internal electric charges:
http://en.wikipedia.org/wiki/Faraday_cage#Operation
This is because in fact the die substrate itself (conductive) is providing the shielding. Even if is only on one side, is practically a Faraday cage for wavelengts of RF up to GHz, because the circuit itself is so close of it:
About Faraday cage and why grounding is used for internal electric charges:
http://en.wikipedia.org/wiki/Faraday_cage#Operation
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I don't want to open old wounds, but I think we're all missing the point here.
Instead of arguing whether metal can is better than plastic DIP or whether one grade of a particular op-amp is better than another grade of the same one, can anybody provide a link to an experiment when a properly constituted double blind trial clearly showed any audible differences between modern high performance op-amps under normal operating conditions?
I await your response, with links attached.
Instead of arguing whether metal can is better than plastic DIP or whether one grade of a particular op-amp is better than another grade of the same one, can anybody provide a link to an experiment when a properly constituted double blind trial clearly showed any audible differences between modern high performance op-amps under normal operating conditions?
I await your response, with links attached.
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You're welcome to your opinion, but opinions have no place in science other than perhaps as hypotheses. So is this a hypothesis to test?
People's descriptions of what they hear is scientifically rigorous. I agree that 'sounds different' is not, which is why I've asked audioman54 for more details.
Abraxalito
People's descriptions of what they hear are most definely NOT scientifically rigorous. They are highly subjective and may be biased by expectations and previous knowledge.
A properly conducted double blind test will tell you whether Audioman's DAC with plastic case op-amps sounds different to an otherwise identical one with metal can op-amps. Did National conduct such a test or a DBT test between their LME series audio op-amps and other high performance op-amps? I'll let Audioman tell us.
The original challenge stands methinks.
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Here you go. The wikipedia entry is surprisingly good in this case.
Null hypothesis - Wikipedia, the free encyclopedia
This is VERY important. It means that the demand to prove that two things sound alike is logically impossible to fulfill. Proof must come from the claim that two things sound different.
Null hypothesis - Wikipedia, the free encyclopedia
This is VERY important. It means that the demand to prove that two things sound alike is logically impossible to fulfill. Proof must come from the claim that two things sound different.
Sy
I understand what you're saying from a statistic viewpoint, but consider this:
The hypothesis in the case under question is that the LME op-amp DIE in a plastic DIP case sounds inferior to one in a metal can case for DAC I-V and o/p stage duties. That was Audioman's contention from his subjective trial. Would you agree so far?
So, let's construct two identical versions of Audioman's DAC using the same parts he used to make the DAC where he allegedly heard a difference when changing op-amps, with the only difference being the I-V and o/p stage op-amp packages, being careful to match component tolerances and o/p levels as closely as possible or better still, to use one DAC and switch the I-V and o/p stages.
Now, let's listen to them through the same system he used in his original test.
If a DBT test shows that, when, switching between the two DACs provides no statistically valid evidence that he can now tell which DAC he is listening to or if indeed a switch has been made at all, in what way does that not demonstrate that the op-amps have no audible differences and that what he thought he heard in his subjective test was erroneous?
I understand what you're saying from a statistic viewpoint, but consider this:
The hypothesis in the case under question is that the LME op-amp DIE in a plastic DIP case sounds inferior to one in a metal can case for DAC I-V and o/p stage duties. That was Audioman's contention from his subjective trial. Would you agree so far?
So, let's construct two identical versions of Audioman's DAC using the same parts he used to make the DAC where he allegedly heard a difference when changing op-amps, with the only difference being the I-V and o/p stage op-amp packages, being careful to match component tolerances and o/p levels as closely as possible or better still, to use one DAC and switch the I-V and o/p stages.
Now, let's listen to them through the same system he used in his original test.
If a DBT test shows that, when, switching between the two DACs provides no statistically valid evidence that he can now tell which DAC he is listening to or if indeed a switch has been made at all, in what way does that not demonstrate that the op-amps have no audible differences and that what he thought he heard in his subjective test was erroneous?
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It proves that this particular listener with this particular setup was unable to distinguish them, i.e., "what he thought he heard in his subjective test was erroneous." It does NOT prove that they sound the same- it's possible that someone else using a different setup (or even someone else using the listener's setup) could hear a difference. I agree that this is highly unlikely, and that the overwhelming probability is that under ears-only conditions, the claimant would be unable to distinguish the two cases, but it's a logical fallacy to either demand that someone prove that A and B are indistinguishable or to assert that because a finite number of tests show null identification that the lack of audible difference is proved.
I think I'll settle for your first sentence and the balance of probability.
Hey, Audioman might prove me wrong and tell us that a DBT did prove an audible difference. All I'm asking was did such a trial take place.
If you're going to market your op-amps as being designed with sonics as a priority I would have thought that's the least you would have to show.
Hey, Audioman might prove me wrong and tell us that a DBT did prove an audible difference. All I'm asking was did such a trial take place.
If you're going to market your op-amps as being designed with sonics as a priority I would have thought that's the least you would have to show.
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In my micromega stage 6 I replaced all the op amps with 4x OPA627BP and 5x OPA637BP.
Originally fitted were 2x OPA2604 and 5 x opa132.
The addition of the new opamps brought a warm fuller sound. Extremely low levels of bass and very clear vocals. Can't say HF was any clearer but overall the levels of midrange clarity increased a lot.
Originally fitted were 2x OPA2604 and 5 x opa132.
The addition of the new opamps brought a warm fuller sound. Extremely low levels of bass and very clear vocals. Can't say HF was any clearer but overall the levels of midrange clarity increased a lot.
Peelaaa - I'm not doubting that you thought you heard a difference several hours after you last heard the player with the old op-amps. After all, you'd feel like a right tw*t if you didn't after spending all that money, but have you actually READ this thread?
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