gpapag said:
Hi George,
You are welcome, and, irrespective of any of my own findings, I would always recommend others to try these things out for themselves.
The only real value in listening to what other people have to say in these cases (including me!) IMHO, is when deciding whether it is worth expending the time and money on such a trial, in the first place.
It may or may not have occurred to you, but don't forget in a case like this that you are not judging the *overall* sound, as much as any*differences* caused by the suggested 'reversal' in question.
Accordingly, when setting things up, it can be on a much more temporary basis (we call it a 'jury rig') when, unless you have done something very drastic, you will still most likely hear the changes, even if the overall quality of sound is not so good.
Peter Danel recently showed a very temporary way of doing this, which I thoroughly uphold, as I have done exactly the same thing, myself, many times.
I seem to recall that some resistors which were under test by him were literally lodged between two connectors (without even soldering) which is fine, provided that if the connection fails for any unexpected reason, it does not cause any damage to the chip etc.
If Peter reads this, maybe he will direct you to his post about this, as I have been posting in many threads recently, and I don't recall which one it was in.
Regards,
Here's the link: http://www.diyaudio.com/forums/showthread.php?s=&postid=123835#post123835 and the pic of a test setup.
Attachments
Problem with these thingies is to investigate the effect that is supposed to be audible while excluding other factors.
Very probable, a 220 k resistor will sound slighty different from a 110 k resistor (besides the change in value). It all depends on the geometry and material change in the resistor for increasing the value from 110 k to 220 k. Also, there could be noise/temperature effects (like mentioned, the 1/4 w and 1/8 w issue).
Fedde
Very probable, a 220 k resistor will sound slighty different from a 110 k resistor (besides the change in value). It all depends on the geometry and material change in the resistor for increasing the value from 110 k to 220 k. Also, there could be noise/temperature effects (like mentioned, the 1/4 w and 1/8 w issue).
Fedde
Dear Bobken
Thanks again, especially for your kind manners. I will do the 'rig" hopefully this week.
Dear Fedde
["Maybe a very obvious point, but do you realize that the value of the resistors is halved by putting two resistors parallel ?
And I wonder how you manage to get the exact same value from the single resistors for the parallel resistors..."]
Yes, this is obvious and i have realised this. In the attached drawing, in the component list you will see the details of the resistor values.
Dear Peter
Thanks for the link. I had lost track of it.
What i am thinking of now, is, that i have to do listening tests for each resistor position (there are three) at a time. And for each resistor the mode has to be: 1.Single resistor in one direction. 2 Single resistor in reverse direction. 3. Two parallel resistors in one direction. 4. Two parallel resistors in reverse direction. 5. Two antiparallel resistors. This is 15 tests in total (confining myself to one resistor brand)! This may turn to be the subject of my thesis with the tittle: "Trying to build a logical statement within an unlogical sentence"
Regards
George
Thanks again, especially for your kind manners. I will do the 'rig" hopefully this week.
Dear Fedde
["Maybe a very obvious point, but do you realize that the value of the resistors is halved by putting two resistors parallel ?
And I wonder how you manage to get the exact same value from the single resistors for the parallel resistors..."]
Yes, this is obvious and i have realised this. In the attached drawing, in the component list you will see the details of the resistor values.
Dear Peter
Thanks for the link. I had lost track of it.
What i am thinking of now, is, that i have to do listening tests for each resistor position (there are three) at a time. And for each resistor the mode has to be: 1.Single resistor in one direction. 2 Single resistor in reverse direction. 3. Two parallel resistors in one direction. 4. Two parallel resistors in reverse direction. 5. Two antiparallel resistors. This is 15 tests in total (confining myself to one resistor brand)! This may turn to be the subject of my thesis with the tittle: "Trying to build a logical statement within an unlogical sentence"
Regards
George
Even taking into account resistor directivity I wouldn't have thought that it could make such a radical change in an amplifier that gpapag suggests. I think bad solder joints in point to point wiring on IC's are more probable seeing the confined spaces and the fact that sometimes you have to resolder the same joint.
In case some of you didn't see my posting in another thread I made some A/B listening tests over the weekend between an LM3875 and an OPA549.
I much preferred the OPA 549. It sounds more controlled ,neutral and robust. Some differences were more obvious with piano music (always a good test I think).It is interesting because pianos can sound either too woody or too steely depending on the amplifier. I think the OPA was blending the two in a correct balance while the LM was a bit "steely".Also the OPA could be driven much louder without sounding stressed, maybe as much as the ALEPH 5s. I can't corroborate this scientifically because I lack a scope of course.
Perhaps though all the differences were due to different resistor directivity
In case some of you didn't see my posting in another thread I made some A/B listening tests over the weekend between an LM3875 and an OPA549.
I much preferred the OPA 549. It sounds more controlled ,neutral and robust. Some differences were more obvious with piano music (always a good test I think).It is interesting because pianos can sound either too woody or too steely depending on the amplifier. I think the OPA was blending the two in a correct balance while the LM was a bit "steely".Also the OPA could be driven much louder without sounding stressed, maybe as much as the ALEPH 5s. I can't corroborate this scientifically because I lack a scope of course.
Perhaps though all the differences were due to different resistor directivity
I made this set up in 5 min. and it's good enough to compare different brand of resisors. If there is any noise pick up, it will be the same for all componenets under test and the difference is detectable anyway. I can clearly hear the difference between Rikens, holcos and Vishays. I wouldn't have the courage to built two different amps just to compare resistors, unless you do production of course.
What you think is a difference between resistors may just be a difference between poor contact with the connectors. Radiation is not steady state, so when performing different tests at different times, one may be subject to radiation that the other is not.
I don't understand how you can go to the extreme lengths to control vibration and "resonance" in your system (based on pics you've posted in these forums) that you do, and then dismiss such effects as completely inconsequential in this type of test.
Do these things matter or don't they?
MR
I don't understand how you can go to the extreme lengths to control vibration and "resonance" in your system (based on pics you've posted in these forums) that you do, and then dismiss such effects as completely inconsequential in this type of test.
Do these things matter or don't they?
MR
Hmm.. I really think you need to solder those suckers in there, Peter. Make up one female-male RCA adapter with each resistor type, or perhaps one RCA adapter with a cheaper connector for the resistor (such as a standard 0.1" pin header, gold plated), such that this is a constant variable for each test. Then do a proper job soldering the resistor leads - as they would be in a real circuit. Without soldered joints, you have no idea how the differences in the oxidation properties of the lead materials / coatings and variances in contact pressure are affecting your results. The process of soldering will clean off the oxides, and provide a good, trustworthy connection, thus eliminating this really big unknown. And for the record... I've found low-force connections like this usually sound pretty crappy, reliablility issues aside. C'mon Pete! I know you can do a more scientific test than this! Let's see those construction skills shine!
It may surprise some of you, but I'll always choose convenience over reliability.
This supposed to be only a temporary and easy introduction to resistors comparison tests. I'm not claiming that this is a best way to do it, but if someone is reluctant to try those tests because of complexity of a setup, this should show a simple way to do it. If you try my method and will find that there is something to the differences presented, by no means go for more elaborate testing and use solder joints and all the rest of "perfect sound forever" accessories. For me this was good enough.
This supposed to be only a temporary and easy introduction to resistors comparison tests. I'm not claiming that this is a best way to do it, but if someone is reluctant to try those tests because of complexity of a setup, this should show a simple way to do it. If you try my method and will find that there is something to the differences presented, by no means go for more elaborate testing and use solder joints and all the rest of "perfect sound forever" accessories. For me this was good enough.
The Sun Don't Shine Out Of My Butt Either.
Hey Steve,
Have you tried reversing the polarity of the input and output connections of your audio isolating transformers, in order to guage any difference ?.
As part of my test bench, I have a pair of audio isolating transformers too, except that I have a DPDT swith wired as a reversing switch in series with the primary.
In previous experiments, I have reversed the polarity of both primary and secondary connections, and detected an audible difference.
I have also made non-directional star-quad interconnects too, and these made a non-subtle audible difference.
As far as sighted VS non-sighted testing goes, your comment is not woth the bandwidth.
You really ought to realize by now that amongst us here, are listeners who are easily able to divorce expectation from any listening testing, and if you are unable to do so, then please understand that other listeners are - Ummmm, fellows like Peter, Bob, Frank, myself and others I have missed mentioning.
The key is an open mind - indeed if you convince yourself beforehand that these such effects are not possible, well then as a matter of course you will never hear them - period.
You know the origin of the Universe is hitherto still unexplained.
If you have a workable theory, then by all means share your wisdom with us.
Eric / - open minded on most things, and intolerant of sarcasm and baseless naysayers.
Hey Steve,
Have you tried reversing the polarity of the input and output connections of your audio isolating transformers, in order to guage any difference ?.
As part of my test bench, I have a pair of audio isolating transformers too, except that I have a DPDT swith wired as a reversing switch in series with the primary.
In previous experiments, I have reversed the polarity of both primary and secondary connections, and detected an audible difference.
I have also made non-directional star-quad interconnects too, and these made a non-subtle audible difference.
As far as sighted VS non-sighted testing goes, your comment is not woth the bandwidth.
You really ought to realize by now that amongst us here, are listeners who are easily able to divorce expectation from any listening testing, and if you are unable to do so, then please understand that other listeners are - Ummmm, fellows like Peter, Bob, Frank, myself and others I have missed mentioning.
The key is an open mind - indeed if you convince yourself beforehand that these such effects are not possible, well then as a matter of course you will never hear them - period.
You know the origin of the Universe is hitherto still unexplained.
If you have a workable theory, then by all means share your wisdom with us.
Eric / - open minded on most things, and intolerant of sarcasm and baseless naysayers.
A Better Test Method ?....
I agree that resistors of differing values will likely behave slightly differently.
So I propose that a more valid test is to connect two suitable value resistors in series (or parallel), and reverse the direction of one or both resistors methodically, in order to detect audible directional differences.
One point worth mentioning here is that it seems that solder joints change according to the maximum level passed through them.
I find after blanket resoldering an amplifier stage, that on initial runup the sound if kept at low or medium levels can sound strangely 'wrong'.
If the amplifier is driven to momentary clip, the sound changes and remains different and stable thereafter.
I do not have a solid explanation for this effect, but I have proven it many times.
For the resistor direction test to be more valid, I feel that attention needs to be paid to this curious effect - ie run the level up to momentary clip and turn down, turn the sytem off and then back on before taking a proper listen for any sonic changes according to direction.
Eric / - The careful listener.
I agree that resistors of differing values will likely behave slightly differently.
So I propose that a more valid test is to connect two suitable value resistors in series (or parallel), and reverse the direction of one or both resistors methodically, in order to detect audible directional differences.
One point worth mentioning here is that it seems that solder joints change according to the maximum level passed through them.
I find after blanket resoldering an amplifier stage, that on initial runup the sound if kept at low or medium levels can sound strangely 'wrong'.
If the amplifier is driven to momentary clip, the sound changes and remains different and stable thereafter.
I do not have a solid explanation for this effect, but I have proven it many times.
For the resistor direction test to be more valid, I feel that attention needs to be paid to this curious effect - ie run the level up to momentary clip and turn down, turn the sytem off and then back on before taking a proper listen for any sonic changes according to direction.
Eric / - The careful listener.
Re: A Better Test Method ?....
That indicates you could have either a bad solder joint or a defective switch/relay contact in the amp. I had a similar problem with an active crossover in my church's sound system. At powerup one of the output bands of the crossover would sound soft and kind of muted. If you gave it a hard hit of signal it would start working correctly, but typically the next time you powered it up the problem would be back. I resoldered all of the XLR connectors and the problem was eliminated. I have since seen this specific symptom mentioned by Ashly and Mackie in technical bulletins describing problems with defective solder joints in PCB mount connectors and ribbon cables.
Switch and relay contacts demonstrate this same behavior. Once current is flowing through a contact there is an electronic self cleaning action that prevents oxide build up. However once the current stops an oxide film begins to build. Small signals lack sufficient voltage to break down the surface film which is why gold flashed contacts are required for reliable use with small signal levels. Once the oxide film is broken, the electron flow in even small signals is enough to keep the contact clean, but the problem comes back when the system is powered down again for any length of time.
In addition to looking for a cold solder joint I would also check any switch or relay contacts in the signal path. The specs I've seen for small signal contacts specifies that they will no longer meet requirements for small signals if the small signal current rating (usually 20 to 40 mA) is exceeded. What happens is that these contacts are the typical silver contacts with a thin layer of gold flashing to prevent oxidation. If the small signal current rating is exceeded, even for an instant, the gold flashing is gone and it becomes a normal high level contact.
Phil
mrfeedback said:
That indicates you could have either a bad solder joint or a defective switch/relay contact in the amp. I had a similar problem with an active crossover in my church's sound system. At powerup one of the output bands of the crossover would sound soft and kind of muted. If you gave it a hard hit of signal it would start working correctly, but typically the next time you powered it up the problem would be back. I resoldered all of the XLR connectors and the problem was eliminated. I have since seen this specific symptom mentioned by Ashly and Mackie in technical bulletins describing problems with defective solder joints in PCB mount connectors and ribbon cables.
Switch and relay contacts demonstrate this same behavior. Once current is flowing through a contact there is an electronic self cleaning action that prevents oxide build up. However once the current stops an oxide film begins to build. Small signals lack sufficient voltage to break down the surface film which is why gold flashed contacts are required for reliable use with small signal levels. Once the oxide film is broken, the electron flow in even small signals is enough to keep the contact clean, but the problem comes back when the system is powered down again for any length of time.
In addition to looking for a cold solder joint I would also check any switch or relay contacts in the signal path. The specs I've seen for small signal contacts specifies that they will no longer meet requirements for small signals if the small signal current rating (usually 20 to 40 mA) is exceeded. What happens is that these contacts are the typical silver contacts with a thin layer of gold flashing to prevent oxidation. If the small signal current rating is exceeded, even for an instant, the gold flashing is gone and it becomes a normal high level contact.
Phil
Re: The Sun Don't Shine Out Of My Butt Either.
ACK! Who wrote this software? Hitting the Escape key wipes out EVERYTHING you've typed. *sigh* Oh well, here goes the second try.
Sure. But when I do stuff like that, I'm just looking to see if I have any particular subjective preference. Not to establish any sort of physical reality beyond my own subjective perceptions.
Well, if there's anything to the audibility of absolute acoustic polarity (see Clark Johnsen's book, The Wood Effect), then making such a switch in polarity could result in audible effects which have nothing to do with the directionality of conductors. You're changing compression to rarefication and vice versa.
Great. However there have been some number of others who have made the same claims of "non-subtle audible differences" only to mysteriously have their ability to discern those "non-subtle" differences evaporate the moment the identity of the cable they're listening to is withheld from them.
Coming from someone who is wholly uncomfortable with the notion that they're a mere mortal human being, this comment is not suprising.
I realize that there are some number of people who believe they can wholly divorce their conscious mind from their subconscious mind. But so far, all we have are empty claims.
Yet the converse is somehow not also true? If one cannot hear something which is actually audible simply because they believe it to not be possible, why cannot someone perceive a difference when no audible difference exist simply because they believe it is possible?
So? This proves your claim how exactly?
Your arguments are souding more and more like the arguments of the charlatans featured on Penn & Teller's new program, ********!
I'm not the one making the empty claims of fact here. Nor do I have any particular desire to attempt to establish any of my subjective perceptions as any sort of physical reality.
Yet you expect others to unquestioningly swallow the baseless claims of "yaysayers." Hmmm...
And FYI, I'm not a "naysayer." I just don't swallow empty claims without question. It's called having an open mind but not one so open their brains slosh out onto the floor.
se
ACK! Who wrote this software? Hitting the Escape key wipes out EVERYTHING you've typed. *sigh* Oh well, here goes the second try.
mrfeedback said:
Sure. But when I do stuff like that, I'm just looking to see if I have any particular subjective preference. Not to establish any sort of physical reality beyond my own subjective perceptions.
Well, if there's anything to the audibility of absolute acoustic polarity (see Clark Johnsen's book, The Wood Effect), then making such a switch in polarity could result in audible effects which have nothing to do with the directionality of conductors. You're changing compression to rarefication and vice versa.
Great. However there have been some number of others who have made the same claims of "non-subtle audible differences" only to mysteriously have their ability to discern those "non-subtle" differences evaporate the moment the identity of the cable they're listening to is withheld from them.
Coming from someone who is wholly uncomfortable with the notion that they're a mere mortal human being, this comment is not suprising.
I realize that there are some number of people who believe they can wholly divorce their conscious mind from their subconscious mind. But so far, all we have are empty claims.
Yet the converse is somehow not also true? If one cannot hear something which is actually audible simply because they believe it to not be possible, why cannot someone perceive a difference when no audible difference exist simply because they believe it is possible?
So? This proves your claim how exactly?
Your arguments are souding more and more like the arguments of the charlatans featured on Penn & Teller's new program, ********!
I'm not the one making the empty claims of fact here. Nor do I have any particular desire to attempt to establish any of my subjective perceptions as any sort of physical reality.
Yet you expect others to unquestioningly swallow the baseless claims of "yaysayers." Hmmm...
And FYI, I'm not a "naysayer." I just don't swallow empty claims without question. It's called having an open mind but not one so open their brains slosh out onto the floor.
se
This is a quote from another thread dealing with similar issues. I think it's not too far from the truth:
"It is not possible to talk about the ear/brain system that is hearing without taking into account 'us'
that is one cannot seperate our conciousness from what we hear. As a consequence we all hear things
differently and we are all quite poor at repeatably hearing a piece of music as identically the same each
time we hear it... Our emotional state has a significant bearing on how we perceive the sound of music
- and since music itself is an emotional state modifier - we have an inherently 'unstable' system. That
is a system in which repeatable results are very very difficult to acheive.
This is the reason that double blind testing is so unreliable an indicator for sound quality - the act of
taking part in a testing process changes the way we hear the music and hence how we score the
sound..."
"It is not possible to talk about the ear/brain system that is hearing without taking into account 'us'
that is one cannot seperate our conciousness from what we hear. As a consequence we all hear things
differently and we are all quite poor at repeatably hearing a piece of music as identically the same each
time we hear it... Our emotional state has a significant bearing on how we perceive the sound of music
- and since music itself is an emotional state modifier - we have an inherently 'unstable' system. That
is a system in which repeatable results are very very difficult to acheive.
This is the reason that double blind testing is so unreliable an indicator for sound quality - the act of
taking part in a testing process changes the way we hear the music and hence how we score the
sound..."
Peter Daniel said:
If nothing else, that quote only reinforces the fact that there's a significant amount of psychology involved in our subjective perception of sound.
However I see a couple of flaws in the argument.
<i><b>...that is one cannot seperate our conciousness from what we hear.</i></b>
More like we cannot separate our conscious mind from our subconscious mind.
<i><b>This is the reason that double blind testing is so unreliable an indicator for sound quality - the act of taking part in a testing process changes the way we hear the music and hence how we score the sound...</i></b>
First, I haven't been referring to blind testing with regard to determining sound quality or personal preference but rather the ability to simply discern a difference between two elements. Not whether one is better than the other.
And the process isn't really different. When you were sitting listening to various resistors connected in both directions using your impromptu test rig, you were listening just as intently and analytically as you would be during a blind test. The ONLY difference is that under blind conditions, you wouldn't know beforehand which resistor you were listening to or which direction it was in.
And if you were able to discern a difference under sighted conditions, then there's no reason you wouldn't be able to discern those same differences under blind conditions if the difference were truly audible.
se
For me it works this way. Let's have that I have a design at task at I don't really know how to go about it. I usually go down to my workshop late at night, look at all the bits and pieces and just contemplate what I want to achieve with it. Finally, around 2 or 3 am I go to bed. Usually, when I wake up in the morning, I have a solution. Isn't it nice?
Observations, Not Theories.
Phil, solder joint problems are not included here - note that I said after 'blanket resolder'.
I am well familiar with noisey contact problems too, and this is not the sound that I speak of, and besides all pot and switch contacts get treated before this initial runup.
I suspect that the resoldereing process demagnetises residual fields in component leads, and clipping level current pulses cause a remagnetising of component leads, and a consequent bias in characteristics.
The solder joints themselves may be part of this equation also, especially if a magnetised component lead is contained within that joint.
This sonic change occurs only once after a blanket resolder, and happens when the amp is pushed to momentary overload.
Eric.
Phil, solder joint problems are not included here - note that I said after 'blanket resolder'.
I am well familiar with noisey contact problems too, and this is not the sound that I speak of, and besides all pot and switch contacts get treated before this initial runup.
I suspect that the resoldereing process demagnetises residual fields in component leads, and clipping level current pulses cause a remagnetising of component leads, and a consequent bias in characteristics.
The solder joints themselves may be part of this equation also, especially if a magnetised component lead is contained within that joint.
This sonic change occurs only once after a blanket resolder, and happens when the amp is pushed to momentary overload.
Eric.
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