It's in the Tapatalk settings.
Profile (funky hexagonal icon, lower right) -> Settings (gear icon, upper right) -> Settings -> Signature -> OFF
Tom
Sent from my MacBook Pro while enjoying a cup of coffee.
Thank-you sir, I haven't laughed that hard in far too long. Next time I'm in the UK I owe you a pint.
Soongsc, you stick to your guns. 100 years of acoustic research be dam**d. All that matters is your human ear.. or some close approximation thereof.
Those science guys can't even define gravity .. and we all know it exists. No wonder the electronic recreation of music and all of its attendant complexities defies a reasonably complete and accurate, objective description (all those silly numbers).
Rock on dude.
Stand up to the man!
sorry, can't find the sarcasm button.
I might be in trouble for this
Modulus-86: Composite amplifier achieving <0.0004 % THD+N.
No sweat. Pros and specialists are narrow minded and focused in a way that make them stand out. But alone, each are limited. People in physics find out about gravity, then you have a different set of people that apply the math integrate it with knowledge from other fields. I am all "ears" to what everyone might say.
Basically, audio technology evolved for the purpose of satisfying the listening experience, thow that goal out the door, you are only doing work to specifications, would be pretty boring. Hey but there are lots of people that deal mainly in numbers and contribute a lot to the world. Can't complain.
Thank-you sir, I haven't laughed that hard in far too long. Next time I'm in the UK I owe you a pint.
Soongsc, you stick to your guns. 100 years of acoustic research be dam**d. All that matters is your human ear.. or some close approximation thereof.
Those science guys can't even define gravity .. and we all know it exists. No wonder the electronic recreation of music and all of its attendant complexities defies a reasonably complete and accurate, objective description (all those silly numbers).
Rock on dude.
Stand up to the man!
sorry, can't find the sarcasm button.
I might be in trouble for this
No sweat. Pros and specialists are narrow minded and focused in a way that make them stand out. But alone, each are limited. People in physics find out about gravity, then you have a different set of people that apply the math integrate it with knowledge from other fields. I am all "ears" to what everyone might say.
Basically, audio technology evolved for the purpose of satisfying the listening experience, thow that goal out the door, you are only doing work to specifications, would be pretty boring. Hey but there are lots of people that deal mainly in numbers and contribute a lot to the world. Can't complain.
Last edited:
It's in the Tapatalk settings.
Profile (funky hexagonal icon, lower right) -> Settings (gear icon, upper right) -> Settings -> Signature -> OFF
Tom
Sent from my MacBook Pro while enjoying a cup of coffee.
Thanks, I did finally find it.
You know, it is a habit of mine to not respond to threads that meet two criteria.
1. Nothing interesting is being talked about.
2. People just do not respond to my posts.
So if people are just trying to attack me personally, they must want me around.
jojip,
no like or dislike is intended. He has posted a number of comments that have left me considering the psychological responses created through listening experiences. For this I offer my thanks. Unfortunately, the constant digressions into generalities, purely subjective unanswerable questions and uncorrelated generalities is creating a...muddle. These conversations may be more appropriate in the Lounge.
Tom has presented a remarkable achievement and I believe taking the time to have a thoughtful technical discussion highlighting its strengths and possible weaknesses is an appropriate compliment to the developer. Integrating the boards into a highly satisfying audio system looks like a good use of my limited time and resources. While I've always thought of perfection as "rarely achievable and seldom worth the effort", going for really, really good seems worthwhile.
Thank-you Tom.
no like or dislike is intended. He has posted a number of comments that have left me considering the psychological responses created through listening experiences. For this I offer my thanks. Unfortunately, the constant digressions into generalities, purely subjective unanswerable questions and uncorrelated generalities is creating a...muddle. These conversations may be more appropriate in the Lounge.
Tom has presented a remarkable achievement and I believe taking the time to have a thoughtful technical discussion highlighting its strengths and possible weaknesses is an appropriate compliment to the developer. Integrating the boards into a highly satisfying audio system looks like a good use of my limited time and resources. While I've always thought of perfection as "rarely achievable and seldom worth the effort", going for really, really good seems worthwhile.
Thank-you Tom.
Thanks guys. I appreciate the recognition for my efforts.
I've come to learn that the thread will drift in and out of topic. That's how forum threads work. I've positioned myself quite squarely as an objectivist, though I try to cater a bit to the subjectivist crowd by offering my listening experience. Sadly, however, sappy marketing verbiage is not my strong suit and many terms used to describe sound are ill-defined. I wish more subjectivists would take a look at the human cognitive aspects of the perception of sound before jumping to conclusions. Our senses are actually quite easy to fool. The phantom stereo image is a great example of this. Two sound sources with the appropriate phase delay between them can create the illusion of a sound stage. There is no sound being emitted from the space between the speakers. It's an auditory illusion. There are many others. On the same token, many objectivists tend to narrow in on one measurement, such as THD as the holy grail. That thinking does have some merit as low THD usually means high loop gain, high supply rejection, etc. but for sound quality IMD may actually provide better clues. There is an overwhelming body of evidence from actual double-blind listening trials involving a significant sample size (>250 individuals) that show a positive correlation between good measurements and good perceived sound quality, both for trained and untrained listeners. This is why I tend to rely on measurements. If I deliver an amp with good numbers across the board, people are more likely to like it.
So anyway. I don't mind the discussion. The name calling gets a bit much sometimes, though. I think toning that down would be in order.
Cheers.
Tom
I've come to learn that the thread will drift in and out of topic. That's how forum threads work. I've positioned myself quite squarely as an objectivist, though I try to cater a bit to the subjectivist crowd by offering my listening experience. Sadly, however, sappy marketing verbiage is not my strong suit and many terms used to describe sound are ill-defined. I wish more subjectivists would take a look at the human cognitive aspects of the perception of sound before jumping to conclusions. Our senses are actually quite easy to fool. The phantom stereo image is a great example of this. Two sound sources with the appropriate phase delay between them can create the illusion of a sound stage. There is no sound being emitted from the space between the speakers. It's an auditory illusion. There are many others. On the same token, many objectivists tend to narrow in on one measurement, such as THD as the holy grail. That thinking does have some merit as low THD usually means high loop gain, high supply rejection, etc. but for sound quality IMD may actually provide better clues. There is an overwhelming body of evidence from actual double-blind listening trials involving a significant sample size (>250 individuals) that show a positive correlation between good measurements and good perceived sound quality, both for trained and untrained listeners. This is why I tend to rely on measurements. If I deliver an amp with good numbers across the board, people are more likely to like it.
So anyway. I don't mind the discussion. The name calling gets a bit much sometimes, though. I think toning that down would be in order.
Cheers.
Tom
Pretty sure Newton discovered gravity and developed Newtonian mechanics from it all by himself. He even developed a from of calculus along the way to solve the problems although leibnitz was probably first independently.
Hi Tom,
Have you characterised the IMD performance? Maybe it's buried in this thread...
What do you think of Mr. Linkwitz's methods/ results?
[wiki=http://www.linkwitzlab.com/LX521/Supplies.htm#Amplifiers]%[/wiki]
Tom
I'm sure I've seen a two-tone spectrum earlier in the thread. Clicking on Tom's website in his sig, I see a numerical spec for IMD.
There's something messed up with your Linkwitz link - this should work:
LX521 Supplies
There's something messed up with your Linkwitz link - this should work:
LX521 Supplies
Sub LME49710 or equiv. for THAT1200?
Question: Just out of curiosity, since the major contributor "bottleneck" for THD performance of the Mod-86 is the THAT1200 (Balanced Line Receiver IC), would using another LME49710 (or, perhaps, the LM4562 which is equivalent to two LME49710 in one package to cover the composite amp integration and the differential measurement) allow you to improve on the THAT1200 imposed (tiny) distortion? Is there a reason this would be a bad/worse idea?
Such as the example circuit figure #85 from the LME49710 data sheet:
http://www.ti.com/lit/ds/symlink/lme49710.pdf#page=20
Boba
Question: Just out of curiosity, since the major contributor "bottleneck" for THD performance of the Mod-86 is the THAT1200 (Balanced Line Receiver IC), would using another LME49710 (or, perhaps, the LM4562 which is equivalent to two LME49710 in one package to cover the composite amp integration and the differential measurement) allow you to improve on the THAT1200 imposed (tiny) distortion? Is there a reason this would be a bad/worse idea?
Such as the example circuit figure #85 from the LME49710 data sheet:
http://www.ti.com/lit/ds/symlink/lme49710.pdf#page=20
Boba
I'm a bit surprised by his choice of frequencies. Typically, 60 Hz + 7 kHz is used for supply-related IMD characterization. An 18 kHz + 19 kHz test would likely reveal more about the loop gain roll-off and associated sonic signature.
I'll see if I can dig out the plot of Modulus-86 R2.0 and Parallel-86. Meanwhile, the plots for Modulus-86 R1.0 can be found in Post #250.
Tom
I'm interested in seeing Tom's answer, but I think I can answer this.
I see that figure 85 is a single opamp with the usual four-equal-resistors differential input schematic. This is the "crudest" balanced input circuit. It may look fine at first glance, but...
Notice that the input impedance at V1 is 2r, as it has two series R's to ground (and the positive input has theoretically infinite impedance). The input impedance at V2 is R, as we have an input R to the negative input, and the R between that input and the output provides negative feedback and makes the negative input a virtual ground, so the impedance V2 sees is only R.
This works fine if both inputs have zero (or very low) output impedance, which is only sometimes the case. Even when they're equal and not zero, they wlll add to the different impedances seen at V1 and V2, and thus have different currents, and the resulting voltages at V1 and V2 will be different for a common-mode input, and greatly reduce the CMRR.
What would be much better is the "instrumentation amp" circuit, but it takes three opamps. The input impedance of it is very high, making the impedance(s) of the driving circuit mostly irrelevant to whether the voltages will be balanced or not.
The THAT chip goes a step further, and its equivalent circuit has FOUR opamps, as can be seen at the datasheet link on this page:
THAT Corporation 1200-series InGenius High-CMRR Balanced Line Receiver ICs
It uses bootstrapping to make the common-mode impedance much higher than the differential impedance, and the datasheet and THAT's website describes the advantages.
Recreating the THAT chip would also take several closely matched resistors, which costs either time (if you do it) or money (if someone else does it). There's also patents involved. You can make one (or even two for stereo) of these for your own personal use, but if you're selling several of these commercially like Tom is, you need to negotiate royalty payments on the patent (or risk being sued) and pay so much for each circuit you make.
And before doing that, I'd want to make a prototype and see if anyone could really tell the difference between a "discrete" super-low-distortion balanced input solution and the THAT 1200. But I wonder if the THAT chip's contribution to distortion is really audible to anyone at all. Perhaps there's someone who can hear the difference, but I'm doubting the design, manufacturing work, and extra cost of parts would be worth it for what would be a very small market.