I used primarily the HD-580 for about seven years, until I switched to Stax electrostatic headphones (Omega 3, that cost about $5000). The 580 were around $250 when I bought them new on eBay and one could probably find them now for $200. Over this time period I auditioned several dozen headphones (I don't have speakers as I move frequently) and in the under $250 range there's nothing that compares. It's a sort of a sweet spot. Anything above that price point is an incremental improvement; most things below are a significant degradation. Even the $5K Stax are not that greatly better (but hey, felt good to buy myself a little present, and it was an excuse to build a high voltage hybrid solid state/tube headphone amp instead of plunking another $5K after one... http://gilmore.chem.northwestern.edu/bluehawaii_moda1.png )
In talks with Hungarian friends, some of which still live there, they seem keenly aware of the poor image their country has in the eyes of the rest of the world. It's a country best known for giving the origins to history's most prolific serial killer, Elizabeth Bathory (killed ~600 young girls with torture methods that make the Spanish Inquisition look like amateur hour), and for being the de facto porn capital of Europe. Worse, the attempts of Hungarians to whitewash haven't made things much better, yet they persist. For example, last year there was quite a bit of drama on the Wikipedia page for the countess, with Hungarians trying to sanitize the Bathory article of some of the more gruesome details and putting in claims that the evidence against her was hear-say and/or politically motivated (veritably and verifiably false, as there were plenty of well-documented witnesses). When this didn't work out and much of the dishonest editing was undone (though I've still been unable to fully restore the article), they tried to shift the blame for the edit attempts on feminists. Which might have been convincing, had I not hang around Hungarian IRC channels in one of which the whole whitewash campaign was discussed.
>the shear number
In the stress tensor, the shear is represented by two components, so there cannot be a shear number.
On the other hand, if you meant sheer, then it makes one wonder in which portion of the curve you write about you are... unless this curve is so "skewed in the wrong direction", to use your words, that it got sheared...
It would be interesting to see if the human expansion into space eventually ushers in further extension of the extremes of inequality, with the first trillionaires (as measured in today's currency, adjusted for inflation) being, say, asteroid mining tycoons. I don't yet have much of an opinion here; I'm more interested on reading others' thoughts on this.
What the hell are you talking about? Many tubes have multiple gain devices within the same envelope. I remember building a hybrid tube/MOSFET headphone amp a couple of years ago using a single 6DJ8, which has two triodes in it. There's no doubt the motherboard in question only used the tube for VAS and not as an output stage, so there's no reason to use a push-pull configuration.
Weird, slashdot cut off parts in the middle of my post....
"and THD" should be ..and THD is <0.1% and mostly 2nd order, caused by the single-ended nature of operation.
"microhollow cathode discharges: sandwich a" should be ...microhollow cathode discharges: sandwich an insulator between two conductors, all <1 mm thick, drill a <1mm hole, apply few hundred volts, and you get a stable glow discharge that itself can serve as a compound cathode for a bigger discharge to a third electrode, since it removes the high voltage gradient near the cathode which causes instabilities promoting glow-to-arc transition. I platinum-plated tungsten pieces (Pt wire from eBay jeweller, distilled nitric acid from sulfuric+nitrate, dash of lead acetate) then baked in an evacuated quartz glass tube in DIY kiln so the Pt diffuses into the surface of the tungsten (else it will just flake off). For the insulator layer, I got 1 mm sapphire wafer as a free sample from an optics company. Drilling was a pain--diamond bit on the Dremel and still took a while. Put third electrode--a nail, a couple cm from the sandwich. 2700-2800 V from the bottom plate electrode to the nail, a resistor chain from the nail to the middle electrode (top plate of sandwitch). The first discharge formed in the hole right away and then jumped to the nail as a big discharge. If you blow out the big discharge, it reignites in the same sequence, it was great. With around 200-250 mA going through, I could stretch it to as much as 5 cm; could be more if one blows air through the microhollow. To modulate with sound, I used a transmitter power tetrode tube, one of those metal/ceramic with forced air cooling (used a server blower fan for that). Put the tube in series with the discharge, ran as voltage-controlled current sink. Worked. Then I dropped a screwdriver into the exposed _linear_ power supply I had built, and it shorted filter capacitors (transformer->
I have one more thought on this: think of how much low level distortion is masked by how crappy speakers are in general. I think many blind tests will have to be revisited when we have truly low distortion speakers. Even electrostatic headphones are not that great. Then there's the French ionic headphones http://membres.multimania.fr/plasmapropulsion/Industrial_issues/Plasmasonic.htm but the bastards didn't measure distortion so one can only guess.
The best performing I've seen is glow discharge plasma. On Google patents you can check US 4,219,705. He used helium to create stable glow discharge (in air, glow discharge is very unstable and inevitably transitions to an arc) and then shaped it in such a way as to get a flat frequency response. Photo: http://3.bp.blogspot.com/_tb6Dp4NFH5w/SxWU_QWONKI/AAAAAAAAAnk/IgXp5VMkZlk/s1600/Plasmacell1.jpg Unfortunately, around 330 Watts in the discharge alone and only above 500 Hz (regular cone speaker for below 500) and you have to refill helium tank at welding shop periodically... But look at waterfall and impulse response: http://tinyurl.com/7d6pdnv and http://tinyurl.com/7xfppsz and THD
I decided to build this without helium. I realized I could do it once I came across microhollow cathode discharges: sandwitch a CRCLC->regulator). 135 uF total at around 3000 V is about 600 Joules or about twice a defibrillator.
One of the huge film-in-oil caps leaked (so much for "designed for pulse discharge") and the oil caught on fire and I was so startled by the mini-explosion that I broke the complex electrode structure. Haven't returned to this project yet, but I think there's something to this approach. There was also virtually no ozone (unlike the usual corona discharge speakers people drive with RF), but UV is definitely an issue to overcome.
Well, human hearing, not including intensity levels beyond threshold of pain, covers 120 dB. Moreover, narrowband signals are perceptible when several dB _below_ broadband noise. This makes me say that audio is not quite a solved problem even on the electronics side (let alone on the speakers side). Various things seem to pop up, and not just from crazed audiophiles. Recently I was reading how it turned out that some amplifiers who were specced at very low THD only made that measurement at moderate signal levels, and had very large distortion for low signals (one ironic example was the hugely overpriced Halcro amplifiers). The thermal memory issue may be another thing.
I did an informal ABC/HR test a year and a half ago with four people, which was blind but not doubleblind as the switching was done by telling another person to switch. It was with the DAC I mentioned. I had two IV's which I could switch in after the DAC using a small relay. One was using the AD797. The other one was derived from Hawksford's discrete current feedback IV (figure 4-4 in http://www.essex.ac.uk/csee/research/audio_lab/malcolmspubdocs/C111%20Current%20steering%20transimpedance%20amplifier.pdf ). To get the distortion of the Hawksford IV near -120 dB (checked with rented distortion analyzer), we added extra gain so we could use more feedback. For testing, we tested each person one at a time using Stax electrostatic headphones fed by this hybrid transistor/tube amp, which is about 5 ppm THD: http://gilmore2.chem.northwestern.edu/images5/gilmore4_1.png
We did eight trials for each person. One couldn't tell the reference (5/8). The other three could tell it (averaging 7/8).
Did another test. There were two of the Hawksford IV per channel, set up as differential since the DAC and the amp were both balanced. Connecting the emitters of the current mirror transistors between the two separate IVs dropped the differential output 3rd and 4th harmonics further (slightly raised 2nd for single ended operation) (I'm pretty sure this infringes on a Nelson Pass patent...). I used a relay for that as well, and did the test switching that connection on and off. Two people could tell the difference (averaging 6.5/8).
Small sample size, not double blind, and ultimately anecdotal. Nonetheless it was sufficient to convince me that the audio hobby has more mysteries to reveal than seems at first.
So where along the spectrum does something like this fall? http://www.aes.org/e-lib/browse.cfm?elib=7497
At first hand it seems implausible that something like this will matter. It doesn't show up in standard THD measurements (though it does show up in Hawksford-style pseudorandom filtered noise measurements). Yet later a few things came out: 1) it's a rediscovery of an effect that was initially confirmed decades ago in tube circuits (though the time constant in tubes is much bigger, far below concern audio frequency), 2) other people measured it, and 3) people built amplifiers that minimize the effect by minimizing variation in power dissipated across the primary gain devices (for example http://peufeu.free.fr/audio/memory/img/complete-schem-1.gif ). In discrete circuits it's not likely to be audible, but one wonders if it might be audible in ICs, especially given the tight thermal coupling between sensitive input stage and high power output stage in the same package. Given this, though we don't know, a perceptible effect to some ears is at least plausible. Just because no one has performed an ABC/HR test to confirm it doesn't mean we should dismiss it.
I guess my point is that it's too easy to make an error when seeing an "interesting idea and no data" and dismissing it. A cursory examination and making a quick call on whether a perceptible effect is audible is bound to lead to sometimes throwing out a baby or two with the bathwater.
I just checked the datasheet and you're right.
Well that's disappointing. It's no better than what I had four years ago when I took four AD1955 and did some analog of dynamic element matching using a Sharc DSP.
Why do you get that impression about them? I've never seen such a scathing attack on the AES before.
I'm skeptical as the only other time I've seen such an attitude against a professional society is when a colleague was dissing the ACM after his paper got rejected by SIGGRAPH.
Slashdot Mirror
I used primarily the HD-580 for about seven years, until I switched to Stax electrostatic headphones (Omega 3, that cost about $5000). The 580 were around $250 when I bought them new on eBay and one could probably find them now for $200. Over this time period I auditioned several dozen headphones (I don't have speakers as I move frequently) and in the under $250 range there's nothing that compares. It's a sort of a sweet spot. Anything above that price point is an incremental improvement; most things below are a significant degradation. Even the $5K Stax are not that greatly better (but hey, felt good to buy myself a little present, and it was an excuse to build a high voltage hybrid solid state/tube headphone amp instead of plunking another $5K after one... http://gilmore.chem.northwestern.edu/bluehawaii_moda1.png )
The lower end Etymotic earbuds are also around $100 and much better than the Bose.
I have multiple experience with them and back up GP's post.
> they can also prosecute a husband who has a picture of his wife's tits if his wife is, or looks, under 18.
Citation needed.
In talks with Hungarian friends, some of which still live there, they seem keenly aware of the poor image their country has in the eyes of the rest of the world. It's a country best known for giving the origins to history's most prolific serial killer, Elizabeth Bathory (killed ~600 young girls with torture methods that make the Spanish Inquisition look like amateur hour), and for being the de facto porn capital of Europe. Worse, the attempts of Hungarians to whitewash haven't made things much better, yet they persist. For example, last year there was quite a bit of drama on the Wikipedia page for the countess, with Hungarians trying to sanitize the Bathory article of some of the more gruesome details and putting in claims that the evidence against her was hear-say and/or politically motivated (veritably and verifiably false, as there were plenty of well-documented witnesses). When this didn't work out and much of the dishonest editing was undone (though I've still been unable to fully restore the article), they tried to shift the blame for the edit attempts on feminists. Which might have been convincing, had I not hang around Hungarian IRC channels in one of which the whole whitewash campaign was discussed.
Did you RTFA? This is about Luddites vs scientists, not democracy vs the, as your brand of Newspeak goes, "1%".
What? They have the best optimizing C++ compiler, and a slate of very high performance computational libraries.
It was one of the best games for the original Playstation.
>the shear number
In the stress tensor, the shear is represented by two components, so there cannot be a shear number.
On the other hand, if you meant sheer, then it makes one wonder in which portion of the curve you write about you are... unless this curve is so "skewed in the wrong direction", to use your words, that it got sheared...
They don't need the MPAA's money, as they can get free money from the European Central Bank.
It would be interesting to see if the human expansion into space eventually ushers in further extension of the extremes of inequality, with the first trillionaires (as measured in today's currency, adjusted for inflation) being, say, asteroid mining tycoons. I don't yet have much of an opinion here; I'm more interested on reading others' thoughts on this.
Would someone be kind enough to post a link to the paper or at least its name?
To all the cretinous imbeciles suggesting this is a way to avoid taxes, you better stop misleading the rest of slashdot readers: http://www.irs.gov/businesses/small/article/0,,id=187920,00.html
Are you retarded? Barter is taxable, and if you don't pay tax on barter, you're breaking the law just as much as if you avoid it for monetary income. http://www.irs.gov/businesses/small/article/0,,id=187920,00.html
No tax, you say? Barter is taxable, just like anything else, and if you're not paying tax on items you barter, you're carrying out a criminal offense. http://www.irs.gov/businesses/small/article/0,,id=187920,00.html
You're either a troll or an idiot--barter is taxable, just like any other transaction: http://www.irs.gov/businesses/small/article/0,,id=187920,00.html
Uh, income from barter is taxable, so get off your high horse. http://www.irs.gov/businesses/small/article/0,,id=187920,00.html
What the hell are you talking about? Many tubes have multiple gain devices within the same envelope. I remember building a hybrid tube/MOSFET headphone amp a couple of years ago using a single 6DJ8, which has two triodes in it. There's no doubt the motherboard in question only used the tube for VAS and not as an output stage, so there's no reason to use a push-pull configuration.
Weird, slashdot cut off parts in the middle of my post....
..and THD is <0.1% and mostly 2nd order, caused by the single-ended nature of operation.
...microhollow cathode discharges: sandwich an insulator between two conductors, all <1 mm thick, drill a <1mm hole, apply few hundred volts, and you get a stable glow discharge that itself can serve as a compound cathode for a bigger discharge to a third electrode, since it removes the high voltage gradient near the cathode which causes instabilities promoting glow-to-arc transition. I platinum-plated tungsten pieces (Pt wire from eBay jeweller, distilled nitric acid from sulfuric+nitrate, dash of lead acetate) then baked in an evacuated quartz glass tube in DIY kiln so the Pt diffuses into the surface of the tungsten (else it will just flake off). For the insulator layer, I got 1 mm sapphire wafer as a free sample from an optics company. Drilling was a pain--diamond bit on the Dremel and still took a while. Put third electrode--a nail, a couple cm from the sandwich. 2700-2800 V from the bottom plate electrode to the nail, a resistor chain from the nail to the middle electrode (top plate of sandwitch). The first discharge formed in the hole right away and then jumped to the nail as a big discharge. If you blow out the big discharge, it reignites in the same sequence, it was great. With around 200-250 mA going through, I could stretch it to as much as 5 cm; could be more if one blows air through the microhollow. To modulate with sound, I used a transmitter power tetrode tube, one of those metal/ceramic with forced air cooling (used a server blower fan for that). Put the tube in series with the discharge, ran as voltage-controlled current sink. Worked. Then I dropped a screwdriver into the exposed _linear_ power supply I had built, and it shorted filter capacitors (transformer->
"and THD" should be
"microhollow cathode discharges: sandwich a" should be
I have one more thought on this: think of how much low level distortion is masked by how crappy speakers are in general. I think many blind tests will have to be revisited when we have truly low distortion speakers. Even electrostatic headphones are not that great. Then there's the French ionic headphones http://membres.multimania.fr/plasmapropulsion/Industrial_issues/Plasmasonic.htm but the bastards didn't measure distortion so one can only guess.
The best performing I've seen is glow discharge plasma. On Google patents you can check US 4,219,705. He used helium to create stable glow discharge (in air, glow discharge is very unstable and inevitably transitions to an arc) and then shaped it in such a way as to get a flat frequency response. Photo: http://3.bp.blogspot.com/_tb6Dp4NFH5w/SxWU_QWONKI/AAAAAAAAAnk/IgXp5VMkZlk/s1600/Plasmacell1.jpg Unfortunately, around 330 Watts in the discharge alone and only above 500 Hz (regular cone speaker for below 500) and you have to refill helium tank at welding shop periodically... But look at waterfall and impulse response: http://tinyurl.com/7d6pdnv and http://tinyurl.com/7xfppsz and THD
I decided to build this without helium. I realized I could do it once I came across microhollow cathode discharges: sandwitch a CRCLC->regulator). 135 uF total at around 3000 V is about 600 Joules or about twice a defibrillator.
One of the huge film-in-oil caps leaked (so much for "designed for pulse discharge") and the oil caught on fire and I was so startled by the mini-explosion that I broke the complex electrode structure. Haven't returned to this project yet, but I think there's something to this approach. There was also virtually no ozone (unlike the usual corona discharge speakers people drive with RF), but UV is definitely an issue to overcome.
Well, human hearing, not including intensity levels beyond threshold of pain, covers 120 dB. Moreover, narrowband signals are perceptible when several dB _below_ broadband noise. This makes me say that audio is not quite a solved problem even on the electronics side (let alone on the speakers side). Various things seem to pop up, and not just from crazed audiophiles. Recently I was reading how it turned out that some amplifiers who were specced at very low THD only made that measurement at moderate signal levels, and had very large distortion for low signals (one ironic example was the hugely overpriced Halcro amplifiers). The thermal memory issue may be another thing.
I did an informal ABC/HR test a year and a half ago with four people, which was blind but not doubleblind as the switching was done by telling another person to switch. It was with the DAC I mentioned. I had two IV's which I could switch in after the DAC using a small relay. One was using the AD797. The other one was derived from Hawksford's discrete current feedback IV (figure 4-4 in http://www.essex.ac.uk/csee/research/audio_lab/malcolmspubdocs/C111%20Current%20steering%20transimpedance%20amplifier.pdf ). To get the distortion of the Hawksford IV near -120 dB (checked with rented distortion analyzer), we added extra gain so we could use more feedback. For testing, we tested each person one at a time using Stax electrostatic headphones fed by this hybrid transistor/tube amp, which is about 5 ppm THD: http://gilmore2.chem.northwestern.edu/images5/gilmore4_1.png
We did eight trials for each person. One couldn't tell the reference (5/8). The other three could tell it (averaging 7/8).
Did another test. There were two of the Hawksford IV per channel, set up as differential since the DAC and the amp were both balanced. Connecting the emitters of the current mirror transistors between the two separate IVs dropped the differential output 3rd and 4th harmonics further (slightly raised 2nd for single ended operation) (I'm pretty sure this infringes on a Nelson Pass patent...). I used a relay for that as well, and did the test switching that connection on and off. Two people could tell the difference (averaging 6.5/8).
Small sample size, not double blind, and ultimately anecdotal. Nonetheless it was sufficient to convince me that the audio hobby has more mysteries to reveal than seems at first.
Oops, meant to write "whether a perceptible effect is plausible" not audible...
So where along the spectrum does something like this fall? http://www.aes.org/e-lib/browse.cfm?elib=7497
At first hand it seems implausible that something like this will matter. It doesn't show up in standard THD measurements (though it does show up in Hawksford-style pseudorandom filtered noise measurements). Yet later a few things came out: 1) it's a rediscovery of an effect that was initially confirmed decades ago in tube circuits (though the time constant in tubes is much bigger, far below concern audio frequency), 2) other people measured it, and 3) people built amplifiers that minimize the effect by minimizing variation in power dissipated across the primary gain devices (for example http://peufeu.free.fr/audio/memory/img/complete-schem-1.gif ). In discrete circuits it's not likely to be audible, but one wonders if it might be audible in ICs, especially given the tight thermal coupling between sensitive input stage and high power output stage in the same package. Given this, though we don't know, a perceptible effect to some ears is at least plausible. Just because no one has performed an ABC/HR test to confirm it doesn't mean we should dismiss it.
I guess my point is that it's too easy to make an error when seeing an "interesting idea and no data" and dismissing it. A cursory examination and making a quick call on whether a perceptible effect is audible is bound to lead to sometimes throwing out a baby or two with the bathwater.
I just checked the datasheet and you're right.
Well that's disappointing. It's no better than what I had four years ago when I took four AD1955 and did some analog of dynamic element matching using a Sharc DSP.
Why do you get that impression about them? I've never seen such a scathing attack on the AES before.
I'm skeptical as the only other time I've seen such an attitude against a professional society is when a colleague was dissing the ACM after his paper got rejected by SIGGRAPH.