Escape Velocity

Escape Velocity is commonly described as the minimum speed an object must reach to escape the Earth (or other celestial body) into space. But this definition is ambiguous and can be misleading.

You can escape the Earth at walking speed, if you could walk straight up; you don’t need anywhere near escape velocity. Imagine a rocket launch; in the first few seconds just as it starts to move, it’s going up at walking speed. Theoretically, it could throttle back the engines to maintain that slight upward speed all the way into space, so long as it didn’t run out of fuel or become unstable. A space elevator could also leave Earth at mundane speeds.

The key to this ambiguity is escape velocity applies to a free body, an object that is passively moving according to the laws of physics, having no thrust of its own. In other words, if a rocket achieves escape velocity, it could at that point turn off its engines and it would still escape the Earth. Intuitively it seems the higher the altitude, the slower the escape velocity. This turns out to be correct.

Escape velocity is easy to understand and derive mathematically with some creative thinking. Imagine 2 objects in space (a big one and a much smaller one, like the Earth and a stone) surrounded by vacuum, no other objects. So there is no friction and no other bodies exerting gravitational pull. Suppose the stone is at rest relative to the Earth and almost infinitely far away. The gravitational pull is effectively zero. Imagine the stone precariously balanced just on the outer rim of Earth’s gravity well. Then you nudge the stone just a smidge toward the Earth, so it crosses that rim and the Earth starts pulling on it (and vice versa). It starts out slow, but accelerates toward the Earth incrementally faster and faster.

Eventually, when the stone reaches the Earth it will be moving very fast. Escape velocity is the speed it is going just before it smashes into the Earth. Or if it misses the Earth, it’s the speed at its point of closest approach. More correctly and completely, the stone is always traveling at escape velocity at every moment along its path. The escape velocity for that distance from the Earth, is the speed at which the stone is moving when it’s that far away.

Note: the bold face statement above is the nut of this explanation. When you grok its fullness, you grok the fullness of escape velocity.

That’s because of conservation of energy. When the stone was at the rim of Earth’s gravity well, it had a lot of potential energy. At the point of closest approach, all that potential energy has been converted into kinetic energy. Assuming no atmosphere, no losses, the two energies are equal. So as the stone speeds past the Earth, slowing down due to the same gravitational pull that sucked it in, that kinetic energy is converted back into potential energy. So it must reach the exact same distance away when it peters out and eventually stops.

The direction of motion is irrelevant to escape velocity. Normally this seems counterintuitive, but understanding escape velocity with our theoretical example, you can easily see why direction doesn’t matter. At that point of closest approach, it doesn’t matter what direction the stone is moving relative to the Earth. It could be nearly straight up (can’t be exactly straight up, or it wouldn’t have missed), or nearly horizontal. If it’s going horizontal, it has to travel further to escape, but being horizontal, gravity isn’t pulling it as hard. These conflicting factors are equal and cancel each other. All that matters is the altitude (distance of closest approach), because the speed depends only how much energy it’s gained from Earth’s gravity field.

If, at that point of closest approach, the stone were moving any slower, then it would have less kinetic energy, and it will not go as far away. That means it won’t make it to the rim of Earth’s gravity well, so it will still be inside the well, reverse direction and eventually come back to Earth. So escape velocity is the minimum speed a free body can have, and escape the Earth.

Of course, in the real world direction does matter. The Earth has an atmosphere that creates a lot of friction and energy loss at high speeds. If you go straight up, you’re in the atmosphere for a shorter time, less energy loss. If you go horizontal, you’re in the atmosphere longer and will lose more energy.

Here is the mathematical derivation:

escapeVelocity

Gun Culture: NYT Op-Ed

Today the NYT published an Op-Ed by David Joy. I enjoyed reading it and share some of his observations. About 3/4 of the way through he suggests an AR-15 is somehow different from other rifles in the store, saying, “the idea of owning a rifle designed for engaging human targets out to 600 meters just never interested me.” He asks a friend why he owns an AR-15 and is unsatisfied with his friend’s response. Here is mine.

First, David’s belief that the AR-15 is somehow different from other rifles in the store, is not justified by the facts.  The AR-15 is a semi-automatic .223 caliber rifle. It is less powerful than most common .30 caliber rifles, like the Savage .308 David uses to hunt deer. These more powerful semi-auto rifles are just as accurate, often have longer range and are commonly used for sport, hunting and self defense.

Second, David mis-characterizes the AR-15 when he describes it as “a rifle designed for engaging human targets out to 600 meters”. For engaging human targets out to 600 meters, look at what military snipers use. They use a rifle that is more powerful, more accurate, and has longer range than an AR-15. This rifle is the M-24, which is a .30 caliber bolt action Remington Model 700 with a 5 round capacity, the same kind of rifle your Grandpa carried through woods, still carried by thousands of hunters across the USA. Later, Army snipers switched to the M2010, which is another .30 caliber bolt action rifle with a 5 round magazine.

In short, according to the US Army, a rifle like David’s Savage .308 is more effective than an AR-15 at “engaging human targets out to 600 meters”. But that’s not a fair comparison; the Army doesn’t even use the AR-15.

People who don’t know much about guns believe, incorrectly, that the AR-15 is a military rifle. They believe this primarily for cosmetic reasons. Instead of steel and wood, it is black with lots of plastic and resembles the M-16 that US soldiers carry. Yet it is unusual to see an experienced gun owner like David make this mistake. The military M-16 is not an AR-15. The M-16 can fire in full automatic mode (a machine gun) which has been strictly regulated since 1934. The AR-15 fires one bullet each time you pull the trigger.

So when David says, “My friends see no difference between the guns I own and their ARs,” this should come as no surprise. The only material difference is magazine capacity.

To David’s final point, there are several good reasons to oppose an assault-weapons ban.

  1. The term “assault weapon” is pure fiction. They’re not machine guns; those have already been virtually banned since 1934. The guns named as “assault weapons” are based mainly on cosmetic features; they’re not functionally different from common sporting and hunting rifles.
  2. The AR-15 magazine holds 30 rounds. This is more than most other rifles in common use and makes it the only functional difference between the AR-15 and these other rifles. It is worth debating whether restricting such high capacity magazines might reduce crime or improve public safety. Yet our country has already had this debate, and more; see below.
  3. The Federal Govt banned “assault weapons” for 10 years, from 1994 to 2004. This included a ban on magazines in any firearm holding more than 10 rounds. Serious academics (such as the National Academy of Sciences) and the Dept. of Justice comprehensively studied the law and found it had no effect on crime, accidents, suicide or public safety.

In short, an assault weapons ban has already been tried, studied, and found to be ineffective. And the reason why is obvious: true “assault weapons” — machine guns — are already banned and have been since 1934.

Note: I don’t own an AR-15 simply because I find other guns to be more useful for sport, hunting or self defense. However, having used one, I don’t believe there is anything about it that makes it more dangerous than other rifles in common use today. I don’t see the AR-15 as a sign of a rift in gun attitudes or culture. The gun owners I know are responsible citizens, whatever kind of rifles they prefer.

Back to the HD-580 – For a While

My Audeze LCD-2 fell off my desk at work and got pranged so they’re going back to Audeze for repair and, incidentally, upgrade to the 2016 drivers. My home pair has  these drivers and they are a subtle improvement over the 2014.

In the meantime, I’m listening to my trusty old HD-580s. Original 18 year old drivers, though I’ve replaced the headband and ear pads, and the cable, a few times over the years. They’re clean and play, fit and look like new.

First impression: these HD-580s are nice headphones! Smooth mids, nice timbres, well balanced. They really were the very first audiophile headphone, SOTA for 1999, a whole different league apart from Grados and the like. But compared to the Audeze:

  • The low bass is rolled off
  • The bass is not as tight
  • The mids are a tad boxy, not as open sounding
  • The high treble is rolled off

Overall, they sound a tad muffled and slow compared to the LCD-2. Conversely, the LCD-2 has:

  • Wider bandwidth: deeper bass, higher treble
  • Better detail & articulation throughout the range
  • More natural, realistic voicing

A gentle parametric EQ helps widen the HD-580’s apparent bandwidth:

  • +3 @ 25 Hz, Q=0.67
  • +3 @ 14 kHz, Q=1.5

I’m enjoying this trip down memory lane. I listened to these same HD-580s during most of the 10,000 hours I put into Octane Software back in the day. They sound nice, but I will be very happy to get my Audeze back.

Audio History

I loved music and was fascinated with audio electronics since I was a little kid. Later I became interested in the physics of sound.

I bought my first audio component in the 1980s in college, a Harman Kardon integrated amplifier. It was simple and cheap, had no tuner, only 40 WPC output, but it did have a phono amp (MM only) and decent gain stage. To find good speakers, my friend Shawn and I visited the local audio store and listened to several different speakers (Klipsch, Polk, and a few others) with a variety of music. We both liked the Polk 10Bs best. They had the smoothest least colored sound for my limited budget. My musical taste at the time was about half classical, half rock.

Back in those days digital audio and headphones were not an audiophile option. Good headphones simply didn’t exist and digital audio was so new, consumer CD players were expensive and tended to have poor reproduction of high frequencies and transient response. Because of this, there were no good cheap paths to high quality sound, like we have today.

I didn’t have a turntable, they were too expensive. But I did get a good CD player, an Onkyo DX-530 which was one of the first CD players to use oversampling, which improved the high frequency and transient response by enabling more gradual slope Nyquist filters.

This little system lasted me through college with many hours of satisfying listening. Then, my junior year in college, the local audio store went out of business and I got their used demo pair of Polk SDA-2 speakers. This was a big upgrade from the 10Bs, and the price was so good it was almost an even trade when I sold the 10Bs.

After graduating from college I was ready for a decent turntable. I visited the local audio store and auditioned a couple of different turntables & cartridges for several hours, picking a Thorens TD-318 MK II with an Ortofon MC-3 high output MC. That was in 1991. That HK integrated amp only had a low-gain MM phono amp, and my budget didn’t allow for a low ouput MC. The high output MC was a little on the bright side, but it had the smoothest, least colored sound compared to the MMs.

This little system lasted me for several years, until around 1995 I got a new job and promotion and my budget was ready for an upgrade. I auditioned a couple of different power amps and pre amps at the local audio store and ended up taking home an Adcom 5800 power amp with a Rotel RC-990BX pre amp, which had a dual-stage phono amp, so I could now try low output MC phono cartridges. And I had enough power to fully drive those Polk SDA-2 speakers.

At this time, digital was improving but to my ears, good vinyl still had more natural sounding high frequencies and transient response. But only good vinyl – like heavy 280-220 gram pressings, half-speed masters, etc. I started collecting MoFi half-speed masters, Cheskys, Audioquest, Telefunken, Wilson Audio, Classic, Water Lily, and other audiophile vinyl. I didn’t have the budget for much, so I carefully selected and treasured each new addition to the collection.

In the late 90s I replaced my Onkyo DX-530 with a Rega Planet CD player. I read so many good things about it, I thought it must be great. I never really got into this CD player, I think the old Onkyo was actually better. The Rega had a distinct sound that grabbed one’s attention at first. But upon further listening it was to my ears, congested and the high frequencies were all wrong. I ended up selling the Rega about a year later. It was so popular, it was easy to sell. I replaced it with a Rotel RCD-1070. Nothing special, but a solid well engineered good sounding player.

Fast forward a few years to 2000, when I sold my first startup (Octane software) and was ready for another audio upgrade. I already had reference quality amplification so this time it was the speakers. I visited the local audio store with my best albums and spent all day listening to every fine speaker system they had. I also did a bunch of research in audiophile channels. I ended up picking Magnepan 3.6/R speakers, as they had the most natural, linear, uncolored midrange and treble of any speaker I listened to. The Adcom 5800 had plenty of power with enough refined clarity to make these excellent speakers really sing.

About a year later I designed and built my own ladder stepped attenuator to replace the preamp. This added a level of clarity and transparency to the system — no active preamp is cleaner than a single metal film resistor in the signal path! And I learned a little about analog audio circuits, grounding and soldering. Now I didn’t have a phono amp anymore. I did a bunch of research and picked up a DACT CT100, which is an excellent reference quality flexible phono amp, but just a circuit card. I designed and built a power supply for it (dual 12V batteries), with a small chassis, cabling & grounding & connectors. I was delighted with the sound, a noticeable upgrade from the Rotel pre amp’s phono amp, which was quite good to begin with.

This new level of transparency revealed the limitations of the Rotel CD player so I looked for alternatives, knowing that DACs were constantly improving. I ended up with another Onkyo, a DX-7555. It had a more refined sound with more natural midrange voicing.

After we moved from Orcas Island to Seattle my listening room changed. I used test tones, microphones and measurements to tune my new audio room. I built floor-to-ceiling height 22″ diameter tube traps for the rear corners, RPG acoustic foam 4 layers thick strategically located on the wall behind the listener, careful room and speaker arrangement, and ended up with a great sounding room that was within 4 dB of flat from 40 Hz to 20 kHz. It wasn’t perfect though. There was a small rise in the mids around 1 kHz, likely inherent to the Mag 3.6 speakers, and the lowest bass octave was from 6 to 12 dB down. Notwithstanding these limitations, it was a great sounding room.

I kept this system for about 10 years, from 2005 to around 2015. Then I replaced the ladder stepped attenuator with an Oppo HA-1 DAC, using the digital outputs from my source components. And I got a Behringer DEQ 2496 and used its pure digital parametric EQ to tame the 1 kHz bump and lift the bottom bass octave. This put the in-room system response within 3 dB of flat from 30 Hz to 20 kHz, which is comparable to a good recording studio. The sound is fantastically natural: detailed yet smooth and not bright, bass is deep, yet controlled and fast, natural voicing through the mids with seamless transition to high frequencies.

Finally, in Jan 2018 I sold my turntable, vinyl, and related analog equipment. I just wasn’t using it anymore, since I had all those recordings on digital, and the sound quality of digital had improved so much, while great LPs do sound great, I no longer felt that they sounded any better than great digital.

Mike’s Best Vinyl LP Records

UPDATE: Mar 2018: These are all sold!

As I’m liquidating my vinyl and playback equipment, I’ve sorted through all my LPs and found about 100 of them to be half-speed masters, heavy vinyl, 45 RPM single sided, Japanese Press, Mobile Fidelity, Chesky, Wilson Audio, Telefunken limited edition pressings, or other such. Many are out of print, all are in mint condition – no scratches, cleaned with the Nitty Gritty 2.5FI, played only on properly aligned high end equipment.

I’ve got a few hundred more LPs not shown in this list, many of which are nice, but they’re standard quality. I’ll probably sell them in bulk for $1 each somewhere.

Here’s the list of my best LPs. Items already sold are highlighted in RED: lpListHighQuality-1712

Vinyl LP Cleaning Solution Recipe

I covered this topic about 10 years ago, offering a recipe for fluid to clean vinyl LPs. I still use that recipe in my Nitty Gritty; here’s a summary and a few more tips.

It has 3 ingredients, one of which is optional:

  • Distilled Water
  • Isopropyl Alcohol
  • Wetting Agent (optional)

Most wetting agents are soaps which contain fragrances and other non-essential ingredients that you don’t want polluting your record cleaning fluid. I’ve stopped using the wetting agent and it still works just fine. If you use a wetting agent, all it takes is a couple of drops for a small batch.

Alcohol is a solvent that may degrade the seals of record cleaning machines. To avoid damaging the machine, keep the alcohol below 20%. That seems to be a conservatively safe level, and it doesn’t take much alcohol to do the job so adding more won’t necessarily get records any cleaner.

Two kinds of isopropyl alcohol are commonly available: 70% and 91%.

  • Recommended: Conservative formula (< 20% alcohol)
    • With 70%: 1 part alcohol to 3 parts water = 17.5% alcohol
    • With 91%: 1 part alcohol to 4 parts water = 18.2% alcohol
  • Aggressive formula (< 25% alcohol)
    • With 70%: 1 part alcohol to 2 parts water = 23.3% alcohol
    • With 91%: 1 part alcohol to 3 parts water = 22.8% alcohol

As for cost (as of Jan 2018):

You can buy 91% isopropyl for about $3.50 per quart, and distilled water for about $1 per gallon. That makes 1.25 gallons of fluid for about $5. Nitty Gritty charges about $80 for 1 gallon of their solution, which is for all practical purposes the same thing.

Updating Celestron Telescope Firmware

Here’s how I update the firmware in my Celestron 6SE telescope from my Ubuntu Linux system. There’s another nice guide here, but it didn’t work on my computer until I figured out the trick below of changing the port name.

Kudos to Celestron for writing the software in Java so it can run on any computer, Windows, Mac or Linux!

My scope has a phone-type connector to the handset and came with a cable that is a 9-pin serial on the other end. Plug this cable into your computer’s serial port and into the bottom of the handset. While the scope is off, hold down the handset Celestron & Menu buttons while turning it on. The handset will say Boot Loader Serial or something like that to indicate it’s in firmware update mode.

Now, find the Linux device file for your serial port by entering this command: dmesg | grep tty

My output looks like this; yours may be different:

[    0.000000] console [tty0] enabled
[    0.671956] 00:06: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A

On my computer, the serial port is /dev/ttyS0

Check this device file’s permissions and ensure you can read & write it. Typically you need to be in the dialout group, or just chmod the device file to 666 to open it to anyone.

Follow Celestron’s instructions to download the CFM software from their web site. Once installed, go to its directory and run it with Java: java -jar CFM.jar

When it starts it will tell you it can’t find the serial port. Select Options|Connections from the menu. In the dialog that appears, you’ll notice it says COM4 (or something similar) as the serial port name. Replace this with ttyS0 (or whatever your port’s name is).

Now click Seek Devices from the app main screen and it will find your telescope. Click the main screen Update button and CFM will find and download the latest firmware for your scope and install it.

Audio: Balanced and Unbalanced

Below is what an unbalanced audio signal looks like. The Y axis is volts, the X axis is time. The red line is the + signal, the black horizontal line is the – signal. The + signal carries the music, the – signal is ground. This is sometimes called “single-ended” because only one wire carries the musical signal.

audioSignal-unbalanced

Below is what the same audio signal looks like when balanced. The red line is the + signal, the blue line is the – signal. Here, neither wire carries ground. Each wire carries the same signal, but they have reverse polarity. The difference between them is a signal having twice the amplitude. At every instant in time, the voltage sum of the + and – wires is zero, so the cable (containing both + and – wires) has a net field of zero, which makes it immune to interference.

audioSignal-balanced

This gives balanced signals 2 advantages: S/N ratio is 6 dB higher (twice the voltage = 6 dB), and immunity from interference.

Balanced audio was designed for microphones, which have low level signals carried on long wires. In this application, noise isolation is important and you need all the S/N you can get. Consumer audio analog line levels are in the range of 1-2 Volts, about 1,000 times or 60 dB stronger than microphones. And cable runs tend to be shorter.

Thus, balanced audio doesn’t make much if any difference in consumer audio applications. It’s a superior engineering design, but it doesn’t necessarily make any audible difference especially in top notch gear that already has S/N ratios well over 100 dB. It’s nice to have, but I would not pay extra, or chose one piece of equipment over another, for this feature alone.

Public Schools and Groceries

As a society we’ve chosen not to let poor people starve. Anyone who cannot afford to feed himself is provided food by the government, funded by taxpayers. But to do this, we don’t have the government running farms and grocery stores. Instead, the government gives people money or food stamps to buy food at the same places everyone else does.

This makes sense because the market economy organizes farms, transportation, and distribution of food far better than government ever could. Indeed, this system works so well, it makes food so abundant and inexpensive that obesity is far more common than malnutrition!

So when our society decides every kid should get a decent education even if his family can’t afford it, why do people assume this means the government has to create and operate schools? Why don’t we let the market economy organize education and give poor people money or vouchers to attend the same schools everyone else does?

Everything I’ve read about economics and education suggests this would work much better. We’d have higher quality education, with greater variety of methods better tailored to the individual needs of students and families, more accountable to families, delivered at a lower price.

Consider the incredible variety at your local grocery store. Not only is food abundant and inexpensive all year-round, coordinated with farmers who grow it world-wide in a complex, efficient distribution network. Yet it also meets the unique needs of small minorities: foods for diabetics, vegans, kosher or halal, etc. In contrast, the 20th century has demonstrated that when governments attempt to operate or micromanage the farming and distribution of food it leads to mass starvation.

It is only fair to assume people on all sides of the debate have good intentions. Just because someone questions public schools, doesn’t mean he is against education, or thinks education should favor the wealthy. Au contraire! The current system of public schools all too often condemns poor people to terrible schools because they live in low-income areas, while wealthy people have better public schools and also the option to send their kids to private schools that only they can afford. These problems result from our government operating schools. That’s unnecessary and counterproductive. Letting the market organize independently operated schools and giving poor people money or vouchers to attend the school of their choice would improve schools and make them available to ALL kids and families.

JDS Element vs Meier Corda Jazz

This is a detailed comparison of the Corda Jazz with the JDS Element. I own one of each and listen to them almost every day, along with an Oppo HA-1. I’ve reviewed each of them separately.

TL;DR Summary: If all you need is a pure analog headphone amp, get the Corda Jazz. It has all the clean neutrality of the JDS Element, but richer, sweeter, more refined. If you want the flexibility of having a DAC and analog RCA inputs and outputs too (even if you won’t always use them), get the JDS Element.

Similarities

Cost: Both cost the same (about $350).

Provenance: Both are built by very small independent companies. Both are designed and built with a no-bullshit engineering philosophy.

Sound Quality: Both have excellent sound quality both subjective and measured that could be considered “reference” from an objective perspective, meaning it’s hard to differentiate them from each other, or from top end reference gear in a properly done level matched DBT. Of course, that doesn’t mean they sound the same (they don’t). In my opinion, they’re in the same league as the best gear I’ve heard costing a lot more, and their relatively low price is the only reason they might not be considered “audiophile” in some circles.

Gain: Both have adjustable gain separate from the volume knob–a switch for high vs. low gain. This enables them to drive anything from efficient IEMs that only need millivolts and milliwatts, to big power hungry planar magnetics.

Power: Both have > 1 watt max continuous power output, enough to drive almost any headphone on the planet, except for electrostats which need a dedicated voltage step-up transformer.

Reliability: I’ve used both near daily for more than a year with no problems.

I believe any pragmatic audiophile (myself included) would be delighted with either one, so long as he valued sound quality and neutrality over fancy knobs, glowing displays and the exclusivity of limited production boutique equipment. Actually, each of these does provide some of the latter exclusivity despite their low price, being less common than mass-produced gear from major manufacturers. When people see one on your desk they ask, “What the heck is that?”

Differences

DAC: Advantage: JDS Element
The Element has a DAC; the Jazz doesn’t. The Element’s DAC is clean, but USB-only and does not run in async; it relies on the source (your computer) to clock the data. JDS claims async mode doesn’t provide any audible benefit, and their measurements support that claim (though that doesn’t necessarily make it true). I do note, when using the  Element, occasional “tics” or brief drop-outs that are not in the source material and occur seemingly randomly. This is consistent with the notion that the clocks (computer source vs. Element DAC) are slightly different and it occasionally re-syncs. This may happen less frequently or never on other computers.

Flexibility: Advantage: JDS Element
If you need a DAC that can drive line-level analog output (for example to a different device), and also a headphone amp, the JDS Element does the job.

The Element has analog RCA line-level output jacks, which the Jazz lacks. The Element also has unbalanced analog RCA input jacks which bypass the DAC and make it a simple analog headphone amp. This makes Element quite flexible as a line-level DAC, an analog headphone amp, or both together. When turned off, the DAC is still on and it routes the USB input to the analog RCA outputs. So you can use the Element as a DAC with line output, and as a headphone amp, leaving both plugged in at the same time. However, it will only drive one or the other, depending on whether it’s turned on. Put differently, think of the Element as “always on” for DAC, line input and output, and its power switch controls the headphone amp.

The Jazz is nothing more than a pure analog headphone amp. It has no analog RCA outputs to drive another analog line level device, nor can this be done from the headphone jack! That’s because of the Jazz’s active balanced ground drive. Line level unbalanced analog inputs assume the entire signal is on the + output, and signal ground is dead zero frame ground–that’s how unbalanced works. The Jazz emits a signal on the ground, which if passed to an unbalanced analog input, would be shunted to ground without any resistor. This makes the Jazz attempt to drive a 0-ohm load, which can blow the fuse or damage the amp. Use the Jazz only to drive headphones — not other audio components!

Volume: Advantage: Corda Jazz
The Element has an analog potentiometer volume control. It’s smooth, wide range, well balanced, but still a pot. The Jazz uses a stepped attenuator triggered by an analog pot; there is no pot in the signal path, only metal film resistors. It has about 30 steps, each about 1.5 dB apart. One can argue whether a stepped attenuator makes any audible improvement, but there’s no question the stepped attenuator is a superior design: cleaner signal with perfect channel balance at all volumes, and unheard of at this price.

Imagery: Advantage: Corda Jazz
The Jazz has a mode to artificially create a more natural stereo image from normal (non-binaural) stereo recordings. It’s a switch that blends channels with phase delay depending on the difference in L / R channels. I’ve used these before and they’re usually gimmicky. Meier’s is not a gimmick. It’s the only one I’ve heard that improves the image while getting out of the way of the music being otherwise sonically neutral or nearly transparent. I said “nearly” transparent. It does make the tone a tad less rich, a small emphasis in the mids to treble. I usually leave it off, except on recordings with extreme L-R separation, where for example a singer or instrument is entirely in one channel or the other. These are hard to listen to on headphones, and this switch fixes that.

Signal Isolation: Advantage Corda Jazz
Both amps have unbalanced analog output to the headphones. But the Jazz adds a twist: active balanced ground driving. Signal ground to the headphone is not the 0V frame ground that it would be with standard unbalanced. Signal ground contains some of the L and R signal combined, such that the net signal at each speaker of the headphone (difference between + and -) sums to pure L or pure R. Because the ground contains some L and R signal, the net field around the cable is near zero (not exactly zero, as it is with balanced). This isolates the signal better, immunizing it to hum or other electrical interference. Some might say this also makes the load easier for the power supply to drive, but the power supply is already over-engineered with its 10 W toroidal transformer.

Build Quality: Advantage Corda Jazz
Both have great build quality, but the Jazz is a small step higher both inside and out: the case, switches, knob, power supply and other internal components. The Element is by no means cheaply made, it’s a pleasure to view and handle. But the Jazz is a step up.

Sound Quality – Subjective Listening

Both sound great: clean, neutral, detailed and fast without brightness, deep bass without being bass-heavy. Both are dead silent even at high gain full volume – no hum or other background noise. Both have excellent measurements comparable to professional reference gear. Not having a DAC, the quality of the Jazz depends on the source. I compared the Jazz & Element using an Asus Xonar DX sound card to drive the Jazz, and driving the Element with a USB bit stream. I used Audeze LCD-2 headphones and extremely high quality recordings of a variety of music, mostly acoustic.

In this configuration, I preferred Jazz in overall sound quality, which countered my expectations since good solid state amps are so hard to differentiate in blind listening tests. The Jazz has the same level of clarity and detail as the Element, yet at the same time sounds slightly more rich in the bass and sweet in the mids and treble. Call it more musical, yet without any loss of neutrality or clarity. I emphasized the word slightly because the difference is subtle. Upon first impression they sound identical, though I feel well trained experienced listeners using excellent recordings would detect the difference consistently with careful listening in an ideal quiet environment.

That said, if I needed the flexibility that the Element provides–listening to music from a laptop where I must stream bits over USB because I can’t install a high quality sound card, or I needed a DAC with line level RCA output in addition to a great headphone amp, or I was using great but less than reference quality headphones like Sennheiser HD-600 instead of the Audeze–I would grab the Element in a heartbeat. To put some meat to that statement, my Element is not for sale.

By comparison, the Oppo HA-1 is the best of both worlds and more. Its analog amp equals or exceeds the Jazz, which is a high bar. Its Sabre ES9018 DAC is fantastic and has coax, toslink and USB inputs. It is fully balanced with both line level and headphone outputs, yet also has a single-ended outputs. It also has great flexibility with numerous inputs and outputs. The only feature it lacks is the Meier’s headphone image circuit, but I only miss it on those rare recordings with artificially extreme L-R separation. But the HA-1 is big and bulky, weighs about 15 lbs, costs 3x the price of the Jazz or Element and is no longer made.