top-quark.blog
Grado SR-60
Thu, 10/19/2006, 19:47Being on campus for 14 hours a day is not particularly fun. Lately, a large portion of that time's been spent with a pair of cheapie ipod-style earbuds stuck in my head. For various reasons, mostly my irrational disinclination for going deaf, I've decided to stop using earbuds. My replacement led me back to a set of headphones I'd had once, and really enjoyed - the Grado SR60.
Some very basic research on the net provides a treasure trove of reviews about the SR60. It's the darling of value-oriented sound enthusiasts, and a common infection vector for audiophilia. I won't really go into a huge analysis of my experiences: after about 48 hours of moderately loud break-in, they sounded excellent. My only complaints are that bass is a little weak, the upper end is a little lively ("bright"), and that there's not a lot of sound isolation, for either the listener or the public. These are expected, if one reads the reviews.
A pair of airline socks valiantly gave their lives to the cause of better sound.
Their sacrifice was certainly not made in vain; the socks improve every shortcoming of these headphones. Bass response is (imo, greatly) improved, with only a trace of muddiness. I think this very slight muddiness might be due to the choice of material; a less "fuzzy" sock might have crisper response. Also, rolling them tighter would probably be an improvement (I'd do it, but then I'd need to resew the stitches holding the "rolls" together). Sound isolation is also much improved over my original pair of "quarter-modded" (i.e., quarter-size hole removed) foam pads. The last major improvement is to comfort; I don't find the stock "comfy" pads to be as offensive as some do, but my last pair of decent headphones had earpads surrounding the entirety of the ear (circumaural), versus the "on ear" (supra-aural) design of the original foam pads on the SR60. Tradition won out, and I find that these new pads are much more comfortable than the stock supra-aurals.
More mods may be coming; I'm pretty sure I'm going to rewire the headphones with cable that's thinner. At 3/16 of an inch, the main cord on these is pretty hefty; enigmatically, the "branches" coming off the y-connector feel cheap and thin.
When I get around to opening up the headphones for recabling, chances are good that I'll be doing a couple other mods. Offhand, I'm thinking about adding jacks to the headphones, and plugs to the cable, so that I won't kill my phones if I stand up with my cable underfoot. I'm also thinking about making the wire connection to just one side, and running the wire up through the headband for the other side. Some audiophile nuts I talked with tried to convince me that this would degrade sound quality, on account of the signals being out of phase, due to the small amount of extra cable run.
Sitting down with my calculator, though, I figured a worst-case scenario of about 2e-4 radians offset. That's 0.0002 radians. If there's nothing else you should learn from this short excursion into the world of higher audio mania, it's that the term "audiophile" is a synonym for "sucker".
With profuse apologies to toshi, whose photographic obsession with desaturation has "colored" me. Ha ha.
Nice surprise
Fri, 08/18/2006, 22:18I'm often in the habit of ignoring my aquariums when my schedule gets into a bind. While usually this has negative effects, such as burnt-out powerheads, stunted plant growth, fish jerky, etc., the neglect does occasionally yield something interesting.
Today while getting my laundry done, I noticed something unusual in my ten gallon soil substrate "natural" tank.
Despite the fact that the plants have a virtual monopoly on that tank, I haven't ever seen Dwarf Sagittaria flower before. There's a half-dozen others in there, too, in various stages of bloom and decay. I suppose it qualifies as something of a "duh!" remark, but submersed culture almost never sees flowers develop in my tanks; it's only when I allow the water level to fall (intentionally, of course) that I see the plants making effort in sending up flower stems. Anubias, Crypts, Bacopa, Anacharis, a dozen other kinds of plants all show the same behavior. Water level drops to where the leaves are just under the water surface, and they send up flowers. Mimicking nature, I know.
There's two bits about the hobby that this emphasizes; for me, at least.
First, that aquatic plant cultivators that limit themselves to strictly submersed culture are depriving themselves of one of the more interesting aspects of the hobby. Yes, I appreciate neatly-trimmed lawns of Riccia just as much as the next guy. Yes, I know it brings one dangerously close to the completely pedestrian realm of terrestrial plants, but who're we kidding anyway? It's not like the "aquatic" plants we see exist only in the bottom of several inches of water; there are wetness cycles in nature, and these plants do sometimes get dry.. This fact being emphasized by the number of bog plants in the hobby sold to unknowing aquarium keepers.
The second point is the mega-tech with water column fertilization is a nice approach to getting tremendous growth, but soil substrate techniques are definitely effective. If this tank had been one of those CO2/PMDD daily water column dose setups, I'm not sure the water level would have fallen this far without the tank rendering itself into a massive bowl (cube) of cellulose soup. With soil, you have a pretty decent supply of macros and micros in the substrate, so there's something of a buffer for neglect. Not that you can't use CO2, PMDD, regular DD, and other wonderful bits of the modern world in these setups...
Incidentally... all the dwarf sag in that tank originates from a single plant that sent out runners to colonize the tank. Will the flowers even be able to pollenate, given that the plants are all clones? I remember my BigAss(TM) Echinodorus rhizome clones having viable seeds after sending up flowers.
$7 laptop stand
Sun, 08/13/2006, 18:23So, several months ago, when I first got my new laptop (yes, the ibook), I went traveling across the net to see what sorts of gimmicky and expensive crap I could buy for my system. Though intrigued by its clean design, high quality, and practicality, I was fracking appalled by the $90 pricetag of this particular stand.
It is undeniably nice. But, I hate apple yuppies, and... I'm a DIY-er.
Anyone with a bit of constructive ability should be able to figure this one out. It's just a bunch of 3/4" PVC with associated fittings, totaling about $7, with plenty of material to spare. If you had a PVC bender, you could build it even cheaper. While it does wobble ever-so-slightly, it's not irritating, and is largely mitigated when you keep your palms on the rests, or use a separate keyboard. The wobble could well be my fault, though, since I haven't actually glued mine together yet. If it *really* bothered you, I suppose it could be filled with sand, or, gods forbid, you could modify it to have additional structural elements.
Aside from the obvious benes like clearing up desk space, it's helped to keep the system a lot cooler. I haven't heard the fan kick in since I built it, which I'm sure the internals appreciate.
There's an ergonomic benefit, too. Your average computer hobbyist/professional has a really fantastically bad slouch. I say this from a position of authority, having once had such a slouch, until the last year or so. Between elevating all my desktop displays on a hutch, and this laptop stand's similar effect, my posture's improved dramatically. Not that the chin-up bar and strenuous physical conditioning didn't help, but the continuous effort typically has more effect than the sporadic. If you were going for that angle, it would probably also help to have a table-level keyboard to prevent shoulder scrunching.
For my apple-loving readership, I know all this practicality talk's irritating. In not so many words, then, what is it that makes this cheap stand better than the premade hoi polloi?
It's white.
Racists, the lot of you.
Signal boost
Mon, 05/22/2006, 00:43I'm pretty used to bad wireless network reception in my section of the house. My Qwest-suppied Actiontec GT701-WG, for lack of more suitable words, is pretty damn shitty. It's got an omnidirectional stubby stick antenna, with no provisions for an external connection. Compound that with it being across the house on another floor, and it's a pretty sad situation for most of my machines. Seeing as the modem is situated on one extreme of my house, having directionality would help a lot.
Now, normally, I'd just drill the casing on the Actiontec, and attach a socket for an external antenna (eg., Pringles cantenna), but this modem's such a piece of crap that we'd be insane to actually BUY one. Consequently, we're actually renting it from Qwest. So my usual approach is out.
Came across this site today, and noticed a very elegant solution in the lower-left - the "Flatenna", from a company called "Tritium". It's a nice idea, but it's expensive (~$15 shipped, IIRC?), too small, and looks a bit too flimsy for me. So, I'm gonna DIY my own.
The biggest issue is getting a good parabola. I could just bend some stuff around, which would work OK, but I intend to make a couple of these, for different purposes, and I have enough interests that parabolas are a frequently-recurring useful shape. For template-type things, my usual approach is to make something in AutoCAD, then print it out. Oddly enough, AutoCAD doesn't have a parabola generating function.
I just came off a project heavily involving graphics generation in Java, though, so I thought I'd put together my own parabola generator. The issue is that the images I was generating are actual images, like jpg, tiff, png, etc. When printed, these don't typically have a consistent scaling or centering, and if they do, they're not controllable. A tool that does have these abilities, though, is the Adobe PDF reader.
Using a PDF Java library called "iText" (cringe), I wrote up some code to generate a PDF of a parabola from coded values, with the focal point marked. Source code, if you're inclined, is here. The pdf I generated to make my pattern is here.
From the parabola trace, I made some reflector holders out of cardboard, and a reflector from cardboard, covered in metal furnace tape. If you're ghetto enough (and aren't we all?), aluminum foil will work in a snap. I used two holders to support the reflector, and drilled a hole through the focal points, for the antenna.
So how's it work? Pretty damn well.
As reported by the driver software, the farthest computer from the station went from -67 to -57 "arbitrary units" (yes, it actually says "arbitrary units"), which is enough to make net connections very stable. As pointed out by a couple people, those "arbitrary units" look a LOT like decibels, which is fairly typical for wireless cards. My only worry is that they're offset somehow, but assuming that the underlying unit actually is decibels, the 10dB difference translates to an order of magnitude difference in signal strength.
Another fringe benefit is that I can no longer lock onto the signal from outside my house, on the other side of the reflector - a significant security boost.
Priorities.
Mon, 04/03/2006, 17:23It's curious when a major factor in your decision to get your hair cut is the degree to which it interferes with your sight picture.
LED Navlight (boring technical)
Sat, 02/18/2006, 19:31One noticeable shortcoming of most weaponlight setups is the lack of a more sane brightness setting for general navigation indoors. If you have white walls, it's a nearly guaranteed self-blinding scenario, or a loss of night vision, at minimum. One of the few exceptions is the Surefire M9xx series. These, however, are expensive. I'm not in the mood to spend that much, so I made my own solution.
There were a handful of influencing factors behind my design.
Firstly, the technique of strobing a tactical light. One of the most common criticisms of tactical lights by non-experienced users is that an opponent will be able to spot your location. This is really only is a problem if you continuously hold down the light switch. The solution is to "strobe" your primary; the technique is usually to press a flashlight's switch intermittently. A company called NightOps recently began selling a strobing tactical light called the Gladius, which I believe intermittently supplies power to a Luxeon LED. It's expensive, though (surprise!)
My current setup consists of a Surefire G2 or Pentagon X2 light; both have the same endcap threads, and both will use the same pressure pad I bought for my G2. Unfortunately, the pressure pad's internals began to fail, so I began an overhaul. The switch is hard to (dis)assemble, though, so I took advantage of the situation to discover that grafting a secondary light in through the pressure pad would be the easiest approach. This has some shortcomings, as I'll discuss later, but this is just a prototype.
Design Criteria:
- LED element - I have some pretty obnoxiously bright keychain LED lights that are overdriven constantly by two button-cells; overall voltage totals 6.5 volts. That some survive is something like natural selection. The LEDs that survive the gross overvoltage are very tough, and should survive the 6 volts I feed them with my two CR123As in the flashlights. Later on, I'll be upgrading to some Luxeon high-output LEDs.
- Strobing - Figuring out what sort of strobe frequency to use was a bit challenging. I wanted a frequency that would be considered uncomfortable to look at directly, and would be difficult to pinpoint the point of origination from. Generating some animated GIFs in ImageReady lead me to believe that 30 Hz was pretty ideal (other tests: 5, 10, 20, 30, 40 Hz). This is pretty subjective methodology, but so too is the objective effect, so I think I'm coming out OK.
- 6V Design, with power supply through grafts on pressure switch wires - The original plan was to wire in the secondary light in parallel with the Xenon bulb, but this wasn't practical, from an easy-modification standpoint, as well as a wire layout perspective. The approach I went with was grafting in the navlight in parallel with the pressure switch. Unfortunately, what this means is that the navlight is run in series with the bulb, which I suspected might hurt efficiency a good bit. How much, though? Incandescent bulbs are not particularly ohmic, so I just experimented, learning that the effect is not so terrible. I learned later that my navlight draws 23 mA at 6V on its own, and 30mA total in series with the Xenon bulb. At 30-some percent loss, it seems like a pretty crappy compromise, but it's really not so bad, when you consider that the Xenon primary draws a full amp.
- Low weight
- High durability
The balance of my design criteria dictated some sort of relatively simple layout, with an IC and epoxy potting. Pretty much out of laziness, I settled on a design using the astable 555 reference circuit. Elements Ra and Rb calculated out with rough values of 22 kOhm and 220 kOhm respectively, with C set as 0.1 uF.
Implementation:
- I put the circuit together on some perfboard I had sitting around. Good performance.
- With a working light in hand, the next step was operational testing on my rifle, which demands a higher degree of durability. Epoxy potting is the answer for things like this. I started by constructing a pour cup from a very high tech source - the lid of a macadamia nut can.
- I don't have a vaccuum pump here, so I get bubbly pours. It's ok, though, since this isn't all that crucial.
- The end product was pretty decent, after a good bit of heat curing. Squared up with some sandpaper, it's almost presentable
Testing indicates that the result is really quite good.
I have some qualms, though. Firstly, that it's a little too fast (20Hz is probably a better choice, in practice), and the light is a little too bright. This leads me to believe that I may have taken the wrong approach. A strobing primary, with a constant dull navlight may be the better choice, or perhaps even just a strobing primary. Without this prototype, though, I wouldn't have known. Call it a win.
I have a Luxeon 5W to play with now, but I haven't figured out an elegant and easy wasy to handle the thermal output. It's basically the same thing, except that the 555 doesn't have enough current handling abilit to handle the 5W the Luxeon needs, so the output uses transistor switching, in the form of a Darlington pair. Hopefully I'll have an update soon.
Entry touched up slightly on 8/13/06, to bring HTML into line, and to correct some layout issues
Most Awesome Page in the Universe
Sat, 01/14/2006, 02:27No, it's not Maddox. This site is something like the most hardcore awesome math/science page ever. It's not too deep, but you'll learn a huge swath of knowledge in short order by sitting down and reading.
Kana-rama
Mon, 01/09/2006, 04:50On prompt from one of my most endearing whitewashed Asian friends, I spent the last couple days reviewing my hiragana and katakana, since I've gotten a bit rusty. For those who aren't familiar, katakana and hiragana (collectively referred to as "kana") are two of four Japanese writing systems; along with romanji, they're the phonetic "alphabets". What I found is that there are some excellent resources available today that weren't available (or that I didn't find) when I was learning. I was especially impressed with two pages for learning stroke orders: http://www.nihongoweb.com/kana.html
http://members.aol.com/writejapan/ Also, there is a quiz page that is incredibly effective for sheer rote drilling:
Real kana The quiz page is a bit like virtual flashcards. Nobody'll claim that you can gain a deep understanding of the underlying material by memorizing, but it's an essential (if tedious) component of any learning. There's an interesting (ADD tangent) tie in with a site I found on digg today, where "Project Implicit" has a method for uncovering societal prejudices through (I theorize) response times and error rates. Applying the same kinds of statistical analysis on response times and error rates of a flashcard program would be very helpful in tuning the frequency of prompts for optimal learning. Maybe one day I'll put together something like that. Long thoughts to follow... It is interesting, though. It's never been a matter of justification for me to learn something new, but some (many) have questioned the utility of learning to read a language I can't speak or otherwise communicate in. To be honest, the question has merit. I asked this myself, but from the perfectly justifiable "shits and giggles", I've developed some reasons that I feel make it worthwhile from a number of perspectives. Firstly, it's not as though it costs you anything, and as far as skills go, learning kana is easy; I think it took me 8 hours the first time around. Also, I do intend to learn Japanese, so I would need to learn the kana anyway. Then you consider that when learning spoken Japanese as a foreigner, knowing how to read kana is a huge benefit, in that learning phonetics is important in learning the proper sounds of words, and is required in learning the ideographs, and that full literacy is the gateway to learning the spoken language well. To point, in languages that incorporate Chinese ideographs, it's difficult to learn the multitude of characters. Chinese itself uses small zhuyin or pinyin phonetics alongside characters to help children and foreigners learn the sounds and meanings. Japanese does the same with their borrowed Chinese characters(called "kanji"). Japanese, though, makes the already-daunting task harder, by having several "readings" available for each character. Unlike Chinese, where each character generally has one pronunciation, and a small number of related meanings, Japanese kanji have several pronunciations and meanings, depending on context. As a foreigner trying to learn kanji in an adult world, a reference is required, and these invariably show pronunciations in kana. Regressing to the bigger picture, learning to read is outright critical. That's not to say that speaking isn't important; it is. But it takes a lot of continuous time, and when you don't have anyone to bother, you can't learn. Learning to read takes an upfront investment of a handful of hours, but the benefits are cumulative. If you're intent to learn, a book lets you study whenever you have time. If you're not so dedicated, there are still benefits. Every time you see a stray piece of packaging, or stumble across a website, you can pick up another piece of vocabulary, or just listen to the sound and structure of the writing. It's like some people I know, who try learning English by conversation alone. They learn basic skills very quickly, but plateau off very fast. People I know who study English and read books in English nearly ALWAYS have a much better vocabulary, flow, and sentence construction, all of which pay off in having a better daily ability to communicate. You have to consider the role of technology, too, in bolstering the importance of literacy. In the world of the internet, you're not limited to some basic instruction books and a limited number of foreign language materials at your local library. The net has plenty of diverse source material to study. You have forums to visit, written tutorials with sound, essays, and plenty of native material, straight from the source. If you're reasonably intelligent, you don't even need guides; you can figure a lot of things out, and with tools like babelfish, you have a virtual Rosetta stone to work with. I think that if you really put your mind to it, it's conceivable that you could learn a language entirely by using the net, and be able to practically use it if you were dropped into a foreign environment.