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>"And don't even get me started on the tube mythologies."

What do you mean? In the end, a tube is just a gain device, like a transistor. Given a distortion spec, one can just as much build a tube amp to match it as a solid state one. There are both SS and tube audio amps that achieve distortion levels in the part-per-million level. Multiple gain stages are required in either case to get very low distortion; the real fault in most consumer tube amps is not the use of tubes, but the use of circuits that are too simple — that's the audiophile fetishist fault. Indeed, a single (constant current source loaded) vacuum triode is more linear a voltage gain device than any single transistor. If you use as many tubes as transistors, you can easily match the low distortion levels of the SS design. Tubes have specific benefits including removing thermal memory distortion (modulation of gain device parameters by the temperature changes caused by varying power dissipation). See for example this AES paper:http://www.aes.org/e-lib/brows... With transistor designs, to deal with the issue you need to add more devices to even out the power dissipation at least in the differential pair input and the VAS, and in the case of chip power amps, add compensation for the effect of the output stage thermal dissipation affecting the previous stages. Then there's the issue that transistor gain curve is exponential whereas the tube's is power-of-two, which makes the distortion profiles of a tube and an SS amp that achieve the same THD quite different, with more of the THD in the tube case caused by lower order and even harmonics — the very ones that the human auditory system masks anyway (psychoacoustics what ultimately matters, and there is interesting research and AES papers on more relevant metrics than THD/IM). Tube's problem is simply one of practicality in regards to their size and the need for filament power. Other issues can all be dealt with. For example, in terms of typical speakers, the low impedance has been traditionally solved with transformers, which introduces phase nonlinearities and some hysteresis effects, so they add distortion. But this is unnecessary. One elegant solution is the replacement of the output transformer with a switching impedance converter that operates far above the audio band; see D. Berning's patent (I think it expires soon). While the converter is an active SS state, it has no gain and no distortion in the audio band. Another solution is to directly couple tube output to electrostatic speakers, which have very high impedance. A third solution is to use hybrid circuits with both SS and tube stages. It's possible to get the best of both worlds there. Here's a great hybrid circuit that achieves a few ppm THD for 1500 kV p-p output for electrostatic headphones:http://headwize.com/?page_id=7... Note especially the hybrid third-fourth gain stage. One reason the amp gets such low distortion with only moderate NFB is that the third stage transistor's nonlinearity, in the operating range, is roughly inverse to the final tube stage's nonlinearity.

even with quite good head phones.

What are you using? I use Sennheiser HD580s at my workstation and Creative Labs Zen Aurvanas on the go. Always interested in hearing other people's opinions.

This is also an excellent resource.

They work well for sounds that are continuous, such as the hum of a refrigerator, but are rather ineffective against speech or other rapidly changing audio signals.

Noise cancellation requires hardware. Headphones use microphones to pick up the sounds which are then cancelled by phase-inversion. It gets vastly more complex when dealing with open spaces. This is nothing that software alone has a solution for.

I found the technique here. Method 4 is what I'm referring to. You can use a metal or plastic spoon, and it won't leave any scratches or cause damage to the housing. The glue is flexible, so it will just stretch and the housings will eventually open. The site also has a lot of other useful information.

One thing I found useful is to hotglue the wires where they enter the cup so they cannot move. This prevents the wires from breaking.

This approach to generating rear ambience from recordings is generally credited to amplifier designer David Hafler, who popularized it in the 70's. For a clear diagram of how to wire this up that may be easier to understand than the text here see http://sound.westhost.com/project18.htm It's also possible to insert a fixed or variable resistor to adjust the volume of the rear speakers relative to the front; see the "Can I play binaural recordings through loudspeakers?" section of http://www.headwize.com/faqs.htm for a sample there. Finally, you can even derive a passive center channel if you're really hardcore; I don't really like the look of the diagrams at http://kantack.com/surround/surround2.html but it covers all these approaches.

Dynaco sold a little box called the QD-1 that simplified the wiring of these during the original Quad craze. They re-introduced a series 2 version as a cheap Dolby Pro-Logic decoder during the beginning of the home theater craze. The newer version is reviewed at http://kantack.com/surround/surround4.html , which is a pretty spot on commentary about the limitations of this type of decoding. Both models are floating around ebay for not much money.

However, note that the effectiveness of this circuit presumes that your amplifier has a shared ground between the left and right channel circuits. While this is generally true, there are amplifiers (like any balanced design) where the ground of the left channel and that of the right are unrelated. Hooking up this circuit to such an amplifier will either a) shut it down, b) trip a fuse, or c) blow the output transistors, depending on the robustness of the design. Be very careful you know what you're playing with here. If you don't know enough about electronics to check if your amplifier channels have a common ground or not, you probably shouldn't be playing around with this circuit.

Dead Can Dance is close to a best case for this approach; really well produced studio work with lots of hard panned instruments sitting in one channel or the other pop into surround this way, and minimal vocals in the center. The best demo I ever found for how effective this circuit could be was the instrumental title track to the Alan Parsons Project "I Robot", which was downright freaky in pseudo-surround.

I have a pair of SR-60's, and they are indeed great.

The only drawback (besides the open-ness, which the poster was specifically asking for) is that they're uncomfortable. Yeah, even hardcore Gradophiles have to admit this.

But this is not a reason to buy something else! Buy the Grados, and then go buy some cheap replacement pads for some Sony headphones (or whatever floats your boat). You'll still be well under budget.

I'm surprised that more people on slashdot (of all places) don't mention hacking their headphones. There's even a Grado hacking underground, for the tweaker in you.

I second this. I used to use a pair as my office headphones at my last job. They fulfilled the chief objectives - good sound quality, don't leak sound to the surroundings, comfortable, and cheap enough that I can afford to leave them at the office and not worry too much if they disappear.

As the poster said, look out for the look-alikes, particularly the V600. It's not the same thing at all. It's well known among enthusiasts that most Sony mass-marketed 'phones are crap, but the V6s are an exception and are well-regarded for their price. In the past, I've picked up good deals on some (gently) used 'phones at headphone forums like Head-Fi and HeadWize. You should be able to find a used pair at around $60, a bit more for new.

But check out this article that references a piece from 1992 - the footnote is for Raia, J., "Exercising While Wearing Walkman-Type Stereo Headphones Can Cause Hearing Loss," Los Angeles Times (Health & Fitness Suppl.), Nov. 11, 1992, pp. 5-6.

Want to touch the stove? Make sure it's not hot. Want to walk through Central Park at night? Bring a friend. Volume on your iPod too loud? Turn it down. There's something to be said for using common sense.

Just like cars are built to exceed safe driving speeds (as well as travel at safe controllable speeds), Apple already built the iPod to play at low, safe hearing levels. It's up to the consumer to decide how to use it for themselves.

The Plug's performance can be greatly improved with some simple modifications. This can also improve the fit. I couldn't get my set of Plugs to comfortably stay in my ears with any of the standard cushons, so I replaced them with some "Earplanes" (Sold at Target and Walgreens) which are much more comfortable and improve the sound.

I found the people at the head-fi forums were of great assistance when it came to earbud choice. It's a forum full of audiophiles, but they're not jerks about it. Tell 'em your price range and what you're looking for (do you like a bassier sound? A higher, brighter sound? etc), and they will undoubtedly help you out.

They're not all jerks, but a significant minority are such blazing assholes that there's been a mass migration from Head-Fi to Headwize (thank God for Chu Moy). The chief asshole is Jude Mansilla, the guy who owns and mismanages Head-Fi. Posts get edited and deleted if he doesn't agree with your opinion, he's banned DIY amp builders who wouldn't buy advertising from him. Jude whines about the cost of hosting the web site, but his brother hosts it all at his Internet consulting business - for free! It's all about the money and if Jude thinks that anybody remotely presents a threat to his cash cow, the hammer drops!

Posted anonymously 'cause my /. ID is my Head-Fi ID and Jude would ban me in a New York second - you can believe that this post will make news there.

I found a nice article that discusses the EU and OSHA regulations, as well as other useful information such as the decibel levels of common sounds.

The OSHA regulations in summary:
90 dbA 8 hrs
92 dbA 6 hrs
95 dbA 4 hrs
97 dbA 3 hrs
100 dbA 2 hrs
102 dbA 1.5 hrs
105 dbA 1 hr
110 dbA 0.5 hr
115 dbA 0.25 hr or less

They also refer to a study that looked at people's headphone settings in different environments. The study found that in a quiet room listeners set headphones volumes at an average of 69 dB. On a noisy street the average was 80 dB. In other words, for most people - this isn't anything to worry about even if you have a long daily commute. Just keep the volume level down.

I've been thinking about this for years, in a minor way off and on, and I'm still waiting for someone to invent a good feedback system for hearing level. If the music can be heard clearly at 80-85db, thenit is probably safe, right? However, all the studies I've seen measure db in the environment, not the energy approaching the ear. And if you're wearing earphones, how do you prevent hearing loss when you don't know what you are delivering to your ear?

Reactive noise-cancelling earphones would seem to be a good idea, especially if they can reduce the ambient noise to 50 or 60db and alow music to be heard at less than 85db. In fact, without music, I would be relieved sometimes to have noise-cancelling headphones to simply provide some near-silence. It would be a worthy project for competent technicians to come up with an inexpensive (less than $20) noise-cancelling headphone with signal contrast (outside noise less than 50db to inside noise less than 85db), easy equalization, and galvanic skin response sensors to indicate when the music was causing discomfort. (GSR might not be sufficient. Many recent studies showed that the type of music listened to can produce a variety of emotional and chemical responses ranging from peaceful, healthy, joyful to irritated, angry and unhealthy. Here's a a different question: If you knew loud rap and metallic rock were as bad for your system over the long run as cigarettes, would you quit listening to it?) An article written in layman's terms with good references can be found here: http://www.headwize.com/articles/hearing_art.htm.

Although the general consensus is that much hearing loss is irrepairable, I have heard rumors of people recovering some hearing ability by listening to specific music. (I think I first saw this in a book called "Superlearning 2000", and have heard subjective reports since then, but I haven't noticed any scientific papers.) Also, if high-frequency loss is a problem to you, I've heard good things about Echophone.

According to http://www.headwize.com/articles/hearing_art.htm in order for 1 hour a day of safe listening you could play your music at 105 db which is louder than a chainsaw!

At 90db or the loudness of a motor cycle you could safely listen for 8 hours a day. so meh.

- Coward

Nice links. And here's some karma whoring (not that me needs it).

Creative people and projects:
- http://www.diyaudio.com/ (DIY audio equipment forum)
- http://sound.westhost.com/projects.htm (audio stuff schematics)
- http://headwize.com/projects/index.htm (DIY headphone stuff)
- http://www.hauptwerk.co.uk/pedalboard.html (DIY MIDI pedalboards, just add keyboards and software and you have a MIDI organ)
- http://www.diysubwoofers.org/ (what it says)
- http://www.plasmatweeter.de/eng_plasma.htm (DIY ionic tweeter)

Places to buy stuff:
- http://www.newark.com/ (major electronics retailer)
- http://www.mouser.com/ (major electronics retailer)
- http://www.tubesandmore.com/ (components for vintage electronics)

Getting stuff made:
- http://www.olimex.com/ (cheap PCBs)

There are two varieties of "5.1" headphones-- one incorporates multiple drivers, so that each ear is subjected to an anterior speaker, a main speaker, and a posterior speaker. The other variety uses head related transfer functions to approximate surround sound on ordinary headphones.

See this paper for more details, including circuit board layouts and a bit of math.

and they sound awesome. :)

I don't want to sound like a snob, but $40 is nowhere near the head-end of headphones. And the ones you get for free with your walkman, forget it. There are lots of good moderately priced headphones that have straight connectors, which might be what you need. Read up a HeadWize or Head-Fi if you are interested in quality headphones.

EverStoned and any others who like to listen to loud headphones, please read this immediately. Quote:

Hearing damage from headphones is probably more common than from loudspeakers, because many people exploit the acoustic isolation by listening at higher volumes. Moreover, the risk of hearing damage from headphones is higher than with loudspeakers, even at comparable volumes, due to the close coupling of the transducers to the ears. One of the benefits of headphone listening is the ability to detect musical details. Any hearing damage would have substantial impact on that experience. This article takes a look at the process of human hearing and offers guidelines for safe listening. (The information given here does not substitute for medical expertise. Readers should consult a physician for a diagnosis of hearing damage.)

If you are turning up the volume to drown out ambient noise, consider getting an set of earbuds like the Etymotic ER-4P.

EverStoned and any others who like to listen to loud headphones, please read this immediately. If you are turning up the volume to drown out ambient noise, consider getting an set of earbuds like the Etymotic ER-4P.

I second this idea. For $200, you aren't going to find anything of audiophile quality in speakers, at least not for a whole system. Read some more headphone reviews at the community forums head-fi and headwize.

Myself, I have a pair of Sennheiser HD-580 headphones (no glasses) and I am completely happy with them. You can also get some good deals on used headphones on the above forums as well.

'Audiophile' computer speakers for that price simply are not made. It's a fact of life.

But... $200 will buy you some pretty nice headphones. I have the Sennheiser HD-580's and they are most excellent. They sound better than any stereo speakers I've ever heard. Check out headroom and headwize for heaphone info.

Though, if you have already decided that speakers are a must and headphones are out, I think Logitech has the best bang for the buck.

Why doesn't someone put a simple anti-noise circuit, a microphone and a speaker on the output of the PSU? It would not restrict airflow if cleverly placed and the sound is consistent enough to easily generate the anti-noise.

A sample link: http://www.headwize.com/tech/anr_tech.htm

Build this.

Cost? About $10 - $20 depending on how much you have lying around. Best thing? It lets you use any headphones you like instead of being stuck with the inferior quality of many noise cancelling headphones.

I've done it and it compares well to most sub $100 noise cancelling headphones.

Headwise has a DIY noise-canceling headphone project. That's probably the most cost effective way to get a pair.

In html:
http://headwize.com/projects/noise_prj.htm

Most of my friends have stopped buying CDs and while I still buy them [...] I do it more from a guilty conscience (and because I can afford to) than due to any real need.

It saddens me when I read comments like these. Yes, MP3's are nice, quick, easy and cheap, but do they deliver good quality music? If your answer is 'Yes', then I suspect you have never really heard the difference between a good CD recording and an MP3 made from the same CD.

Allow me to suggest that the one and only reason why MP3's have caught on is due to the crappy plastic stereos most people use in their 'home theaters' and elsewhere. The sound you get if you combine a decent pair of headphones, an at least halfway decent CD player and perhaps a homemade headphone amplifier is absolutely out of this world compared to the digital line noise called MP3. The fabled SB64AWE Gold and directly ripped WAV files (ie. no compression) is not even close to natively played CD's on decent playback equipment. If you are stupid enough to connect your high quality headphone amplifier directly to any sound card, then you will quickly discover that computers generates noise and distortion in more ways than by the spinning of fans and HD's. That people dont notice can only be attributed to the crappy japanese department store plastic they hook up to the PC.

Do I have a large HD shock full of MP3's? Sure I do, but they are mostly used as background noise when programming etc. When I really want to listen to music, then the PC's are shut down and the tubes are heated up. These days I mostly download MP3's to seek out new musical waters before diving in with my wallet. You just might get a feel of the real thing by listening to MP3's, but to get the totally enveloping experience you just got to have a CD (or LP). If you think differently, then you have a problem, pal...