Tube amplifiers are traditional, and many audiophiles feel that tube monoblocks are the best amplifiers around. However, the price for good quality tube gear is high - with the exception of some cheap Chinese-made amplifiers, a full tube setup can cost hundreds and hundreds of dollars. Is the extra cost worth it?
In a word - no.
Tube amplifiers are inherently superior to transistor amplifiers by nature, but with the exception of some really high-end tube amplifiers, the number of compromises that must be made generally results in poorer quality sound for the dollar. Furthermore, many faults of transistor amplifiers can be overcome by simple good design.
For starters, tube amplifiers run at high voltages - often 300v or more - and are very inefficient. This means that power supplies are expensive, and the output power is generally very low. The price of a tube is also far greater than that of a transistor, while due to the complexity, the tolerances are also far more loose.
Furthermore, because they're power hogs and expensive, less of them are used. A tube amplifier often has only one or two stages for the pre-amp and power amplifier, making compensating for the non-linearity of tubes - which is often very high - a difficult task.
However, the #1 problem with tube amplifiers is in the output transformer - the device that allows the high-voltage low-current output of a tube amplifier to drive an average pair of high-current low-voltage speakers. These devices work like any other voltage-to-current transformer, but they must work equally well at both very low and very high frequencies - a difficult task indeed.
While it is possible to build a transformer that will work at frequencies from 20hz to 20khz without distortion, most tube amplifiers make compromises to cut costs - such high-end transformers can be hundreds of dollars apiece. Many transformers do not function properly at lower frequencies, or have internal inductances that eliminate higher frequencies.
As a result, most tube amplifiers - I.E., those that cost less than $500 after including the preamp and phono stage - simply can't compare to a well-made solid state amplifier for the same price. Distortion is higher, power output is lower, and several other annoying characteristics, like warm-up time, make a good solid state amp a better choice.
On the other hand, tube amplifiers do have their own merits. When a tube amplifier attempts to go above its maximum voltage output and "clips off" the top of the sine wave such as may happen during a loud cymbal crash, the distortion is far lower and less unpleasant than that of a solid-state amplifier. In addition, tube amplifiers - especially "single-ended", or class-A, tube amplifiers - have far less of the crossover distortion found in most solid-state amplifiers.
While there are plenty of stellar tube amps out there, most people simply cannot afford them. Of course, there are plenty of problems with solid-state amplifiers, which I'll go into tomorrow.
Sunday, April 8, 2007
Saturday, April 7, 2007
Headphones Made Slightly Less Complex
Headphones - sometimes also called cans - seem simple. You plug them into a jack, put them on your head, and listen to music.
If only they were.
In reality, there are many varieties of headphones, and just like speakers, they're all slightly different. While they both fit on your noggin and make sound, the difference between a pair of Sure E3Cs and some Stax electrostatic headphones is huge.
Thankfully, there are a few things that can make deciding the right headphones easier. There are really only four types, and variations upon them: open-back, closed-back, in-ear (earbuds), and electrostatic. In addition, they all have several varying characteristics which much be taken into account.
The standard-issue pair of headphones is "Dynamic" - it has a magnet and a cone and a little coil, and works just like a tiny speaker. This single driver produces a full range of sound - hopefully, from 20hz to 20khz, at least in theory. However, much like any other speaker, different headphones have different frequency response - some have a far better range than others.
However,because they're so close to your ear, headphones don't need to make nearly as much sound, and use a tiny amount of power. As a result, a pair of headphones' impeadance is usually much higher than that of normal speakers - usually between sixty and six hundred ohms. Headphone impeadance and sensitivity are both important factors in deciding the right headphones for your application - a pair of 600 ohm headphones simply won't be as loud as a pair of far more sensitive 60 ohm headphones on the tiny voltage output of an iPod.
Of the four types of headphones, closed-back are generally the most common. They have a small chamber on the other side of the driver from your ear, and hence do a very good job of eliminating outside noise. Though small headphones do exist, the lack of a good seal around your ear generally results in much poorer sound quality, and as a result, most high-end headphones are very large with big cups that fit over your ear. Some popular examples of these include Beyerdynamic, AKG, and Sennheiser.
Another, somewhat less common, type are open-back headphones, which lack the outer chamber. While this can help eliminate back resonance and, as some claim, distortion, the lack of a rear chamber results in a lot more outside sound getting through. Popular examples of these are the Grado SR60's and SR80's, which have won a variety of accolades for high-quality sound at a low pricetag over the years.
Of course, a good pair of cans is an inherently bulky object. Earbuds work slightly differently, vibrating a small "plug" that is sealed in your ear. (As a rule of thumb, proper earbuds will work much better than pseudo-earbuds that only fit loosely in the ear.) Because they fit snugly in the ear, well-made earbuds can block more noise than any other kind of headphones. Excellent earbuds can be had from Etymotic Research, Sure, and several other manufacturers.
Finally, there are electrostatic headphones. With the exception of oddball electrostatic-hybrid headphones like the AKG-340s, these headphones require high-voltage sources - also called "energizers" - to create the electrostatic charge necessary for them to function. In addition, they're also highly inefficient, requiring far more power than any other type of headphones.
On the other hand, electrostatic headphones can have far better high-frequency response than any other type of headphones, and can dodge many problems with resonance or energy storage found in most dynamic headphones. While not portable, electrostatic headphones are regarded by their owners as far superior to most loudspeakers - then again, there are many others who disagree with them.
If only they were.
In reality, there are many varieties of headphones, and just like speakers, they're all slightly different. While they both fit on your noggin and make sound, the difference between a pair of Sure E3Cs and some Stax electrostatic headphones is huge.
Thankfully, there are a few things that can make deciding the right headphones easier. There are really only four types, and variations upon them: open-back, closed-back, in-ear (earbuds), and electrostatic. In addition, they all have several varying characteristics which much be taken into account.
The standard-issue pair of headphones is "Dynamic" - it has a magnet and a cone and a little coil, and works just like a tiny speaker. This single driver produces a full range of sound - hopefully, from 20hz to 20khz, at least in theory. However, much like any other speaker, different headphones have different frequency response - some have a far better range than others.
However,because they're so close to your ear, headphones don't need to make nearly as much sound, and use a tiny amount of power. As a result, a pair of headphones' impeadance is usually much higher than that of normal speakers - usually between sixty and six hundred ohms. Headphone impeadance and sensitivity are both important factors in deciding the right headphones for your application - a pair of 600 ohm headphones simply won't be as loud as a pair of far more sensitive 60 ohm headphones on the tiny voltage output of an iPod.
Of the four types of headphones, closed-back are generally the most common. They have a small chamber on the other side of the driver from your ear, and hence do a very good job of eliminating outside noise. Though small headphones do exist, the lack of a good seal around your ear generally results in much poorer sound quality, and as a result, most high-end headphones are very large with big cups that fit over your ear. Some popular examples of these include Beyerdynamic, AKG, and Sennheiser.
Another, somewhat less common, type are open-back headphones, which lack the outer chamber. While this can help eliminate back resonance and, as some claim, distortion, the lack of a rear chamber results in a lot more outside sound getting through. Popular examples of these are the Grado SR60's and SR80's, which have won a variety of accolades for high-quality sound at a low pricetag over the years.
Of course, a good pair of cans is an inherently bulky object. Earbuds work slightly differently, vibrating a small "plug" that is sealed in your ear. (As a rule of thumb, proper earbuds will work much better than pseudo-earbuds that only fit loosely in the ear.) Because they fit snugly in the ear, well-made earbuds can block more noise than any other kind of headphones. Excellent earbuds can be had from Etymotic Research, Sure, and several other manufacturers.
Finally, there are electrostatic headphones. With the exception of oddball electrostatic-hybrid headphones like the AKG-340s, these headphones require high-voltage sources - also called "energizers" - to create the electrostatic charge necessary for them to function. In addition, they're also highly inefficient, requiring far more power than any other type of headphones.
On the other hand, electrostatic headphones can have far better high-frequency response than any other type of headphones, and can dodge many problems with resonance or energy storage found in most dynamic headphones. While not portable, electrostatic headphones are regarded by their owners as far superior to most loudspeakers - then again, there are many others who disagree with them.
Friday, April 6, 2007
Commentary.
This commentary brought to you by Sinfest.net's Tatsuya Ishida, and IRC chatrooms.
I'll post something more useful later today.
Thursday, April 5, 2007
Replacing Speaker Surrounds
Well, I need to sleep, so I suppose it's time for more filler, eh?
Speaker surrounds are the bits of flexible material that join the cone - the part of a speaker that makes noise - to the frame. They must be flexible to a precise degree, as the resistance of a surround can make a huge difference to how a driver performs.
While not so common today, several varieties of foam rubber were very popular for use as surrounds, and could be found on almost all speakers, from the worst to the best. As opposed to earlier solid-rubber and cloth surrounds, they were much less resistive, and were far superior sonically.
The problem is, though, that these foam surrounds degraded quickly, and as a result many fine old speakers are useless because the surrounds are gone. Without a surround, the driver no longer is usable, and a perfectly good speaker goes to waste.
However, so long as the rest of the speaker has not been damaged by rubbing, the driver is repairable - just add new surrounds. While having the procedure done by a professional is not a bad idea, it's not terribly difficult to replacee speaker surrounds, and it's a great way to get a terrific deal on speakers - many really excellent old speakers are viewed as worthless simply because people do not know how to do this simple repair.
http://www.speakerworks.net/kits.html
Speaker surrounds are the bits of flexible material that join the cone - the part of a speaker that makes noise - to the frame. They must be flexible to a precise degree, as the resistance of a surround can make a huge difference to how a driver performs.
While not so common today, several varieties of foam rubber were very popular for use as surrounds, and could be found on almost all speakers, from the worst to the best. As opposed to earlier solid-rubber and cloth surrounds, they were much less resistive, and were far superior sonically.
The problem is, though, that these foam surrounds degraded quickly, and as a result many fine old speakers are useless because the surrounds are gone. Without a surround, the driver no longer is usable, and a perfectly good speaker goes to waste.
However, so long as the rest of the speaker has not been damaged by rubbing, the driver is repairable - just add new surrounds. While having the procedure done by a professional is not a bad idea, it's not terribly difficult to replacee speaker surrounds, and it's a great way to get a terrific deal on speakers - many really excellent old speakers are viewed as worthless simply because people do not know how to do this simple repair.
http://www.speakerworks.net/kits.html
Wednesday, April 4, 2007
How SPL works.
Sound is a funny thing. The loudness of a frequency - as we percieve it - is not related to its actual power at all, and it's not even directly related to the amount of power used.
SPL is a measure, quite literally, of the pressure a sound wave exerts - how loud it is. The unit of measure is the Bel - or, more commonly, the decibel, or 1/10 Bel. Louder sounds, of course, exert more pressure than softer sounds. However, SPL is not measured linearly - it's logarithmic.
Every time a signal increases in strength, it increases by 3 dB. To make your stereo 6 db louder requires a whopping four times as much power to the speakers - give or take. This also means that a seemingly small difference in efficiency - the amount of sound produced at a given amount of power, measured in dB at one watt at one meter - can make a huge difference: A 91db/w efficient speaker will produce 100db at one meter using eight watts of power, while an 82db/w speaker would require sixty-four watts - a substantial increase, indeed!
However, making your stereo twice is loud is not so simple as doubling the power to the speakers - human ears don't work that way. Instead, we percieve a doubling of loudness every time the signal strength is increased tenfold - or, in other words, a 10db increase.
This is very important for subwoofers and other highly inefficient speakers - in a stereo where only twenty watts go to each of the 91db/w efficient tweeters, the 84db/w subwoofer requires two hundred watts to keep up. This is also why seemingly tiny differences in loudness can mark the difference between a car stereo and an electrical substation.
Of course, distortion of almost all amplifiers is inherently lower at low frequencies, and subwoofer amplifiers - usually built-in as "plate amps" - can be of a much lower grade than the other amplifiers in the system without a decrease in sound quality. This is especially important for class-D amplifiers - while a high-grade class-D amp is fine for any application, lower-quality class-D amps' distortion can be awful at high frequencies, but is nearly unmeasurable at the low frequencies used with subwoofers.
SPL is a measure, quite literally, of the pressure a sound wave exerts - how loud it is. The unit of measure is the Bel - or, more commonly, the decibel, or 1/10 Bel. Louder sounds, of course, exert more pressure than softer sounds. However, SPL is not measured linearly - it's logarithmic.
Every time a signal increases in strength, it increases by 3 dB. To make your stereo 6 db louder requires a whopping four times as much power to the speakers - give or take. This also means that a seemingly small difference in efficiency - the amount of sound produced at a given amount of power, measured in dB at one watt at one meter - can make a huge difference: A 91db/w efficient speaker will produce 100db at one meter using eight watts of power, while an 82db/w speaker would require sixty-four watts - a substantial increase, indeed!
However, making your stereo twice is loud is not so simple as doubling the power to the speakers - human ears don't work that way. Instead, we percieve a doubling of loudness every time the signal strength is increased tenfold - or, in other words, a 10db increase.
This is very important for subwoofers and other highly inefficient speakers - in a stereo where only twenty watts go to each of the 91db/w efficient tweeters, the 84db/w subwoofer requires two hundred watts to keep up. This is also why seemingly tiny differences in loudness can mark the difference between a car stereo and an electrical substation.
Of course, distortion of almost all amplifiers is inherently lower at low frequencies, and subwoofer amplifiers - usually built-in as "plate amps" - can be of a much lower grade than the other amplifiers in the system without a decrease in sound quality. This is especially important for class-D amplifiers - while a high-grade class-D amp is fine for any application, lower-quality class-D amps' distortion can be awful at high frequencies, but is nearly unmeasurable at the low frequencies used with subwoofers.
Tuesday, April 3, 2007
Car Stereos 101.
-NOTICE-
I am not infallible. If you have brands you'd like me to add to the lists, or think I made a mistake - leave a comment!
While I'm hardly an expert on car stereos (seeing as how I don't own a car), I can at least comment on them from what I've learned over at DIYmobileaudio.com, and hopefully save people from the agonies of a lousy-sounding or overpriced car stereo.1. Subwoofers are not everything. You will not get better sound quality from a subwoofer, except for at very low frequencies. Strictly speaking, a car subwoofer is unnecessary - some unusually well-built mid-woofer/tweeter combos can do the full range from treble to bass, just like in a home stereo.
Sadly, it's true that it's much harder to get nice perfectly-sized ported cabinets in the kickpanels of your econobox. Bass response is sacrificed for convenience, and a subwoofer is often even more necessary in a car than in a home.
2. Louder is not better. Simply because something is very loud, does not mean it sounds better than is very soft - strictly speaking, a pair of Beyerdynamic headphones put out a lot less noise than do, say, a cheap pair of speakers from RadioShack, but the Beyerdynamics sound a lot better.
Many high-end systems don't use much power at all, and are not really all that loud. A solid 50wpc reciever will go miles farther than 5,000 watts of cheapness.
3. More power is not necessarily better. Amplifiers are measured by distortion specifications, not by how many watts they can put out. In fact, better-quality amplifiers - those heavily biased into class A/B and which inside look oddly similar to a high-end home audio amp - inherently have less power output than a crappily-made monstrousity.
4. Cheap components rarely live up to spec. While a cheap amplifier rated for 3,000 watts might produce that amount of power for a brief moment, that moment would be the tiny fraction of a second while the "magic smoke" is let out. On the other hand, a massively expensive amplifier - say, a Sinfoni - will put out its rated power 24/7 day after day without batting an eyelash.
5. Make sure you have the drivers placed properly. Strictly speaking, the placement of the mid-woofers and tweeters is just as tricky as the design of a standard loudspeaker - except slightly harder, because normal speakers generally give a larger degree of freedom. Badly-placed tweeters and mid-woofers will cause a sonic nightmare.
6. Make sure you have a good install. Improperly-mounted drivers will cause nasty buzzing, rattle, and simply not sound good. In addition, mid-woofer enclosures must be heavily damped to keep your doors from buzzing like bees.
Furthermore, car audio cables, due to the low voltage, must pass a far greater amount of current than normal stereo equipment. If you don't know what you're doing, you'll likely end up with a massive fire. Be very careful of how your equipment is mounted, and make sure that all connections are insulated. Or, better still, have a professional do it.
7. Check your configuration.
There are half a million ways to wire a car stereo - but make sure that you've got an appropriate crossover, or a well-calibrated active crossover. Lower-quality high-power amps go on the subwoofer; higher-quality lower-power amps should go on the mid-tweeters.
Coaxials and "component" (mid + seperate tweeter) sets are both good, but the nature of the crossover can make some better in certian placements. Experiment - and audition - for best results.
8.. This is likely the most important of all: Get "high-end" equipment. While cheap junk might be loud, a quality setup will simply sound better.
Brands to look for:
-MB Quart
-Vifa
-Seas
-Peerless
-Ascendant
-Adire
-LPG
-Zapco
-Dayton
-PPI
-Rainbow
-Pioneer (For head units)
-Aurasound
-Morel
-Dynaudio (warning - OVERPRICED!)
-JL (I'd avoid the coaxial mid/tweeters, though)
And many more.
Brands to avoid:
Sony
Boss
Pyramid
Power Akoustik
Crunch
Pyle
Craig
Jensen
Rockford
Lanzar
Audiovox
Kenwood (except for amps)
Hifonics
Kenford (similar name - cheap crap!)
There are plenty of exceptions to these lists, but you'll be happier with better-quality components, no question. Yes, you'll need to spend a little more - but then again, a professional install's not cheap either!
Monday, April 2, 2007
Speaker placement: The cheapest upgrade of all. Also, geometry!
Good placement of speakers can make a huge difference in sound quality - and it won't even cost you any money!
Even better, you'll find a use for all that pointless geometry you learned in high school.
Here are a few general guidelines.
1. Make sure you keep speakers at least 2'-3' away from walls. With the exception of a few home-theater designs, speakers are generally intended to be used away from walls, which can act as an extension to the front of the speaker, or baffle, and affect frequency response, usually by creating a funny peak in mid-bass frequencies.
Conversely, some speakers are meant to be wall-mounted. If they are not, the reverse will happen - the much, much smaller effective baffle will reduce midbass performance, and adversely effect sound quality.
2. Make sure that the distances between you and each speaker are the same, and that the speakers are the correct distance apart. Stereo (and 5.1) sound is mixed as if the microphones were a given distance apart. If the speakers are not the same distance apart, it won't sound as good.
Needless to say, speakers should also be the same distance away from you - if they're not, the music will be out of phase, and one speaker will appear to be louder than the other. While it's possible to compensate by adjusting the balance, you're better off just making them equidistant from you.
Place speakers in an equilateral triangle for listening to music - the distance between each speaker and yourself should be equal to the distance between the speakers.
However, Dolby HT recordings are intended for the speakers to be closer together - for 5.1, the triangle is a 45-degree isosceles triangle. As a result, the distance between the speakers should be equal to 3/4 the distance between each speaker and you.
4. Toe-in is your friend. While having both speakers directly forward is common, better performance can sometimes be had by moving them so that they face inwards (towards you) a few degrees. They should'nt necessesarily be pointing directly at you, though - experiment for the best results.
5. There's an old trick for subwoofer placement that I've found works pretty well, odd as it is. It works best for down-firing subwoofers; front-firing subwoofers should generally be placed between the two front channels.
First, move the main viewing/listening chair over. Place the subwoofer where the chair once was, plug it into an audio source, and turn it on. While not my first choice of music, I've found that 50 Cent is a good choice for this, as many of his tracks have a somewhat bloated bassline that is very audiable.
Then, move around on the floor, keeping your head close to the ground, until you find a place where the bass seems to be coming from everywhere - this is the correct place for the subwoofer. Replace your head with the subwoofer, and return your head to the correct position.
If you did this right, you should have the same sense of being surrounded by bass in your listening chair as you did on the floor. Of course, this method is not foolproof, but it beats randomly shuffling your sub about the floor.
6. Adjust the crossover point.
Often, HT recievers and powered subwoofers have an adjustable crossover point. Different speakers should be crossed over to the subwoofer at different frequencies for best results, and tinkering with these two frequencies can help keep nasty bumps and dips from appearing in the frequency response.
Commonly, non-HT speakers are designed to work down to about 50hz, while average HT subwoofers are designed to work below 100hz. A bump between 50hz and 100hz may occur, which can cause a "bloated" sound.
Even better, you'll find a use for all that pointless geometry you learned in high school.
Here are a few general guidelines.
1. Make sure you keep speakers at least 2'-3' away from walls. With the exception of a few home-theater designs, speakers are generally intended to be used away from walls, which can act as an extension to the front of the speaker, or baffle, and affect frequency response, usually by creating a funny peak in mid-bass frequencies.
Conversely, some speakers are meant to be wall-mounted. If they are not, the reverse will happen - the much, much smaller effective baffle will reduce midbass performance, and adversely effect sound quality.
2. Make sure that the distances between you and each speaker are the same, and that the speakers are the correct distance apart. Stereo (and 5.1) sound is mixed as if the microphones were a given distance apart. If the speakers are not the same distance apart, it won't sound as good.
Needless to say, speakers should also be the same distance away from you - if they're not, the music will be out of phase, and one speaker will appear to be louder than the other. While it's possible to compensate by adjusting the balance, you're better off just making them equidistant from you.
Place speakers in an equilateral triangle for listening to music - the distance between each speaker and yourself should be equal to the distance between the speakers.
However, Dolby HT recordings are intended for the speakers to be closer together - for 5.1, the triangle is a 45-degree isosceles triangle. As a result, the distance between the speakers should be equal to 3/4 the distance between each speaker and you.
4. Toe-in is your friend. While having both speakers directly forward is common, better performance can sometimes be had by moving them so that they face inwards (towards you) a few degrees. They should'nt necessesarily be pointing directly at you, though - experiment for the best results.
5. There's an old trick for subwoofer placement that I've found works pretty well, odd as it is. It works best for down-firing subwoofers; front-firing subwoofers should generally be placed between the two front channels.
First, move the main viewing/listening chair over. Place the subwoofer where the chair once was, plug it into an audio source, and turn it on. While not my first choice of music, I've found that 50 Cent is a good choice for this, as many of his tracks have a somewhat bloated bassline that is very audiable.
Then, move around on the floor, keeping your head close to the ground, until you find a place where the bass seems to be coming from everywhere - this is the correct place for the subwoofer. Replace your head with the subwoofer, and return your head to the correct position.
If you did this right, you should have the same sense of being surrounded by bass in your listening chair as you did on the floor. Of course, this method is not foolproof, but it beats randomly shuffling your sub about the floor.
6. Adjust the crossover point.
Often, HT recievers and powered subwoofers have an adjustable crossover point. Different speakers should be crossed over to the subwoofer at different frequencies for best results, and tinkering with these two frequencies can help keep nasty bumps and dips from appearing in the frequency response.
Commonly, non-HT speakers are designed to work down to about 50hz, while average HT subwoofers are designed to work below 100hz. A bump between 50hz and 100hz may occur, which can cause a "bloated" sound.
Subscribe to:
Posts (Atom)