Sound

Sound - the vital link to the world

Doing it on the cheap

When it comes to PC gaming, Home Theater or listening to music, no other part is more vital than sound. Some can spend thousands, but we're going to do it on the cheap :-)

Sure we'd all love to own a real large size screen, you can still get away with watching a movie on a smaller than preferred screen (screen types etc are another wiki). However, using poorly matched or otherwise unsuited sound gear will poison the experience far worse than a small screen ever will.

When it comes to kitting your system up with audio gear, it's not about how much money you have, it's how you set things up.

Amplifier:

Your first step is the amplifier. This is where your experience can be enhanced or obliterated.

You don't want a weeny amplifier. You want somthing that has a couple inputs, a pair or speaker outputs and a decent amount of grunt.

The best way to start is a weight test. how heavy is the unit. A heavy unit usually means a big power supply. Check the power consumption figures on the place card near the power input. a 2 channel amp that uses about 150 watts at 240v should give you near on 40-50 real watts a channel into 8 ohmes.

If you go for the older equipment, you could save heaps. Older gear doesn't have the cred' that newer stuff does, but what you get is usually alot louder, stronger and forgiving than some of the new stuff. cheap too.

$50 - $100 is a good price for this gear. Some may have a tuner intergrated which can increase the usability.

Speakers:

Now what do you do about speakers? Rule of thumb here is, if your 3 year old can pick one up, forget it. The speaker box is as much a vital element as the drivers are. There are several options here, depending on space, budget and intended purpose. Anything from a set of small bookshelf speakers to a set of giant floorstanders may fit the bill.

When looking for bookshelves, look for something that is reasonably heavy and sports decent sized drivers (no matter what the manufacturers say, you will not get decent bass from a 2" woofer). Note: bookshelves are not always renowned for their great bass, and often need to be paired with a subwoofer.

In the way of floorstanders, you can generally get 2 or 3 way systems (ie. woofer/subwoofer, midrange and tweeter), although many 2 way systems are of higher quality than similarly priced 3 way sets. Make sure the cabinets are well constructed (no gaps, fairly heavy), and always check that these work and there are no scratching sounds when the drivers are being driven. You can score a set for an easy $50 from alot of 2nd hand shops Simply because they 'don't look good'.

So after a trip to a 2nd hand shop or 2, you'd have scored a nice 2 channel amp (these usually ran around the 30 - 50 RMS REAL Watts per channel at 8ohms, and a pair of 3 way speakers that together weigh a tonne, your next stop is the local Dick Smith or Jaycar. You are going to buy some cables. What you need depends on what you are plugging in to. Generally if you are using a DVD player, Set Top box or VCR, all you need is a pair of RCA's (2x male RCA to 2x male RCA) However if you are connecting your PC to it, a 3.5mm" (small headphone plug) to 2xRCA cable. Also grab some speaker cable, the cheap 2 core stuff will be fine, get whatever tickles your fancy, its all the same stuff at these power levels. Maybe grab an AM loop antenna and FM Wire Antenna if your amp has integrated tuners.

Now that you've coughed up about $150, let's go home and plug it all in.

You can also add a subwoofer to this system cheaply by either building one yourself like right here on our own OCAU Forums or buy a cheap premade subwoofer from stores like DSE, Strathfield etc...

If you are looking for a quick sub upgrade, look no further than DSE's own 100W 10' Subwoofer. Going now for less than $150 and going down as low as 25 Hz with a bit of extra padding, it is a steal!

Setting Everything Up:

Set your amp up in its location, set the speakers up either side of the audio source, plug the 2x RCA to 2x RCA cable into the AUX-IN of the amp and the output of your device (HI-FI VCR's are good for this, they can act as a vision switcher, as well as a stereo decoder for FTA TV) Connect the amp to the speakers (the cable has a stripe on one cable - General rule is to use the stripe as negitive. Which ever way you do it make sure that both channels follow the same for each other. This is how you keep speakers in phase. An out of phase speaker will reduce bass responce and produce strange effects.

Now you have it all plugged in, get your audio source playing somthing (CD, Radio etc) Select AUX on the AMP and turn it on. After 2 - 3 seconds most amps will 'click' then audio will start. Set bass control to 1/2 way, treble 2/3 and loudness ON. Keep an ear on distortion (the haze sound you get when you turn something up too high) This distortion is the amp maxing out and possible damage being done to the speakers, bring the Bass setting down or turn loudness OFF. Learn where this distortion level is and stay below it at all times, It simply ruins the experience. (SEE BELOW REGARDING CLIPPING)

Now its all set up, you have a room filling sound system that will easily give a great experience regardless of what you feed in to it, It may not be true surround sound, But it will give you somthing that $150 surround sound systems can't, Immersion.

About CLIPPING - FROM JAYCAR'S WEBSITE :

"Little amps, big speakers - a potential problem"

The problem with all amps (excluding valve amps which behave slightly differently), is that when they reach the limit of their rated power, a rather drastic thing happens. Before I elaborate on this, it is important to remember here that the limit to an amps power is almost ALWAYS reached well befor the volume control (if it has one) is turned to the max. You must realise that the level of a typical signal varies by a staggering amount. This is called the "Dynamic Range" of a signal and it is no big deal that one part of a signal is 1000 times stronger than the next. That is why signal levels are expressed as logarithmic, or decibel (dB) scale. The volume control on an amp (or from a mixer etc) sets a level for an AVERAGE signal level. It is quite common for example, that a Hi Fi amp set on, say "half volume" will occasionally process peak signals that go way beyond its power capability when driven from a wide dynamic range source such as a CD player.

This is where the trouble comes in. When a transistor, mosfet, bipolar - it doesn't matter - amplifier processes a signal peak that is greater than its ability to completely amplify it, the level of the signal is ultimately limited to the internal DC power rails.In other words, if the DC power rails on th amp are +/- 35V, then the signal output voltage cannot exceed that (a bit less, really). When a sine wave signal (for clarity) reaches the limits of the power supply rails, the tops of the sine waves are "flattened" because the voltage limit of the power supply rails has been reached. The signal still goes through to the speaker/s with the flattened tops.

The phenomenon is called "clipping". THIS PRESENTS A SERIOUS THREAT TO THE LIFE OF THE SPEAKER. The flattened bit at the top and bottom of the signal is in fact raw DC across the speakers voice coil, positive one instant, negative the next. The DC causes the voice coil to heat up rapidly, cooking the insulating enamel on the wire and burning away the adhesive holding the assembly in place. How long the voice coil will survive under these conditions depends on many factors; the repetition rate and timeduration of the DC component of the signal is the most important, but voice coil construction, magnet size and ambient temperature also have a bearing. PA, Hi Fi and car speakers are all at risk, but especially PA (disco, musical instrument etc). It does not matter whether it is an expensive European, American or lower cost Asian unit, they are all vulnerable. You can generally hear that an amp is clipping quite easily. The sound from the speaker becomes very harsh.

http://www.jaycar.com.au/viewmessage.asp?forumid=15&messageid=861&ForumName=Power