I see A LOT of people asking about amplifiers, and what does what, and why is a monoblock better than bridged 4 channels etc etc. I hope that in this tutorial I can resolve some issues from it. I will endeavor to explain how it works, what the terminals on them are, and other things such as speaker level input converters, and pass thru RCA's as well as what all those little knobs and dials on the amps do.
Amp basics: 3 main things that all amplifiers have are power, ground and remote trigger terminals.
Power: this is the wire coming straight from the battery positive terminal. It should be fused no more than 20cm from the battery. Although this is optional in SPL, as due to the high current draw, they could blow right in the middle of a burp. This wire should grow in size in proportion to the power your amp puts out...
Ground: this goes to the car body/chassis. The best ground will have all paint around the ground point sanded off, so there is only bare metal showing. The size of the ground cable should be at least the size of the power wire, if not bigger.
Remote Trigger Wire: this comes from the H/U. it basically tells the amp when to turn on and off. It’s a 12volt, low current wire.
See this thread about wire sizes
Amplifiers also have Gain Controls most of the time will have Crossover Frequency Dials. The gain control is not merely a volume control for the amp. See here about gain and crossover setting
Bridging is where two channels of an amp are joined to create a high power output. For example, the negative terminal on Chan 1, and the positive terminal on Chan 2. These are often marked on the am, and in the manual, as they are internally configured to produce the out put for those channels. So
2 CHANNEL AMPLIFIERS
Like the name says, these have 2 channels. So when you look at them, they have the power, ground and remote terminals, but 4 other ones as well. Two are for channel one and the other 2 are for channel two. These are normally used for front stage amplification. 2 channel amplifiers will have only two RCA input sockets, one for left one for right. Therefore, channel 1 will be one side of the car, and channel 2 will be the other side. Since each channel will play different sounds, it is important to get it right, to obtain the desired “stereo” effect.
Most 2 channels amplifiers are designed to run only speakers. They can be bridged, but often only 4ohm stable, and not providing a whole heap of power, as they aren’t designed specifically to run subs. Take my old MTX RT202. At 2 ohms stereo it produced like 2x75wrms, but bridged it made 150wrms at 4ohms, and was only stable to this. Not a heap. The jaycar 2x150wrms on the other hand will bridge to 500wrms, although it is only stable when bridged to 4ohms. Some though, can be bridged for crazy high amounts of power down to 2 ohm without smoking….For 2 channel amplifiers, one left signal and one right signal is used to drive a mono speaker load.
bridging link
i will go into it further, later when i have a bit more time, but this basically shows how joining the signals from both will increase the power
4 CHANNEL AMPLIFIERS
4 channels….will be like the 2 channels, but with an extra 2 pairs of speaker output terminals, an extra pair of RCA inputs, another freq crossover knob, and often another gain knob. These can be used for either front and rear stage (so Chan 1+2 for front, and 3+4 for rear) if you are running an active front setup (Chan 1+2 for tweets, 3+4 for woofers) or even a three way setup (1+2 for front woofers and tweets run passively and 3+4 running midbass woofers)
They can also be used to run front stage and a sub. A lot of the time, in a budget setup, this is the case. Therefore, some 4 channel amps will produce more power when the 3+4 are bridged, than when 1+2 are bridged. Let’s take the Alpine MRV-F545 for example. When the first two channels are bridged, it only makes 125wrms but when 3+4 are bridged it can make 500wrms@4ohm. .once again, most will only bridge down to 4ohms, some will go to 2ohms
MONOBLOCK AMPLIFIER
Only 1 channel. The only have 1 gain knob, one crossover knob, and one pair of RCA inputs, but can also feature loads of other ones, like phase control, subsonic filter, and others, which I will move onto in a minute. Monoblocks are designed for one thing, and one thing only, to push out subbass frequencies. They have beefy power supplies, often draw lots of current, and can be very very powerful. Monoblocks generally produce best power at 2 or 1 ohms. If your amp is stable to 1ohms, then wire it down to it…..if not, best to leave it at 2ohms. Some amps though, can be wired down to as little as .5, or .25ohms!!!!!!! The SPL boys and girls do it quite a lot, even sometime when the amp is only rated to1ohm!!!!!!!
Some monoblock amps will have 2 sets of terminals, with a label bridge across them. This is for ease of wiring. Take my Blaupunkt Velocity Burning Desire, at 4ohms it makes 1x1000wrms, at 2ohms it makes 1x 1750wrms and at 1ohm it makes 1x2000wrms
. I have SVC 4ohm subs. To make my life easier, I can simply wire each one to its own pair of terminals, creating a 2ohm load, therefore the amp will produce 1x1750, and each sub will get half of this. If I had one of them, then I would bridge it, for a 4ohm load, getting 1000wrms going to the sub. Also remember that the more you load an amp down, the power you need to supply. A run of 4 gauge power wire may be suitable when an amp is only running 1 sub at 4ohm for 500wrms, but if the same sub is loaded down to 0.5ohm, and 4000wrms, then it will need a whole lot more power, so the wire will need to be upgraded to cope with the current draw.
OTHER COMPONENTS OF AN AMPLIFIER
Speaker Level Input: you may have seen the David Navone LLC advertised on CAA. Some amplifiers have these built in. They are often of inferior quality, and it is best to use an external one, such as the David Navone one, or another brand.
Pass Thru RCA’s Basically this allows the use of two amplifiers without RCA splitters. So if I have two subs and two amps, then I can have one RCA cable from H/U to first amp RCA in, and then from that amp, from the marked RCA output into the second amps RCA input. Jaycar amplifiers have these, although many people have seen that the quality of them is not so good. Basically it just splits the RCA signal inside the amp. Doing this is also referred to as “daisy chaining”. BE AWARE THAT THIS IS NOT THE SAME AS STRAPPING AMPS!!!!!
Strapping Amps: Strapping is basically joining two monoblock amps together to make one super big amp. Note that not all amplifiers can be strapped. Basically it is like bridging two amplifiers together, so taking the positive from one amp, and the negative from the other. There is a master and a slave amp, the master receives the RCA’s from the H/U and the slave receives from the master…there are switches on them to set what is master and what it slave...there are some amps that rent able to be strapped, but strapping modules can be bought…such as a Crossfire VR2000, but modules such as these can be very hard to come by. Also remember to continually check power going to amps, as strapping can draw a lot more current then you think
Phase Control: Basically determines what phase your sub is in…..if your sub sounds muddy or laggy from the front seat, maybe it is out of phase, so you can adjust it from 0 degrees thru to 180degress.
Subsonic Filter: when subs are in ported boxes, playing below the port frequency is very very bad….. i.e., if the box is tuned to 45Hz, and you play a 35Hz tone, the sub will bottom out, lose cone control, and get into all types of trouble. The subsonic filter allows you to block out any frequencies below you cut off point….kind of like a highpass filter, but in complete reverse.
Bass Boost: this goes up from 0dB. Basically just increases the output level of bass from the amp.
FURTHER READING
Wire Size Tute
Fusing Tute
Ohms Law Tute
Wire Size Conversion Table
More Fuse Theory
Subsonic Filters
Contributors to this Tute
Devinchy and Tarja
Gonadman2
Liquidity
http://www.bcae1.com
if anybody has anything to add, just holla
trism