sub and amp question

[Flip_SideEX]

The number of channels = how many subs I can hooked up right?

The range on the ohms = the lower the number the more power it has?

what is bridged?

Finally, if I had 2 subs rated at 400 rms each would that mean that I should get a 2xchan amp that produced 800 rms at 2 ohms? Or should I go with 2 amps which each had monochan that put out 400rms at 2 ohms?

If you need any more info post the question.

[Rastus]

For the most part, the number of channels is the amount of speakers/subs you can hook up. A 4-channel amp takes two full RCA inputs. A 2-channel amp will just have the one set of RCAs.

Bridging is when you connect a 4-channel amp up to two speakers, or a 2-channel to one speaker. You do this by putting the positive lead on the positive terminal on one channel, and the negative lead on the opposite channels negative terminal. Doing this theoretically doubles the power. Not all amps support bridging, and some amps require them bridged on certain terminals to work.


Technically, the ohms is how much resistance the speaker has in the system. A lower resistance means more power. To be quite honest, I don't know a whole lot about ohm measure and how it effects sound.


It's just my opinion, but I usually get subs that are rated a little bit over what the amp is rated for. Some subs are different than others, so it's always been a good general rule for me.


Just a note for if you want to go with more than one amp; you will have to install a relay on the switched 12V source. It's not a big deal to install it, just something else you gotta buy to do the install correctly.


Feel free to correct me if I'm wrong. I'm still fairly new. :)

[Flip_SideEX]

thanks

Also, in my sub spec's it says "Impedance Dual 4 ohms" Does anyone know what that means? Does it mean that for best sound that I should run it at 4 ohms? Cause with the amp I will we be getting, it would be nice to run it at 2 ohms.

[Plante400]

since you guys are chatting about this.

i have 2 12 inch kickers. what amp do you recommend

[Flip_SideEX]

What are the watts on the kickers and what ohms do you plan on running it?

[Regular_Joe]

Amps are dumb and are rated at some power at a certain ohm load.

If you have an amp w/ specs:
- 500 watts @ 4 ohms
- 1000 watts @ 2 ohms

Thats just a guideline of what the amp can do. If you hook up something 8 ohms it will only put out 250 watts. If you hook up something 1 ohm then it would try to output 2000 watts and most likely go into protection or burn up.

Now speakers are dumb too. They have an ohm rating that they run at. There are SVC and DVC. A SVC sub has one coil and a DVC sub has two coils. So an SVC 4 ohm sub has one 4 ohm coil. A DVC 4 ohm sub actually has two 4 ohm coils.

When you wire up more than one sub the overall ohms the amp "sees" changes. There is parallel and series wiring. If you have a 4 ohm DVC sub, in parallel the sub acts like a single 2 ohm sub, and in series it acts like a singe 8 ohm sub.

I gather you have a pair of DVC 4 ohm subs rated for 400rms each. So you need an amp that puts out 800rms at 4 or 1 ohm.

* 4 ohms if you use a combination or parallel and series wiring
* 1 ohm if you wire all 4 coils together in parallel

Again all these numbers are ballpark numbers. Any amp thats in the 700rms to 1000rms range should work as long as its rated to put out the max power at 1 or 4 ohms. Something like a Hifonics Brutus BX1000D would be a pretty cheap option for a 1 ohm setup.

[Trevor]

The more power the better get as powerfull of an amp you can get for the price you want to pay.

[maskale]

Some info on Subs

Fs (Hz)
The frequency at which a speaker naturally resonates in free air (measured in Hz).



Impedance
The load value (in ohms) that the speakers present to the amplifier - the amount of resistance to the current flow. Low-impedance subs (less than 4 ohms) or multiple subs wired in parallel can cause problems with amplifiers which are not designed to deliver large amounts of current at a low impedance. This is especially important if you want to bridge your amplifier and run multiple subs.



Cone Material
Materials the woofer is made of. To operate efficiently, a woofer cone should be made of material that is stiff, yet lightweight. Poly cones provide excellent sound, and stand up to the heat, cold and moisture that car speakers face daily. Paper cones treated for moisture resistance also do an excellent job, and are usually very efficient.

"Poly" refers to Polypropylene, thermoplastic plastics or fibers that are polymers of propylene. "IMPP" is Injection Molded Polypropylene, a common material and process used in car speaker cone manufacture.

"Pulp" refers to processed wood products, or paper.



Surround Material
The flexible ring around the edge of the woofer cone. Surrounds are usually made of cloth, foam or rubber. Rubber and composites tend to last longer and hold up better in harsh environments.



Sealed Box Volume (cubic feet)
The recommended interior volume in cubic feet that a sealed box needs in order for the sub to deliver its rated performance.



Ported Box Volume (cubic feet)
The recommended interior volume in cubic feet that a ported box needs in order for the sub to deliver its rated performance.



Port diameter (inches)
The recommended internal diameter for a port tube in the recommended ported enclosure.



Port length (inches)
The recommended length for a port tube in the recommended ported enclosure.



Free-Air
A free-air system consists of woofers mounted to a board attached to the rear deck or placed in the trunk against the rear seat. The trunk acts as the enclosure housing the subwoofer. Free-air systems save space and have flat frequency response. The woofer must be specifically designed for free-air use, and the trunk must be airtight for the best results.



Dual Voice Coil
Also called DVC speakers. For subs, they provide two pairs of inputs allowing you to drive one sub with two amp channels, or let you wire the voice coils in parallel or series to reconfigure the speaker's impedance. For full-range speakers, it allows you to drive the speaker's mids and highs with one amp, and the lows with another.



Sensitivity
An efficiency or sensitivity rating tells you how efficiently speakers converts power into sound. The higher the number, the louder the speakers will play. An efficient speaker helps you maximize your available power.



Frequency Response
The range of frequencies the speaker will reproduce (lowest frequency to the highest). The wider the range, the better. Optimal is 20 - 20,000 Hz, the range of human hearing.



RMS Power Range (Watts)
The range of RMS power the speaker requires to operate safely and properly. RMS Power Handling refers to the amount of power a speaker can handle on a continuous basis.



Peak Power Handling (Watts)
Peak power handling refers to the amount of power a speaker can handle during a brief musical burst. The RMS power range figure is a much more reliable rating for determining the speaker's power requirements.



Top Mount Depth (inches)
The speaker's mounting depth when it's installed as a top-mount. Your vehicle will need this much clearance in order for the speaker to fit properly. This is an important dimension to consider if you're installing your new speakers in a non-factory speaker location. If you're installing a subwoofer in a box, you'll need to make sure there is this much clearance between the outside of the box opening and the opposing inside surface.




Bottom Mount Depth (inches)
The speaker's mounting depth when it's installed as a bottom-mount. Your vehicle will need this much clearance in order for the speaker to fit properly. This is an important dimension to consider if you're installing your new speakers in a non-factory speaker location. If you're installing a subwoofer in a box, you'll need to make sure there is this much clearance between the inside of the box opening and the opposing inside surface.



Cutout Diameter or Length (inches)
The actual diameter of the hole you will need to cut out if you are creating a new mounting location for this speaker, or if you are mounting a subwoofer in a box. Length is the measured length per side of a square subwoofer or speaker. The cutout or length dimension is important if you're installing your new speakers in a non-factory speaker location or building a box.



Vas (liters)
Volume Acoustic Suspension - the volume of air having the same stiffness as the speaker's suspension (measured in liters).



Qts
The total "Q" of the driver at the given free air resonance of the driver. Q is the magnification of resonance factor of any resonant device or circuit. A driver with a high Q is more resonant than one with a low Q.



Xmax (millimeters)
The measure of a speaker cone's maximum excursion in one direction while maintaining a linear behavior.

[maskale]

Some info on amps.



RMS Power Output (Watts x Channels)
The amount of continuous power, measured in watts, that an amplifier produces is called RMS power. The higher the RMS figure, the louder and cleaner your music sounds.



Frequency Response
The range of frequencies, low to high, the amp can reproduce. The standard is the range of human hearing, which is 20-20,000 Hz.



THD at Rated RMS Power
The amount of change in harmonic content of the signal as it is amplified. A lower figure indicates less change and a more accurate amp. THD below 0.10% is inaudible.



Signal to Noise Ratio
Measured in decibels (dB), this spec compares the strength of the desired signal (music) to the level of background noise. A higher value indicates less background noise.



Input Voltage
The input voltage used to measure the power output. Most car batteries, though rated at 12 volts, actually deliver 14.4 volts.



Peak Power Output (Watts x Channels)
Stereo manufacturers often display peak power ratings on the face of their products. The peak power rating tells you the maximum wattage an amplifier can deliver as a brief burst during a musical peak, like a dramatic drum accent. The RMS figure is more significant.



Power at 2 Ohms (Watts x Channels)
This spec tells you how much more power your amp delivers when presented with a 2-ohm load. You can achieve a 2-ohm load by using two 4-ohm subs wired in parallel, or by using a 2-ohm sub.



Bridged Power (Watts x Channels)
The output wattage (RMS) per bridged channel.



Minimum Impedance Bridged
The lowest impedance the amp is designed to handle when it is in bridged mode.



Minimum Impedance Unbridged
The lowest impedance the amplifier will handle when it is in unbridged mode.



Amplifier Class
Each amplifier "class" has different performance characteristics, determined by its internal circuitry:

Class A amplifiers are desirable for the high quality of their sound, but, because of the configuration of its transistors, a pure class A amplifier is inefficient and runs very hot.

By far the most common car amp design, Class AB amps run cooler, and therefore, more efficiently than a class A, with low distortion and high reliability.

Class D amps (usually used to power subwoofers) boast higher efficiency, produce less heat, and draw less current than Class AB amps. Class D amps produce higher distortion, but this distortion occurs at high frequencies that are typically removed by a low-pass filter and is therefore inaudible.

Class BD amps give you the super-efficient design of a Class D amp with the clarity and sound quality of a Class B amp.



Tri-Way Capable
Sometimes called Dual Mode, this setup powers a pair of stereo speakers and one subwoofer simultaneously from the outputs of a single 2-channel amp. An affordable way to drive a subwoofer, it requires an external Tri-Way adaptor/crossover that connects in-line between your amp and speakers.



Low-Pass Crossover Frequency
The cutoff frequency or frequencies for the built-in low pass crossover. Crossovers are characterized by their frequency (Hz or kHz), and by the steepness of their roll-off slopes (the rate of attenuation outside their pass bands) as measured in decibels per interval (dB/octave). A low-pass crossover is generally used for subwoofers - it allows frequencies below the crossover point to pass, while frequencies above the crossover point are gently or harshly rolled-off, depending on the slope.



Low-Pass Slope (dB/octave)
Crossovers are characterized by their frequency (Hz or kHz), and by the steepness of their roll-off slopes (the rate of attenuation outside their pass bands) as measured in decibels per interval (dB/octave). A lower slope results in a gentler frequency roll-off, while a higher slope causes a far more sudden roll-off.



High-Pass Crossover Frequency
The cutoff frequencies for the built-in high pass crossover. Crossovers are characterized by their frequency (Hz or kHz), and by the steepness of their roll-off slopes (the rate of attenuation outside their pass bands) as measured in decibels per interval (dB/octave). A high-pass crossover allows frequencies above the crossover point to pass, while frequencies below the crossover point are gently or harshly rolled-off, depending on the slope.



High-Pass Slope (dB/octave)
Crossovers are characterized by their frequency (Hz or kHz), and by the steepness of their roll-off slopes (the rate of attenuation outside their pass bands) as measured in decibels per interval (dB/octave). A lower slope results in a gentler frequency roll-off, while a higher slope causes a far more sudden roll-off.



Bass Boost
Some amps include circuitry that allows you to boost the bass output. In some cases it is simply a knob or button that provides a set amount of boost, and in some cases it may be a built-in parametric equalizer with many possible configurations and adjustments.



Bass Boost Frequency
The frequency(s) at which bass boost is applied.



Speaker Level Inputs
Useful if you're adding an amp to a factory radio, or don't have enough preamp outputs on your aftermarket receiver.



Preamp Outputs
Number of RCA outputs. An RCA output lets you pass the preamp signal to additional amps, and in some cases the internal crossover from the first amp can send a filtered signal, eliminating the need for an additional crossover.

[rubiowner01]

just go here: http://forum.sounddomain.com/

all you would ever want to know...

[wilkin250r]

Ok, serious, nobody is going to read all that.

You want the lowdown on Power output and Ohms, I'm your man. I'm an electrical engineer, I know a thing or two.

Let's look at basic electronics, first, and Ohm's Law. I'll use very simple terms.

Current is equal to voltage divided by resistance. Current is denoted as "I", voltage is "V", and resistance is "R".

So, I=V/R

This is simple. That means, if you have 12 volts, and 3 ohms, you get 4 amps. Simple.

Power is Voltage times Current. P=I*V. So, in the above example, at 4 amps and 12 volts, power is 48 watts.

[wilkin250r]

That's simple enough, right? Voltage, current, resistance, it all fits nicely together.


Believe it or not, your amplifier doesn't produce "watts". It produces a voltage. You're not exactly sure what that voltage is, but let's pretend that it is 48 volts. That's a nice simple round number.

How much current does that produce? Well, you need to know the resistance, don't you? Let's say the resistance is 4 ohms. 48/4=12 amps. Now, for power, I*V is 18*12=576 watts.

But what happens if we have 2 ohms? 48/2=24 amps. And for power, 48*24=1152 watts!

Resistance is the key. You amplifier produces a voltage, and it's your SPEAKERS that determine resistance.

Do you want more detail than this?

[Flip_SideEX]

Has anyone heard of MA Audio? Do they seem as a good company? Any complaints or info on them?

[jay's 300]

Originally posted by wilkin250r
That's simple enough, right? Voltage, current, resistance, it all fits nicely together.


Believe it or not, your amplifier doesn't produce "watts". It produces a voltage. You're not exactly sure what that voltage is, but let's pretend that it is 48 volts. That's a nice simple round number.

How much current does that produce? Well, you need to know the resistance, don't you? Let's say the resistance is 4 ohms. 48/4=12 amps. Now, for power, I*V is 18*12=576 watts.

But what happens if we have 2 ohms? 48/2=24 amps. And for power, 48*24=1152 watts!

Resistance is the key. You amplifier produces a voltage, and it's your SPEAKERS that determine resistance.

Do you want more detail than this?


Nicely put! I was thinking the whole Ohm's Law theory myself. Sucked filling out all of those R.V.I.P charts, lol. :D

[Butters]

Originally posted by wilkin250r
That's simple enough, right? Voltage, current, resistance, it all fits nicely together.


Believe it or not, your amplifier doesn't produce "watts". It produces a voltage. You're not exactly sure what that voltage is, but let's pretend that it is 48 volts. That's a nice simple round number.

How much current does that produce? Well, you need to know the resistance, don't you? Let's say the resistance is 4 ohms. 48/4=12 amps. Now, for power, I*V is 18*12=576 watts.

But what happens if we have 2 ohms? 48/2=24 amps. And for power, 48*24=1152 watts!

Resistance is the key. You amplifier produces a voltage, and it's your SPEAKERS that determine resistance.

Do you want more detail than this?


thanks for posting that. i knew a little bit about electonics but this helps me better understand what it is i thought i knew :D . anyways i always like to learn new stuff and i think its pretty simply said.