CarlssonPower

Hi, I am currently shopping for subwoofer system for my car but since I am completly new to these stuffs so I am all confused with the terms..

what is "ohms"? what's the difference between 2 ohms and 4 ohms?

what is "bridged"?

what is "crossover"?


Thanks in advance and sorry for my dumb questions..



By the way, is this amplifier good?

Sony XM-2150GSX 760 watt 2/1 channel amplifier

2/1 Channels
MOSFET Final Output Stage
MOSFET Power Supply
50-300 Hz Crossover frequency
1x Crossover frequency capability
Hi/Low Crossover type
12 dB/Oct Crossover slope
Equalizer (0 to +10 dB @ 40 Hz)
Test tone
Parallel protection circuitry
1 Line in (pairs)
1 Line out (pairs)
High level inputs
Recessed Connections
760 watts maximum power(into 2 ohms)
150 watts x 2 into 4 ohms, 20-20 kHz, at 0.04% THD
380 watts x 1 into 4 ohms, at 0.1% THD
Variable Lo-Pass/Hi-Pass filters (50-300 Hz)
Line-level and speaker level inputs
High current MOFSET power supply
MOFSET output stage
Aluminum die-cast heat sink
Low boost 0-10 dB at 40 Hz
Gold-plated terminals
One-sided terminal layout
Dual mode capability
Through outputs

CBus

O.K. Here Goes:

OHMS- Is a measure of resistance (load). In your case, ohms is the measurement of inductive resistance (Speaker Coil). Some speakers are 4ohm, some 2ohm, and so on... The lower the Ohms (Resistance), the higher power being delivered from the amplifier is possible. The amplifier has to be capable of driving these loads, so it is a good idea to check the specs of the amplifier to verify that it can run 2ohm loads etc.

Bridged - Lets say you have a two channel amplifier. One channel for left, and one for right. If the amplifier is capable of "bridge mode", both channels can be "combined" to drive one load, therefore, your power is increased to one load and you are using the amplifier efficiently.

Crossover - A crossover is a way of seperating, or sometimes, passing certain frequencies. If you have a subwoofer, you would only want the lower frequencies to be sent to the sub. By using a "low pass" filter or a crossover, the higher frequencies are filtered out. Some of this is done electrically already. A "sub out" has already been filtered to eliminate high frequencies.

There is MUCH, MUCH more to this, but I hope these basic explanations help.

There is info on the net, here is an example http://www.rexc.com/services/ohms.htm


BMK

jimmydagreek

I would like to also add a couple of easy/simple things to remember (not too technical) that are usually standard in car audio systems.

Ohms: Generally, 4 ohms amps/systems are standard for car audio systems (8 ohms for home systems). For a high bass system (for more power) 2 ohms amps are generally used for more bass as they provide max power from the amp to the subs.

Bridged: I can't explain it any better CBus other than, you can turn a 2-channel amp into a 1-channel or a 4-channel amp into a 2-channel by bridging. For example, you would use the positive connection on channel 1 and then the negative connection on channel 2 for 1 speaker/sub. Simply put, you are using the combined power of 2 channels + 50% on 1 speaker.

Crossover: It's basically the separation of your highs, mids and lows through a head unit or amp. Most newer amps today come with built-in crossovers so that you can run an entire system (for example) off a 6-channel amp instead of 3 separate amps for each of the frequencies (high, mid, low). The crossed-over amp would separate all of the frequencies for you.

BTW CP, the amp you mentioned above is a good amp to use to power your subs. It is only a 2-channel amp and in order to run your high and mids (crossed-over) you will need a 4-channel amp.

CBus, great link! I used to install car audio systems way back in the day and still play a little. The site you provided has some great info. on how systems are set-up and run. Thanks!

CarlssonPower

Thanks guys for the info! That really helps.

rgiorgio

The advice you got on ohms, bridged, crossovers, etc are all accurate. The problem is the advise you recieved on that amplifier. Sony makes great home audio equipment but their car audio is years behind the rest of the industry. I have been in the car audio buisness for over 10 years and am a MECP certified installer, so trust me when I tell you that that amp will give you nothing but problems. If you want some good advise on amps and car audio in general please feel free to e-mail me at theitalianstallion@earthlink.net to awnser any questions. Thanks

Terrence
Audio Designs
Florida
305-852-7405