Comments on: Difference betwwen 4ohm, 2ohm, bridged?? Im buying a car amplifier.?

By: Audio Freak

Audio Freak — Tue, 18 Dec 2007 08:40:44 +0000

Some of the other answers are wrong in the basics. You can’t hear the difference between a 2 ohm sub and a 4 ohm sub. The writer, however, was right to say that ohms are a rating of impedance. Ok, of you have two 300 watt-rated subs…then the type of amp you need depends on the impedance of your subs. If the subs are 4ohm single voice coil then an amp that is rated to handle approx. 600 watts at a 2 ohm load would suit you. But again, this all depends on the impedance of your subs. I recommend using Alpine USA’s great website and ask a tech for an email response to your question, or there may be a phone number.

By: casaudiotc

casaudiotc — Mon, 17 Dec 2007 05:58:30 +0000

With the details provided, and assuming your subwoofers are 4 ohm, bridging is not going to be an option with that amplifier. Bridging (2) 4 ohm speakers will generate a 2 ohm mono load (mono = 1 channel = bridged on a channel amplifier).

Sounds like your only option is to wire them in stereo and run the amplifier in stereo mode. Unless, you buy 2 more Alpine subwoofers to run off of it. Then, you could actually wire the subwoofers in a way that you could achieve either a 4 ohm mono load or a 2 ohm stereo load.

Best advivce I can give is to look for an amplifier that is 2 ohm mono stable (something that will give you a power rating like ohms)

By: sparky3489

sparky3489 — Fri, 14 Dec 2007 15:27:35 +0000

……… for real “sound” advice.

Your system won’t mean squat without a well designed box to put your subs in. Some manufacturers have recommendations as to dimensions of various types of boxes. It is best to find someone who builds boxes if you go with something other than a sealed box.

You should always match up RMS (Root Mean Square) watts of Subs and amp per channel as well as impedance’s(resistances).

If your amp is rated at 4? don’t subject it to 2?, it will fry.

Here is the formula for subs in parallel:

Z = 1 / (1/sub1 + 1/sub2 + 1/sub3 + ….)

For series, just add them up (sub1 + sub2 + …).

You can mix and match these equations to get the right impedance required by your amp.

Example: 4 subs @ 4? each. If I connect two in parallel and the other two in parallel and tie the two pairs in series, I would have a total impedance(resistance) of 4?. So to the amp, it’s just one sub.

You should use a capacitor as well.

Recommend for every 500 watts MAX you use a .5 Farad cap
Example: 1000 watts MAX - 1 Farad cap

Try you can find some really good deals, and this site is manufacturer certified. VERY IMPORTANT WHEN SHOPPING ON-LINE!!!

You will also need what’s called a “line level converter” if your stock head unit doesn’t have RCA outputs or your amp doesn’t have high-level inputs.

If you like I can send you some plans for reference. My plans are for a 4-th order band pass bass box that holds two 12’s. Also included are java calculators you can use to figure parallel and series values given ? values.
Just e-mail me

My system

Blaupunkt TSw1200 subs with a Sony Xpl?d XM2200GTX.
My amp is 1200 watts, subs are 600 watts each, cap is 1.2 Farad

SPL is about 112 db

Total cost(so far) = $410

By: Jason z

Jason z — Thu, 13 Dec 2007 09:16:46 +0000

The ohm rating on speakers tells you the amount of impedance the speaker has. Lower ohm rate allows the amp to produce more wattage. bridging the output means you are using the neg. side of one channel and the pos. side of the other. This results in a 1 channel output (mono) at greater wattage. If you run speakers with lower than 4 ohm rating the amp will become unstable, overheat and burn up. High quality amps may be stable to 1\2 ohm or lower. The power ratings you listed should be fine to drive your 12’s.

By: kidmccloud

kidmccloud — Wed, 12 Dec 2007 00:19:57 +0000

bridging is making both 320 watts into 960 wats thats wat you do for better bass. ohms are resistance to your woofers, less ohms (less resistance) better sound. trust me i have 4 tens in my truck