The subwoofer is the most important component in home theater systems because it produces deep bass sounds. However, subwoofers are normally placed at the back of the room which means they are too far away from the listener’s ears to fully take advantage of them. Building a subwoofer bridge or completing the so-called “sub crawl” will allow you to bring the subwoofer closer to your listening spot, saving you time and frustration.
Let’s be with Hooke Audio to learn the ways to bridge subwoofers in this article.
- 1 What Is Car Amp Bridging?
- 2 How To Bridge Subwoofers – Connecting to a Bridgeable Amplifier
- 3 FAQs
What Is Car Amp Bridging?
Bridging allows you to get the most power from your car amplifiers by using a built-in channel-sharing design. In car audio applications, bridging is often used to provide more power to sub-woofers or larger full-range speakers.
This refers to using two amplifier channels together to drive a speaker or set of speakers. The power is normally split between two channels.
This is a fascinating topic and extremely useful! For example, I used to own many car amplifiers. I usually used a 4- or 5-channel amplifier. In bridged mode, I drove a single subwoofer in my trunk or two subwoofers on the car’s 2 channels.
This allowed me to have more power and flexibility, even if my speaker configuration was changed later.
What Makes An Amp More Powerful When It Is Bridged?
It is important to remember that we are assuming certain things, such as that the amplifier can provide this much power.
Some amps are not capable of delivering that much. It all depends on the limitations of each amp and how it was designed.
You should also note that each channel handles a lot more electrical current than it did before. It will therefore draw more power from your car’s battery.
How Can Car Amplifiers Make It Possible?
This is because today’s car amplifiers have, a design where one of the 2 audio channels is inverted (or 180 degrees out-of-phase). However, it is connected to the output in an inverted manner.
This is because it doesn’t have any effect on the end-user.
This means that bridge mode uses a bridge connection so that amp channels have a difference from the output voltage. This voltage difference is twice as large as the one-channel channel.
How To Bridge Subwoofers – Connecting to a Bridgeable Amplifier
Method 1: Preparing to Wire Your Subs to Bridged Amp
Find the specification labels for your system. An amp label should be placed near the speaker output jack. It should indicate the amp’s output power (measured as Watts) along with the minimum impedance, measured in Ohms. The bridged mode should have a label near the speaker output jack that indicates the maximum output power (measured in Watts) and the minimum impedance (measured in Ohms). This is because you will need to use a higher impedance to run a bridged setup. You should label your sub-woofers with an impedance (in Ohms), and a power input (in Watts).
Most amps for home theater are stable at 4 ohms when they are bridged. Most car amplifiers are capable of 2 ohms.
These values should be written down. At least four values should be written down.
- Amp Bridged Output Power
- Bridged Amplifier Minimum Impedance
- Speaker Power Rating
- Speaker Impedance
Calculate the impedance total of all your speakers. Add up the speaker impedance numbers for each speaker to get this figure. The impedance should be equal to or less than the channel’s minimum impedance. It shouldn’t exceed 16 Ohms unless the amp is specifically rated for higher impedance values.
For speakers wired in series, the formula to find total impedance is Z1 +Z2 + Z3 …. = Ztotal. Where Z is the impedance for a speaker.
If you have three speakers that have impedance values 4 Ohms 6 Ohms and 8 Ohms respectively, your total impedance wired together would be 18 Ohms (4+6+8=18).
It is slightly more difficult to find the total impedance of speakers wired together. It is (Z1xZ2xZ3 …)/ (Z1+Z2 + Z3 …) = Ztotal.
Let’s say that you have speakers with impedances of 6 Ohms and 8. It would look something like this: 1) Multiply both the values. 6 x 8 = 48 Ohms 2. Add the values. 6 + 8 = 48 Ohms 2) Add the values. 48/14 = 3.43 Ohms (rounded).
Determine the power that each speaker will receive based on the amplifier’s power output and total impedance. Alterations of Ohm’s Law can be used to calculate the power or you can use the online calculator. You don’t want to overload your speakers.
Make sure your amp is able to power your subs. Measure the output power in Watts. The wattage should be included on the label of your speakers. Your speakers should be labeled with a wattage. It must equal or exceed their total output wattage. If you have subs that pull 200 W each, an amp should produce at least 400 W. This is called “headroom” and helps avoid clipping.
Unplug equipment. Wiring powered devices could be dangerous. You can unplug the battery terminals if you’re working on a car audio system.
Method 2: Wiring Single Voice Coil Subs to a Bridged Amp
Get a roll stereo wire. This wire is needed to connect your amplifier to the sub-woofers.
Subwoofers can be used with speaker wire in the 12- to the 16-gauge range.
Connect the amplifier to the subwoofers. Make sure to check which terminals are used to switch to bridge mode. These will be marked on the amp. Run a wire from your amp’s positive terminal to the sub’s positive bridge terminal.
Connect the second subwoofer with the first. Run one wire from the negative end of the first subwoofer to link to the positive end of the second. You can wire them to parallel by running two wires between each sub. The first will link to the positive terminals and the second to the negative terminals.
Complete the circuit. Connect the wire from the second sub’s negative terminal to the negative bridged terminal of the amp. This completes the circuit, regardless of whether you’re wiring in parallel or series.
Method 3: Wiring Dual Voice Coil Subs to a Bridged Amp
Connect the amplifier to the subwoofer. This wiring will be the same as wiring a single voice coil (SVC) subwoofer. You should keep in mind that dual voice coil (DVC) subs, have two coils and therefore four input terminals. Two are positive terminals, and two are negative terminals. Connect one of the positive terminals to the positive bridged terminal on the amplifier. Connect the coils. The two coils in your DVC can either be wired in parallel or in series, just like two speakers.
If wiring coils are in series, run a wire from one coil’s positive terminal (the one wired directly to the amp) to another coil’s negative terminal. Then, run a wire again from the first coil’s negative terminal to the second coil.
If wiring parallel coils, run one wire from the first to the second positive terminal, and another from the first to the second negative terminal.
Connect the second subwoofer to your first subwoofer. You have again the series verses parallel debate.
If you elect to wire the subs together, connect the negative of the second coil of the first sub to that of the first coil of the second sub. These circuits can be complicated quickly. Next, link your negative coil’s end to the positive coil’s end. Connect the negative end of the second coil to its bridged terminal.
If wiring parallel, link both the negative and positive ends of the second sub’s second coils. Connect the positive coil end of the first subwoofer to the coil end of the second sub.
Connect the second coil to the sub. Use the same instructions as the first coil.
Finish the circuit. Now, the fun part. It doesn’t matter which combination of parallels and series you used above to achieve the correct impedance or power distribution, closing the circuit is an easy step. To link the second coil of your second sub to its negative bridged terminal, run a wire.
Check for inconsistencies. Turn on your system and try it out. You can start at a low volume, then gradually increase it until you hear any unusual sounds. You may have miswired sub-bass or bass.
What Is Bridging A Subwoofer?
A bridged amplifier refers to the combining two of four amplifier channels into one or two-channel amp with half the ohms. The technique has become very popular among many car owners because it allows amplifiers to send out more power for the mono signal to the subwoofer or speakers.
What Happens If You Bridge Non-bridgeable Amplifiers?
Bridging them will work but won’t change output voltage – therefore won’t change power output. In order to bridge the car amplifier phase of one channel has to be inverted.
Does Bridging An Amp Make It Louder?
Yep, the distortion specs generally get worse with bridged amps — standard PA deal. Get a bigger amp. Note that a 50-watt amp is only 3dB louder than a 100-watt amp. You need ten times the power for an amp to sound twice as loud as a smaller amp.