Speaker / Amplifier Wiring Guide (2024)

DIY Audio Speaker / Amplifier Wiring Guide / FAQ

This is the resistance (impedance) presented by the speakersthat is seen by the amplifier. This can also include any crossoversand circuits connected to the speakers. When the load decreases, theamplifier's output increases. There is less resistance to the current,and the speakers can draw more power from the amp. Drawing more powerthan the amplifier was designed for will damage the amp.

Every amplifier is designed to handle a certain load. Forhome amplifiers this number usually starts with 8 ohms. With caramplifiers it is usually 4 ohms. All amplifiers can handle a higherresistance (load), but they will produce less output. Most qualityamplifiers can also handle a lower resistance. Most car amps canhandle a 2 ohm load, while some can go as low as 1/2 ohms.

First, make sure that the amplifier you have is bridgeable.If you try to bridge an amp that is not designed to be bridged, you candamage the amp. Basically, when you bridge an amp you use the +terminal from one channel and the - terminal from the other.The instructions that came with the amp should describe whichterminals to use. If not, look for some indication next to the speakerterminals on the amp. Sometimes, there will be lines connecting thetwo terminals you should use to bridge the amp, as shown on the right.

Theoretically, the output should be 4 times the powerof a single channel on the amp. A 50Wx2 amp bridged would act asa 200Wx1 amp. Unfortunately, you only see about 2/3 to 3/4 of thispower. This number is usually the same as the combined power ofthe 2 channels at half the load. Take the following example ofa 2 channel car stereo amplifier:

Unless stated otherwise, this amp would be unstable below 2 ohmsstereo or 4 ohms mono bridged. Attempting to use an amplifier atan unstable load will damage the amp.

Note that some high end car audio vendors intentionally underrate their amplifiersso that a 50x2 Watt amplifier @ 4 ohms really does produce 200x1 @ 4 ohms.This is done so that car stereo systems using their equipment can entercar audio competitions in a lower Wattage category, giving them an edge overthe competition. Meanwhile, many low end manufacturers overstate the powerof their amplifiers.

Wiring speakers in parallel is simple. Connect the + terminalon the amp to the + terminal on each speaker. Then do the same forthe - terminals. An example of this is shown below.

For two 4 ohm speakers, the total impedance would be 2 ohms.To find the total impedance of speakers in parallel, use the formulabelow.

It is not suggested that you run speakers in series.No two speakers will be exactly identical, even if they are thesame model from the same manufacturer. This means that theywill act slightly different from each other when presentedwith the same input signal. When wired in series, thesedifferences will cause distortion in the form of back EMF.

You can however run both coils of a DVC (Dual Voice Coil) speaker in series.The cone movement for both coils will be identical, and willnot cause distortion problems. This is the formula to calculatethe impedance of speakers in series.

A DVC speaker has 2 coils instead of one as in aSingle Voice Coil (SVC) speaker. Both coils have the sameresistance, and both coils MUST be hooked up to the samechannel of the same amp. You cannot run both coils off differentchannels of the same amp with the same signal, and you must useboth coils.

DVC speakers offer a lot of flexibility. Given 2 DVCspeakers, there are 4 different wiring methods. These 4 methodsare shown below for DVC drivers with 4 ohm coils.

There are even more possibilities when more than 2 DVC driversare used in a series/parallel configuration. For example, 3 DVCJL Audio 12W6 woofers at 6 ohms per coil can be wired into a single4 ohm load.

Bi-Amping refers to using different amplifiers (or different channelsof the same amp) for the low and high frequencies in the same speaker.On a 3-way speaker, usually the mid and tweeter are driven by one amp, and thewoofer is driven by more powerful amp. This allows you to purchase a highquality low power amp for the highs, and a more powerful amp for the lows.With the proper pre-amp you can also have more control over the bass output.On a 2-way speaker, the mid and tweeter are driven by different channels onan amp. This is usually done so that you can use an active crossover before the amplifier.

In DIY audio, bi-amping has even more advantages. Low pass crossoversfor woofers require very large inductors. These inductors are basicallyvery long coils of copper wire which can have a very high resistance.Using an active crossover before the amplifier removes the need for theseinductors. Bi-amping also removes the need for any circuits to fixproblems caused by different sensitivities or impedances between drivers.

If a speaker is capable of bi-amping, then the plate on the backof the speaker will have 4 binding posts: 2 + terminals and 2 - terminals.Both + terminals and both - will have a piece of metal connecting themtogether. To bi-amp the speaker, remove the metal piece. Then, use thetop 2 terminals for the high frequency amp, and the bottom two terminalsfor the bass amp.

Note: some professional audio equipment has 4 binding posts on theback. This is for ease of running multiple speakers in parallel.It is not for bi-amping, and the terminals should not be connected.

There is only a difference of .1db between 18 gauge and 12 gauge.Usually, 18 gauge wire is sufficient, except for high power (subwoofer)applications. Different wires will have different line capacitances, whichcan cause the wire to act as a low pass filter. This is one of the sellingpoints of high end cables.

You may be temped to use typical electrical wire instead of speakerwire to save money. The copper in electrical wire is of less quality thanspeaker wire, and will be prone to rust. Also, the insulation isn't of the samequality as speaker wire. These points are especially important when dealingwith car audio. Still, it can be done. It would be best to solder terminalsto the ends of the wire to prevent the rust problem.

Use the following table to determine what size power wireyou should use. Use the same thickness for the ground wire. Keepthe ground wire length to 1.5 feet or less. Any more could introducenoise in the system.