How to Solder Wires to Car Stereo


All the electrical connections in car stereos must be long-lasting, secure, accurate, and clean. There are several ways to connect wires in the car audio, like soldering the wires, use crimps or posi locks, or even directly connect the wires with tape.

According to the experts, and I fully agree with that statement, soldering is the best way to make electrical connections for car audio, but how do you solder wires to the car radio? Let’s find out.

As a general rule, to solder wire with the stereo, you must first remove the insulation from the wires ensuring they are clean. Next, join both wires together and place the solder on top of them. Finally, touch the solder with the soldering iron for a few seconds until the solder melts.

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Tip: Some of the electronic components of car audio are very small. Therefore, it becomes difficult to solder them with the naked eye. For a higher level of precision, use a soldering magnifying glass. 

My favorite magnifying glass comes with a magnetic stand and a light, so you don’t have to hold the wires and worry that something will misalign or move.

If you want to make your soldering a simple task, click the above link and check the latest price of this fantastic tool on Amazon.

In the article below, I will detail the soldering process in the car audio.

What is soldering? 

Soldering is the process of joining two items or metals by putting molten solder into the joint.

Solder is a wire made from an alloy of tin and lead which acts as a filler between two items. The solder is melted beyond its melting point by using hot iron above 600 degrees Fahrenheit and then cooled, thus creating a solid metallic connection. 

Unlike welding, soldering does not melt the joining metals. Therefore, soldering is used not only in car audio but also in different industries like making jewelry, general automotive repairs, connecting electronic components, etc. 

How to Solder Car Stereo Wires Together?

The soldering process, although simple, requires few steps to make sure soldered wires have a robust connection:

Prepare the Car Radio Wires for Soldering

Preparation is the first step and involves cleaning the wires that you are soldering so that they are free from any rust or oxidation:

  • Remove the insulation up to 0.25″ (5mm) from the end of the wire only with a good stripper. First, make sure that the soldering iron tip is clean and free from any contaminants.

To do that, you can use sandpaper to clean the tip or simply rub it with a cement wall.

  • Now tin the end of the soldering wire with solder. Tanning improves the conductivity of heat of the soldering iron tip and reduces oxidation. 

Heating the Wires and Soldering

When you have cleaned all surfaces that have to be connected, the next step is actually to start soldering:

  • Take two soldering items and join them together.
  • Hold the soldering iron at the joint for a few seconds and make sure not to overheat the wires.
  • Now simply move the soldering iron away from the joint. Avoid putting stress on the joint and let it cool itself.

If you notice any bubbling, then remove the solder and let the joint cool before starting again.

What Are the Types of Equipment Needed for Soldering Car Stereos?

To make precise and strong soldering joints, you need high-quality soldering equipment. Although a piece of quality equipment may be more expensive, investing in good tools saves a lot of time and effort afterward.

You need the following things for soldering car stereos. If you do not have any at your garage, I added the links to the items that I use, and I am happy with the quality.

All of these items are available on Amazon, so if you need any of them, click the links below and check the most recent price:

Soldering Iron

Soldering iron is used to melt solder. It is in the form of a pen, and an electrical plus is attached to one side of it.

When turned on, it gets heated up, and now you can use it to melt solder. You can use a soldering iron holder to hold the hot soldering iron. 

Although there are many available and can be found everywhere, my favorite is the YIHUA 926 III digital soldering station. It does regulate temperature by knob, and you can use two “helping hands” to place the wires for a more precise connection.

Soldering Flux Paste

Soldering flux is used to clean metal parts before soldering. This chemical agent removes oxides from metal which in turn leads to solid solder joints. 

You can do soldering without flux, but the joint will not be as strong. The soldering paste I use is the Delcast Rosin.

Solder

Solder acts as a filler between joining metals. Therefore, the solder should have a lower melting point than joining metals because it will form a strong connection. The solder I use is the HGMZZQ 60/40 Tin Lead Solder Wire.

Should You Solder Car Stereo Wires?

To make professional and long-lasting joints, you should solder them with precision, and these types of joints are hard to get damaged. In addition, soldering, if done correctly, ensures maximum signal transfer.

It is mandatory to cover the joints with heat shrink tubing to avoid short circuits, among other joints. Many people tape the joints, but taping is not a long-term solution for insulation as it melts down in hot climatic conditions. 

If you do not feel comfortable with soldering tools, do not worry.

You can use advanced soldering equipment like a soldering stationsoldering gunsoldering pencil that can be adjusted to your personal needs and help make the soldering more enjoyable.

If you are inexperienced and have not done soldering before, another option to connect stereo wires is crimping.

For car stereo, I use 18-gauge crimp connectors that are standard, except for the thick speaker wires, but for these, it is always better to run one wire through the whole distance.

Crimping connectors come in various types, like crimp caps or butt connectors. For proper crimping, you will also need a crimping tool and a wire stripper.

The preparation process for crimping is the same as for the soldering – both wires have to be stripped and clean for better connection. The whole crimping process does not take more than a minute. 

Is Soldering Car Audio Better Than Crimping?

To repair car stereos, I believe that one must know how to solder two items because the electronic components in stereo are small and have to be soldered carefully not to cause damage to the entire radio.

Both soldering and crimping have their advantages and disadvantages. To find out which connection type is better, let’s explore them. 

What Are the Advantages of Soldering? 

  • Soldering is a traditional and economical method because you don’t need specialized equipment. You can terminate any wire size with the same soldering tools. 
  • Soldering connections ensure that there is the proper passage of electrical signals. 

What Are the Disadvantages of Soldering?

  • Soldering is more time-consuming, and it takes some experience to precisely solder joints. 
  • Soldered joints are more sensitive to corrosion if not done correctly. 
  • In soldering, we are dealing with high temperatures, which can result in the melting of connectors and wire. 

What Are the Advantages of Crimping?

  • Crimping is less time-consuming, fast, and simple. 
  • Crimping connections are protected from moisture and dirt. 

What Are the Disadvantages of Crimping?

  • It can cause problems if the joint is not crimped correctly. 
  • Crimping requires different sizes of crimping tools for different wires. So crimping is more expensive than soldering. 

Many professionals combine these two methods. First, they take the ends of two wires and solder them separately. After this, they put the soldered end of wires into caps and crimp them using a crimping tool.

What Type Of Solder Should I Use for Car Audio Wiring?

As solder is an alloy, several varieties are available in the market based on different combinations of metals like led, tin, and flux.

For car audio wiring, you should use flux core soldersHGMZZQ is the best flux core solder with a 60/40 ratio of metals – lead and tin. It is reliable, and after soldering, it does not produce any residue. 

To explain this choice, let’s look at different types of solders available in the market. 

Lead Based Solders

Lead-based solder is the most popular solder type in the electronic industry. It is a combination of 60% tin and 40% lead.

The percentage may vary between the producers, but the most common combination is 60/40. The melting point of lead-based solders ranges from 356-374 °F (180-190 °C) 

Using a combination of lead and tin is beneficial because tin has a lower melting point, and lead prevents the formation of tin whiskers in the wires.

Lead Free Solders

Lead-free solders became popular when some countries banned the presence of lead in consumer electronics. In lead-free solders, the tin is added to metals like nickel or copper to avoid tin whiskers.

Lead-free solders have a higher melting point than lead-based solders. 

Flux Core Solders

They are also called rosin flux-cored solder because these solder wires have flux in the center for better soldering results.

Both lead-based and lead-free solders can be flux core solders having flux in the core. 

As we know, flux is used for cleaning the surface of PCBs to prevent oxidation. Therefore, these solder wires have flux built-in, leading to the joint’s high precision.

That’s why you should use flux-cored solders for car audio wiring. The disadvantage of these types of solders is their higher price in comparison to the previous ones. 

Can You Overheat Wires When Soldering?

You can overheat the wires when soldering, and when you do, the wire will melt, and the whole soldering point will be entirely damaged, so you have to be careful. 

The most common melting point of all the soldering wires is around 361°F (183°C ), and it becomes liquid at 374°F (190°C). 

With practice, you will be able to judge the amount of heat needed for perfect soldering. Before soldering actual speaker wires, practice joining spare wires with an extra PCB board

What Type of Solder Do I Need for Speaker Wires?

For soldering speaker wires, the melting point of solder should be lower than the melting point of speaker wires. In addition, it should be a resin core type, and for safety purposes, you can use lead-free solders.

Here is the list of the top 5 soldering wires that you can use for speakers. Although all are very similar with the melting point, and all come in various wire diameters. There are slight differences in the composition, and the only significant difference is in the Flux Content.

Soldering Wire Name Wire CompositionFlux Content
MAIYUM 63-37 Tin Lead Rosin Core Solder WireTin (63%) and Lead (37%)1.80%
HGMZZQ 60-40 Tin Lead Solder Wire With RosinTin (60%) and Lead (40%)2.20%
SONEAK 60-40 Tin Lead Solder Wire With RosinTin (60%) and Lead (40%)2.00%
WYCTIN 60-40 Tin Lead Rosin Core Solder WireTin (60%) and Lead (40%)1.80%
Kester 24-6337-0027 Solder RollTin (63%) and Lead (37%)3.30%
Soldering Wires Comparison

Does Solder Affect the Sound in Car?

Yes, the quality of soldering connections affects the sound of car stereo significantly.

As long as the soldering is done correctly, it does not affect the sound, but it degrades the sound quality of speakers if done incorrectly. 

This is because the wires’ resistance is directly proportional to its length and inversely proportional to a cross-section area. It also depends on the material of the wire, whether you solder OFC or aluminum wires.

If the soldering joint is too long, it offers more resistance to the sound signal, and in effect, it decreases the quality of sound. So keep the soldering joint length as small as possible. 

Moreover, the resistance of the soldering joint is bigger than in the wire. Therefore if soldering is done improperly, it increases resistance which lowers sound quality. 

In general, I can tell that the effect of soldering flux affects the quality of sound, as follow:

  • With too little soldering flux used, it is harder to solder the wires, and also, the sound is harsh. 
  • Using too much flux, on the other hand, makes the sound more boomy and heavy.

Another thing is that the age of soldering joints has a significant impact on sound quality. As the joints get older, the quality of sound also degrades. You may find that especially in older cars with aged audio installation.

So, you need to do soldering like an expert or hire a sound technician. 

Conclusion

Soldering a car stereo requires expertise, and you can master this skill through practice. Before soldering car stereo parts or car speaker wires, you should try soldering toys or other PCB boards. 

The choice of equipment used for soldering plays an essential role in enhancing the quality of your joint. So, choose your gear wisely. 

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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