How to match electrolytic capacitors and film capacitors

Capacitors are common electronic components, and a wide variety of capacitors are available on the market for different applications. To enhance understanding of capacitors, this article will explain the compatibility of electrolytic and film capacitors.

In an electrical appliance, especially in a CD, capacitors play a huge role. Because in audio equipment, the amount of capacitors used is quite large, especially in CDs. Many integrated circuits are necessary and there is almost no room for choice. Unlike the amplifier tubes in the power amplifier, there are many options. Therefore, in a CD, once the integrated circuit is fixed, the only options you can choose are capacitors and resistors. Since resistors have a much smaller impact on the sound than capacitors, capacitors are our top priority. Of course, the smaller role of resistors is also relative. For example, the input and output resistors have a greater impact on the equipment, while the other resistors have a smaller impact.

Since a large number of capacitors are needed in a device, a series of questions arise: with so many brands available, which one should I use? And how should I pair these capacitors? Few designers of domestic equipment pay attention to these issues, especially the latter. This is a key reason why, despite having comparable chips and amplifiers, domestic equipment often sounds noticeably inferior to foreign equipment. My experiments have shown that if your CD player uses a DAC filter chip like the CS4390, CS8412, CS8414, PCM1732, PMD-100, or PMD-200, and an op amp no less powerful than the OPA2604, re-pairing your capacitors will significantly improve the sound, easily surpassing the original. Below, I'll use a CD player as an example to illustrate capacitor selection and pairing.

To meticulously match the capacitors in your instrument, besides having a sufficient supply of high-quality capacitors, another crucial prerequisite is a keen ear. Instruments can provide very limited assistance in this process, especially with film capacitors, where standard instruments are almost ineffective. This is where the sound is completely determined by your own evaluation criteria and ear. When pairing capacitors, first fix the larger capacitors, then add the smaller ones. You may have several brands to choose from for each position, and there's no better way to choose than through patient comparison. After you've fixed each capacitor, you must reverse the process: remove the smaller capacitors you added, starting with the smallest and ending with the largest, to see if the sound changes. Because we're recombining capacitors in multiple locations, there's a chance that the sound changes will overlap, making this final step essential.If the sound doesn't change after you remove a capacitor, it means your modifications are overlapping and the modifications you've made elsewhere are already making the difference to the capacitor you removed. In this case, the capacitor can be removed. If the sound deteriorates after removing it, it means the capacitor is essential and should be retained. Also, it's important to note that after installing a capacitor, the sound will subtly change over time. Generally speaking, a capacitor that sounds rough at first will become thinner, and a thinner capacitor will become rougher after a while. So don't jump to conclusions based on a simple listen after installation; be patient and let it burn in thoroughly.

Whether designing equipment or modifying a machine, it's crucial to understand that everything we do is aimed at restoring the signal. Modification is only a necessary measure when the signal cannot be fully restored. Therefore, when modifying a machine, it's crucial to follow this principle: the farther away from the signal's final output, the more important it is to consider restoration. Closer to the output, however, the signal has already inevitably distorted and deformed, so more consideration should be given to modification.

There are three main areas where capacitors are needed for CDs: the filter capacitors for the turntable's power supply, the D/A converter and subsequent op amp filtering, and the output coupling. The first section is farthest from the final signal output, while the third section is closest. Therefore, when it comes to the turntable's power supply, focus on restoration rather than modification. Among the high-end capacitors currently available, the ROE electrolytic capacitors are the least likely to modify the sound, so consider using them instead of Rifa or Sibi.We all know that capacitors have a frequency-dividing function. Different capacitance capacitors allow signals of different frequencies to pass through better. Generally, large capacitance capacitors are suitable for low frequencies, while small capacitance capacitors are suitable for high frequencies. Common equipment often uses two 3700u capacitors in this area, and some use 4700u. All signals pass through these two capacitors, which results in relatively smooth low-frequency signals, but attenuation of high-frequency signals. Therefore, we need to connect two small high-quality film capacitors in parallel to provide a direct path for high-frequency signals.

To ensure that each frequency band has a dedicated channel for signals, filter capacitors with varying capacitance should be used. For example, capacitors of varying capacitances from the same manufacturer, model, and voltage can be connected in parallel. Specific options include 2200u, 1000u, 680u, 470u, 220u, and 100u. For capacitors below 100u, film capacitors can be considered. However, it's currently difficult to find such a comprehensive range of ROE capacitors on the market, so a combination of 2200, 1000, and 470u is recommended. Note that two 1000u capacitors should be used to achieve a capacitance of approximately 5000u per channel. If the capacitance is too small, the machine will have trouble reading the disc and may experience disc pickiness.To protect high-frequency signals, high-quality film capacitors are essential. We recommend ERO film capacitors in 10u, 1u, and 0.1u configurations. If the sound feels too bright, you can also add a Sibi capacitor with a capacity of 1-2u. Don't deviate too much from this value. Regardless of whether you add a Sibi capacitor or not, the smallest capacitor must be ERO. This significantly impacts the soundstage. You don't need to go through a complicated combination of multiple capacitors at this stage; as long as the sound is good, the fewer the better.

Next comes the digital-to-analog conversion. Regardless of the method used, the signal will be significantly distorted at this stage, so modification is essential. Of course, while this modification is important, restoration must also be considered. Therefore, the only filter capacitors available are RIFA capacitors. Since RIFA capacitors are relatively easy to find, we can select from the same series, arranging them from large to small. We also need to pair them with film capacitors, which effectively improve linearity during filtering.However, film capacitors can also affect the sound quality. For example, the tube flavor of Rifa capacitors is very rich, but after you use film capacitors, the tube flavor will be reduced, and the larger the capacity of the film capacitor, the weaker the tube flavor, while at the same time the sound layering becomes richer and richer. According to my test results, after using too many film capacitors, the treble will be affected to a certain extent, not as brilliant as the original Rifa electrolytic, but the texture and brightness of the bass are very good. As for how to do it, it depends on your taste. I suggest that you can use electrolytics in 47u. For smaller ones, it is better to use film capacitors. You can use 22u, 10u, or 4.7u Rifa film capacitors. These capacitors are in large quantities on the market. The 2u capacitor below is very important. It is best to use the Rifa aluminum shell capacitor I mentioned in the article above. It has a great impact on the sound quality. Especially when you use film capacitors to deteriorate the treble, using this Rifa capacitor is even more necessary.For capacitors under 2U, you can pair ERO and Sibi, with Sibi for larger capacitors and Ero for smaller ones. You can also pair Sibi + Ero + Sibi + Ero, gradually decreasing in capacity. However, use Ero for the smallest capacitor. If conditions permit, it's best to coat this final capacitor with copper foil. At this level, keep the total capacitance below 4000 Ω. Too much capacitance will make the sound too heavy and lacking in spirit.

In addition to the filter capacitors, a number of electrolytic capacitors are used in this area. Sanyo solid capacitors are recommended for those under 16V and under 47U. They work very well, but the downside is that they don't withstand high voltages and have very small capacitances. 25V, 100U capacitors are hard to find. For other electrolytics, try Rifa capacitors. Rifas are very effective at eliminating digital noise, so use them as much as possible. Next, we move on to the coupling capacitors. Coupling capacitors are generally considered a priority on most devices, and the electrolytic capacitors used here are often significantly higher-end than other types. However, I've found that even high-end electrolytics still don't perform as well as film capacitors.The main difference is that electrolytic capacitors produce relatively high levels of acoustic noise. It's recommended that you use film capacitors with all coupling capacitors. The typical coupling capacitor capacity for multi-bit machines is under 4.7u, while for single-bit machines it's around 100u. Most CDs on the market today are around 100u. You can pair them up like this: start with four 22rifa film capacitors. Once you use these capacitors, you'll immediately notice a significant boost in low-frequency impact, especially in bass texture. For example, the subtle stickiness between the hammer and drum skin, which we often talk about, will become audible.The overall soundstage is quite clean, though the only drawback is the reduced high-frequency extension. Don't worry, though; let's tackle the treble. We'll use an Ero 4.7u film capacitor to restore and refine the mid- and high-frequency ranges. Then, we'll use the Rifa 2u aluminum-shell capacitor we've mentioned repeatedly. This capacitor is crucial for the treble, not only compensating for the treble loss caused by the 22u film capacitor, but also ensuring a vibrant and vibrant treble.It is best not to use other types of capacitors for this purpose. I have used quite a few capacitors for testing and found that none of them can replace this capacitor. Then use a 1u Sibi capacitor below, which can make the sound looser and more natural, greatly reduce the traces of artificial modification, and make the sound of the machine appear more lovely.Generally speaking, this capacitor cannot be replaced with another manufacturer's capacitor. Immediately following the Sibi is an Ero 0.47u capacitor, properly contracting the Sibi to achieve more accurate high-frequency soundstage positioning. Each step of the release must be followed by a contraction, which is crucial during setup. Generally speaking, this capacitor is the complete pairing. If the treble isn't quite as satisfying, add a 0.22u Ero capacitor. Note that the final capacitor is still Ero and still uses copper foil as a sheath.

The total capacitance of the coupling capacitor should not exceed that of the original capacitor. A larger capacitance will result in a dull sound. A slightly lower capacitance is generally better, but not too low either. Some literature suggests that using film capacitors instead of electrolytic capacitors as coupling capacitors requires only two-thirds of the electrolytic capacitance, or even less. I suspect this listener's filter capacitance was too large, forcing them to reduce the coupling capacitance. If your coupling capacitance is large, you can reduce the filter capacitance, and vice versa. The two can complement each other to a certain extent.If you're using RIFA for filtering, a larger filter capacitor will give you richer midrange harmonics and a stronger tube-like feel. A larger coupling capacitor will give you a more powerful and textured bass. However, finding the perfect balance between the two is incredibly difficult. Based on my experiments, it's best to keep the coupling capacitor close to its original capacity. First, set the coupling capacitor as described above, then adjust the filter. Using film capacitors for the coupling capacitor improves the sound quality and makes adjusting the filter capacitor much easier.

After using this method to refurbish your machine, the sound will be truly beautiful, and your machine will have a truly luxurious feel! However, a new problem arises: space. The 4700u capacitors used in CDs are typically no larger than a thumb, while 3300u capacitors are smaller. The 100u coupling capacitors are only slightly larger than a kernel of corn. Following my method, you'll need to add three circuit boards, reducing the size of two kernels of corn to a single circuit board about the size of a palm. This increases the space requirements. It's recommended to install the new circuit boards as close as possible, building a two-story structure. Cover the new circuit boards with copper foil.If you want to use the idle space of the machine for installation, the newly added board may be far away from the original installation location of the capacitor. At this time, it is strongly recommended that you remove the capacitor with the smallest capacity on each board and install it near the original installation location of the capacitor, otherwise it will affect the high frequency.

Matching capacitors is a very time-consuming and expensive task. I hope this article can help you and save you some energy and money.