Comparison Pro-Ject Tube Box DS2 vs Pro-Ject Tube Box DS

The range of sound frequencies reproduced by the phono stage. When evaluating this parameter, it is worth keeping in mind several important points. Firstly, in this case, not the entire bandwidth is taken into account, but the range in which the uneven frequency response of the phono stage (according to the RIAA standard) does not exceed the value specified by the manufacturer. Secondly, the human ear is only able to perceive sound within the range of 16-20,000 Hz (in some people, up to 22,000 Hz). Ideally, the audio system should cover this entire range — otherwise, some of the low and/or high frequencies may be cut off; but to provide a wider range from a practical point of view does not make sense. Nevertheless, there are phono stages with quite solid performance, for example, 5 – 35,000 Hz. These specifications are usually a "side effect" of high quality audio circuits and are advertised by the manufacturer for promotional purposes.

Another point to consider when choosing is the frequency range of other components of the audio system. For example, it is hardly worth looking for a phono stage with a lower threshold of 16 Hz, if the power amplifier only supports frequencies from 40 Hz and higher.

As a note to this clause, the RIAA ripple present in the frequency range may be indicated. In most models, it is from ±1 to ±6 dB; the lower the value, the smoother the frequency response and the better the sound.

The coefficient of harmonic distortion provided by the phono stage when working with an MM type pickup (see "Intended use").

The lower this indicator, the less distortion the phono stage gives, the more reliable the output signal is. It is impossible to completely avoid such distortions, but it is possible to reduce them to a level that is not perceived by a person. So, it is believed that the level of harmonics of 0.5% and below is no longer audible even to a “trained ear”. However, it should also be borne in mind that the quality of the audible sound is also affected by distortion from other components of the audio system. Therefore, the harmonic distortion of the phono stage should not just be below 0.5%, but as low as possible. Values in hundredths of a percent are considered a good indicator, values in thousandths and below are considered excellent.

The input capacitance of the phono stage when working with an MM type pickup (see "Intended use").

This parameter determines compatibility with a specific pickup. The selection rule in this case is as follows: the total capacitance of the phono stage and connecting wires must correspond to the capacitance of the “head”, in extreme cases, at least not exceed it (otherwise the sound will deteriorate noticeably). In order to simplify this matching, it may be possible to adjust the input capacitance(see "Adjustments").

The coefficient of harmonic distortion provided by the phono stage when working with an MC type pickup (see "Intended use").

The lower this indicator, the less distortion the phono stage gives, the more reliable the output signal is. It is impossible to completely avoid such distortions, but it is possible to reduce them to a level that is not perceived by a person. So, it is believed that the level of harmonics of 0.5% and below is no longer audible even to a “trained ear”. However, it should also be borne in mind that the quality of the audible sound is also affected by distortion from other components of the audio system. Therefore, the harmonic distortion of the phono stage should not just be below 0.5%, but as low as possible. Values in hundredths of a percent are considered a good indicator, values in thousandths and below are considered excellent.

The gain provided by the phono stage when working with an MC type pickup (see "Intended use").

This parameter describes how much the signal level at the output of the phono stage increases relative to the level at the input. It is traditionally written in decibels; you can convert decibels into "times" using special formulas or tables. Knowing the gain, you can estimate the actual level of the output signal when using a particular pickup. For example, if the characteristics indicate 74 dB (5010x), and the pickup outputs 0.5 mV, then as a result, the signal level at the output of the phono stage without additional adjustments will be 0.5 * 5010 = 1005 mV, which is more than enough for direct connection to power amplifier (the minimum level for this is 150 mV). At the same time, we note that among MC phono stages there are models with a rather low gain, designed for specific application formats — for example, to work as a preamplifier for an MM phono stage.

The input capacitance of the phono stage when working with an MC type pickup (see "Intended use").

This parameter determines compatibility with a specific pickup. The selection rule in this case is as follows: the total capacitance of the phono stage and connecting wires must correspond to the capacitance of the “head”, in extreme cases, at least not exceed it (otherwise the sound will deteriorate noticeably). In order to simplify this matching, it may be possible to adjust the input capacitance (see "Adjustments").

— Level. The ability to adjust the level of the output signal (RMS). This function is used primarily to adjust the phono stage for an external power amplifier. Any such amplifier has a limit on the maximum input signal power, otherwise there is an overload with all the ensuing consequences (from sound distortion to electronics failure). This control allows you to avoid such situations: if the output level of the phono stage is too high, it can be lowered, and when connected to a less sensitive amplifier, it can be increased accordingly. Theoretically, due to this setting, you can also change the overall volume of the sound, but in fact this is highly discouraged, it is better to use controls specially designed for this.

— Input sensitivity. The ability to change the input sensitivity of the phono stage. For details on input sensitivity, see the relevant paragraphs; here we note that ideally its value should be the same or slightly lower than the input signal level. For example, for a 4 mV MM cartridge, a corrector sensitivity of 3 mV or 4 mV is allowed, but 5 mV will no longer be enough. Conversely, too low a sensitivity threshold can lead to system overload. This setting allows you to set the optimal value for a particular pickup.

— Input impedance. This adjustment allows you to select the optimal ratio between the output impedance of the pickup and the inp...ut impedance of the phono stage. For details on input impedance, see the corresponding paragraphs. Also note here that this function is especially important for MC cartridges (see "Intended use"), because. MM-heads usually have a standard resistance of 4.7 kOhm and do not require tuning.

— Input capacity. The ability to change the input capacitance of the phono stage to adjust it to other components of the system — in this case, the pickup and connecting wires. Recall that, ideally, the total capacitance of the corrector and wires should be equal to the capacitance of the "head", otherwise an unpleasant coloration and additional distortions may appear in the sound. Without adjusting the input capacitance, achieving this match can be very difficult. This feature is especially relevant for working with MM cartridges.

— Balance. Ability to manually distribute the volume level between the right and left stereo sound channels. In this way, you can "shift" the audible sound to the right or left as you wish. In phono stages, this function is useful primarily because on worn and/or poor-quality records, the balance is often knocked down, and in order to bring the sound back to normal, you have to resort to manual tuning. This setting can also be useful in other cases, for example, if the acoustics of the room itself lead to a balance shift. At the same time, we note that balance control is not a key function for phono stages: firstly, it can also be provided in other components of the audio system (receiver, power amplifier); secondly, additional adjustments complicate the device and increase the likelihood of sound distortion. As a result, this feature is practically not found in high-end models.

— Phono. Input for connecting a pickup; available in all phono stages by definition. At the same time, different types of connectors can be used for this input in different models. The simplest option is standard RCA ("tulips"); such connectors are relatively small, but not very resistant to interference, they are used mainly in entry-level and inexpensive mid-level models. A more advanced option is XLR input, a characteristic round plug with three pins and a round rim. It usually works in a balanced connection format, in which the wire itself plays the role of a noise filter; this allows you to achieve high-quality clear sound even with long cable lengths, which is especially important for professional audio equipment. There are also models with both types of connectors.

— RCA. Line input, made in the form of a pair of RCA connectors (for left and right channels). By themselves, the line inputs are used to connect external analogue signal sources — for example, a CD player, tuner, etc. Initially, working with such equipment is not the main task of phono stages, therefore this interface is rarely found in them. However, in some cases, it may come in handy: for example, if there are digital outputs (see below), the equalizer can be used as an analogue-to-digital converter for an external audio device. Specifically, RCA, also known as "tulips", are very popular in stationary audio equipment, but they have a relatively low noise immuni...ty (lower than that of the same XLRs).

— XLR. In this case, we mean a line input using a pair of XLR connectors. For more information about the line input and the XLR connector, see above (items "RCA" and "Phono" respectively). Here it is worth saying that the presence of linear XLR is a sign of a professional-level device.

— Mini-jack 3.5 mm. Line input using a standard 3.5 mm mini-jack. For line interface in general, see "RCA" above. And the mini-Jack standard is notable for both its small size and the fact that it allows you to transmit stereo sound through a single jack, while the RCA and XLR interfaces require a pair of connectors, one per channel. At the same time, it is inferior to larger connectors in terms of reliability and connection quality, moreover, it is designed more for portable devices like pocket players. Therefore, such inputs are found mainly in entry-level phono stages.

— RS-232. Also known as a COM port. Service connector used to connect a phono stage to a computer and control settings via a PC. Such control can be more convenient and give more opportunities than your own panel or corrector console.

— Trigger. Service input designed to turn on the phono stage by a signal from another device with a trigger output — for example, an amplifier. This feature facilitates the “waking up” of the entire audio system: the corrector does not need to be turned on separately, it is enough to turn on the control device.

- RCA. Most often, in this case, a linear output is meant in the form of a pair of RCA connectors (“tulip”) - one for each stereo channel. This output is designed to transmit a line-level audio signal to other system components - for example, an audio receiver or active speakers. The RCA connector itself is considered standard for a linear interface; inputs of this type are available in most stationary audio devices.

- XLR. Another type of line output (see “RCA” above), in this case, built on XLR connectors. The main advantage of this interface is that it provides the so-called. balanced connection, allowing you to work with long cables without compromising sound quality. In addition, the connectors themselves provide a tight connection and are equipped with latches for additional reliability. On the other hand, they are noticeably larger than the same RCAs, and therefore are used mainly in professional phono stages, for which the mentioned advantages are key.

- USB (type B). Output for connecting a phono stage to computer equipment. The presence of this connector allows you to digitize audio compositions from records and other media (for example, from tapes and reels) and save them in computer memory for further processing or for transferring to a smartphone/MP3 player, for example.

— Coaxial S/P-DIF. Audio output...for digital sound transmission via RCA connector. This connector should not be confused with a “regular” linear RCA - in this case, one socket and a fundamentally different signal transmission format are used, it is also advisable to have a special shielded cable. In terms of capabilities, the coaxial interface is similar to the optical one and differs from it, on the one hand, in being more sensitive to interference, and on the other hand, in being a more durable and unpretentious cable.

— Optical. Another type of digital audio output that uses, as the name suggests, a fiber optic cable. The main advantage of this connection is its complete insensitivity to electromagnetic interference. On the other hand, the cable itself is quite delicate and requires careful handling.

- On headphones. Specialized output for connecting headphones directly to the phono stage. Typically uses a 3.5 mm mini-Jack or 6.35 mm Jack connector. Note that direct connection of “ears” in this case is provided not so much for ordinary listening to music, but for special tasks. For example, a DJ playing a set or a sound engineer recording music from a record to an external device can use headphones to constantly monitor the sound entering the phono outputs.

- Trigger. A service output that allows the phono stage to be used to automatically turn on other components of the audio system. When “waking up,” the corrector sends a control signal through this output, and devices connected to it with trigger inputs turn on automatically. This eliminates the need to enable each component separately.