Power and Weakness - Part 1

The February issue of the Audio magazine published a comparative test of five stereo amplifiers for PLN 20-24 thousand. zloty. They can already be classified as high-end, although the pricing framework is not regulated by strict standards. And although there are even more expensive amplifiers - especially the "preamplifier - power amplifier" combinations, among the integrated amplifiers they are the most advanced designs.

It is worth taking a look at them at least "shortcuts". What special solutions can be found on this ceiling? Where are their advantages over cheaper devices? Are they more modern, versatile, stronger, more solid or, above all, more luxurious, bringing with the price only a suggestion of quality?

An audiophile will protest at this point: the real quality of an amplifier or any audio device is not measured by the rated power, number of sockets and functions, but evaluates these issues based on the sound!

We won't argue with it at all (at least not this time). We will bypass the problem posed in this way, for which we are authorized by the purpose and place of this study. We will focus on pure technique, while discussing many general issues.

Digital inputs

With the growing importance of digital signal sources, more and more amplifiers are equipped with digital inputs, and therefore digital-to-analog converters. Let us explain, just in case, that in this sense we do not consider a CD player as a "digital source", as it is equipped with a D / A converter and can send an analog signal to the amplifier. So it is primarily about computers, laptops, servers, etc., on which we keep at least some of our music libraries more and more often. Their operation is possible by variously configured systems, but there must be a D / A converter somewhere in them - either as an independent device or as a system built into another device.

One of the possible and convenient solutions is to install a DAC in the amplifier, as an amplifier must in principle be present in every audio system, usually also acting as a "headquarters", collecting signals from various sources - so let it also collect digital signals. However, this is not the only and binding solution, as evidenced by this test (even too emphatic and not very representative for all amplifiers). As many as three out of five tested amplifiers did not have a DAC on board, which is neither a disgrace nor a reason for praise. It may result not so much from the "delay", but from politics and the assumption that the owner of a high-class system will be willing to buy a separate, adequately high-class DAC, not being satisfied with the circuit built into the integrated.

Arcam A49 - works only on analog signals, but is the most complete in this respect: it has a phono input (MM) and a headphone output.

Of course, you can see it differently, that is, expect a high-class amplifier to be as modern and versatile as possible. However, it depends on personal preferences and the concept of the entire system. The fact is that in amplifiers from the lower price ranges (apart from the cheapest ones), built-in drivers are even more common, so the first conclusion about the most expensive integrated amplifiers is that in this field they do not collectively demonstrate their advantage over cheaper models.

However, there are cases, and it happened also in our test, when the amplifier is perfectly equipped, using the latest digital circuits, which we will not meet (at least not now) in cheaper designs, even playing the role of a stream player (apart from converting digital to analog, being able to also unpack files, for which you need other layouts). So if we are looking for a very modern and "cool" amplifier, we will find it sooner on the higher price levels, but ... you also have to look for it there, not take it first from the bank - the price alone does not guarantee it.

Phono-stage

Another important piece of equipment in a modern amplifier is the turntable input (with MM / MC cartridges). For many years on the margins of interest, it regained its importance, of course, on the wave of the renaissance of the turntable itself.

Let us remind you briefly that the signal from MM / MC cartridges has completely different parameters than the signal from the so-called linear, for which the amplifier's "line" inputs are prepared. The signal straight from the board (from MM / MC inserts) has a much lower level and non-linear characteristics, requiring serious correction and gain to reach the parameters of the linear signal and can be fed to the linear inputs of the amplifier, or directly to its downstream circuits. One can ask why the phono-stages are not built into turntables (like D / A converters are built into CD players), so that a linear signal would flow straight from the turntable? Recently, some turntables with built-in equalization have appeared, but for years the standard has been established that the user has to take care of the correction himself; at the level he can and cares about.

The exact characteristics of the correction and amplification of the signal coming from the cartridge should be matched to its parameters, and these are not strictly regulated by standards (they are within wide limits). Most of the cartridges have parameters close to the values ​​that are well supported by popular circuits installed in integrated amplifiers (let's call it a basic solution). However, getting the best results, especially with high-end cartridges, requires both finer equalization adjustments and an adequately higher quality circuit overall. Such a function is performed by separate phono stages, in the form of independent devices, smaller and larger, often with the regulation of many parameters. Due to this concept of building a high-class system, in which vinyl records are to play an important role, the omission of the MM / MC correction circuit in the integrated amplifier becomes understandable, similar to the lack of a D / A converter circuit. It is because one should not expect - even from the best integrated amplifier - the operation of a very advanced and sophisticated phono-stage. It would be too expensive element of even a high-end design, unnecessary for the vast majority of users.

Hence, only one of the five tested amplifiers has a turntable input, and in the most modest version, for MM cartridges. In fact, such an input is enough for 95% of all analog users, and probably half of analog users in high-end systems - almost everyone wants a turntable today, but few people chase its sound at a high cost. Nevertheless, such a situation (only one out of five) is a bit disappointing. The basic MM equalization, even for a good start to playing with the analog, would not hurt any integrated amplifier, neither cheap nor expensive.

Gato Audio DIA-250S - modern, with a digital section (USB, coaxial and optical inputs), even with the addition of Bluetooth, but without phono input and headphone output.

Headphone output

It would seem that in times of enormous popularity of headphones, an integrated amplifier must have a proper output. And yet… Only two models had them. Here, the (weak) justification is again the concept of using specialized devices, in this case headphone amplifiers, which can provide a better sound quality than the modest circuit built into the integrated amplifier. However, many users of even very expensive systems, including amplifiers and loudspeakers, treat the headphones as an alternative, backup listening method, they do not spend large amounts on them, and even less do not intend to spend even more on a special headphone amplifier ... They just want to connect their headphones "somewhere". headphones (not including portable equipment).

Bluetooth

Bluetooth comes from a completely different parish. One of the five amplifiers is also equipped with it, and of course it is one of the two that have a digital section. In this case, it is not about "opening" to alternative sources of high-quality signal, but about modernity in the sphere of communication, although the quality is seriously limited by the parameters of the Bluetooth standard itself; It is certainly not an audiophile accessory, but you do not need to use it. And again - this type of gadget (although it may be tempting and useful for many) also appears in much cheaper amplifiers. So although still relatively rare, it is not the attraction for which we have to pay over PLN 20. zloty…

XLR sockets

Let us also mention the XLR type sockets (balanced), which are finally an element of equipment much more often found in more expensive amplifiers than in cheaper ones. All five models of the mentioned test have XLR inputs (also on "regular" RCAs), and three also have XLR outputs (from the preamplifier section). So it seems that for an amplifier for 20 thousand. PLN would be a handicap, the lack of such inputs, although their practical significance can be discussed. In none of the tested amplifiers the XLR sockets are part of the so-called balanced, allowing you to transmit and amplify signals in a fully balanced circuit. In the tested models, the signal supplied to the XLR inputs is immediately desymmetrized and further processed in the same way as the signals supplied to the unbalanced RCA inputs. So there are only advantages of the signal transmission in a balanced form (for which, of course, you also need a source device with an XLR output), which is less susceptible to external interference. However, this is of practical importance in the case of long connections and in an environment full of sources of interference - hence it is a standard in studio technology, while in an audiophile system it remains rather a "fancy". In addition, potentially lowering the quality, because additional desymmetrization circuits (signal after input) may be a source of additional noise. Be careful with the use of XLR inputs and do not assume that they will give better results.

Hegel H360 - wide possibilities of the digital section (accepts not only PCM via USB, but also Flac and WAV files via LAN). Unfortunately, also here there is neither a turntable input nor a headphone output.

Menu

Only in more expensive amplifiers we sometimes find additional functions, organized in the menu (along with a more or less extensive display), allowing the user to set the sensitivity for individual inputs, give them their own names, etc. However, such attractions are not necessary for everyone to be happy, nor are they permanent become mandatory even among top-class amplifiers. Hence, in the tested group, none had them, although as many as four had displays, but only to show basic information (symbol of the selected input, volume level, and in one case also the sampling frequency of the digital signal supplied, and in one case only the volume level, but with exceptional accuracy - up to half a decibel).

A better receiver?

Summing up the functional sphere, the tested amplifiers as a group did not impress with anything, taking into account their prices. Some of them are very basic, which, however, is enough for many audiophiles, whether they are building a "minimalist" system (e.g. with a CD player and loudspeakers only) or ready to buy specialized devices tailored to individual needs (DAC, phono-stage , headphone amplifier). The "depressing" of the discussed constructions can be added that today AV receivers can boast better equipment - and equipment in the range discussed here, not counting the rich additions related to signal processing and multichannel sound. They all have headphone outputs, all of them have D / A converters (because they must have digital inputs, including USB), most of them have digital inputs, only the worst ones do not even have a simple streaming player (LAN input), and many have also simple, but still - phono-stage ...

The fact that all the tested amplifiers are remotely controlled should not even be mentioned, because it is the basic thing today.

The final quality assessment is still open. In a month's time we will discuss the internal circuits and parameters of the most important section - the power amplifiers of these models. After all, as the name suggests, the amplifier is designed to amplify ...