It seems that the threshold has long been passed. The threshold after which the inscription on the “Made in China” label no longer has any emotional impact on a person. Then there could be an approving text, which would say that even the bitten apples are the idols of millions - and they are made in China.
But today the case is a little different: this product is not only made in China, but also comes from the Middle Kingdom. “Designed and made in China” - surely someday these words on the label will no longer confuse anyone. But let's move directly to the object - this is the Cayin CS-100A amplifier using EL34 tubes.
Cayin brand products have long been popular, although by modern standards it is still quite young - founded in 1993. But we know at what pace scientific and technological progress is accelerating in the country, which has become a haven for the production and assembly of the vast majority of modern technology of all directions. So in this case, most likely, a year can be counted as two. Especially considering that Cayin is a brand of a subsidiary of the state aerospace corporation, created specifically for the development of high-end and high-end in its home market.
Of course, in the history of Cayin there was everything: amplifiers, DACs, power supplies... I’m sure you know what Cayin N6 and its successor Cayin N6-2 are. These portable Hi-Res players made a splash back in the day—and still do.
Now the brand is doing well: it has its own factory, and a full cycle one at that. There, transformers are wound, amplifiers are assembled by hand, and Karl and Marx are honored. Maybe. And they don’t need resources with such a parent corporation.
↑ Amplifier circuit
I chose the scheme “according to Manakov”:
I started, as always, by assembling the case. I will not dwell in detail on the technology of its manufacture; I spoke about this in detail in my other article on Datagor. As always, I assembled the amplifier on a separate metal chassis mounted inside the case on stands. This allows you to minimize the number of holes in the top cover of the amplifier. To make the case, I used an aluminum corner 20x20x2.0, duralumin sheets, 1.5 mm thick (for the top cover) and 1 mm (for the bottom cover and chassis). The paneling is made of beech, painted with stain and varnish in several layers. Dural is spray painted. This time I used ready-made caps for transformers, having ordered them in advance.
All mechanical work was performed on the balcony. I used a folding workbench, a drill, an electric jigsaw, a disc sander, a hand router, a Dremel and a professional miter box. Over the years of amateur radio, I have acquired a lot of good instruments. This allows me to complete many complex jobs much faster and more accurately. But most of this work can be done manually. With more effort and time, of course.
Radio components, in general, are the most common. I used capacitors K78-2 and K71-7 as isolation capacitors, everything else was a “hodgepodge”.
I bought EL34 lamps already selected in the “four”.
Power transformer: torus, 270Vx0.6A - anode secondary, 50Vx0.1A - bias secondary, 2x6.3x4A - for filament power supply.
Lighting the lamps
Everything happened quite quickly: the Cayin CS-100A was only a little slow after turning on, but very quickly came to its senses and, by clicking the relay, let us know that it was ready to work. Here I came across a remote control, which is made very well. There is metal everywhere, even on the buttons, and milled ends. This is truly a pleasure to hold in your hands.
Its functions are the bare minimum: change the volume, select a different input and... select the operating mode of the amplifier. Triode or ultra-linear - each of these modes has its own personal indicator on the front panel and its own personal sound. It's like having two different DACs in the system with the ability to change the sound using the remote.
I must say that this game is addictive. I would like to listen this way and that way. In the end, we can completely forget about the reason why we lit the lamps. Therefore, at the first stages of listening, the triode and ultralinear modes were switched until their genre affiliation was identified.
But before this huge secret is revealed, we need to briefly introduce the remaining components of the system: the Arcam CDS50 universal source and the Monitor Audio Gold 100 bookshelf speakers.
Now let's go!
↑ I made some changes to the diagram
Instead of a 6N9S lamp, I first arrogantly tried to use a 6N2P (EV). The result was... a “dead” sound. Not that! Not at all. And the holes for the panels are drilled, and the chassis is already installed. What to do? I started looking for a replacement for this lamp. It turned out that the ECC85 lamp (according to reviews from colleagues on the forums) is “very good.” I bought a pair. Changed the values of the “piping” resistors. The anodes have 36 kOhm (2W), the cathode resistors have 180 Ohm, and the bias is about 1.5 V. I’ll say right away that this has greatly benefited the sound!
↑ Electronic throttle
Instead of conventional chokes, I used an “electronic throttle” assembled according to this scheme:
I note that the actual voltage drop across the inductor is about 20-25 V. Take this into account in your design! The inductor circuit board is also included.
↑ Input selector
I organized an input selector on three TAKAMISAWA relays (according to the number of inputs), which switch a low-current signal. I didn’t make a printed circuit board for the switch; I assembled everything on a breadboard.
The scheme is something like this:
For the sake of beauty, I installed dial indicators. The indicators are controlled by the domestic K157DA1 microcircuit. The circuit has been converted to single-pole power supply, a printed circuit board is included.
The switch, K157DA1 microcircuit and indicator backlight diodes are powered from a single stabilized voltage source.
Classic again
So, we have before us a completely classic layout for a tube amplifier. And you can’t really go crazy with the design with this arrangement. However, there are a couple of lamp devices that are fun to look at, but simply expensive to buy. So the classic manufacturers are left with only anodized aluminum and blue paint with a metallic effect.
The CS-100A has a front panel made of anodized aluminum, which is literally replete with all sorts of toggle switches and indicators. The Alps potentiometer and input switch are understandable and familiar to everyone. Miniature diodes to indicate the selected input and operating mode are quite a solution. But here are four toggle switches for working with adjustment of bias currents...
Between the lamps there is a window with a dial indicator for monitoring the level of currents, and on the sides of the case there are four more recessed screws, with which you can pass the time by adjusting these same currents that have shifted somewhere...
Perhaps, for lovers of tube technology, this procedure is akin to setting up a tonearm for vinyl guides. If so, then all questions are removed automatically. Although, of course, the CS-100A could also automatically adjust the currents for the lamps... But that’s probably a completely different story.
With switching, Cayin engineers can be said to have hit the nail on the head. Although there is not much of it, and there are no balanced inputs, there are three line inputs, one input for sending a signal directly to the power speaker and an output to the subwoofer.
The Pre-In input feeds the signal directly to the power amplifier - this function is very useful for integration into a home theater, and for connecting to various sources that already have their own pre-amplifier.
The Cayin CS-100 A also has terminals for connecting speakers with impedance of both 4 Ohms and 8 Ohms. Three pairs of terminals look elegant. If you look into the circuitry, you can find everything that Chinese engineers with access to the most modern technologies are capable of.
For starters, there is a so-called “soft start” that will protect your lamps from the negative effects of high currents at startup. A very useful feature that will delay the adjustment of the bias currents for as long as possible.
Otherwise, the manufacturer claims that the entire circuit is implemented at a high level: almost everywhere there is surface-mounted installation with silver conductors and only high-quality capacitors and resistors made of carbon film.
↑ Amplifier settings
Here I fully quote Manakov:
The first stage is adjusted by a drop in DC voltage of 1.8-2 V at the control point on the cathode resistor by selecting the value of this resistor. The second stage is adjusted by the DC voltage drop at the control points on the cathode resistors of the 1 Ohm lamps of the output stage, by adjusting the bias voltage on the control grids of these lamps. The voltage drop across them should be 0.035-0.04 V, which corresponds to an anode current of each lamp of 35-40 mA. The most “economical” ones can reduce the currents of the output lamps to 25-30 mA. I think it is unnecessary to remind you that all these settings need to be made in silent mode. By alternating voltage, the phase inversion stage is adjusted by applying an alternating voltage of about 0.5 V with a frequency of 3 kHz to the grid of the left triode of the 6N9S lamp; a trimming resistor in the grid circuit of the right triode of the lamp sets the same alternating voltage on the anodes of the lamp. In this case, you need to use a voltmeter with an input resistance of at least 1 megohm.
I will only add that when using EL34 lamps, the quiescent currents can (and should!) be safely raised to approximately 56 - 60 mA, with an anode voltage of about 350 V.
The lamp lights up!
Come on, tell me how to choose genres for a lamp. And in the case of the Cayin CS-100A on EL34 lamps, genres also had to be selected for each of its operating modes!
Just don't think that this was a difficult task or the purpose of the test. Genres from Tidal playlists followed the rules, and the CS-100A's modes switched to the beat.
In triode mode, the lamps actually shine with a softer and calmer light, on the edge of the shadows of which a myriad of shades can be detected. This sound is very similar to what you would expect from tube technology.
However, it’s hard to call this sound “dark” or “muddy”. Rather, it is a neutral-light side that retains the pleasant openwork of additional harmonics.
However, we arrived at this light with a good rhythm: a neutral-light presentation does not mean a lack of bass. Even with the not-so-bass-heavy Monitor Audio Gold 100, this tube integrated amp successfully fended off your doubts about its lower-register abilities.
In short, jazz, any vocals, sometimes classical, blues and everything related to these styles are very interesting to listen to in triode mode. Even Alexander Gradsky with the track “How Young We Were” was listened to to the end for the first time and inspired a wave of unknown but pleasant nostalgia.
Another track that blew my mind is “Let It Take You” by Goldfrapp. The recording is not the most audiophile and the genre is not clear at all. But this time the soloist’s vocals found some kind of loophole to new sensations and established a stable connection with them. Super!
“Ultralinear mode” sounds very pretentious! But in fact, there is no pathos there, there is only hard rock. The Cayin CS-100A, charged with EL34 tubes, began to break stereotypes with the track “All Nightmare Long” by Metallica. Fans of this kind of music will confirm that this is not the simplest track, which is too tough for even many transistor amplifiers.
And then the lamp tapped the barrel so much that an irresistible desire arose to drag the Monitor Audio Gold 300 floor-standing speakers to the setup being tested. Fortunately, the administrator of the Audiomania salon, where the test took place, was busy with something and could not resist the impulse of the soul.
Of course, the Gold 300 is no longer a match for our Cayin - both as a load they are not easy, and as a companion in one system they are also hardly suitable due to the difference in price. But if you really want...
Here the ultralinear mode showed what punch, resolution and speed are! Of course, you shouldn’t get your hopes up that the CS-100A will match these parameters with a transistor integrated circuit designed for high rate of fire. But as a complement and opposite to the emotional triode mode, hardly anyone expected it to be so cool.
I wanted to change my repertoire to use different acoustics: Bruce Wayne himself ordered me to listen to the soundtracks from the movie “Joker” with such floor-standing speakers. And here something went wrong - there was not enough gloom and, as a result, the atmosphere of what was happening. It is clear that a neutral-light source in company with the same amplifier and acoustics is unlikely to plunge you into darkness and darkness. But I wanted it so much...
Finally, let there be something special. For example, "Strong" from London Grammar. And sure enough, something went wrong again. In the process of searching for the darkness and atmosphere of the Joker, I did not at all notice that the “UL” indicator on the front panel of the CS-100A was lit - the ultra-linear mode was turned on. Immediately, by pressing a button on the remote control, I corrected the situation: the triode mode was “ON”, and the listener literally melted in his chair.
