„01.01.2009 a new person appeared in the company Struss Amplifiers Mr. Jacek Hrynkiewicz-Struss (36 year old son of Zdzisław Hrynkiewicz-Struss). The son took over manufacturing and marketing. This meant, that the manufacturing was transferred to Bielsko-Biała. Mr. Zdzisław Hrynkiewicz-Struss is still dealing with designing new products and service.” That was the information we published some time ago in the news section. For people, who do not deal with audio, especially Polish audio for a long time, this is not a very important message. But for me it was the key to the rest of the text, describing the construction and background of the newest amplifier proposed by the company, called Chopin MkIV.
I came across an amplifier from this Pruszków based company in 1997, reading a text in the magazine “Hi-Fi i Muzyka” and looking at its picture on the cover. In that magazine, this device was very well received and left in the editorial office as the reference amplifier, where the ‘140’ replaced the first model they ever produced, the quite ugly, 01-2. And looking at the design of the 140 amplifier, reading its catalog data, including its substantial power of 140W/8Ω we could understand why that happened. At that time I was working as an acoustics engineer in a theatre (the J. Słowacki theatre in Krakow) and power meant for me quite a lot – the stage loudspeakers were powered with over 20kW… It turned out quite quickly, that this wasn’t my last meeting with this company. It happened almost at the same moment, that my brother bought the 140 for his system, and I changed my employer and started to work for the distribution company Audioholic, where we sold the Struss, among other things, the models 140SE, 140L and 140S. So I had a quite close and extensive contact with them. So I could gain my own opinion about the tests of those units, and things the constructor wanted to achieve. To keep things short – this was not “my” sound. One of the basic ideas of Struss, used since the first model, is a distortion reduction system, called Distortion Free Power Supply. And in reality – the sound was clear, free from sanding of the treble, quite common for powerful devices. It turned out, that this contact with the company was the last one for almost ten years.

When Mr. Jacek called me with the proposition of testing the newest product of Struss, called Chopin, in the improved version Mark IV, I agreed immediately. As we can read in the materials received by us, with which we started this text, the amplifier has a seven year long history, and its sound was perfected based on, among other things, tests in the magazine “Audio-Video”. The first one appeared in June 2002 (6/2002) and until 2009 another editions were presented. The fourth one, MkIV, was released for testing in 2008. The test appeared in the October 2008 issue (10/2008). It turned out, that also this test resulted in some improvements that were applied to the device, in the mechanical construction as well as in the sound path. Mr. Jacek Struss quotes the following upgrades:

Mechanical changes:
1.Exchange of the loudspeaker terminals.
2.Exchange of transformers to ones made using Danish cores.
3.The construction was made more rigid by adding copper inserts below the transformers.

Changes in the signal path:
1.Exchange of the cable between the input selector and potentiometer to Gotham GAC1.
2.Exchange of the volume potentiometer to Alps Blue Velvet.
3.Exchange of the electrolytic capacitors to the exclusive Jamicon „for audio” – HT105, 835k0(M), 4x22 000 μF.
4.The headphone amplifier was modified (adjusted to work with headphones with low impedance).
5.Changes in the MM phono preamplifier.
6.The bias of the output transistors was increased.
7.The paths of the loudspeaker outputs were shortened by ½.
Due to those actions the parameters of the amplifier changed.

It is known, that tests in brand magazines have a big impact on manufacturers. A reviewer is in fact a qualified (I assume that optimistically…), beta tester, knowing the problems and having a vast comparative material (yes, I believe in people!). And as such it is valuable for every company. But not everybody admits that. Because it can suggest the companies incompetence, etc. This is not true! If the test was made according to the rules, if it was fair, and the reference system much better than the tested product, then it was just another test in the ongoing, and never ending, process of designing the product. This is why I understand Mr. Jacek, and admire his honesty.
The test was conducted using two sets of speakers – the large, full range Dobermann Harpia Acoustics and the small, and paradoxically more difficult to drive properly, Spendor SP1. The headphones were the AKG, Ultrasone and Beyerdynamic (as described below). Unfortunately during the test I had no MM or MC HO cartridge – only MC ones – so I did not test the gramophone input, so please forgive me this omission.

Discs used for testing:

• Wes Montgomery, So Much Guitar!, Riverside/Universal Music Japan, UCCO-5103, CD.
• The Doors, L.A. Woman, Elektra/Warner Music Japan, WPCR-12721, CD.
• Depeche Mode, Sounds Of The Universe, Mute/Emi Music Japan, TOCP-66878, CD+DVD; review HERE.
• The Beatles, Beatles For Sale, Parlophone/Apple/Toshiba-EMI, TOCP-51114, CD.
• John Coltrane, Lush Live, Prestige/Universal Music Japan, UCCO-9255, CD.
• Carmen McRae, Book Of Ballads, Kapp Records/Universal Music Japan, UCCU-9634, SHM-CD.
• The Oscar Peterson Trio, We Get Request, Verve/Lasting Impression Music, LIM K2HD 032, K2HD; recenzja HERE.
• Danielsson/Dell/Landgren, Salzau Music On The Water, ACT Music+Vision, ACT 9445-2, CD; review HERE.
• Henry Purcell, Ten Sonatas in Four Parts, Retrospect Trio, Linn Records, CKD 332, SACD/HDCD.
• e.s.t., Viaticum, ACT Music+Vision, ACT 6001-2, CD; review HERE.
• Kate Bush, Aerial, EMI, 43960, 2 x CCD; review HERE.

SOUND

Almost 14000zl is a lot of money. Especially for an integrated of Polish make. In this price range we can find some very well done devices coming from known and renowned manufacturers, as well as from small companies, tube and solid state. The most important ones are, in my opinion, the following: Krell S-300 and Aaron No.1.a, not forgetting about the CS300 Leben and the fantastic Audiomatus, composed of the preamplifier PP-03 and AM500R monoblocks. And just a step away are the integrated Accuphase E-250 and Luxmana L-550A II. So the tested Chopin is in a difficult position from the very beginning. Because this is a product from a company, which is not very known in the world, and coming from a country not very embedded in the world hi-end – from Poland. Like I wrote in the editorial to this issue (No. 65, Bellum omnium contra omnes), the choice of Polish products, their positive reviews, etc, in Polish language magazines (this is true for any country and products, but we are talking about Poland here) cannot be dictated by the country of origin. This is the dumbest division from the ones I know. “It is good because it’s Polish” (“This is good because it’s German”, French, etc) is a logical nonsense. “Good and Polish”, and finally, with lots of bad will – “Polish, and still good” are acceptable. Again, this has nothing to do with the idea of hi-fi, high quality sound, but it broadens the area of evaluation, it does not exclude so many devices, that we can go in that direction. But I think, that when something is “good” because it is good. Period. It is nice to test good, or very good devices, with which we are emotionally connected in some way – by the personality of the constructor, or the philosophy behind the product, or – indeed – the country of origin. But it cannot influence our review of the product. The worst thing we could do is to turn a blind eye to something, because we know the constructor, because we like the philosophy of the product or because it comes from a country we promote. This is like – please forgive me – castrate it in the very beginning, because the feedback to the manufacturer, and a test is a kind of it, becomes distorted, becomes false. And only comparing with the competition, with constant improvement we can achieve the goal, high quality sound. This is why there cannot be any kind of priority for Polish products. I will even say more – they have it tougher, because their comparison with foreign competition must be very thorough and critical.

And the Chopin performs well against this background. If I would have to choose a point of reference, at least in terms of tonal balance, and take the integrated Krell and Aaron as masters, then the Struss would be closer to the first one. It is surprising, how well the manufacturers eliminated many of the shortcomings of the solid state technology, making the sound so close to the natural and physiological one, so many times associated with tube amplifiers. For this unit the midrange, and its border with bass, are the most important. Just behind them are the mid and lower bass, but about that in a moment. I started the session with the mono version of the disc Beatles for Sale. Its sound surprised me, mostly because of the splendid coherence of the sound, very well preserved phase relationships, cohesion of harmonics and pure “musicality”, if I may say. It could be heard from the very beginning, that the treble is a bit withdrawn, not that resolved as in the Aaron, or even my Leben CS300. But the choices of the designer went to homogenous sound – it can be heard, that when there was a choice between, for example, a slightly better definition of the sound source on one hand, and their depth on the other, then the latter was chosen without any doubt. It really doesn’t happen often in solid state technology, especially for the money, that the sound is so smooth – in the good meaning of this word – fluent, homogenous in all ranges, making most of tube amplifiers in this price range not “tubey” enough! Only such well made amplifiers, like the P40 Unison Research could create something similar. This was brilliantly shown by the disc Salzau Music On The Water trio Daniellson/Dell/Landgren, recorded without plugins, compression, with closely positioned microphones. Only in hi-end we can fully appreciate what was achieved by the musicians and the sound engineer, and what bases on the unity of all components of the musical event, the servitude of each of the elements towards others. Just to make this clear – the midrange on this disc is extremely well saturated and has lots of energy. And it is not about underlining this part of the sound spectrum, but about the instruments emanating with energy, being very three-dimensional. If an amplifier has underlined the mid frequencies, then this turns into a pulp, especially when resolution is not too big. Chopin, although I wrote it seems to favor the midrange, played this disc with ease, with a kind of solemnity, without bulkiness.

The disc I am talking about impressed me, because it was not handled as well by such nice amplifiers like Leben CS600 (tube), Ayon Spark II (tube) or Primare I30 (solid state). In fact I appreciated this coherence most with two utterly distinct discs: Ten Sonatas in Four Parts Henry Purcell, performed by Retrospect Trio and Sounds Of The Universe Depeche Mode. Those two are separated by everything, except one thing: to extract as much music as possible for them, they need to be reproduced with respect to the musical tissue. The Polish amplifier showed its weaker sides with them, like the not very resolved and worked out treble, or not very thorough depiction of the sound stage depth. But it was not in the center of the events, there was no feeling of “loss”. The violins from the disc with Purcell sonatas were smooth, they had also beautiful timbre, similar to a good tube amplifier. We can get similar timbre for less money – in the amplifier JAG 300B on 300B tubes in SET, but there is no such dynamic of the lower and midrange sections and the easiness of sound with a variety of loudspeakers, like with the Chopin Mk IV. The other disc sounded in exactly the same way, without emphasis of the upper midrange and with rounded treble. Here it not only did not harm, but even helped in the creation of a full, saturated sound of the analog synthesizers, and truthful placing of the voices of Gahan and Gore within them, what is not so easy. There was no talking about a perfect mix of voice/effect/background, as from my reference system, but the money is also different. I would only like to remember, that we are talking about an amplifier for 14000zl, so we just start our adventure with the hi-end. When we take this into account, then we cannot look indifferently at this proposition.

Especially, because bass is especially well done in the Polish amplifier. Without a doubt it is responsible for the fantastic saturation and “quietness” – it is not about sedation, hence the quotation marks – of the midrange, and vocals. I heard that effect before – in the P-7100 Accuphase, and in the EVO 402 Krell, and to some extent in my Leben, and most beautifully in the Siver Grand Mono Ancient Audio. It is about playing in a way, that gives us breath and reserve of dynamics, what gives us “freedom”. And something like this, to a great extent, is given by the tested unit. Dynamics is very big, what can be heard in percussive elements, like snare drums, which have splendid attack and very good reverb with that amplifier. This is an asset of good solid state amps, and only few tubes can compete with those – maybe not with ultimate power and bass extension, but with amount of harmonics and their integration with the upper ranges. What results in a similar effect. This is why the lazy themes from the disc Aerial Kate Bush had a reserve of dynamics and were not snoozing. The first plane was strong and full, and behind it we had some kind of a “cushion” from air recorded by the microphones and other elements behind that.

One of the characteristics of the Chopin is the integrated headphone amplifier, working independently from the main part. Because I spend much time using headphones, I devoted an equal amount of time to evaluate the Struss working with those, as I did for loudspeaker tests. I think, that the headphone amp sounds similar to that, what we can hear from the loudspeakers. This is a slightly warmed, not so resolved, but incredibly sensual, fluent, coherent sound, with a splendid bass. My AKG K701 had a bit too “plushy” midrange-bass border, but I got used to that quickly, and then I would not have exchanged this combination for anything else. Ultrasone PROLine2500, with a stronger top and low ranges were not a step forward, but rather to the side and back, especially when we talk about the integrity of the sound. The quality of this amplifier is really outstanding, we can easily resign from amplifiers like Canor SH-1 (earlier Edgar SH-1), Pro-Ject or Heed. Only the Leben CS300, working as a headphone amplifier showed, that timbre can be differentiated better, that the sound stage (in headphone terms of course) can be deeper and wider. But this does not diminish the fact, that Struss designed this “addition” well – how many headphone outputs in integrated amps have a similar or better sound? Two, three? At maximum.

Getting things right can take long in audio. Even if earlier Struss products were good, had enthusiastic reviews and happy users, the Chopin shows, that those were only fitters for that, what was presented today. This is not an universal amplifier, or “even” in the sense, that it does not try to fit everybody. This would not be a good way, and it usually results in a little interesting sound, or even an irritating one. I like the approach showed by the Chopin MkIV much better. This is a hellishly fluent, heavenly tame, incredibly saturates amplifier. It will perfor best with open loudspeakers - Harpia Acoustics (Amstaff or Marcus), Monitor Audio Rx, Gold, or even Platinum). This is not world master class (this is my opinion, not a fact) in manufacturing quality and external design, for example I like design of Primare better, but still this is a good level. Together with a headphone amplifier, worth about 3000zl – for free, it results in a device you need to listen to.

DESCRIPTION

The amplifier Chopin MkIV from the company Struss Amplifiers is a small, but very happy device. Its power, although lower than that from the model 140 (respectively 105W/8Ω vs. 140W/8Ω) has more meaning, because it almost doubles when impedance halves (195W/4Ω). From listening sessions it turned out, that the amplifier has a very good dynamics. This is an element, that was perfected by the company for a long time, what resulted in an European patent (RP Zdzisław H-S, PL176514), describing the symmetrical audio signal processing path.

The enclosure is made from sheet metal, the front from a thick aluminum block, and on the sides wooden elements were bolted – exactly like in the model 140 and some Japanese devices - Accuphase or Leben. Their function is aesthetical, but they reduce also the vibrations of the enclosure. The front is nicely composed, a chrome plated steel rhombus is placed on a black background. Almost all functions controllers were placed on that rhombus. We have there a medium sized volume knob with a red LED showing its position, a small knob for the headphone amp volume (sadly without any markings) and the input selector with blue LED indicators. There is also a headphone socket, 6.3mm diameter. On the other side of the front panel the power switch was placed. On the back we have four line inputs, all RCA unbalanced, MM cartridge input with a ground connection and two pairs of loudspeaker sockets, gold plated. Those aren’t of the “jewelry” kind, but they look very solid. However those are quite close together, so I’d recommend to use banana plugs, as the spades could short circuit.

From the very beginning the company’s amplifiers were made in dual-mono setting, with two power transformers. It did not change in the Chopin. But we can also directly see some details, which are not easy to find in more expensive constructions. The most important ones are related to the mechanical setup. Below the transformers, two large toroidal ones, made to the company specs by a Danish company, 400W each, we have a thick copper plate, making the enclosure more rigid and at the same time working as a shield. Also the power stage PCBs have a nice basis. This is a big slab of aluminum – a part of the heat sink, the power transistors are bolted to it - and at the same time a perfect strengthener of the construction.

The circuitry is divided between a few, specialized, PCBs. The input sockets, are not gold plated at first sight. But Mr. Struss tells: “The gold plated RCAs come from the company Yalco (Japan) and are imported from UK. According to the RoHS norm those are gold plated on the outside, and the soldering connectors are covered with lead-free solder with addition of silver (this is why they do not look gold plated). Those are much more expensive than the Chinese ones, where varnish is called gold.”

At input we have a PCB with hermetic relays. There is a single chip there, the Burr-Brown OPA2134, and it seems to be responsible for the RIAA correction for the MM phono input. Then the signal goes to a small PCB with a symmetrical input on J-FET transistors and a single IC TLE1072. Initially I thought this is a part of the preamplifier, but Mr. Struss corrected me: “This is not a preamplifier. This is an inverter (patent pending) built on J-FET transistors, which is there to introduce the second harmonic, what deprives the amplifier from “solid state dryness”. The TLE1072 is a auxiliary element, not in the sound path.” The PCB is bolted to a heat sink, which helps in cooling of the power transformer aluminum plate.
From that PCB we go via shielded Gotham GAC-1 cables to the mechanical, motor controlled Alps Blue Velvet potentiometer, and then, with long cables, to the power stage PCBs. The power transistors are two pairs of HEXFET transistors (IRFP240+IRFP9240) working in push-pull. The whole power stage is solid state. The signal on the PCB runs via short traces, and the whole circuit is not very worked out. The filtering capacitors, the mentioned Jamicons, have a total capacity of 88 000μF. The power supply for the preamplifier is taken from one of the channels power stage supply. Everything looks very solid, and although I would change some elements (like bolter RCAs, a better headphone socket [the socket is maybe not very pretty, but we can give 100 years of warranty for it, we use this simple, yet effective solution on purpose – J. Struss], long interconnects), but in general this is a very competent design – mechanical and electrical. Big companies, like Primare, can make better enclosures, but this is just the fate of small companies like Struss. Fortunately the sound allows for a simple choice. The remote controller is ugly, big, but extremely easy to use – we have only two buttons: louder and quieter. The company VTL has a similar solution, and this is enough. Maybe a mute button would be handy. Let’s add, that the power amplifier has a full, 100% protection against short circuit on the loudspeaker outputs and DC protection.

Technical data (according to manufacturer):
Sinus power: 2x105W/8Ω, 2x195W/4Ω
Music power: 2x125W/8Ω, 2x210W/4Ω
Frequency response:10Hz-150kHz (+/- 0.1dB)
Input sensitivity: 325mV – line inputs (4), 2.5mV - "phono" MM
Input impedance: 100kΩ line, 47kΩ "phono"
Output impedance: 0.05Ω
THD: <0.1% (1W/8Ω)
Noise on loudspeaker output: max 60μV – wide band measurement
Dynamics: 130dB
Current output: 50A/1ms
Maximum operating temperature: 50oC