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Phonostage | MM/MC

RCM Audio

Manufacturer: RCM s.c.
Price (when reviewed): 35 000 EUR

Contact: ul. Czarnieckiego 17
40-077 Katowice | Polska


Provided for test by: RCM s.c.


Text: Wojciech Pacuła
Images: Wojciech Pacuła | RCM Audio

No 197

November 1, 2020


RCM Audio is the manufacturing branch of the well-known Polish distributor, RCM. Its owner is ROGER ADAMEK, a fan and propagator of analogue audio well-known in Poland. Their first product was the Bonasus integrated amplifier, and the next was the SENSOR Prelude IC phono stage, which is still our reference preamplifier today.

he Big Phono preamplifier is a top product of the Katowice-based RCM Audio company. Its offer also includes two less expensive phono preamplifiers: the Sensor Mk2 and The RIAA Mk2. Its first product related to the amplification of the signal coming from a phono cartridge was the Sensor Prelude IC. Even in its case, although it cost "only" PLN 9500, some of the same solutions were used as can also be found now in the new project, costing about 150,000 (PLN).

First of all - an external power supply. In the tested device it is a huge, heavy as hell casing with three separate power supplies. Secondly - an active amplification of the MC section, due to a reluctant approach towards stup-up transformers. Although Roger, the head of the company and the originator of new products, as well as their first and most critical listener, recently said that Thrax Audio has just prepared such a transformer, which is truly unique, it should be treated as an exception.

And finally, there is a third characteristic of the RCM Audio phono preamplifiers, namely the selection of amplification elements. In the audiophile world, one of the axioms is that there is a distinct gradation. At the very top there would be tubes, or rather triodes, below transistors - preferably field-effect (JFET, MOSFET, etc.), and in the cheapest products - integrated circuits.

This view was explicitly expressed by the Musical Fidelity, which has just launched the Musical Fidelity M6x phono preamplifier costing PLN 8395. This is a good example of the hierarchy that I am talking about in practice. Unlike the most expensive preamplifiers from this manufacturer, which feature tubes (nuvistors) and the cheaper ones, which use integrated circuits, the new version of the M6 features discrete circuits.

Its press release reads:

Musical Fidelity justifies the departure from the use of op-amps in two ways. Firstly, their sonic character, which, according to MF engineers, does not correspond to the company's current mission, i.e. to provide devices that sound: neutral, natural, dynamic and colorful. Secondly, designing devices based on discrete circuits allows, as we read, to obtain a much more precise, individual end result.

Musical Fidelity also emphasizes that designing discrete circuits is the domain of the largest manufacturers in the industry, who can spend hundreds of hours selecting the best combinations of components, which requires an appropriate scale of sales. But manufacturers achieved the right scale are able to offer an advanced solutions in proprietary edition at a much better price than manufacturers focusing solely on constructing devices based on op-amps.

More HERE, accessed: 22.09.2020

I believe that in many cases, maybe even in majority of them, this approach works well. But not in every one of them.


Integrated circuits are at the heart of all RCM Audio preamplifiers. Without knowing it, I would never have said it. I would have a hard time pointing out the type of amplifying elements that work in it. Comparing the Sensor to many other, usually much more expensive devices, I would say that it sounds denser and more resolving than them.

The Big Phono model is a logical extension of all these solutions and it also features integrated circuits. The development took four years and we could see and hear its some prototypes during Audio Video Shows. Jakub, then still a student, or shall I say Mr. JAKUB CIEŚLIŃSKI, today an employee of DELFI, is responsible for its layout and logic circuits programming; Let me remind you that the Sensor was designed by ROBERT ROLOF.

The chassis is made by Thrax Audio - they manufacture casings for many high-end manufacturers from Europe and the USA - and the precise PCB is prepared by Techno-Service. WOJTEK HRABIA prepared the mechanical design and the greater part of the artistic design (let me remind you that my namesake prepared a short guide for you on how to set up a turntable: TURNTABLE CALIBRATION - a course for beginners | HF № 140) It is a collective work, but its coordinator and originator of most solutions was Roger Adamek.

| A few simple words…


⸤ The first power supply prototype, ver. 0, still on a board, literally…

There is a company called Vitus Audio that manufactures such a phono preamplifier as the MP-P201 from the Masterpiece series, which can serve as one of the examples of how a good, or actually - very good, and really - awesome phono preamplifier should sound like. But, as it happens in life, we listened to it, got amazed by it and ... got envy. As always, chasing or wanting to equal the Master is not easy and takes a long time - we needed four years for that. But it was worth it.

⸤ The second power supply prototype, already with EI transformers and copper plates dissipating heat from voltage stabilizer circuits

As always, from the innocent idea of improving the power supply for TheRIAA model and inspired by some solutions observed in products from other brands, a completely new preamplifier was born, because the idea for the power supply was already there. We then asked ourselves what would happen if ... we were to use it with a different (maybe not entirely different, but still) solution than before, with more precise signal guidance, with perfect attention paid to the noise level and distortion from the power supply?

⸤ A final version of the phonostage in a workshop

Step by step, after many more prototypes, we came to the final circuit, and still "tweaking" it took us over half a year. It was all about the selection and sequence of the operational amplifiers we used, type and manufacturer of capacitors in the power supply (we tested four different sets), etc.

In the meantime, Wojtek Hrabia made technical drawings of the interior and the external outline of the device, with the arrangement of buttons, display and sockets on the back panel. We then sent it to Rumen Artarski, head of Thrax Audio, where the design was refined and the chassis for The Big Phono were made. The entire assembly, both of the PCBs and mechanical, and of course testing, was executed by Marek Piotrowski.

And my role? Well... I just listened to the music. RA

THE BIG PHONO is a phono preamplifier, supporting both, MM and MC cartridges, offering two RCA inputs and two outputs - one unbalanced RCA and one balanced XLR. Each input has a separately adjustable load - the selection is visible on a large OLED display with an amber screen. There are eight impedance values to choose from, from 20 Ω to 47 kΩ, and seven gain positions, from 0.3 mV to 5 mV. Importantly, the change can be made either with the buttons on the front panel or using the Apple's programmable remote.

THE CURVE | You have probably noticed this, but one of the "hot" additions to many phono preamplifiers in recent years is the ability to change the correction curve. In the 1940s and 1950s, each label used their own curve. One of the first manufacturers today to offer this function was Zanden with the 1200 model; today we can find it even in inexpensive preamplifiers.

So I asked Roger why didn’t they include a curve selection in The Big Phono:

One can’t find an information regarding a curve used for particular release on LPs, so one actually doesn’t know whether it was RIAA or not. It is very difficult to find such information, and trying to establish that by "ear" is like using the tone control. Plus, the curve has been the same for the last 50 years - it's the RIAA. So why do other companies offer different gain curves? It's just a cheap marketing gimmick ...

CIRCUIT | The pre-amplification is done in four stages in which many ICs work. These are low-noise operational amplifiers from Texas Instruments operating with low gain. Thanks to such an arrangement, they work almost effortlessly. The RIAA curve is obtained in a passive system, and after RIAA correction, there are further gain stages.

The whole circuit is assembled on printed circuit boards made of a thick FR4 laminate, and the tracks are made of a thicker copper layer, which was gold-plated. The boards are double-sided and feature shielding. Both surface mounting and through-hole mounting methods were used. As Roger said, these are the best industrial components you can get, regardless of the price. The elements are assembled on PCBs in-house by MAREK PIOTROWSKI, who is also responsible for the mechanical assembly of devices.

In an almost identical chassis, but without a display, there is a power supply section. It is even heavier than the amplification circuit itself. It is based on two very large transformers with EI sheets, 200 W each. They supply the left and right channel separately - The Big Phono is a dual-mono design. The third power supply is for logic and display circuits. The symmetrical power supply features a multi-stage stabilization (12 degrees). Voltage stabilizing circuits are cooled by two large copper plates bolted to the housing. The power supply is connected with the preamplifier using three cables terminated with multi-pin Neutrik plugs.

The housing is made of aluminum elements milled inside and fitted in a perfect way. The visual design of the device is simple, but - it seems to me - timeless. I have believe that the reference point for this device could have been products of the British Rega - there, too, the chassis was composed of two identical elements - top and bottom. I would like to add that the RCA connection sockets are also excellent in the tested preamplifier - these are the top sockets of the Japanese company Furutech with rhodium-plated contacts. From Furutech, also comes the IEC power socket and a fuse. XLR connectors (including multi-pin ones) come from Neutrik.


HOW WE LISTENED The Big Phono preamplifier was placed on the Finite Elemente Master Pagode Edition rack - the amplification section on a separate shelf, and the power supply on the top of the Ayon Audio Spheris III line preamplifier - there was just not enough space for it otherwise ...

The test was conducted as an A / B / A and B / A / B comparison with A and B known. The reference point was the RCM Audio Sensor Prelude IC. It is an inexpensive device that I bought in 2007 and that has been with me ever since and I used it in every cartridge, turntable and phono preamp review - and it's been 12 years!

I listened to the latter with such turntables as:

J.Sikora Reference,
Transrotor Argos,
SME 20/3, |PL|
Avid Acutus Reference,
Kuzma XL2,
Kronos Pro Limited Production MkII,
TenToGra Oscar,
Benny Audio Immersion,
Scheu Analog Premier Mk2,
And above all with the whole family of TechDAS products including the AIR FORCE ONE.

When testing The Big Phono I used the Thrax Audio Yatrus record player with Etsuro Urushi Bordeaux cartridge and the Shroeder CB tonearm.

I divided the listening session into parts of three - this is my way to get to the bottom of a reviewed device. In the case of turntable related products, it means that I search for and combine three albums that have a common publisher, producer, are similarly released, recorded, etc. They offer me variations on a given topic - similar, repeatable and yet different. This allows me to assess even minor changes and how the product reacts to them. During this test I had over 20 such sets - below there are four of them.

Records used for the test | a selection

⸤ The Modern Jazz Quartet,Fontessa, Atlantic Records AS 128 019, LP (1956)
⸤ Julie London, Julie is her name. Vol. 1, Liberty Records LPR 3006, LP (1955)
⸤ The Dukes of Dixieland, The Dukes of Dixieland, Audio Fidelity AFSD 9004, LP (1957)

⸤ Frank Sinatra, Swingin’ Session!!!, Capitol Records/Mobile Fidelity MFSL 1-407, “Special Limited Edition | No. 346”, 180 g LP (1961/2012)
⸤ Dire Straits, Brothers in Arms, Vertigo/Mobile Fidelity Sound Lab MFSL-2-441, „Special Limited Edition | No. 3000”, 45 RPM, 2 x 180 g LP (1985/2014)
⸤ Dead Can Dance, Into The Labyrinth, 4AD/Mobile Fidelity MoFi-2-001, “Silver Line Special Limited Edition | No. 1545”, 2 x 140 g LP (1993/2010)

⸤ Miles Davis, Miles Davis and The Modern Jazz Giants, Riverside/Analogue Productions AJAZ 1106, “Top 100 Jazz, 45 RPM | Limited Edition #0706, 2 x 180 g, 45 rpm LP (1956/?)
⸤ Nat ‘King’ Cole and his Trio, After Midnight – Complete Session, Capitol/Analogue Productions APP 740-45, 45 RPM, 3 x 180 g LP (1957/2010)
⸤ John Coltrane, Blue Train, Blue Note/Analogue Productions AP 81577, „The Blue Note Reissues | 45 RPM Limited Edition | # 2365, 180 g LP (1957/2008)

⸤ Count Basie And His Orchestra + Neal Hefti , Basie, Roulette/Nippon Columbia YW-7508-RO, „Roulette Jazz Library | No. 8”, LP (1958/1978)
⸤ Sonny Clark Trio, Sonny Clark Trio, Time Records/Teichiku Records ULS-1801-V, „Time Original Collection”, Japan LP (1960/?)
⸤ Falla, The Three Cornered Hat, Decca/Esoteric ESLP-10003, „Master Sound Works. Limited Edition”, 200 g LP (1961/2008)

A COMPARISON of a phono preamplifier costing at the time of its premiere, twelve years ago, PLN 6,000 (the Sensor mk2 version currently costs PLN 12,000) with a device priced at PLN 150,000 may seem absurd. And so it may seem pricing a phono preamplifier at 35,000 EUR and building it with the use of integrated circuits. But not for me - both in terms of comparison and pricing.

It is so, that while listening with the small Sensor Prelude IC preamplifier to the best and most expensive cartridges in the world, the best and most expensive turntables in the world, comparing it with expensive and very expensive preamplifiers I never felt that I was missing something, that something in its sound was missing. It was and is a complete device offering a "fulfilled" sound. I am familiar with its disadvantages (inside out), I know where budget and size constraints influenced the final result. But it didn't matter to me.

Because the Sensor Prelude IC offers something that probably no other phono preamplifier has given me: incredible energy transfer. I wrote about it on the occasion of the review of the Closer Acoustics 300B Provocateur amplifier, which was developed by the same man - Robert Rolof. It is an element that every musician, every sound engineer is looking for in the sound, and which almost always disappears, partly in the post-production phase, partly while playing music at home (more HERE).

And although I haven't heard the newest Robert preamplifier, the Flō model yet, I thought that it would stay that way and I would evaluate all subsequent new devices of this type through the prism of a small, relatively simple, integrated circuit-based RCM Audio preamplifier. But I heard The Big Phono and my perspective changed. Maybe not completely, but enough for me to repeat after the classic: "I have fought a good fight, I have finished my race, I have kept my faith" ...

The thing is that the top RCM Audio preamplifier does just do everything better - although it does - but does everything “more”. 'Better’ suggests a lack, something inferior, and yet I’ve just said a moment ago that I did not miss anything in the 'small' RCM Audio. By saying 'more' I mean that somehow the 'big' preamplifier was able to lead to a natural complement, fullness, to the conclusion of all the components of the sound. I am not saying that there is nothing that can be further improved, that this is a perfect device. I'm just saying that everything The Big Phono does is done well enough that you don't even get to the point where you start looking for flaws, just immersing yourself in the music.

Tonally it is an incredibly well-balanced device. A big surprise for me was the comparison with the Sensor, in which I heard for the first time that a small preamplifier has an emphasized low midrange, which makes its presentation large and massive. If it sounds bright and "light" in some system, it means that this system has problems with these elements and it takes a large amount of information, mainly regarding dynamics and energy, for aggressiveness. This often happens, so designers of cheaper devices mask information which such a product does not know what to do with, and therefore it sounds worse than if it were less resolving. It's just one of the strategies.

The Big Phono doesn't get there at all. I do not know if you remember my test of the Ayon Audio CD-35 HF Edition SACD player, in which I wrote that it does not sound like a "digital" or "analog" source, and I understood the latter as "vinyl record sound". This is a player that sounds more like analog tape. Today this distinction - vinyl vs tape - is clear, mainly due to the popularization of auditions and shows, but I thought I was talking to the wall and that "analog" means "turntable" for most music lovers and audio designers .

I am coming back to this unique experience because I had the same feeling of something groundbreaking when I listened to the new RCM Audio preamp. And although in the context of a turntable, saying that it does not sounds like "vinyl", but more like "tape" might seem out of place, I believe that today we are all on a completely different level of knowledge and a different mental state than a few years ago and you know what I am talking about.

It is an extremely dark sound. It means that when listening to music, we do not pay attention to whether the high tones are clear, whether there are a lot of them, etc. Because these are not only high tones, but drum cymbals and then high tones - yes at least it was my line of thought. With The Big Phono noise including crackles was less audible, although I never complained about it with the Sensor. And yet, with the reviewed preamplifier, you can hear incredibly well what is recorded on the disc. Like when The Modern Jazz Quartet's album begins, the Fontessa and after a moment of silence there is a high noise and hum - elements remaining from the Atlantic Records recording studio, or when Count Basie's album entitled Basie opens also with a quite high noise.

The noise itself is a distortion, an error, but we got used to it because - after all - it is not as annoying as distortions of another type. With the reviewed preamplifier this distinction was clear like almost never before - maybe, like when we listen to, I have to repeat it, analog tape. So it is a dark sound with an incredible amount of information regarding treble. They are smooth and silky. The Sensor - in comparison - sounds more raw, in a less real way. Thanks to outstanding energy, it arranges the whole presentation in a unique way, but it lacks sophistication.

And The Big Phono is fantastic in that respect. This is a refined full range sound. The bass extends very low and has great articulation, although it seems warmer than with the Sensor. Anyway, the whole sound could be described as “warm”, if it wasn't for the fact that there is nothing warmed up in it, and such a perception results from the fact that we have a better understanding of the presentation. So it is perfect for both direct-to-disc records and discs produced in the studio from start to finish, with many tracks, digital recording process, etc.

The former sound very natural, their energy is outstanding, but they are also not dry, which is often the case with when they are played by audio systems. They are in a way better produced, denser, simply better. The latter, in turn, are less "technical". They sound warmer and darker. Both types of recordings are also outstanding in conveying details, but they are never in the center of attention, but rather always a part of something bigger. Anyway, as I said, we don't pay attention to details. The more so that somehow the crackles and noise are less audible here than with other preamplifiers, and the treble is more open.

So what do we pay attention to? It depends on our experience, but even more so on our expectations. In my case, it was probably about engagement. When I listened to a live recording, I was immersed in this event, no matter what the technical side of the production was. When I listened to live-in-studio recordings, which is almost all jazz recordings from the 1950s, I heard perfection, even though many of these tapes were edited before their release, some downright cruelly (Gil Evans excelled in this). Fragments of other takes were glued in, vocal parts were glued in, elements cut out, etc. But these editions served to raise the class of the piece - and that was how I perceived them.

Finally, I would like to add another thing that I might as well have started this test with: The Big Phono is a bit like The Big Boy: it phenomenally builds the bodies of the instruments, their three-dimensionality and textures - when they are close, in the foreground, they are large and dense, when placed further away - smaller, but never small. When they are more "porous" they are shown this way, but when they are smooth - you hear them in an ultra-smooth way. This level of sophistication is found in the best analogue tape recorders and in the best digital DSD recordings. This is the world's top class.

| Summary

I revolve around the classic audiophile categories, not emphasizing them too much, because this device offers a performance of the absolute highest level. The Big Phono's presentation is ultra-smooth, ultra-dense and ultra-resolving. But none of these terms come directly from what one hears, they are just words. Real, true, but still secondary, and therefore less important. With the reviewed preamplifier we find ourselves in a new "reality" where all that disappears. The presentation in front of us has a large volume, the space is large and perfectly organized, but neither the instruments, nor the voices, nor, finally, the layers are “separated” from each other, nor are they emphasized.

And yet… Listening to music with The Big Phono, we reach a place where we can relax on our journey. There is definitely something better out there and even more addictive, because this is the nature of audiophile exploration. But not yet, not here. For, as Sinatra sings:

When you're smiling
When you're smiling
The whole world smiles with you
When you're laughing
When you're laughing
The sun comes shining through

Joe Goodwin/Larry Shay/Mark Fisher When You’re Smiling (The Whole World Smiles With You), w: Frank Sinatra, Swingin’ Session!!!, Capitol Records (1961)

Therefore The Big Phono receives our highest award GOLD FINGERPRINT, that during 16 years of our magazine’s existence only a handful of products had received; it’s a token of our appreciation for pure perfection.


Technical specifications (according to the manufacturer)

Input sensitivity: 0.3 - 5 mV (variable in 7 steps)
Gain: 52 - 74 dB (nominal output 2 V rms)
Input impedance: 20 Ω – 47 kΩ (in 8 steps)
Input capacity: 100 pF
THD: <0.01%
S/N: 89 dB (at lowest gain)
Linear precision of RIAA: +/- 0,1 dB (20 Hz-20 kHz)
Output impedance: 70 Ω
Nominal output: 2 V rms
Maximum output: 9 V rms
Dimensions (W x D x H):
• preamplifier – 430 x 410 x 145 mm
• power supply – 430 x 410 x 145 mm
• preamplifier – 25 kg
• power supply – 32 kg
Power consumption (max): 250 W


Reference system 2020

1) Loudspeakers: HARBETH M40.1 |REVIEW|
2) Line preamplifier: AYON AUDIO Spheris III Linestage |REVIEW|
3) Super Audio CD Player: AYON AUDIO CD-35 HF Edition No. 01/50 |REVIEW|
4) Stands (loudspeakers): ACOUSTIC REVIVE (custom) |ABOUT|
5) Power amplifier: SOULUTION 710
6) Loudspeaker filter: SPEC REAL-SOUND PROCESSOR RSP-AZ9EX (prototype) |REVIEW|
7) Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|


Analog interconnect SACD Player - Line preamplifier: SILTECH Triple Crown (1 m) |ABOUT|
Analog interconnect Line preamplifier - Power amplifier: ACOUSTIC REVIVE RCA-1.0 Absolute-FM (1 m) |REVIEW|
Speaker cable: SILTECH Triple Crown (2.5 m) |ABOUT|

AC Power

Power cable | Mains Power Distribution Block - SACD Player: SILTECH Triple Crown
Power (2 m) |ARTICLE|
Power cable | Mains Power Distribution Block - Line preamplifier - ACOUSTIC REVIVE
Power Reference Triple-C (2 m) |REVIEW|
Power cable | Mains Power Distribution Block - Power amplifier - ACROLINK Mexcel 7N-PC9500 |ARTICLE|
Power cable | Power Receptacle - Mains Power Distribution Block: ACROLINK Mexcel 7N-PC9500 (2 m) |ARTICLE|
Power Receptacle: Acoustic Revive RTP-4eu ULTIMATE |REVIEW|
Anti-vibration platform under Acoustic Revive RTP-4eu ULTIMATE: Asura QUALITY RECOVERY SYSTEM Level 1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RPC-1 |REVIEW|
Power Supply Conditioner: Acoustic Revive RAS-14 Triple-C |REVIEW|
Passive filter EMI/RFI: VERICTUM Block |REVIEW|


Speaker stands: ACOUSTIC REVIVE (custom)
Hi-Fi rack: FINITE ELEMENTE Pagode Edition |ABOUT|
Anti-vibration platforms: ACOUSTIC REVIVE RAF-48H |ARTICLE|

  • HARMONIX TU-666M "BeauTone" MILLION MAESTRO 20th Anniversary Edition |REVIEW|


Phono preamplifier: Phono cartridges: Tonearm (12"): Reed 3P |REVIEW|

Clamp: PATHE WINGS Titanium PW-Ti 770 | Limited Edition

Record mats:


Headphone amplifier: AYON AUDIO HA-3 |REVIEW|

Headphones: Headphone Cables: Forza AudioWorks NOIR HYBRID HPC