RCM Audio The Big Phono phono stage

TheRIAA (and more recently TheRIAA Mk II) by Polish company RCM Audio has been my go-to phono stage for more than 10 years. This big, two-box, integrated-circuit-based phono box builds on the strengths of the company’s entry-level Sensor Prelude IC. Recently, however, RCM Audio produced an even higher-end, integrated circuit-based, MM/MC phono stage called The Big Phono. Coming in at more than double the price of TheRIAA Mk II, what can The Big Phono offer aside from two very big, heavy, and well-built boxes?

The differences soon become clear, although it’s hard to get past the sheer heft of that external power supply when placed next to the juice box provided for TheRIAA. The power supply is more than added mass. The Big Phono has three entirely separated power feeds. It also moves the adjustment of cartridge parameters to a front panel display instead of rear panel DIP switches.

Twice the fun

In moving to logic control, The Big Phono also includes two inputs. The revised rear panel layout makes left and right inputs closer. This is handy as it’s a bit of a reach on theRIAA Mk II. The Big Phono has single-ended inputs and both balanced and single-ended outputs, all using Furutech connectors. The logic control can deliver a very wide range of gain and impedance parameters for each input (seven gain settings, from 0.3mV to 5mV, and eight impedance settings, from 20Ω to 47kΩ), and these are stored in The Big Phono’s memory. 

Setting up The Big Phono is easy, especially as you can use the supplied and pre-set Apple remote to navigate the settings or use three of the four unlabelled buttons on the front panel. While the obvious starting place is the cartridge maker’s specifications, you can start at the lowest gain and keep raising the numbers until it sounds right (there are ‘clipping’ indicators on the display). This is all explained in the supplied manual, although in an ideal world, I’d like the functions of the front panel buttons made clearer for those who don’t have the manual to hand.

Four stages

As with theRIAA Mk II, The Big Phono uses integrated circuits (specifically low-noise op-amps – operational amplifiers – from Texas Instruments) to create a four-stage amplification circuit with a passive RIAA curve. It’s built on ultra-thick double-sided PCBs with equally chonky gold-plated copper tracks.

The power supply chassis sports two very large transformers to supply the left and right channels separately, with a third power supply for logic and display circuits. The symmetrical power supply uses multi-stage stabilisation, and two large copper plates cool these circuits bolted to the housing (the transformers and this plate go some way to explain the 32kg weight). Each section has a cable connecting to the main phono stage case, each terminating in its own Neutrik plug. 

There is a sense of ‘good’, ‘better’, and ‘best’ in RCM’s phono stage line-up now; the Prelude is a stereo design, theRIAA Mk II is a dual mono version of the same, and The Big Phono extends that to separate power supplies for each of those phono boards. Of course, the cynical will just see this as taking one circuit and ‘blinging it up’, but The Big Phono is the result of four years of development and extensive listening tests. While The Big Phono follows a well-trodden path in high-end design (take a good product and isolate and improve each part of the signal chain), there’s a world of difference between simply doing a thing and doing it properly. That difference took four years.

Fun fact: elsewhere in this issue, there is a review of a Thrax Audio integrated amplifier, a solid-state design of uncommonly high mass (and high performance). Thrax Audio makes a lot of high-end metalwork for European audio brands… Including a two-box phono stage called The Big Phono.

Two-way trepidation

I approached The Big Phono with some trepidation in two ways. What if it is just theRIAA Mk II with a few embellishments, a heavier box, and a forty-grand price tag? On the other hand, if it is vastly better than theRIAA Mk II, how do I reconcile that in my listening? Once fully run in and warmed up, I would have to come to terms with the second question and the first dissolved before my ears.

Regardless, to test that, I used it with a few turntable front ends, including the VPI Avenger Direct with anniversary Blood-wood cartridge (made for the company by Miyajima) and a Kuzma Stabi R turntable with a 4 Point 9 tonearm and CAR 40 cartridge. This last is especially useful as RCM Audio is the Polish distributor for Kuzma and the company’s products are used in its listening tests, so should give a good idea of what RCM was looking for in The Big Phono.

Great News

The great news is RCM Audio didn’t try to hype up the sound of The Big Phono. It retains the absolute honesty and balance of theRIAA Mk II and that phono stage’s unsullied dynamic range and contrast, detail, and articulation. But it’s where theRIAA Mk II (and, by extension, most other phono stages) have their limits is where The Big Phono shows what it’s made of. Where the others run out of steam is where The Big Phono pulls away from the pack.

This doesn’t sound like most phono stages; it sounds like what most phono stages purport to be; that level of outstanding fidelity to the performance we rarely hear. You need a damn good cartridge, though; The Big Phono is so good at its job that the tiny channel imbalances you get from fractional changes in magnetic flux between channels are easy to hear through this phono stage.

Rich yet full of life

It’s intrinsically rich yet equally full of life and energy. Soundstaging is astonishing and shows how much we’ve lost in listening to even the best in digital. Yes, of course, this demands the best records. But, what pulls so much information from a cartridge also brings out the best in the worst of vinyl. Pops, crackles, and bad recordings are respected, even if undeserved. And when the music is good, the sound is sublime. My early copy of Somethin’ Else by Cannonball Adderley [Blue Note], for example, has some surface noise, but it doesn’t detract from the naturalness of that early mix. You hear that natural balance on theRIAA Mk II. However, on The Big Phono, you are left speechless by the incredible amount of information you haven’t heard before. It’s like master tape, and it leaves you hungry for more.

Your first listening sessions with The Big Phono are short because there’s so much new sound on offer. You’ll play one or two albums… then stop. This isn’t because the sound is exaggerated or foreshortened. No, you need some time to process because you are taking on so much new information from discs you thought you knew backwards. But you are left with what must be one of the finest sounds you’ll ever hear from vinyl. Everything you want from your music is here and a joy to experience. 

Fantastic full-range

It would be remiss of a reviewer to fail to find fault in a product. However, the drawbacks of The Big Phono have more to do with ‘admin’ than ‘performance’. It’s back-bendingly heavy. Running in takes days, and warming up from cold takes half an hour. And, like its smaller brothers, The Big Phono is resolutely RIAA only; those wanting other EQ curves should look elsewhere. 

And then there’s the price. No amount of wishful thinking will make spending just shy of forty grand on a phono stage go away. You can’t dismiss The Big Phono as an expensive and heavy luxury. It’s also jaw-droppingly good. It’s the easiest product to write about because it does everything to the highest possible level. I thought theRIAA Mk II was secure in its giant-killing position. But RCM Audio’s The Big Phono is one giant it cannot slay! It’s an outstanding phono stage tour de force.  

Technical specifications

• 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: 2V rms
• Maximum output: 9V rms
• Dimensions (W×D×H): 43 × 41 × 14.5 cm (each chassis)
• Weight: Preamplifier, 25 kg. Power supply, 32 kg.
• Price: £39,950

Manufacturer

RCM Audio

www.rcmaudio.pl

UK distributor

Fi Audio

www.fiaudio.co.uk

+44 (0)1563 574185

Back to Reviews