Feb 14

Feb 14 Icon Audio PS1 Mk. II All Valve Phono Stage

UK-based Icon Audio is a maker of ‘Award Winning Valve Amplifiers’. Icon also manufactures valve preamplifiers and phono stages (FYI: ‘valve’ is Brit speak for ‘tube’).

I was contacted by a local Icon Audio dealer followed by the Canadian distributor to gauge interest for a review. I heard the subject of this review, the PS1 Mk. II All Valve Phono Stage, at last year’s Toronto Audio Show. It had impressed, prepping lots of varied vinyl repertoire under show conditions. Sweet. ‘Yes, I’d like one to review’.

The PS1 Mk. II is comely and petite, housed on two chassis—power supply and phono preamplifier. Other than the sexy look of appropriately placed tubes, what struck me was on the front plate of the preamp unit—a ‘volume control’ (acting as a gain dial) and, Saints Be Praised, a mono switch, rarely included on quality phono stages. In fact, the recently reviewed tube $3750 Allnic Audio H-1202 through the $4000 solid state, mono block Sutherland Engineering DUO up to my daily reference, the Allnic Audio H-7000 LCR Phono Stage ($16,500), do not include this very handy feature.

So, the PS1 Mk. II has a very solid build, a well thought out tube design, cool aesthetics, a ‘volume control’ and a mono switch for a relatively inexpensive $2400.

Valves and stuff

For the power supply, Icon uses a large transformer and a EZ80 valve rectifier followed by two chokes. Power is regulated by an EL84 tube controlled by a 12AX7 tube. The phono stage unit has 3 ECC83 tubes. The ECC83 is reported to offer substantial gain coupled with low noise.

There are inputs for two turntables, with a moving coil option using Icon Audio’s proprietary moving coil transformers. The two chassis are connected by a supplied umbilical.

The PS1 Mk. II is a feature-rich, tube performer on a couple of easy to rack chassis. So, is anything missing?

My Use

From the feature set, we can see what added value is there. Yet, all the other MC phono stages I’ve reviewed offer cartridge loading choice (a search on Audiophilia will find many more than the three noted examples above). This important feature, especially when using expensive, low output moving coils, is not included on the PS1 Mk. II. On others, I’ve seen loading changed by dip switches on the rear, side or bottom plate, switches/connectors inside the chassis, a bag-o-resistors (you’re on your own, mate!), step up transformers using, let’s say, ‘unique’ number crunching, to the very expensive Allnic Audio H-7000 and its step up transformers and impedance ‘tower’.

As such, the PS1’s loading is factory set to MM 47k and MC 100Ω. Happily, my reference cartridge, the Phasemation PP-2000 MC Phono Pickup Cartridge ($6000), is very comfortable at 100Ω. And in another fortuitous circumstance, the Miyajima Infinity Monaural Cartridge ($3375—review forthcoming) is also specced for 100Ω. As such, the Miyajima matched perfectly with the Icon and its mono switch. Rarely is logistical life made so easy for a reviewer.

Cartridge loading and its efficacy can be a contentious issue among vinylphiles. So, I asked Icon Audio’s designer/owner David Shaw about his decision to hard set 100Ω for his MC option. Was it a philosophical, financial, or design choice? Here is Shaw’s very detailed and informative response:

Hi Anthony

I start my story with a visit to Ortofon’s factories and offices in Denmark some years ago. An amazing company dedicated to phono cartridges, they have tremendous knowledge and expertise. I learned a lot.

Behind closed doors they said two things I have never forgotten.

1. They only really make MM cartridges because the market demands it and MC is superior in just about every way.

2. If you are using MC you will only get the best results with a step up transformer. A $2 chip with 10x gain on the front of MM phono stage is just not the same.

At least part of the reason lies in the fact that the normal loading for an MM cartridge is a resistor, 47,000 Ohms and by convention a passive unchanging load.

Whereas a transformer is reactive load who’s impedance is constantly changing with frequency and amplitude. Therefore, any measurements must be qualified by stating whether it’s a DC measurement or AC and then things like frequency and level come into play. (For example a so called “8 Ohm speaker” (which usually measure 6 Ohms DC) will vary its impedance often between 2 Ohms and 30 Ohms, depending upon how easy it do that frequency).

For example the spec for Ortofon’s superb Cadenza Bronze says:

Recommended Load Impedance: 50 - 200Ω

A pretty wide tolerance don’t you think?

And the £4,000 “Expression” model says “greater than 10 Ohms”, they do not even specify an upper limit! The reason why is that it simply does not matter very much, the impact on the sonics will be small.

So, loading the cartridge with a minimum of 10 Ohms resistor will deliver the correct voltage to the next stage.

But loading the cartridge with a step-up transformer gives coil to coil transfer, then something magical happens! The energy transfer happens with all the micro detail that gives the flavour and emotion of the original recording. It’s “organic”.

So, that is why IMHO (and Ortofon + others) a good quality 10x step-up transformer is all you need. (at about 100 ohms).

I should also add that again IMHO a “pure” tube phono stage is always preferable.

Why? Because when in 1957 RCA/CBS/Decca/HMV agreed on the LP stereo format and agreed on the RIAA EQ as standard, they did this with tubes in mind as transistors were not advanced enough at that time. So, for a high quality accurate reproduction of the RIAA curve with a MM cartridge requires just two medium gain tubes. Doing this with transistors is actually not that easy and requires a lot more complexity. Of course, these days, the use of very high quality, low noise chips is the norm. Technically superb!

But (and this is a very big BUT!), as we know chips contain a huge number of junctions inside so the signal becomes highly processed though possibly hundreds of junctions, micro resistors, micro capacitors. Whereas the simplicity of just two triode valves (plus one for output) gives a much more “open” and “honest” presentation.

This is the basic idea, let me know if you need more.

Regards

David Shaw

Icon Audio (UK) Ltd

Thank you, David. Lots of food for thought, there.

I’ll take the science as read. But, my experience with loading is a little different than ‘…it simply does not matter very much, the impact on the sonics will be small.’

Granted, I have experienced the negligible differences in sonics. But reading on below will explain why I have a small divergence of opinion. The following was written before I received Shaw’s kind reply.

Some eschew cartridge loading as unimportant, especially with so many moving coils specified for 100Ω, while others, important, especially those vinyl enthusiasts who want to use more than one cartridge. At a past Toronto Audio Show, I attended a masterclass by Angie Lisi on cartridge loading—the ins and outs, and the important differences the loading numbers can make. Changes in sound, for better or worse, were more than significant. And, many times the improved sound’s setting differed from the spec published by the manufacturer. From that moment on, I was a convert. Let your ears be your guide.

For the many audiophiles who agree with Smith, I’m far more on their side of the fence than the stereotypical self-anointed vinyl ‘gurus’ who blather on about why this or that cartridge is specified at 100 but ‘comes completely out of its shell at 900!’. That may be so, but I have my doubts.

My suggestion to the loading converts out there: if the Icon Audio is in your price range and you appreciate my listening notes and experiences, don’t let that one specification put you off. I didn’t play a cartridge other than specified at 100/200, but the performance of this $2400 beauty is so good, I think you will be more than accepting of the single loading number.

Back to my Icon day in, day out.

The fit & finish is exemplary. The Mk. II has been upgraded from its predecessor with an improved power supply and changes to the circuit and wiring. I did not hear the original PS1.

The review unit was driven by thee integrated amplifiers, my reference (Jeff Rowland) and two in review rotation (MBL and Vinnie Rossi). They retail from 10K to almost 20K. All have wonderful, unique qualities and topologies and made the PS1 shine brightly. Cabling and power cords were by Allnic Audio. Exemplary, brilliant wire.

The review unit had some hours on it, but I played my standard 50 hours run in before I had a long sit down, after which, I turned it on in the early morning and let it warm up for at least an hour before I began my daily listening.

Features & Specifications

Built-in volume control, will drive most power amps (I used it as a gain at maximum 72 dB, always using the integrateds’ potentiometers for volume control.)
Stereo/mono switch for better S/N and distortion from mono and worn stereo records
Choke regulated power supply
Separate power supply for lower noise
All hand-wired point to point
No printed circuit board to colour sound
Japanese Blue ALPS volume pot
All Triode valves
Heater circuit floated to minimize heater-cathode noise
Stainless steel chassis
Gold-plated Input terminals
Silver PTFE audio cable
Polypropylene audio capacitors
High quality 2w metal film and wire-wound resistors
Gain: MM 53db; MC 72db
Output Impedance: 50 ohms
S/N: -75db (MM unweighted)
RIAA Accuracy: 20Hz: 0dB; 20kHz: -1dB
Power: Voltage: 120VAC @ 60Hz; Consumption: 50W; Fuse: 1.0A
Dimensions: (HWD) Preamp: 6.7x10.4x4.1" @ 6.3Lbs; PSU: 4.7x9.3x6.3" @ 8.6Lbs

Listening

The Icon bared its soul very quickly and was further refined after run in (soundstage and timbre, specifically). I was surprised at the headroom the PS1 offered—many phono stages I’ve heard compress the soundstage as the volume is increased, usually with solid state phono stages, but also some tube designs. It’s small but mighty; don’t let the size fool you.

Can a $2400 tube phono stage ever be considered ‘entry level’? I’m afraid for all the qualities we desire as vinyl enthusiasts, it’s getting there. For sure, there are sub $2000 phono designs that can do the business—Rega’s wonderful $1500 solid state, dip switched Aria prime among them—but I find good tube designs give me more timbral refinement and transparency. These design qualities are reflected in the price. The wonderful, $2900 ModWright Instruments PH 9.0 Tube Phono Stage is a perfect example, exuding all the qualities heard from the Icon, but at a $400 premium—which brings you the best loading choice, on-the-fly design I’ve used, fantastic for cartridge reviews or those lucky audiophiles with multiple arms and/or turntables.

The PS1 worked its design magic on both stereo and mono cartridges. It’s going to be difficult giving up that mono switch. And if you think a mono choice is not important, you were not the one purchasing a large number of superb pre 1960 vinyl mono records last year. They sound very good on my stereo cart, but on this Miyajima mono cart, it’s a world of difference. And those magical contrasts (see below) were portrayed beautifully by the PS1.

For both stereo and mono, the Icon circuit gives tube fans exactly what they desire—headroom. timbre and transparency. The mono Columbia Debussy/Ravel conducted by Herbert von Karajan with the Philharmonia Orchestra was specific in relaying the gorgeous, diaphanous sound both composers demand (Rhapsodie Espagnole & La Mer). Mono gives you enviable depth and width when recorded correctly, and heard in this Miyajima/Icon Audio pairing, a wonderful discovery for this confirmed stereophile. Post 1967 monos or reissues can sound wonderful on stereo cartridges, too, as the smaller .7 mm groove (compared to the 1 mm groove on pre ‘67 pressings) is easier for a stereo cart with a non-elliptical styles to navigate. However, the result with the correct stylus profile, size, pure mono cart wiring and a wonderful mono performer like the Icon, is a very low noise floor, unnervingly so.

This was evident on the first record I played with the mono switch on (after Icon break in, not the cart); Walter Gieseking playing Debussy Preludes Book 1. A staunch German in this most French, rubato-laden music could make for strange bedfellows, but Gieseking’s Debussy is famous and should be heard by all who admire the composer (in fact, the pianist was born in France of German parentage). They match Casadesus and Michelangeli for recording and interpretation, surpassing both on piano sparkle. So much sparkle shook me to my core when listening.

The phrase ‘Mono? Really?’ kept jumping into the exquisite musical picture.

So, I went with the flow and listened and listened to the more than forty top class vintage mono LPs purchased last year. And during that period, other than the questioning phrase, what lingered most was ‘intimacy and immediacy’.

Not forgetting stereo, the PS1 Mk. II continued over three months to control and manipulate beautifully any repertoire I threw at it. On Tea for the Tillerman I listen for those consequential guitar overdubs for their timbral quality (few do instrumental or voice overdubs as musically as Cat Stephens). Played through the Icon, the overdubs produced the correct effect—rich and refulgent voicing—but led a careful listener as to no doubt the provenance and choice of the mix.

One of my favourite Strauss tone poems, Tod und Verklärung, Op. 24 (Death and Transfiguration), was written in his 20s and needs a great orchestra to emphasize the changes happening in the protagonist’s life while the players and conductor follow Strauss’ scrupulous micro and macro dynamic markings. Thus, very weak, irregular heartbeats (violas in syncopation) as the old man lays dying at the opening of the piece must be emphatic and important, but maintained pianissimo. Does that make sense? No, right? Now you know the difficulty presented to the performers. Nothing, even the most gentle accent or changes in timbre as the bow intensity is increased or decreased, escapes the PS1. As such, very quiet playing is heard with the musicians’ timbral intent accurately conveyed. So, when the man (loudly) recalls his magnificent successes in a surprising spate of energy (Strauss autobiography?) as played by an orchestra like the Vienna Phil (RCA Shaded Dog Classic Records stereo reissue with Fritz Reiner conducting), the Icon can handle anything that is thrown at it. Even when Strauss pulls out all the dynamic stops in the coda of the ‘Transfiguration’, the gigantic power of the orchestra holds know fear for the little phono stage.

Summary

At $2400 and compared unfairly to my $16,500 Allnic Audio, what will you be missing? Well, like all very good tube designs, the PS1’s dynamic renderings are excellent and there is a sweetness to quality instrumentals and vocals that typifies its design heritage. However, the H-7000 is a supermodel of advanced LCR design, $12,100 above the Icon’s price. The Icon can play along side the Modwright and dance with the Allnic H-1202 and the Sutherland DUO, both of which I feel play above their respective price points. That’s quite an achievement. The H-7000 brings ultimate headroom, supreme timbral refinement, transparency, enviable dynamics and a soundstage to die for. Yet, phono stages such as the Icon and the Modwright, Allnic H-1202 and Sutherland are to be admired. They do much of what we love exceedingly well—all are splendid and will set your musical taste buds ablaze for years. It just so happens the PS1 Mk. II does it for less.