Product: Graham Slee Revelation Phono stage
Manufacturer: GSP Audio - UK
Cost, approx: £700 (YMMV)
Reviewer: Geoff Husband - TNT France
Reviewed: December 2010
Some reading the following will see it as an insult to their intelligence – to many I hope it will be illuminating of a subject that they know something about – for a few, particularly the 'children of the digital age' it will totally new. I can't please all the people all of the time, so if you are in the first category then please skip this bit and go to the next section...
Taking the 'vinyl-for-dummie's' approach – when you look at an LP record you can see it consists of a spiral groove cut into plastic – the groove running from the edge of the record to the centre. That groove isn't a smooth spiral, rather there are microscopic wiggles in it – you can see the big ones with a hand lens. The stylus on the end of a cartridge sits in this groove as the record turns, and of course is forced to wiggle back and forth to follow the variations in the groove. At the other end of the cantilever is a little generator – either coils on the cantilever move whilst surrounded by a magnetic field produced by small magnets (a Moving Coil Cartridge - MC), or a small magnet moves whilst surrounded by metal coils (a Moving Magnet cartridge – MM). This movement in either MC or MM cartridge works exactly like generator, producing a small current flow one way or the other. That current then goes to your amplifier which 'amplifies' it and pumps the resultant big current out to the loudspeaker cones which reverse the process and turn the current energy into mechanical energy by causing the coil of the speaker (and thence the cone) to move in the magnetic field of the driver magnet.
There are two snags.
First is that the cartridge 'generator' is tiny. Tiny coils and tiny magnets means tiny, nay minuscule current. Compared to the output of say a CD player it's laughable. Plug the tonearm cable direct into one of your amp's line-inputs (CD or Aux for example) and it'll sound like you've got mice.
So what is needed is another amplifier between the cartridge and the main amplifier. This amp can be built in, or in a second box which then goes into a standard line-input. In the good old days very few amps came without such an amplifier, but now the opposite is true – so you need to buy one if you want to play the black stuff.
The second snag is less simple. Remember I said it would sound 'like mice'? Well not only very quiet, but scratchy and tinny, lacking all tone and substance. Amplifying the signal up to line-level will just make it loud and tinny. It's here where we meet one of the limitations of vinyl.
Remember I said you could see some of the wiggles with a hand-lens? Well those are the really big wiggles, and I guess you won't be surprised to hear that what you looking at are the big bass notes – midrange wiggles are smaller, high frequency tiny, and of course all those sexy details we pay so much to get off the disc are so small you need an electron microscope to see them.
But big though those bass wiggles are, they are nothing like big enough. In a record that was cut 'flat' they would be much bigger, the result would be that the stylus would have a nightmare trying to track them, and that they would take up so much space that you might only get 5 minutes play from an LP side.
What do I mean by 'cut flat'?
A record is cut in an exactly reverse process to when we play it. The music signal in the form of electricity is pumped into a beefy cartridge with a very sharp stylus (cutter) and so it acts as a motor rather than a generator, making the cutter move back and forth in time to the music. If this was done with a 'flat' signal, i.e. one that produced all frequencies equally, then we'd end up with that 5 minute LP that no stylus could track. So the cutting signal has to go through a transformation whereby bass frequencies are highly attenuated and the treble boosted.
When you play back the record that's why it sounds tinny.
This was the dilemma of the engineers who produced records all those years ago and the solution was obvious. As the cutting is a reversal of playing simply add a special amplifier that reverses the frequency shift so that what comes out of it is a music signal that is once again 'flat' with the bass and body restored to the original. And the gadget that combines this frequency correction with an amplification to line-level is called a 'phono stage'.
So Problem Solved?
Um... Not really. Remember all the format wars we've had over the years? Betamax vs VHS? SACD vs DVD-A? Cassette vs 8-Track? And those are just the big bone-crushing battles that changed the world. There've been many many such battles over the years and 70 years ago the big one was between the companies involved in making records, in particular the new, and then revolutionary 'microgroove' LP. Although there were of course fights over the record speed, whether it should rotate at constant or changing speed (like a CD) the size and so on, these had to be resolved because if your record spun at 35 rpm and your rivals at 33 1/3 then you risked your records being unplayable on many machines. In the end sanity prevailed and we ended up with the 33 1/3 12” LP we know so well.
But unfortunately, though the obvious differences between systems were resolved, another more subtle, but just as important one remained. Remember that little snag with cutting LP's? The need to alter the frequency response when cutting a disc, and then reversing the process in a phono stage for playback? Yup you've guessed it, the argument centred on how much you should cut various frequencies, and this argument wasn't completely resolved. Different companies went to the market using different correction curves! So if you bought an RCA record in 1950 it would have a different tonal balance to a Colombia pressing and so on. In 1950 those differences weren't massive, but significant enough to be clearly audible, and that's on the equipment of the time – you needed an RCA record player to get the best out of those RCA recordings. The provision of tone controls in these dark days was essential to get over the worse missmatches.
Moving to the present we now play those same recordings - and many from the 1950's are truly spectacular - on our modern systems with massively improved resolution. And yes some will sound dull, some overbright and so-on. Not only that, with most amplifiers lacking tone controls there's nothing you can do about it, and even those with such controls are merely trying to cover up the problem rather than playing records back properly...
In the end sanity prevailed (in theory in 1954 but the changeover seems to have been slow)) and the RIAA curve was introduced as an industry standard for both cutting and playback. It had anomalies, such as a recommendation for a warp filter which on modern equipment sits on the bass, but such a filter is easy to dispense with and it no difference to the overall balance.
But what if your collection contains some of the masterpieces from the 1950's? Even some 1960's recordings don't follow the RIAA curve accurately? Are you doomed to be hearing them at well below optimum quality? What about 78's – these sound truly dreadful, but is that because the curve used all those years again is different again to the RIAA standard? Well the answer to all those questions is frankly – yes. Phono stages are very clever with different gain for MC and MM cartridges, different loadings for the best match with MC's and so on, but all use the standard RIAA curve with no choice at all – all but a very, very few.
Graham Slee has been producing some pretty good phono stages over the years, some of which I've had the pleasure of testing, and one of which I bought for my own use. The Revelation is something else again. Based on the Era 'Gold' stage that I own, it adds three three-way switches on the facia. By altering these it is possible to cover all the correction curves used by the industry, from 30's 78's to modern RIAA recordings – the stage also comes in both MM and MC versions.
At this point I could copy and paste the comprehensive guide to correction curves and the switch positions that they correspond to, but as Graham Slee has it all beautifully laid out on his website here so forgive me if I send you there.
A quick look at this is a bit of an eye opener. For example all those highly collectable and expensive FFRR recordings require a quite different curve to the RIAA standard, got some beautiful American Columbia recordings – different again and so-on. The different 78 curves are even more extreme. What this boils down to is that most audiophiles with a large record collection are playing some of their discs with the wrong correction curves. So lets have a listen and see if this is simply academic or something we should actually worry about...
Much to my surprise the importance of correct curves was made blindingly obvious the first time I switched the Revelation on... I set all the switches to their centre position (or 'off') for standard RIAA and played some of my records. As I expected they sounded OK, but a little bit edgy and I put that down to all those switches somehow degrading the 'Gold' sound I was used to. I fiddled with the switches in a rather derisory way just to make sure everything worked before starting to do proper listening. Almost immediately I found that having the centre switch 'up' made the whole tonal balance snap back to that of the Gold. It's not just a tonal shift (though in essence it is precisely that), just that the sound was simply 'wrong' before and 'right' with that switch up... A look at the manual (I never read the things normally) made the reason apparent – the true RIAA curve is achieved with that middle switch up – I also missed the fact that Graham had thoughtfully printed 'RIAA' on those switch positions – doh....
Nothing could have convinced me more. By ear I had immediately heard the original curve as wrong, and had found the correct curve easily by experiment and although it wasn't a massive change it was FUNDAMENTAL. Of course you see the point of this – if my familiar records were obviously wrong with the wrong curve, what about the records in my collection that didn't use the RIAA curve? Inevitably they would be effected in exactly the same way.
The truth of this took just a few minutes to confirm – pulling out a beautiful old FFRR recording – Eroica – conductor Erich Kleiber and the Amsterdam Orchestra, I suddely hear a balance and openness I'd never heard before. This is a great recording, but previously I'd only been hearing 60% of it. Dragging out another slab (and I mean 'slab') of vinyl, the LSO playing 'Le Sid' conducted by Robert Irving dating from the '50's - another mint FFRR copy – and yes suddenly it just sounded so modern! What I had put down to rolled-off frequency response, antique mics and poor tape recorders suddenly opened up to produce real 'you are there' moments.
I don't want anyone to think this was something terribly subtle and marginal – the clear tonal shift was audible from the next room, in fact probably from next door. Now these classic recordings (and I tried several) are highly collectable and fetch high prices, not least because of the quality of the performances. Well I'm here to tell you that if you have such records in your collection you are hearing a fraction of what they contain. As important is that when such recordings are remastered the job is frequently done by parametric equalizers and the like – not by using the correct curves. As well as adding another component and associated cabling into the chain, these things frequently introduce phase errors. The Revelation on the other hand is simply a phono stage that can be configured to give the correct curve – it doesn't add any more processing steps than you'd find in any other phono stage.
Of course then there're 78's – I don't have any way of playing these, but the variation in curves is far greater than with microgroove records, and a 78 played with an RIAA phono stage is simply a joke. In fact I do have a few LP's which are transfers from 78's and I found that fiddling with the Revelation made a huge difference to their quality.
Which is all great, but to be brutally honest, most of my musical enjoyment comes from the 60's onward and mostly 'classic' (my daughter calls it 'old man's') rock... So for me the lower cost Era Gold would cover 99.9% of everything I played. Except that after a couple of weeks of fiddling about with the Revelation I began to know what the result of each switch change was and you know what? A hell of lot of music from the 60's and even 70's sounds like they were recorded with something well away from the RIAA standard! A flick of a switch and early Stones took on body for a start! Now whether these recordings were indeed made with an incorrect curve, or that the mastering engineer/producer screwed the EQ I don't know, but quite a few albums sounded better with non RIAA curves, in fact I'd say that the majority of early 60's popular music benefited from a curve that gave more body to the sound, reducing the tinny aspect that characterises much of that era, some others, especially some 70's stuff from the USA seemed to prefer a little treble cut (Stevie Wonder's 'Musiquarium' for example) and so on...
Of course all this is of academic interest to the true audiophile if the actual phono stage doesn't sound good, but in fact it sounds EXACTLY like the Gold that I own and use regularly, and that makes it a very fine stage regardless of its flexibility, and certainly one capable of taking on anything I've heard in its price range. I'm not going to waffle on for 2000 words on the performance taken simply as a stage because you can of course read it all here
'Revelation' is a rather presumptive name for a product, but in this case it might even be merited , with many recordings the result is simply 'ear opening'. The original multi-curve stage from Graham was called the 'Jazz Club' and the name rather gives away the intended market. Well after having lived with the Revelation myself I would say that for me such a stage** is a must-have unless your collection is made up solely of well recorded 70's and later records. Going back to listening to woolly or harsh sounding discs just because they are recorded with obsolete correction curves, or poor EQ isn't an option for me. I'm fortunate in having three turntables running, one runs the superb and very expensive ESE Nibiru, and another now has the Revelation permanently attached. Though ultimately I think the Nibiru the better stage, the Revelation isn't far behind, and with records requiring different curves it's obviously a street ahead.
Now all I need is to start digging up a load of early 50's Jazz records:-)
*Well obviously there's all that stereo nonsense but it's beyond the scope of this article and the principle is the same.
**There are a couple of phono stages that offer variable curves, but they are several times the price of the Revelation...
© Copyright 2010 Geoff Husband - firstname.lastname@example.org - www.tnt-audio.com