Why do we splash in Op 10, no 1?

[hmpiano]

...because we are only able to 'will' the same arpeggio to repeat as we go up the keyboard.  In reality, because there's quite a change in position as we go up, the body has to compensate in various ways for each individual octave.  There's a dissonance here - consciously we're repeating something as we go up, physically we're not.  Even if we wanted to we would not have access to the physical changes - we're only allowed to 'order' actions.

[j_menz]

In reality, because there's quite a change in position as we go up, the body has to compensate in various ways for each individual octave. 

Why pick on 10/1? To the extent that this is true, it is true of any piece that repeats a sequence an interval apart. Nothing special about 10/1, nothing special about the octave step. And nothing really by way of a surprise; we've all been dealing with this since grade 2 or earlier.

[hmpiano]

we've all been dealing with this since grade 2 or earlier.

At crotchet = 176?

[j_menz]

At crotchet = 176?

Probably not at grade 2, but certainly later; and sometimes even much faster.

[zjazzchopin]

Can you explain what you mean by "splash"? I'm having a bit of trouble following your sentences. Perhaps explain what you are talking about in clearer terms?

[hmpiano]

Can you explain what you mean by "splash"? I'm having a bit of trouble following your sentences. Perhaps explain what you are talking about in clearer terms?

Inadvertently putting down an extra key beside the one you intend..

[49410enrique]

Inadvertently putting down an extra key beside the one you intend..

i prefer to call them 'spontaneous non-chord tones' or SNCT's for short. but sometimes i just refer to them as 'sprinkles'

[outin]

Are these the eggs from the coloured chickens?

[nyiregyhazi]

...because we are only able to 'will' the same arpeggio to repeat as we go up the keyboard.  In reality, because there's quite a change in position as we go up, the body has to compensate in various ways for each individual octave.  There's a dissonance here - consciously we're repeating something as we go up, physically we're not.  Even if we wanted to we would not have access to the physical changes - we're only allowed to 'order' actions.

Patent nonsense. We can check the differences via slow practise. Nevertheless even at speed I have plenty of conscious awareness of how my upper arm drags the hand into the alignments. Also, you can say the same of any scale or arpeggio. If you cannot play scales of four or five octaves without splashing (which your argument would apply equally to, by logical extension) there's something seriously wrong with your technique. The issue of different alignment in different octaves should be mastered very early on via basic scales and arpeggios. This should not even be an issue for anyone attempting this.

The real reason why this study is prone to slips is extremely simple. There are big gaps of variable sizes to cover quickly- which is more hazardous than small and familiar interval patterns. It also means that that the fingers cannot always get right into the plane of each key- often putting them at a diagonal, which necessarily reduces the room for slight error. If a player cannot cope with the basic issue of lining the arm up differently in different registers, he's not ready to even consider Chopin études. Such basic problems should not come into it. Perhaps you need to engage in a little less "mental practise" and do enough actual practise to familiarise yourself with the basic real world geography of the keyboard?

[hmpiano]

Patent nonsense. 

That's as far as I'm reading - your insults know no bounds.

[nyiregyhazi]

After spending a minute or so playing through the start of the Etude, the greatest fallacy of the argument was immediately exposed. It hinges on a person thinking that picturing the notes in an advanced etude is enough to actually play them- without any consideration of the process of actually sitting down and learning the optimal technique. When I play I don't consider the fact that I am repeating the same unit in various octaves. Obviously I have previously noticed that- but then I got on with LEARNING how to execute each individual one in the easiest way. There are no comparisons when I execute it any more (if ever previously). Each unit is just what it is- something to be learned and then executed. I couldn't give a damn what exactly is different and what is the same. You just find what is right for each one and then execute it. Then you chain them together, without conscious consideration of what is the same and what is different. If you can't chain them together without consideration of what is different in different octaves, you just didn't learn the basic components properly and that's nature's way of telling you that you screwed up and have more work to do. The reason why we practise (often in very small chunks, to get each individual part right) is to eliminate such mundane considerations. It's not enough to understand construction. You have to learn effective movements- whether it goes in various octaves on stays in one. If "willing" it doesn't work, all that shows is that you haven't put the right quality of work in yet.

It's no surprise that that the poster plays the etude like this:

It's not about what is the same and what is different. Technique comes from feeling effective movements- not from the assumption that ability to analyse something into constituent parts might have be enough to execute it. If these things are not looking after themselves, it points to a fundamentally flawed manner of practise and/or flawed general technique. If that's not there, it will be all over the place- whether you are dealing in a motif that repeats in different octaves or something that stays in the same place. It's simply a matter of getting on with learning to play what you are asked to do- instead of using pretentious language in a bid to make a statement of the obvious look profound.

[nyiregyhazi]

That's as far as I'm reading - your insults know no bounds.

I backed it up with a rational proof. If you indeed struggle with the entirely analagous example of four octave scales (compared to two octave ones), you simply have poor technique and should be going nowhere near Chopin Etudes. If you do not struggle with multiple octave scales, your argument that this is specifically what makes the etude difficult falls apart at the seams. Covering multiple octaves is not what is unique to this etude. Many easy pieces do the same.

[ajspiano]

I can't say I agree at all with the OP here. Thats really not the issue at all. As has been pointed out, most of us probably started dealing with that problem very early on.

If I have to answer the OP question specifically - it's because the wide, fast and subtly changing intervals make it very demanding to maintain the structural integrity and balance of the finger/hand/arm. Breaks or weaknesses in the structure throw the mechanism off balance and it leaves the performer in a position where they must make a wide fast leap without a stable starting point. It's enormously difficult to do that accurately.

[hmpiano]

Is that the greater problem?  I think of no less importance is the fact that you will the repeated action of each arpeggio (say bar 1 of op 10 no 1) but the actual movement for each arpeggio is slightly (I would say at the top greatly) different as you ascend.  I suppose you'd need to feel that dissonance to come to this conclusion.   

[nyiregyhazi]

Is that the greater problem?  I think of no less importance is the fact that you will the repeated action of each arpeggio (say bar 1 of op 10 no 1) but the actual movement for each arpeggio is slightly (I would say at the top greatly) different as you ascend.  I suppose you'd need to feel that dissonance to come to this conclusion.  

this only serves to reveal the flaws in your attitude. I will no such thing. Every note or group of notes is taken on its own merits. I make no assumption that anything is necessarily the same or different. I simply learn each small unit and chain them together.  If you think that recognising repetition in different octaves ought to be enough to magically make it work, you're mistaken. It's simply about feeling what is right for each movement. Understanding that r repetition occurs in each octave does not create technique by magic. You need to go back to basics and stop expecting such a simplistic observation about repetitions to make it work. Unless someone has the technique of volodos noticing a pattern does not make you able to execute it. If you assumed it would by mere"will" you were simply guilty of blind optimism.

This boils down to nothing more than the fact that intellectual analysis of  musical construction only assists organisation. It doesn't create technique by magic, if you're not getting the physical nature of technique right.  Strength of intent can work in easy music. Difficult music requires quality of intent and that requires a good deal more than obvious structural analysis.

[werq34ac]

I'm calling BS on this one. The differences between each octave is present, but subtle. In fact, anyone at the level to learn this piece has probably played piano for long enough that their bodies automatically adapt to different octaves so we don't need to take into account something as tedious as the physiological differences of playing a pattern one octave higher. Seriously, if you think that differences between each octave is the main difficulty of this piece, you're making yourself look foolish by attempting to appear insightful in something where not much insight is needed.


And as for splashing, I find most of it happens in the awkward sections of the piece. I don't know the measure numbers off the top of my head but it's the part where you get a crapload of black keys on your 5th finger.

[hmpiano]

There's a vid of a Garrick Ohlsson interview.  He plays the first bar - where does he splash?  the top note i.e. the one most physiologically different.

20:24

[lostinidlewonder]

Splash?

[hmpiano]

Splash?

Definition above.  I added the Ohlsson vid if you missed my edit.

There's also another phenomenon - by the time I get to the top notes I've often forgotten which arpeggio I started with.  That's a short term memory problem (it's in my long term - I've been playing it for years) - a phenomenon that's obviously linked to the OT.  If the top octave is different on a physiological level and I'm trying to match it with a lower octave, physiology there will be a dissonance (cognitive that is).

Seriously, if you think that differences between each octave is the main difficulty of this piece, you're making yourself look foolish by attempting to appear insightful in something where not much insight is needed.

But that's all there is.  You do the same thing four times (occasionally three).  Think how easy it would be if it was only twice, and your hands stayed out in front of you.  Imagine you played in the dark and had light spots on your joints - I think you'd see a lot of differentiation between octaves.  In the long run I suppose it depends on how you play it.  Play it like Czerny and maybe not such a contrast.

[lostinidlewonder]

It's all gobbledygook can you define for me?

[hmpiano]

Which bit?  I've already defined splash:

Inadvertently putting down an extra key beside the one you intend..

[lostinidlewonder]

Meh I've lost interest don't worry.

[nyiregyhazi]

Definition above.  I added the Ohlsson vid if you missed my edit.

There's also another phenomenon - by the time I get to the top notes I've often forgotten which arpeggio I started with.  That's a short term memory problem (it's in my long term - I've been playing it for years) - a phenomenon that's obviously linked to the OT.  If the top octave is different on a physiological level and I'm trying to match it with a lower octave, physiology there will be a dissonance (cognitive that is).

As already pointed out, all this shows is your limited technique. I don't think I can recall a single occasion where I've lost track of what arpeggio I'm playing, after having successfully iniatiated the first group. Sometime my fingers will fail to do what I wish, but I find it plain bizarre to think that anyone could forget the basic note grouping after successfully beginning it. It shows that YOU have a highly significant conflict between the nature of visualising the grouping and the means of executing it. They should never interfere with each other. If you think that understanding the notes of an advanced etude ought to have been enough for the fingers to execute the notes, you are not living in the real world when it comes to technique. It's a very easy etude to visualise the patterns of- arguably the easiest of all to picture mentally. It's just hard to get the fingers to actually execute those notes. Equally, if you forget what you are executing due to a struggle with physical issues, you have simply failed to put in the proper groundwork. You need to get properly stuck into the process of mastering each individual movement on its own terms- so the visualisation leads directly to the execution without any physical struggle. That doesn't happen by magic. It requires QUALITY OF PREPARATION! If you're having to think so hard about physical issues that you can lose track of what notes you are playing, you have a considerable amount of work to do on the basics. It's a matter of picturing the individual demand and then figuring out how to do it. If you do a proper job of that, you will not get confused by the differences. Each one just is what it is. Comparison to others does not even enter my mind- assuming I've learned the bar properly. If you can't do without it, you haven't done the work to an adequate standard. There's a big difference between profound observations and very simplistic ones that stem from a lack of proper groundwork.

Also, the Ohlsson example illustrates nothing. It could perhaps be argued that it is generally more hazardous when playing at the upper end of the keyboard- due to both reaching the arm out more and having less clear sight of the keys. But pianists are more prone to slips in the outer registers regardless of whether repetion has occurred. Frequently pianists miss the top of an arpeggio with the 5th finger, after hitting every repetition in new octaves just fine. That is the only movement that is NOT being repeated from prior octaves!

[hmpiano]

As already pointed out, all this shows is your limited technique.

As there was nothing on TV I thought I'd give you one last stab.  Unfortunately, I can't get further than this - what could you possibly know about my technique?

[nyiregyhazi]

As there was nothing on TV I thought I'd give you one last stab.  Unfortunately, I can't get further than this - what could you possibly know about my technique?

If you think you're fooling anyone by exposing the same personality traits under nothing more than a new username (note also the use of the word "splash" in the description), you're kidding yourself.

[hmpiano]

If you think you're fooling anyone by exposing the same personality traits under nothing more than a new username (note also the use of the word "splash" in the description), you're kidding yourself.

I see nothing wrong with the video you posted, it's quite mesmerizing.  Don't get your point.

[nyiregyhazi]

I see nothing wrong with the video you posted.  Don't get your point.

Quite. The fact that you are unable to put aside your delusions of grandeur for long enough to be slightly self-critical (even when trying to pose as somebody else) is what makes it so obvious who you are. A pianist who has played this piece for years and thinks that what is on offer there is "fine" (including misreadings, severe uneveness and a complete break in the rhythm prior to the return to C major)? You're kidding yourself if you think that is supposed to be believable.

[hmpiano]

I fail to see what this vid, or your thoughts on the quality of playing therein, has to do with the OT.  Please stop bloating this thread.  I'll be shouting troll myself soon!

[werq34ac]

Definition above.  I added the Ohlsson vid if you missed my edit.

There's also another phenomenon - by the time I get to the top notes I've often forgotten which arpeggio I started with.  That's a short term memory problem (it's in my long term - I've been playing it for years) - a phenomenon that's obviously linked to the OT.  If the top octave is different on a physiological level and I'm trying to match it with a lower octave, physiology there will be a dissonance (cognitive that is).
But that's all there is.  You do the same thing four times (occasionally three).  Think how easy it would be if it was only twice, and your hands stayed out in front of you.  Imagine you played in the dark and had light spots on your joints - I think you'd see a lot of differentiation between octaves.  In the long run I suppose it depends on how you play it.  Play it like Czerny and maybe not such a contrast.

I miss the notes in the middle, especially the ones on black keys much more often than I do the top notes. Could be just chance that Ohlsson missed that note. You do the same thing 4 times but that same thing is difficult because of the intervals. Changes in octave don't change the fact that the intervals aren't easy. And is it easier if it were only two? Look at the section where it is only two octaves going up and down. That's not an easy section. It's more difficult than the first theme.


As for your video,
1. It's way too slow.
2. The lack of musicality is almost unbearable
3. It's on an electric
4. It's only the first page. You never got to the hard parts.

Nothing wrong with the video? You yourself said that the metronome marking is 176 to the quarter note. That has to be at most 120.

[hmpiano]

I miss the notes in the middle, especially the ones on black keys much more often than I do the top notes. Could be just chance that Ohlsson missed that note.

Chance?  and one of the world's top Chopin pianists?  I don't think so.  It's telling us something.  As for the vid Nyer.... posted - totally irrelevant to the discussion.

[ajspiano]

Can't say I'm entirely convinced that hmpiano is a reincarnation of keyboardclass - though certainly possible looking at the way he words his posts.

Is that the greater problem?  I think of no less importance is the fact that you will the repeated action of each arpeggio (say bar 1 of op 10 no 1) but the actual movement for each arpeggio is slightly (I would say at the top greatly) different as you ascend.

Plainly, no.

The problem you are presenting is one that I addressed VERY early on in the learning of this piece, observing the specific physical difference between each group. I also rapidly concluded that each individual note needed to be treated in this manor, not each octave of arpeggio. Every note, and subsequent transition needing to be as efficient and effective as possible. Which was the point of my "reason we splash" every note must be stable and controlled or subsequent notes will be unstable. This requires a 'feel' for every note. Willing octave groups, (while certainly a relevant part of my learning process) was not sufficient to develop that at all.

Beyond that, to successfully play the piece... - while aurally there needs to be some octave by octave focus to bring out the accents - physically, you need to feel entire ascents and descents as single flowing motions.

Not only is this relevant physically for the RH, but also because there is such a strong melodic component in the LH. The RH can be felt in waves of whole bars or phrases in order for you to feel the full length of the long octaves in the LH.

For the record, I make no claim claim to be perfect in this regard, you can review a semi oldish take by me here - https://www.pianostreet.com/smf/index.php?topic=47541.0 - there is certainly some "splashes". When I say old, i don't mean in time, rather as far as technical and musical development in the piece - I have changed things since the videos in that thread. When the videos there were taken the piece had been under my fingers for ~6 months.

[werq34ac]

Chance?  and one of the world's top Chopin pianists?  I don't think so.  It's telling us something.  As for the vid Nyer.... posted - totally irrelevant to the discussion.

Horowitz misses notes on purpose? 

As for the video, if you really are keyboardclass (which you haven not denied), then it is a good indication of how you play. And since it shows how you play, it's a good indicator of your authority on this subject. His point is that you show little mastery over the piece, and so you really aren't in a good position to make deep insights into the piece just yet.

[hmpiano]

Nice playing ajs and as you say the entire sweep up (and sweep down) must be perceived as a single unit - both physically and aurally.  And maybe that's the answer.

werq, you don't even need to play the piano to make my original observation.  The best formula one driver is not the best authority on how his car functions.

[j_menz]

you don't even need to play the piano to make my original observation

Indeed, it would only be possible to make it if you didn't.

[49410enrique]

Indeed, it would only be possible to make it if you didn't.

..but he does think it was really funny

[nyiregyhazi]

Nice playing ajs and as you say the entire sweep up (and sweep down) must be perceived as a single unit - both physically and aurally.  And maybe that's the answer.

werq, you don't even need to play the piano to make my original observation.  The best formula one driver is not the best authority on how his car functions.

That's a piss poor analogy!  that would be comparable to whether a pianist needs to know the inner workings of a piano action.

Your delusion of insight is like some tool who once did a lap round a circuit in a bashed up old lada and who kept skidding off the track, yet who believes that gives him insight into the difficulties faced by a serious driver. The most insightful commentary on formula one driving issues always comes from former drivers-not the outsiders.

[outin]

Can't say I'm entirely convinced that hmpiano is a reincarnation of keyboardclass - though certainly possible looking at the way he words his posts.

It was actually made pretty obvious in a certain earlier thread that is now closed.

ajspiano:
Loved you technique, when I get my own jet I'll book one of your Tuesday lessons...although I want to keep my present teacher as well

[hmpiano]

How about "I renounce keyboardclass and all his works and all his ways".  Is that enough denial?

[nyiregyhazi]

How about "I renounce keyboardclass and all his works and all his ways".  Is that enough denial?

The fact that you have been quite so inept at concealing your identity makes me extremely doubtful that you'll do anything other than continue to behave exactly as the person you so clearly are. Your manner stands out from a mile off.

[werq34ac]

How about "I renounce keyboardclass and all his works and all his ways".  Is that enough denial?

How do we know you aren't lying now that it has been pointed out that all the evidence (according to other people) indicates that you are indeed keyboardclass. You seem to have the same kind of threads that kbc tended to post. Like some ridiculous claim that attempts to sound like wisdom?

[hmpiano]

You have a point werq, after all, only the true keyboardclass would deny that he's keyboardclass.

Anyway, back OT - so, the consensus is others don't have extra difficulty with the top two octaves as I seem to?    

[nyiregyhazi]

You have a point werq, after all, only the true keyboardclass would deny that he's keyboardclass.

Anyway, back OT - so, the consensus is others don't have extra difficulty with the top two octaves as I seem to?    

actually, I wouldn't necessarily disagree that it's harder when away from your body. What is so naive is the belief that this might be a profound revelation (rather than an amateurish problem that ought to be dealt with in the very first steps of practise) and this nonsense of supposedly willing the same thing to happen four times. You speak solely for yourself. In good practise, each movement is studied on its own merits.

[49410enrique]

i don't understand this thread at all? what's a splash exactly? the OP said something about inadvertently putting down a wrong key?  are we taking wrong notes, that's it? why not just call it inaccuracy, and since when is simply hitting the correct note the big goal? isn't the point to refine techincal and physical approach to the difficulty of the study so as to allow for musical freedom?

sorry if it's a needless reply, i just don't understand the point of the thread (initially, i think i follow some the 'argument') but the motivation for the thread is puzzling (note i am not neccessarily taking aim at the OP just trying to understand a bit better).

at the end of the day isn't accuracy (when not playing from memory) an issue when you're playing faster than you can handle? i.e at a quicker click than you're just ready for? if that's the case can't you just 'stop splashing' by playing slower until you know the piece well enough to increase tempo?

[hmpiano]

Enrique, you're probably right on how to solve the problem but I'm more interested in why there is a problem.  Why repeating the same arp pattern should get more difficult as you move up the keyboard. 

[49410enrique]

Enrique, you're probably right on how to solve the problem but I'm more interested in why there is a problem.  Why repeating the same arp pattern should get more difficult as you move up the keyboard. 

oh ok. got it. thanks for clarifying. i'll not discuss further since i try to 'speak not what i know not of' and as i have not studied or performed this piece ever, it'd be silly for me to try and interject any truely relevant 'insight'.

 

[nyiregyhazi]

Enrique, you're probably right on how to solve the problem but I'm more interested in why there is a problem.  Why repeating the same arp pattern should get more difficult as you move up the keyboard.  

Then it's time to redirect your concern to how to SOLVE the problem, instead of why there is a problem. Otherwise, your musings are of as little value to you and your development as they are of  interest to others. If you're only looking at the self-evident fact that the arm is in different positions within different octaves, all you are doing is distracting yourself from the broader technical reasons why such a standard feature of all advanced piano music is a problem for you. With sound fundamentals, it should not be. It strikes me that, deep down, these musings are nothing more than a way of trying to distract yourself from your real technical problems- by kidding yourself that an extremely superficial and self-evident observation is something profoundly deep. You're lying to yourself, if you feel that this kind of ultra-superficial analysis is going to effect any changes.

Ask yourself this- can you play the unit itself (minus any repetitions in other octaves) cleanly and precisely at at least 140 bpm (which is about the bare minimum for any serious performance)? If not, you haven't mastered the quality of movement that is necessary for the most basic unit- so it's small wonder you can't get around it properly in other octaves either. Plodding along at the speed seen on your video will teach you nothing. The reason different octaves are notably harder for you is because the basic fundamentals are not in place.

[nyiregyhazi]

Incidentally, it strikes me that your bizarre concern is comparable to a beginner who successfully analyses that the reason that the Chopin 3rds Etude is hard is because you have to play two notes at once, not one- and thinks he's somehow hit on some amazing explanation for why he cannot play it. Such an observation, like yours, is extremely superficial and of zero value to learning. A pianist who is up to the job doesn't care about the incidental fact that it's hard because you play two notes a once. They care about HOW to get their basic fundamentals up to the point where they are good enough to execute that particular demand. Similarly, pianists who want to play op. 10 no. 1 get on with getting their technique in general up to the job- not trying to blame their lack of success on self-evident analysis about repetition in different octaves.

Stop being a coward who looks for things to blame and get on with learning to play the piano better.

[hmpiano]

Then it's time to redirect your concern to how to SOLVE the problem, instead of why there is a problem. ... by kidding yourself that an extremely superficial and self-evident observation is something profoundly deep. You're lying to yourself, if you feel that this kind of ultra-superficial analysis is going to effect any changes.

Firstly I have no wish to look into solving the problem till I've understood it - it certainly is not as simple as the arm being in different positions.  Secondly, I don't know where I referred to these musings as 'profoundly deep'.

[pts1]

I've played this piece for many years and its one of my favorite Chopin Etudes, and in a way perhaps my absolute favorite. So I'll try and give a few helpful hints since there are "secrets" to the playing of this successfully which are not readily self-evident.

First of all the etude does not take a lot of power. The fortes are accomplished with an abundance of sound not forcing "loud" sounds. So right there, is a key to the playing of it.

Forcing, straining, muscle exertion, etc., will be your downfall.

This is about keeping the hand light and supple.

It is about keeping the hand "small" and not "large" or stretched, which seems quite counter intuitive.

Once you stretch past a comfortable degree of extension, the hand binds and you will soon falter.

So the trick is to maintain the feeling of "compactness" and energy in the hand by perfect placement on the key before its played in small intervals with a continuously floating forearm and hand, repositioning and adapting to each interval as you transition to the next. Also one must realize the arpeggios played closer to middle C will have different hand positioning than the high arpeggios, in which the hand needs to "point outward" slightly as in the Opus 10 No 2.

Actually, both No 1 and No 2, which seemingly couldn't be further apart are actually closer together than one would think, since the suppleness, positioning, and clustering of the notes for play take the same type of technique, though on a much different keyboard landscape.

I don't think its coincidence that Chopin numbered these two etudes one after the other as both a riddle which I'm sure he took some amusement in, well realizing if you can really learn to play one then you can play the other.

Unfortunately, No 1 can be plodded through on strength, giving the player the illusion he's making progress, when in fact, this is not the case, whereas, No 2 is really not possible to "muscle" one's way through because it will sound terrible, even if you're able to do it.

If these are played as a set -- Opus 10 -- No 2 does follow No 1, and if you force your way through No1 then you're dead. So the goal would be to be able to play No 1 so you can go into No 2 successfully with only about 10 seconds or so of rest. This requires a high degree of perfection in both etudes.

Can you imagine how many pianists Chopin had completely blown up with the first 2 etudes back when these truly revolutionary studies were written? They likely thought of them as impossible.

Valentina has a good video of this showing the proper technique. You'll see how light and supple her hand and arm is, and her excellent "placement and adjustment" on the fly.

Another thing that is probably THE most helpful point is to have a musical idea of what this piece is about. It is, after all, music first and last.

My particular idea is that this Etude is very cathedral-like. Each base octave is a pediment and the arpeggio rising above is an arch rising to its ceiling peak and then gracefully arching back down.

So for me, there is a reverence in this etude, therefore to play it with this "cathedral" approach, tells me a lot about the necessities of the technique to form the proper sound picture.

Mostly, you will have to find your way by yourself in this piece, since everyone's hand, arm, finger, etc., is different, and the quick micro-adjustments can only be tailor made by yourselves.

One other hint is to practice is piano or mezzo piano so as to find the right shape, movement, etc.
Adding power from the get go will get in the way of discovering your correct fit with the keyboard.

[nyiregyhazi]

Firstly I have no wish to look into solving the problem till I've understood it - it certainly is not as simple as the arm being in different positions.  

Precisely the point that is being made to you. If repeating something in different registers causes problems, that is a mere symptom. The underlying problem lies in your core technical foundations. The change in register merely exposes the problems in your basic quality of movement. As long as you waste time thinking that observing the self-evident fact that things are slightly different when repeating octaves is of any use, you will continue to miss the actual solution to your problems.

The answer lies in reliability. A quality of movement that is naturally consistent will work- regardless of adaptations between octaves. A quality of movement that cannot be reproduced consistently will cause the problem you describe. Things go wrong when a style of movement is erratic.