Blüthner grand aliquot modifications

[lluiscl]

Hi. I have a 190 cms Blúthner grand aliquot from 1921 (series VIII), all in original shape (incredibly good shape) except a new Abel Blüthner (soft) hammers. After voicing and full regulation everything (including its Patent action and correcting bedding -no frame glides here-) it begins to sound great... The question here is that the famous aliquot 4th string doesn't perform (in my opinion) well. In this piano from G4 to G6 there is the first section of Aliquot, tuned an octave above. The rest (G#6 to the treble end) there is the second section, tuned as unison with the three strings. Well, if I hit a note from the first section, the 4th string doesn't move. Nothing. It's very easy to test stopping the three strings after the blow (keeping the key/damper pressed). Instead this 4th string sounds when I hit the octave above (of course, for resonance unison...). So I believe this first section is only "partial useful" playing octaves... May be when it was young were some kind of sympathetic resonance with the second harmonic... But looking for the äctual new Blüthner grand I see they have only the second aliquot section.
What now I am planning is a full rebuilding of this instrument, looking for the best sound performance. And I am thinking two solutions for the aliquot system.
1. Eliminate completely the first section (and all their parts), keeping the second one. It'll be less load to the soundboard...
2. Install the brass aliquot guide of the first section (or similar lighter one) in to the same bridge, as the second one has, transforming the octave in unison. In this way sure it'll vibrate, adding power and colour... There is room in the bridge for this delicate operation, when I am saving the full structure (dampers, hitch pins). Even the central aliquot bridge may be the support for a retractable top system rail damper for these four strings...
I know this second way I am moving the impedance from the aliquot bridge to the central bridge... although the load of four strings (I think) is minimal.
May be I am dreaming? Anyone tried before?
All your comments are welcome!!

[Colin Nicholson]

Restringing a grand is relatively straight forward in terms of practicality, however restringing a grand that is about 90 years old is a different story. By loosening off the tension alone (of the old strings), you may open a new "can of worms".

When strings stretch (particularly steel ones), they actual become slightly oval in shape throughout their circumference over years of stretching - this often gives rise to poorer resonance, inharmonicity and false beats. For the fourth string to vibrate freely, regardless of it being at the right tension/ pitch/ string gauge.... whatever, there may also be a lack of downbearing on the bridge, or the contact area near the hitch pin/ agraffe. A piano of this age may also have "moved" over the years, so the relationship of the bridge attached to the soundboard may not be right..... its not just a question of restringing, so best check out the downbearing with a downbearing gauge - and it may transpire the bridge will need to be capped or raised slightly..... a difficult job, and a piano of this age, its risky business.

[lluiscl]

Although the soundboard (at 440) is almost flat I see a good downbearing with my micrometer gauge. The sustain is excellent in all the notes. I know restringing an old grand is an aventure... but my thoughts here are if the original aliquot system was really running (or it was really a real "marketing"...). The 4th string sounds good if I pluck it, or for resonance with the octave, but not for the actual key.

[Colin Nicholson]

Not sure what you mean by "although the soundboard is almost flat" ??
A soundboard is never flat! it should be slightly crowned and raised in the middle, basically, its a huge diaphragm, like a loudspeaker. Whe a soundboard is new, the shape can be seen, but as tension is added to the strings, this forces & squeezes the soundboard slightly flatter. When a piano is restrung, the soundboard may never regain its original shape, and there are also the soundboard ribs to take into consideration - possibly separating.

The only way to measure down-bearing accurately is to use a downbearing gauge, not micrometers - this instrument straddles over the bridge, and strings are about a two degree angle downwards (or less) from the horizontal. Micrometers only measure distances/ thicknesses, not an overall surfaces where there is string length. A downbearing gauge also looks slightly "off-set" - to do its job.

Once you start to reapply about 16 - 20 tons of pressure with new strings, old glue joints may come apart, the soundboard may flatten itself even further (as it may not bounce back to its original diaphragmatic shape when de-strung). If you detect poor downbearing and adjust this, this can also have dramatic effects on the strings. Although the strings will be louder, they may lose their sustain value. Also depending on whether the soundboard is screwed and glued, screwed, or just glued - again, who can tell what may happen? Old Pianos sometimes have the opposite effect, so too much down-bearing can also cause strings not to vibrate properly.

Hope it all goes OK for the restring!

[lluiscl]

Obviously "almost flat" means "slightly crowned", yet... (measure with thread at back of the sounboard).
My micrometric unit is the central leg of the three legs unit gauge to measure concretely downbearing at the bridges.
Thanks for the info, Colin. Again: I'd like to share experiences with this particular aliquot. Anyone?

[Barrie Heaton]

Although the soundboard (at 440) is almost flat I see a good downbearing with my micrometer gauge. The sustain is excellent in all the notes. I know restringing an old grand is an aventure... but my thoughts here are if the original aliquot system was really running (or it was really a real "marketing"...). The 4th string sounds good if I pluck it, or for resonance with the octave, but not for the actual key.

Bluthner has changed the aliquot as it was self defeating, it added power to the piano but the extra bridges on the soundboard made it stiffer, so killed some of the sustain. This gets mores so as the pianos get older as the fibres in the soundboard wood get tired so they lose some of there resilience. The octave aliquot need to be tuned pure and the union's ones need to be tad sharp

Now the new system is is very good, it is part of the main bridge the fourth string is set just above so the hammer is not coming into contact and because you have no extra bridge on the soundboard the sustain is much improved As to tuning the new ones if you want a pure sound then you tune the aliquot dead in However, Bluthners likes them to be tuned 3 bets sharp to give the piano that distinctive Bluthner sound I have on of their Concert grands on my round I think the piano sounds better with just one beat sharp on each of the aliquots

Barrie

[lluiscl]

Thanks Barrie. As I wrote I am planning a full rebuild of this grand and it's obvious that the separate aliquot bridge is not working more. With my first option (eliminate this bridge, as the actual Blüthners are) I'll reduce the stiffness of the soundboard. It's better or worst for the killer octave? (locate in this area).
The second option is risky but innovative. It touches me... Structurally I'd be only changing the 4th strings impedance of place. Can it works?

[Barrie Heaton]

Thanks Barrie. As I wrote I am planning a full rebuild of this grand and it's obvious that the separate aliquot bridge is not working more. With my first option (eliminate this bridge, as the actual Blüthners are) I'll reduce the stiffness of the soundboard. It's better or worst for the killer octave? (locate in this area).
The second option is risky but innovative. It touches me... Structurally I'd be only changing the 4th strings impedance of place. Can it works?

IF you go for the removing the first section would I would extend the the bridge agrafs for the six notes that have a bridge and remove that bridge However, it will devalue the piano

the aliquot manly comes into play when you have the sustain on. We did an experiment at college back in the 70s a blind test with the aliquot muted and unmuted most could not tell the difference

Barrie

[joe]

Be interesting to know whose carrying out the refurb and to what extent ?

[lluiscl]

Thanks for all your inputs. I am fully convinced that the octave 4th strings don't vibrate more in this grand... In my tests I discover curiously that the non speaking section of these strings (double larger that the speaking ones -Withdrawing the individual felt-) are able to vibrate for resonance at unison with the key notes!!
In your opinion has any sense to reduce the wire of these 4th strings? (reducing its tension). May be can they so vibrate?