[pianotech] SWELL was What is bloom

[John Delacour]

At 14:15 -0500 17/03/2011, Ron Nossaman wrote:
]
>On 3/17/2011 1:54 PM, John Delacour wrote:
>
>>I would suggest therefore that the effect is caused by the system using
>>the available energy to produce and recycle vibrations which, when the
>>dampers are down, is converted into heat.
>
>I agree. This happens in any case, in all pianos. The difference in 
>those few that exhibit that swell effect is, I think, mostly 
>soundboard efficiency.
>
>I wonder at this point, how many have actually heard a piano do this.

As both you and I have said, it is rare.  I've mentioned the 6'3 
Brinsmead where I first noticed the effect, and it had it in spades. 
I had the piano at home for a long while and was eventually prevailed 
upon, when I was more than usually skint, to sell it to a colleague 
in France for his daughter.  She has since gone on to become a 
professional pianist.

Now I have the disadvantage of seeing very few pianos but those that 
end up, often to stay, in my shop.  Once or twice I have heard a 
piano somewhere else which had this special quality and later sought 
out pianos of the same make and age, sometimes waiting years for them 
to turn up, only to be disappointed.

Now "efficient soundboard" is quite a wide net.  Not even the most 
learned of acoustical engineers is able to describe let alone explain 
all that happens in a soundboard. Of all makers I know, Brinsmead was 
the most adventurous with the soundboard over the years, and at the 
time that piano was made he was advertising a special new design of 
soundboard, whose name I forget but will try to remember.  I have 
experience the effect in some of his uprights as well.

Last year I acquired, for nothing, two pianos from the same maker, 
one vertical and one overstrung, in order only to study a special 
feature used only by this maker.  They are commercial pianos 
1900-1920 built to a very low price, the actions don't fit, the sides 
warp, the case is mainly plain poplar faked to walnut etc. but, apart 
from the special feature that interested me, and which is unrelated 
to tone, I noticed some other features that had me thinking 'Why on 
earth didn't this man go upmarket?!'.

Both of them, even the lousy little straight-strung, have/had the 
quality I'm talking about and I shall be rebuilding the overstrung. 
The vertical I have this week broken up.  The soundboard has the 
grain running horizontal and the (quite flimsy) bars vertical. 
Although the thing has been outside under the rain and snow for 8 
months the soundboard is still in one piece although the bars have 
come loose and I noticed yesterday that the spruce is cut right on 
the quarter.  So far so good.  More significant to my mind is the 
freedom the board has.  It is glued and screwed to 1" fillets on the 
bass backpost and at the bottom just past the centre, where it goes 
up diagonally to the treble backpost, where it is again screwed and 
glued.

At the top, except where it is screwed and glued to the two middle 
posts, it is free, with just a 1" x 1/4" rail to reinforce it.  The 
diagonal is also free.

The overstrung is similarly conceived.  I shall be ripping out this 
wonder-soundboard and replacing it with one of my super-efficient 
wood-free soundboards, significantly lighter and much much stiffer 
fitted in exactly the same way.  My bet is that I will end up with a 
fine-sounding piano and that I will, alas, _lose_ that special 
quality.  If I don't, then it will be extremely interesting.

I have another early Brinsmead overstrung grand waiting in the queue 
for rebuilding and this was untunable when I got it so I have no idea 
how it should sound, but this piano has the whole length of the 
straight side floated.

Today I took delivery of the 1870 parallel-strung Brinsmead and have 
been getting to know it.  It has 90 notes,  22 bass, sostenuto 
device, full duplex scaling and strings that from note 8 upwards are 
longer than a Steinway D.  The covered trichord, note 20, is 164 cm. 
long -- the Steinway is 137 cm.  I have high hopes of this piano, but 
the "swell" effect is completely lacking.  I should say that the 
soundboard is as good as new and the sustain is excellent.

JD