Piano World Home Page Forums Our Most Popular Forums Piano Forum FAQ - Piano Forum Duplex-like thingies on Bösendorfer, Grotrian, Petrof, Samick, and Nordiska

No, I’m not. I probably still do have at least some of the test data available somewhere. But I’m not going to go looking for it. I already spend way to much time at this—if I spend much more time at this and I’m going to have serious wife problems.

Besides, I do this stuff for a living. At least I try to. I’m willing to set up most any experimental process anyone wants, but I’m not independently wealthy and the nasty problem of earning a living keeps interfering. These setups take time, the tests themselves take time and the equipment needed to measure the results is expensive. Some I still have, some I would have to purchase and I don’t have any compelling reason to do that just now. It’s not necessary for the work I’m currently involved in. As for the time, I don’t remember how long I worked on this project while at Baldwin but by the time I designed the tests and the test setup, built it all, and then conducted that actual tests it was more like a few weeks than a few days of tedious and repetitious work. I’m not about ready to go through that again unless I’m going being well paid to do so. Even then the results would go to the client and it’s doubtful most clients would want to share that information publicly. Nor am I convinced that kind of data would be all that useful to even the most dedicated piano buyer. I’d like to bring a higher level of understanding to the folks running the gauntlet between themselves and the piano they would like to spend their lives with but for the most part I think those decisions should be made by spending some time with the pianos, listening to them and living with them. Just like I found all the technical details of the high-tech engine and suspension system in my car interesting, in the final analysis it’s how the car felt on the road that was most important.

The posts I write to this list are not intended to be full research reports. They are simply summaries of some of the stuff I have learned over the past 40 plus years of piano servicing, rebuilding, remanufacturing, building and researching and testing. Mostly I try to explain, in layman’s terms, how the piano works more in broad strokes than in great detail. Hopefully I can bring light to some of the mythology and misinformation that still swirls around the instrument. That’s all. I really don’t have time to go beyond that. Hopefully it is useful as such. If not, well, it’s the best I can do for now.

Del

Grotriman,
My experiments are much more simple. I carry some of the lines that have tunable duplex scale segment. The aliquots in some of the lines that I'm very familiar with can be moved, tuned or replaced in small segments or individually and I have experimented with them many times before under real conditions. Meaning, a complete instrument that has been design to have a properly working duplex segment.

The only results I can measure are those that I hear, and that may not be good enough for you or others...yet I spend my time and work with those aliquots often enough to feel that I can change and improve certain things in the instruments sound.
I'd like to think that others recognize the advantages of what I do, otherwise I'd be wasting a lot of time...and the only way I know how to measure if the time wasted was worth it or not is by the end result.
The people playing the pianos I prep in our showroom often wouldn't care if there is a duplex or not, they just want the piano to sound beautiful.
Sometimes I wish I felt that working with these aliquots is unnecessary, as it would save me time, but I think that it's something worth working with.

In my first post I wrote about the tunable duplex segments:
And in my next post I added:

I believe that this is about as much as I can say at this point and think that these remarks, given in the beginning of the thread were as clear as possible saying that this isn’t a black and white issue, and that there are those that are skeptic about it's advantages.

Grotrian’s explanation to Pique makes sense to me, and this can show again that there are many variables regarding a piano design, and many contradicting philosophies by piano designers.
There is no one person in the industry that is right all the time no matter how knowledgable he is simply because much of what’s right is subjective.
So again I would suggest to people to judge things in this regard by the tonal results of the complete piano.
No piano will fall apart because it doesn’t have (or have) a duplex scale.

Should you want to know more, you're welcome to come here and visit me. Our showroom is only 45 minutes from NYC by car or train.
Until then, all I can do is post pictures of different instruments with different duplex scale systems for you and anyone else to better understand the issue.

Here are the pictures:
.


Mason & Hamlin front duplex. The aliquot segment can be moved in sections and by replacing these with higher bars or moving them back and forth the string angle and length can be adjusted:
.




.
.
.
.


Mason & Hamlin back duplex. The aliquots are tunable individually and the strings in the aliquot segment are relatively long:
.





.
.
.
.


Estonia front duplex. The aliquots are tunable individually, by replacing them with larger or smaller bars, and moving them back and forth the string angle and length can be adjusted for each note:
.




.
.
.
.


Estonia back duplex. The aliquots are tunable individually and the strings in the aliquot segment are again relatively long:
.



.
.
.
.


Bluthner front tunable duplex. The aliquot segment can again be moved in sections:
.



.
.
.
.


Bluthner fourth aliquot string. Can be tuned to sympathetically resonate to the other three. The fourth string is slightly elevated and is not struck by the hammer:
.





.
.
.
.


Steinway front duplex segment. This is tuned to the speaking part of the string but isn't tunable.
The aliquots are a part of the plate design and can't be moved:
.





.
.
.
.



Steinway back duplex segment. The aliquots are in long segments and can actually be moved very little.
The duplex segment of the strings is relatively short in comparison to the individually tunable segments on the Mason and Estonia.
.

The pictures came up as a link...
Can anyone tell me how to get the pictures to come up without the link?
Ax maybe?

I think I got it done thanks to pique!

ori, i think what you did was bracket the photo locations with

what you want to bracket the info with is [img] [/img]

here let's see if i'm right:



Steinway back duplex segment. The aliquots are in long segments and can actually be moved very little.
The duplex segment of the strings is relatively short in comparison to the individually tunable segments on the Mason and Estonia.

Well, that got me interested. So I looked on the front of my Baldwin L's strings and lo and behold, I see the same thing, though perhaps not going as low as in your picture. (My Baldwin was built about 1967; don't know what more modern Baldwins have.)

Chris

yup. just bracket each link with the code [img] [/img] and you will be all set.

Mason & Hamlin back duplex. The aliquots are tunable individually and the strings in the aliquot segment are relatively long:

The back end of my Baldwin L's strings are terminated exactly the same way, all the way down to middle C.

Chris

pique,
Thank you for your help with the pictures.
For the amount of time it took me to figure it out I could have driven down to the city, pick up Grotriman, bring him here, show him the actual pianos and then drive him back...


Chris W,
Among the many pianos I have here there is also a 1980's Baldwin L. This one has different duplexes then what you describe. The front is fixed/un-tunable and a part of the plate.
The back is not a duplex scale at all and is nothing like the Steinway D picture that curry posted.
If you'd like then post pictures of your piano to verify that the models are different and that there isn't any misunderstanding here.

The front pressure bars on early Baldwin grands are inverted V-shaped brass bars which are movable. The rear aliquots originally had pins in the bottom that fit in holes in the plate, but were later movable. Around 1967, the hitch pins were replaced by vertically mounted roll pins, with the strings held by friction at a height which would allow changing the downbearing on the bridge. This was the Acu-Just system. There were changes in the front bearing system as well, particularly in the SF 11 and SD 10 models, which have adjustable devices which I have never quite figured out.

Like all this other stuff, this was all of mostly dubious value overall, except for the cumulative effect of the Acu-Just pins, but other manufacturers control the downbearing with careful bridge and plate placement. I just don't feel any of it makes so much difference in the sound that if you had one piano with any or all of these things and another without, it would really shout out at you as being a different piano. Not as much as the changes that a good voicer could make, for instance.

Darn that earning a living thing! Understood. Those of us amateurs who bought grand pianos have already gotten through the wife thing. For better or for worse...

I hereby solemly promise that when I win the powerball in an amount in excess of 100 million dollars. I will set up a piano research play room for Del and others (who pass the application exam - I have to be careful here in case I really do win) to use. And will support their piano research.

In your research Del did you ever determine that a duplex segment sang only because of it's struck segment? Or did you determine they all sing to some extent when any nearby note is played?

Ori - great pix! Thank you for all the work. Very informative. (BTW - I would love to stop by your shop some time.)

Anyhow - duplex, duplex scale, tuneable duplex. Somebody's going to have to write a definitive piano dictionary here. I am still very much of the opinion that any freely vibrating string segment constitutes a duplex. And whether it is in the front or in the rear is a qualifier, and if it is tuneable is a qualifier as well. But I see this is one opinion.

i'm still confused.

when our esteemed piano professionals say that the grotrian does not have a duplex scale design, do they mean that the conventional meaning of the term must include aliquots and tuning ability?

The duplex string segment sings anytime its natural fundamental vibrating mode ends up close to the fundamental, or some partial of that fundamental, and the string deflection angle is small enough to constitute an inefficient termination to the speaking length.

To repeat—energy transfer across the string termination is a function of the shape of the termination point (i.e., usually the V-bar), the string deflection angle, and the length of the duplex string segment.

With one or two notable exceptions, upright pianos rarely, if ever, have string noise problems through the tenor and treble sections even though their string deflection angles across the V-bar are often quite low. And despite the fact that vertical piano V-bars are often very poorly shaped. The reason they do not is because there is a pressure bar very close to that V-bar. The duplex string segment between the V-bar and the pressure bar is very short. Hence the string termination is very efficient despite the shallow string deflection angles typically found here.

Rear duplex string segments do ring in sympathy with vibrating strings some unisons away—they are driven by the vibrating bridge, not by energy bleeding across the bridge (and through the bridge pin offsets). The front duplex string segments are driven by energy bleeding across the V-bar. Hence they are unison specific.

And, while I’m thinking about it—if anyone is interested in doing some experimenting along these lines you must use appropriate materials. In my first round of tests I was not getting nearly the anticipated energy losses that typically accompany this design. Then I realized I was using steel sections for my V-bar/capo tastro bar and tuning pin panel (with the accompanying bearing bar rest). I then changed the test setup using appropriate sections from a broken plate. Once gray iron entered the picture the energy losses appeared. It was only with some combination of a larger string deflection angle and/or a shorter duplex string segment that the energy losses diminished.

Yes, we do need some consistency in terminology when discussing these things. Without it it is all too easy for the salesperson to point generally to the area where all the fancy little bars are located and point out the “duplex scale” to the unwary customer adding nothing of value to the customer’s usable store of information but adding considerably to his or her level of confusion. Of course the salesperson would then have to actually know something about what he or she was talking about and I’ve only met a few who were willing to spend the time to really learn much about the product they were selling.

Del

All three strings of the backscale length must be terminated at the same length(via duplex bridge,or aliquot), and tuned to the same pitch, same with the front, to be a tuned duplex scale. As mentioned previously, the Grotrian/Bösendorfer backscales are not. Each string has a different pitch. This would not be a tuned duplex scale.

Pique,
What I mean by it at least, is that unless the duplex scale segment is tuned to be sympathetic to the speaking part of the string (higher pitch note or a fifth), and unless all three strings of the note are tuned this way...then it isn't what is usually referred to as a duplex scale (although should more accurately be referred to as tuned duplex scale).

Took the words right out of my mouth Ori.

You're faster on the draw!

So it seems the discussion is winding down. We are still a bit confused about the proper use of the term duplex, but there is a truce if we use "tuned duplex" and refer to any vibrating string as a duplex segment.

Here is a theoretical brain teaser. What accuracy in placement would be needed for the front aliquot bar on a medium length string (lower treble for instance approximately 24" let's say) in order to tune it to the fundamental?

The string having a length of 24" would have a certain tension. This same tension would exist in the front duplex portion. The front duplex being approximately 4" in length would then need an lenght accuracy of _______ to be a harmonic of the fundamental? If one bar is terminating a group of strings, it must be angled to obtain the proper tuning of all of them for each of their respective speaking length strings. Right? I am still skeptical that there is much to the "tuned" argument, unless you call being "in the general vicinity" tuned.

You should reread my post about the futility of trying to tune these sections. Then realize that 24" is a very long string, somewhere around middle C, in most pianos. Then consider that you need to double the accuracy for each octave you go up the scale.