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Hey there folks, any notion of what intervals the duplexes should be tuned to on M&H CC2. They were all over the map when I disassembled it.
Thanks

That shows you how (un)important they are!

I have tried making spreadsheets to figure out what intervals Mason & Hamlin aliquots should be tuned to, and have had varying degrees of success. That is the way I would go. I could send you a sample if you contact me through a PM with your email address.

I am assuming that what you are calling "duplexes" is the string rest between the bridge and the hitch pin. I call these the hitching rest. When stringing a M&H I just place them so they fit properly on the plate in relation to the string paths and progress in an even looking way regarding speaking length.

Then I use string braid at least up to the top of the tenor to mute the noisy things!

The duplexes are the bars between the capo and tuning pins. The pitch relationship of the duplex length to the speaking length is very important. You must avoid making a harmonic relationship between the duplex and the speaking length or you will get odd ringing.

I have a patent pending on what I call a Fully Tempered Duplex Scale. There is a PW thread on this forum about it.

Ask M&H. They are tuned in a manner similar to mixtures on organs. That is, octaves, octaves plus a fifth, and double octaves, for example, depending on the pitch it is related to. The underlying plate should give you an idea of the string length ratio between the speaking length and the "hitching rest" , and therefore the correct "harmonic" to use. The duplexes are also "harmonically" related to the speaking length.

Ed, I think most times they are referred to as aliquots, but let's not get hung up on terms. As to the string rests that you are referring to as duplexes, I have the original understring felt as a sample for where the string rests should be. It seems though, like a rather sloppy method. I like things with less options for failure. I fully apprehend the necessity for that relationship between the string rest and the capo, but how do you actually determine what it should be or better yet what it shouldn't be?

For setting the duplexes, measure and calculate.

For setting the hitching rests, moving them with the strings at pitch will destroy the plate finish. They want to slide around when stringing quite a bit. Having them ring with a finely tuned pitch relation to the struck string does not improve the tone. Most people want them muted.

Are not the front duplexes to be simply considered as a form of string termination ?

They have no way to resonate by themselves, no soundboard, for instance. Sort of filters?

Ed, what were the original intentions of M&H in having these individual moveable back duplex hitching rests? My M&H BB has these of course, and when I listen to the pitch of these by plucking the area in between, they do not match the string harmonics at all.

Other pianos have them, Steinway etc, but they are not individual and I don't think some of them a moveable.

As to the front duplex moveable rosewood/brass bars, do you know if there is any advantage/disadvantage in having these be rosewood or brass? Also their position....from previous info I have found, it was suggested not to have too much of an angle from these bars going to the capo bar. Mine might have too much of an angle downward.....

In the pictures below for example, on a 1920's M&H BB, not mine, you can see where the plate drops off at a downward angle before the capo bar. The rosewood bars are set so that the right ends of the bars are at the end of the downward slope, in other words, they are resting on this downward slope. Is this angle important for both stability in tuning and would it have any effect on the tone?

The reason I ask this, is that on my BB, we replaced these rosewood bars with a solid 1 piece brass bar in both upper sections, however, we did not place them at an angle on the downward slope, but kept them straight, and at the edge of the plate before it starts to slope down....I am thinking that this angle is too steep and may be causing a tuning stability issue, as the 2 upper sections where these solid bars are located is where it is always going out of tune a lot quicker than the rest of the piano.


Original configuration M&H 1920's BB




Original configuration M&H BB 1920's BB (same piano)





Another M&H BB circa 1930 using brass bars

Grandpianoman,
I don't know what M&H's original intentions were.

Sounds like you have converted your duplex to what I call a mono-chord duplex. BB's have a high counter-bearing duplex angle. This makes fine tuning slow.

I am just finishing a BB that I converted to my Fully Tempered Duplex Scale. It took me three days of grinding and filing to configure the duplex area for the new duplex positions. I also reduced the counter-bearing angle significantly. Especially in the high treble. I am fitting hammers today so off I go to work.

Over time if your treble is tuned carefully it should stay in tune better than the rest of the piano. But it is hard to set the strings perfectly up there when tuning. When the strings get around 4-5 years old with regular tuning-the unisons in the treble should stop going out. Much depends on the skill and care of the tuner.

Thanks Ed....did not know that what we did was called a mono-chord duplex. When the piano was re-built, he put the rosewood back as he found it in the pic below. I think the people who had it rebuilt in the 60's must have done that to calm down the "noise" in that front duplex? The felt in front certainly muted any noise. I never did hear my piano with the rosewood bars and the felt behind it as in the original config.


My original configuration:


This in effect killed a lot of the sustain and the tone as well. After putting the 2 brass rods in there, thanks to a suggestion from Del, the sustain and tone improved. Here is a picture of an early 1930's BB that has the solid metal bars:

A different 1930's BB


When you say a "high counter-bearing", is that a steeper angle?

In any case, it's been about 4+ years since those bars were installed. it is a little better in stability, but I have changed temperaments several times, and had several different tuners tune it, besides my tuning it. Perhaps keeping one temperament and my tuning it more than anyone else will help.

Another contributing factor could be the tuning pins themselves. The Falcowood pinblock was drilled without the customary slight backward tilt/angle for the pins. The pins are straight up in the block. One pro suggested that this may cause a very slight flagpolling when played hard, which my 2 machines do on a fairly regular basis.

if you ever record/video your BB, would love to hear it. You are not that far from me, perhaps a visit at some point.

in fact those aggressive solutions used to damp the front duplexes mostly show that the re-builders do not know they are necessary.

I also find that when the tuner does not know how to tune , and cannot quiet the duplex noises, that is enhanced by hammer mating problems.

I was surprised to discover it was more common than I thought.
Working on Steinway's in good condition help the tuner to learn what it is about, probably.