Better Bass Scale for M&H A

[Delwin D Fandrich]

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----- Original Message -----=20
From: "Farrell" <mfarrel2@tampabay.rr.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: November 03, 2002 5:51 AM
Subject: Re: Better Bass Scale for M&H A


> > > 3.  With out doing a more complete analysis, my gut feel tells me =
there is
> > > very little pivoting at the traditional hitch pins.
> >=20
> > There is none. The string lays across a flat in front of the hitch. =
This
> > felt-covered flat varies from as little as perhaps 10 mm (if you're =
lucky)
> > to as much as 25 or 30 mm. It's out there that the string has to try =
to
> > bend.
>=20
> I think this is the key here. I understand clearly how moving the =
bridge is going to free up movement, but I was picturing the traditional =
loop on a traditional hitch pin pivoting easily at the point where it is =
wedged into the hitch pin & plate. This wedging certainly will restrict =
a pivoting motion, and you are right that there is often some felt or =
shelf or whatever in front of the hitch pin further restricting any =
pivoting motion at the hitch pin.

Ah, but there is ALWAYS some felt or shelf or whatever along the =
hitchpin riser in front of the hitchpin. It must be there for the =
support of the hitchpin. Though not as much as is often provided. (Back =
in the dark ages I used to grind off some of that shelf to increase the =
backscale length. Switching to vertical hitches is much easier and more =
effective.) And then there is the twist that extends some distance =
beyond that. Keeping in mind that impedance is primarily =
stiffness-controlled at low frequencies you can see the problem =
developing right there before your eyes (ears?).

>=20
> I noticed on your M&H A photos that the mono cords had vertical hitch =
pins, but the bicords retained the original hitch pins. Any specific =
reason for that? I suppose the laws of diminishing returns & =
benefit-cost analysis apply as the backscale length increases in the =
bicord area?

My, what sharp eyes you have, grasshopper! The only reason was cost. =
This was one of those jobs in which we were trying to gain the maximum =
benefit for the least cost. Originally, we weren't going to do much of =
anything to the bass bridge other than clean it up and replace the =
bridge pins. But as the original bridge cap and much of the body =
disintegrated as the pins came out a new bridge body began looking =
increasingly desirable. And then, as long as we were replacing the =
bridge body anyway, it seemed a good idea to notch it and place it =
forward some on the cantilever. As long as we were going that far =
replacing the mono-chord hitches wasn't much more of a stretch. I didn't =
go beyond the mono-chords with the vertical hitches because the =
backscale is already some longer up where the bi-chords start. It's only =
down toward the very end that they get criminally short.

In all, I was quite happy with the result.=20

Del


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