[CAUT] Duplex angle

[Alan McCoy]

Hi Ric,

Sorry for the delay. Just got back to school to check my messages.

I agree that we are finally speaking the same language. Thanks for sticking
with me on these posts. Your last post was very clearly written and made
good sense to me. I hadn't though much about the relationship between
speaking length and front length but it does offer an avenue for exploring
why some longer lengths are "excited" while neighboring long lengths are
not.

Regarding the why some are excited (thus "noisy") I think it is mostly that
longer lengths (not so much shallow angles) are more susceptible to giving
off higher amplitude harmonics. Now though, I'll have to toss in the above
relationship to the analysis. BTW, I spent an hour this weekend rereading
Del's articles from June and August 1995 on this issue. Worth reading if you
haven't done so. He did do some experimenting back while at Baldwin.

I have McMorrow's book. Thanks for the suggestion.

As far as voicing goes, if the voicing is otherwise smooth from note to note
and yet a front length is still sticking out, then IMO voicing the hammer is
not the treatment of choice.

Thanks again Ric. A great opportunity to clarify some of my thinking on this
issue.

Alan


> From: RicB <ricb at pianostemmer.no>
> Reply-To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org>
> Date: Thu, 16 Nov 2006 01:15:31 +0100
> To: <caut at ptg.org>
> Subject: [CAUT]  Duplex angle
> 
> Hi Alan
> 
> Me thinks we are getting closer to each others thinking on this.  Lets
> assume we are pretty much in agreement relative to your first paragraph.
> I'll only raise a pinky with regard to the use of the term <<duplex
> noise>> since you seem to distinguish between sizzling (buzzing at the
> capo) and what you refer to as duplex noise.  I'll raise this pinky
> because of what you follow up with in your second paragraph.
> 
> When you decide to use the word noise in this context, it strikes me as
> because the front duplex is not working as designed. When it works
> "properly" you say yourself you actually kind of like resulting sound.
> I'd agree myself tho I'll be the first to let that drop into the realm
> of subjective.  But what is it that makes it not work properly....  that
> which prompts you to use the word noise in that instance ?  Do you think
> it has to do with counter bearing angle ? Why would you think that ? Are
> there experiments or data to connect these two thus ?  Not that I know
> of in any case.  Length then ?  Ok... we have quite a bit of information
> floating out there both of the hearsay sort and the more concrete  that
> connects specific lengths to what perhaps we both will agree is
> <<noise>> connected to the front duplex itself and not the sting/capo
> contact area.  But that relationship doesn't have anything to do with
> <<shorter is better>> per se.  It has to do with specific relationships
> between the speaking length and the front length.  Thats no doubt a big
> part of why pitch locks which were invented for an entirely different
> reason seem to have a positive effect on a improperly functioning front
> duplex. Glue too for that matter, as has been stated by several here in
> the previous discussion.
> 
> My point is again we have a separation of issues here, and I think we
> are in agreement on that if I understand your post correctly.  I'll put
> that distinction this way.
> 
> <<Capo noise>> is icaused directly by combinations of too long a front
> length, too mild a counter bearing angle, and the condition of the capo
> profile.
> 
> <<Duplex noise>> comes into play about when the front length shares a
> certain harmonic relationship with the speaking length.
> 
> Seems clear to me that going about creating a good duplex is very
> doable.  One needs to arrive at a solution for front length, angle, and
> capo condition that yields minimal capo related noise issues while
> maintaining a harmonic relationship between speaking length and front
> length that does not throw the front length into these whistling /
> noise-ish modes of operation.
> 
> McMorrow has a good deal to say on both issues and is definitely worth
> reading.  He's in Seattle... not far from you.
> 
> As for how a field tech is to deal with unwanted <<Duplex noise>> (Now
> that we have our P's and Q's nicely separated)...,  I agree 100 %. Tho I
> haven't had the opportunity to try pitch-locks.  Also in concert
> situations we agree.  And thats an important point you make IMHO.
> Sitting on top of an instrument dissecting its sound as a piano tech
> inevitably does is not necessarily the best thing to do in each
> instance.  I would also like to point out that I tend to hedge from
> using voicing in either case unless its my last resort.  Its not really
> a hammer voicing issue IMB... at least not primarily so.  I'd like to
> minimize the problem without taking away from the power of the
> instrument if I can.
> 
> A nice exchange of posts Alan. Thanks muchly.
> 
> Cheers
> RicB
> 
> 
>     Ric,
> 
>     Thanks for your clarification.
> 
>     I make a distinction between what I call string sizzle (buzzing at
>     the capo)
>     and duplex noise. String sizzle I deal with by reshaping and voicing the
>     hammer, mating the hammer to string contact, reshaping the capo to
>     get rid
>     of a groove. In that order. I deal with duplex noise by hammer voicing,
>     using pitch locks in the segment, or glue on the offending
>     string(s), and as
>     a last resort muting out the segment with a tiny fragment of bushing
>     cloth
>     woven in that unison right up against the counter bearing bar.
> 
>     To me the front duplex adds to the overall sound scape as does the
>     back length. I have no objection to this when it works properly, in
>     fact I
>     like it. But when a higher-than-normal harmonic in the duplex is
>     excited and
>     stands out and annoys me, I try to deal with it. Same with string
>     sizzle.
>     But they are different phenomena.
> 
>     For me venue plays a role here. On a concert instrument in a larger
>     hall, I
>     never mute out a duplex segment even if it bugs hell out of me while
>     I'm at
>     the piano because I don't want to risk dampening projection. Unless
>     it bugs
>     the pianist too.
> 
>     Maybe we are ships passing in the fog here.
> 
>     Alan
>