DIYAPASON-L Digest #259 - Saturday, February 10, 2001
 
Re: [Residence Organs] 1/2 length resonators
  by "steve c bournias" <chrisbournias@hotmail.com>
Re: 1/2 length resonators
  by <TheGluePot@aol.com>
Re: [Residence Organs]  Re: 1/2 length resonators
  by "Bob Loesch" <rrloesch@jps.net>
last chance!
  by "Caroline Kehne" <ckehne@accglobal.net>
 

(back) Subject: Re: [Residence Organs] 1/2 length resonators From: "steve c bournias" <chrisbournias@hotmail.com> Date: Sat, 10 Feb 2001 15:34:57 -0500   i say at least 2" larger in diameter than the 8" full length   >From: Bob Loesch <rrloesch@jps.net> >Reply-To: "Residence Organ List" <DIYAPASON-L@pipechat.org> >To: "Residence Organ List" <DIYAPASON-L@pipechat.org> >Subject: [Residence Organs] 1/2 length resonators >Date: Fri, 09 Feb 2001 17:55:31 -0800 > >A question for the voicers of the list: I have an opportunity to obtain a >set of 16' Tuba boots with no resonators. I have in mind making a set of >1/2 length wood resonators for it. >In a rank with the 8' octave full length and 16' octave 1/2 length, how >much larger in scale should the 16' 1/2-length resonators be, assuming >normal theatre-type 'tuba horn' voicing? > > >Regards, >Bob, in beautiful Lake County, California, USA >NAWCC 140818 >http://www.jps.net/rrloesch >alternate mailto:cuckoobob@eudoramail.com > > >DIYAPASON-L: a Discussion list for owners and builders of their own >Residence Pipe Organs. >HOMEPAGE : http://www.diyapason.pipechat.org >List: mailto:DIYAPASON-L@pipechat.org >Administration: mailto:owner-DIYAPASON@pipechat.org >   _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com    
(back) Subject: Re: 1/2 length resonators From: <TheGluePot@aol.com> Date: Sat, 10 Feb 2001 16:46:39 EST   > A question for the voicers of the list: I have an opportunity to obtain = a > set of 16' Tuba boots with no resonators. I have in mind making a set = of > 1/2 length wood resonators for it. > In a rank with the 8' octave full length and 16' octave 1/2 length, how > much larger in scale should the 16' 1/2-length resonators be, assuming > normal theatre-type 'tuba horn' voicing? > Regards, > Bob, in beautiful Lake County, California, USA > NAWCC 140818 > http://www.jps.net/rrloesch > alternate mailto:cuckoobob@eudoramail.com >>   Hello Bob:   While you can make a half-length resonator work, the efficiency of = coupling the fundamental to the surrounding air drops way down and you end up with = the first harmonic being dominant. In Physics terms this is called acoustic impedance and is analygis to electrical impedance. The reed tongue may be =   doing the correct pitch but the air column normally in the resonator will respond with diminished output at 16'. How the air column in the pipe transfers energy to the surrounding air is the problem. A 16' pipe is producing a 32' long wave so it already is at half-length. When you try = to get the 32' wavelength from an 8' long pipe you have to increase the scale =   markedly. This is primarily to increase the air mass within the pipe by increasing scale. I sat down with my TI-85 and calculated that to even approach the efficiency of a 16' resonator you would have to have sides of =   24" for your resonator mouth at CCC. May I suggest you use a folded horn approach to get all 16' of length so that a solid standing wave may be generated? If you do go by an 8' resonator of "half-length" I would = advise you to first voice the reed tongues to vibrate on pitch without any resonator. This means adjusting the Willis weights, the curve, and the tuning point to be spot on. Then with the resonator added you will have = to tweek the resonator until the reed tongue responds to it by coming back to =   the original pitch; otherwise, the two will always be fighting for = dominance.   Good Luck,   Al Sefl  
(back) Subject: Re: [Residence Organs] Re: 1/2 length resonators From: "Bob Loesch" <rrloesch@jps.net> Date: Sat, 10 Feb 2001 14:15:10 -0800   Thanks, Al. I've been kicking this one around for some time, and my choices are full length, 1/2 length, and Haskell. While my normal choices would be (in order) full length, Haskell, 1/2 length, I am trying to put the proverbial 10 pounds in a 5-pound sack, as usual... ;-)   At 16:46 02/10/2001 EST, you wrote: >Hello Bob: > >While you can make a half-length resonator work, the efficiency of = coupling >the fundamental to the surrounding air drops way down and you end up with the >first harmonic being dominant. In Physics terms this is called acoustic >impedance and is analygis to electrical impedance. The reed tongue may = be >doing the correct pitch but the air column normally in the resonator will =   >respond with diminished output at 16'. How the air column in the pipe >transfers energy to the surrounding air is the problem. A 16' pipe is >producing a 32' long wave so it already is at half-length. When you try = to >get the 32' wavelength from an 8' long pipe you have to increase the = scale >markedly. This is primarily to increase the air mass within the pipe by >increasing scale. I sat down with my TI-85 and calculated that to even >approach the efficiency of a 16' resonator you would have to have sides = of >24" for your resonator mouth at CCC. May I suggest you use a folded horn =   >approach to get all 16' of length so that a solid standing wave may be >generated? If you do go by an 8' resonator of "half-length" I would = advise >you to first voice the reed tongues to vibrate on pitch without any >resonator. This means adjusting the Willis weights, the curve, and the >tuning point to be spot on. Then with the resonator added you will have = to >tweek the resonator until the reed tongue responds to it by coming back = to >the original pitch; otherwise, the two will always be fighting for = dominance. > >Good Luck, > >Al Sefl > >DIYAPASON-L: a Discussion list for owners and builders of their own >Residence Pipe Organs. >HOMEPAGE : http://www.diyapason.pipechat.org >List: mailto:DIYAPASON-L@pipechat.org >Administration: mailto:owner-DIYAPASON@pipechat.org > > >   Regards, Bob, in beautiful Lake County, California, USA NAWCC 140818 http://www.jps.net/rrloesch alternate mailto:cuckoobob@eudoramail.com    
(back) Subject: last chance! From: "Caroline Kehne" <ckehne@accglobal.net> Date: Sat, 10 Feb 2001 19:06:46 -0500   time is fast running out for a rank of 16' open woods and swell box. Premises must be vacated in a few days. Please help save these pipes from a fate worse that death... all offers considered. The pipes are in Poughkeepsie, NY   Robert Pelletier (450)294-3377