Re: [Hornlist] Couple of technical questions
Bill, I may be wildly wrong, but I'm not sure that there are a lot of technicians out there who apply methods scientific and accurate enough to keep up with the technical questions you asked in one of your first mails on the subject. I've seen many shops where replating the valves to fix supposed leaks involved nothing more than a bucket with the solution, an electric motor so that the valves could spin in the solution under a current, and some fine-grained sandpaper. In any case, you're not getting many technical answers to your technical questions. I wonder what the Lawsons would have to say? If I brought a horn in to a good technician, how would he measure it to determine it needs a valve job. ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
RE: [Hornlist] Couple of technical questions
I used to be 1 of those people -- that is, until I tried a new Yamaha & discovered how much better it is playing on a horn with tight valves -- so much better that I then had my old beat-up leaky-valve Alexander 103 totally restored & modified -- custom lead pipe (with water key), valves replated & refitted, cut-bell conversion, ambronze bell flare, the works. Wow, what an improvement! -- Alan Cole, rank amateur McLean (Fairfax County), Virginia, USA. Just a side note, there are a few people out there who like their valves a little less than perfectly tight just for the feel of the horn. -- No virus found in this outgoing message. Checked by AVG Anti-Virus. Version: 7.0.308 / Virus Database: 266.9.13 - Release Date: 4/16/2005 ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
I keep hearing these 'machine' numbers. 90% of what and measured where. To characterize a leak you at least need to specify pressure differential and leak rate. If I brought a horn in to a good technician, how would he measure it to determine it needs a valve job. I recently fixed up a horn for a lister that was unplayable, and he was told by repair people in the Boston area (no one was named) that it needed a valve job. The valves were fine, but there was a very subtle leak doing some strange things acoustically. Fixing the leak, once it was located, was not a big job, but I don't think anyone would have questioned the cost of the valve job based on the improvement, even though unnecessary. All that you need is a stopper for the bell and a bathtub full of water, and you can check your own horn for leaks. It doesn't take a rocket scientist to interpret whal streams of bubbles mean. If the valves are really leaky, you'll see bubbles coming from the rotor bearings. If you can substantially stop it by pushing the rotor to the bottom of the casing, tightening the bearings will help a lot, but it's the side play that has to be removed with a shrink collet. ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
RE: [Hornlist] Couple of technical questions
Just a side note, there are a few people out there who like their valves a little less than perfectly tight just for the feel of the horn. (not me) Aleks Ozolins NYC ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
RE: [Hornlist] Couple of technical questions
Bill, from a simpleton's point of view (namely mine), leakage is leakage. It doesn't matter where it leaks _to_, it just matters if the air stays on the side of the valve to which you're applying pressure or it doesn't. It could very well be that some leaks are more functionally a problem than others but wouldn't you agree that if a valve tests at a good number, e.g., 90%, then it's good and not going to be an impediment to proper playing? Put another way, it might be that not all low/bad numbers in valve compression tests yield poor playing results, but it seems that high/good numbers ought to yield good playing results (within the capabilities of the rest of the instrument, of course). -S- > -Original Message- > From: > [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > du] On Behalf Of [EMAIL PROTECTED] > Sent: Friday, April 15, 2005 5:27 PM > To: horn@music.memphis.edu > Subject: Re: [Hornlist] Couple of technical questions > > 80% at 1pound pressure above atmospheric is a number that > must be measurable in some reproducible way. Do you have a > set volume that is allowed to leak backwards through the > rotor? What is it leaking to. Is it measured across to the > other valve port , crosstalk, or is it measured to the > outside world.? My experience is that there can't be a leak > in the tubing of the other valve port, or else it will allow > flow between the ports. I have a lot more experience leak > checking vacuum systems, but I find significant valve leaks > to be much more subtle than that, particularly on double > horns. Is there a recognized industry standard for measuring > leakage past a valve when there are other ports nearby? What > is allowable crosstalk between ports, and how is that measured? > This question comes up regularly, but I have never seen a > standard I could apply. > I'm not actively working on lamp process vacuum systems > right now, so leak checking is not readily available to me at > the moment, but I could set up all kinds of relevant tests > with the equipment I usually have access to. I'd be > interested to set up my own test set-up, if anyone would > kindly define the relevant tests between ports and completely > past valves.. For instance, would it be relevant to blow up > a balloon through the valve I want to measure, then measure > the leak rate back through the closed port, both to the > manifold and to any adjacent ports, and at what pressure differential? > ___ > post: horn@music.memphis.edu > unsubscribe or set options at > http://music.memphis.edu/mailman/options/horn/steve%40fridaysc > omputer.com > ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
I'd tend to agree with that, but side play is the real issue. IF I remove .002 of side play, that should reduce the gap by .001. With my tapered Starrett feeler gauge, I can often pin a .002 gauge to the rotor wall using just valve taper. My question is, how much nickel plating should I request from the plater to ensure a .005 clearance after lapping, using shims to space the rotor above the casing during lapping, and what grade lapping compound should I use with the rotor raised above the casing. My experience nickel electroformers is that a good plater should be able to provide a minimum of .030" of pure nickel, and forget the copper entirely. How does the finish of lapped copper compare with that of pure nickel, both in appearance and tenacity? ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
At 6:27 PM -0400 4/15/05, [EMAIL PROTECTED] wrote: >For instance, would it >be relevant to blow up a balloon through the valve I want to measure, then >measure the leak rate back through the closed port, both to the manifold >and to >any adjacent ports, and at what pressure differential? Hi, Bill - Man, what a great idea!!! I'll try that at some rehearsals I have next week. Wouldn't it be funny if the balloon slipped off the tube? Thanks! Carlberg Carlberg Jones Guanajuato, Gto. MEXICO ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
80% at 1pound pressure above atmospheric is a number that must be measurable in some reproducible way. Do you have a set volume that is allowed to leak backwards through the rotor? What is it leaking to. Is it measured across to the other valve port , crosstalk, or is it measured to the outside world.? My experience is that there can't be a leak in the tubing of the other valve port, or else it will allow flow between the ports. I have a lot more experience leak checking vacuum systems, but I find significant valve leaks to be much more subtle than that, particularly on double horns. Is there a recognized industry standard for measuring leakage past a valve when there are other ports nearby? What is allowable crosstalk between ports, and how is that measured? This question comes up regularly, but I have never seen a standard I could apply. I'm not actively working on lamp process vacuum systems right now, so leak checking is not readily available to me at the moment, but I could set up all kinds of relevant tests with the equipment I usually have access to. I'd be interested to set up my own test set-up, if anyone would kindly define the relevant tests between ports and completely past valves.. For instance, would it be relevant to blow up a balloon through the valve I want to measure, then measure the leak rate back through the closed port, both to the manifold and to any adjacent ports, and at what pressure differential? ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
RE: [Hornlist] Couple of technical questions
Thanks, Bob, for that very useful information. Your comment about the 662 having a medium bell surprises me, though. Yamaha's web site says that the current model for the 662 is the 668, and that the 662 has a large bell. Here's a link: http://www.yamaha.com/yamahavgn/CDA/ContentDetail/ModelSeriesDetail/0,6373,C NTID%253D24389%2526CNTYP%253DPRODUCT,00.html and here's the copy from that link: Model: YHR-662 Years: 1974-1980 Key: F/Bb Bore: .469" Bell Throat: Large Bell Material: Yellow Brass Detachable Bell: No Wrap: Kruspe Finish: Lacquer Current Model: YHR-668 The information on the 666 is quite similar, listing the 668 as the current model. -S- > -Original Message- > From: > [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] > du] On Behalf Of Robert Osmun > Sent: Friday, April 15, 2005 3:10 PM > To: 'The Horn List' > Subject: RE: [Hornlist] Couple of technical questions > > Hi Steve, > > Signs of loose valves: sagging pitch in the upper register, > very wide slots, weak low register, fuzzy, diffuse sound. We > like to see at least 80% tightness (measured at 1 pound > static air pressure). Most new horns range from about 70% on > up. The so called "pop test" is virtually useless for > determining valve sealing, for reasons described by Bill > Bamberg in his post. You can test your valves by oiling with > SAE 90 gear oil. The heavy oil will make the valves seal more > like the valves in a new horn. You can decide for yourself > whether the difference is significant. Flush the valves with > regular valve oil when you're done. > > The YHR662 is a medium bell yellow brass horn. It would be > most like the modern YHR667. > > Hope this helps, > > Bob Osmun > www.osmun.com > > > > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Steve Freides > Sent: Friday, April 15, 2005 2:25 PM > To: 'The Horn List' > Subject: [Hornlist] Couple of technical questions > > 1. Can anyone give ballpark numbers of what valve > compression percentages feel like, e.g., I know that 90% is > considered good. Is, e.g., a horn completely unplayable with > 50% compression? Do new valves test out at 100% or very > close to that? I'd love to see a link to the actual > equipment used to test valve compression. > > 2. I understand that Yamaha's 668, the horn that came after > the 666, is quite similar to the 666 I'm now playing. Does > anyone know anything about the 662, which is the horn that > came before the 666, in terms of how similar > or not it is?There's a used one on one of the horn web sites I'm > considering. > > Many thanks in advance, everyone, and wishing you a good > weekend as well - the weather here in the Northeastern United > States promises to be beautiful. > > -S- > > > ___ > post: horn@music.memphis.edu > unsubscribe or set options at > http://music.memphis.edu/mailman/options/horn/rosmun%40osmun.com > > ___ > post: horn@music.memphis.edu > unsubscribe or set options at > http://music.memphis.edu/mailman/options/horn/steve%40fridaysc > omputer.com > ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
RE: [Hornlist] Couple of technical questions
Hi Bill, I got to thinking about your remark that you could tighten a loose valve by taking out the end play. I figure that , assuming a 1 degree taper, for every .010" you set the rotor down in the casing you would loose .0002" in side clearance (per side). Since .010" would be a very large amount of end play to remove and .0002" would be an insignificant amount of clearance to loose (assuming the rotor and casing have the same taper, which they don't, and assuming the sides of rotor and casing are straight, which they aren't), I don't think any reasonable amount of end play adjustment would have a significant effect on the tightness of the horn. Bob Osmun www.osmun.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, April 15, 2005 3:29 PM To: horn@music.memphis.edu Subject: Re: [Hornlist] Couple of technical questions Different horns react in different ways. Some are quite insensitive. Tightening the bearings theoretically cuts the valve spacing in half, if the bearings were loose to start with. The problem with predicting leak behavior is because the critical factor is the gap being large enough to break down the oil film. That's why serious leaking seems to start suddenly. Also, leaks between adjacent ports can be substantial, but the valve might still seal to the ouside world. That's why a leak in the valve tubing usually effects both sides of the horn. It allows cross port leaking because the pressure in the unused tube can't build up. ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/rosmun%40osmun.com ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
RE: [Hornlist] Couple of technical questions
Hi Steve, Signs of loose valves: sagging pitch in the upper register, very wide slots, weak low register, fuzzy, diffuse sound. We like to see at least 80% tightness (measured at 1 pound static air pressure). Most new horns range from about 70% on up. The so called "pop test" is virtually useless for determining valve sealing, for reasons described by Bill Bamberg in his post. You can test your valves by oiling with SAE 90 gear oil. The heavy oil will make the valves seal more like the valves in a new horn. You can decide for yourself whether the difference is significant. Flush the valves with regular valve oil when you're done. The YHR662 is a medium bell yellow brass horn. It would be most like the modern YHR667. Hope this helps, Bob Osmun www.osmun.com -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Steve Freides Sent: Friday, April 15, 2005 2:25 PM To: 'The Horn List' Subject: [Hornlist] Couple of technical questions 1. Can anyone give ballpark numbers of what valve compression percentages feel like, e.g., I know that 90% is considered good. Is, e.g., a horn completely unplayable with 50% compression? Do new valves test out at 100% or very close to that? I'd love to see a link to the actual equipment used to test valve compression. 2. I understand that Yamaha's 668, the horn that came after the 666, is quite similar to the 666 I'm now playing. Does anyone know anything about the 662, which is the horn that came before the 666, in terms of how similar or not it is?There's a used one on one of the horn web sites I'm considering. Many thanks in advance, everyone, and wishing you a good weekend as well - the weather here in the Northeastern United States promises to be beautiful. -S- ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/rosmun%40osmun.com ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
Regarding #2, Johnny Woodie once explained to me the difference between the 862 and the 868 (both Kruspe wraps from the old Yamaha 'custom' line), and I would think these differences would hold up for 662 vs 668. He told me that the 868 had a tighter wrap than the 862, and I believe there is an additional tuning slide on the 868 for the B side of the horn. As I recall (this was years ago), he much preferred the feel and response of the 862, but that may be a purely personal point of view of his. If you can get ahold of him, he knows 'everything' about Yamaha horns, as he helped design and market alot of them. My contact info is very old, so probably not good anymore. Fred Steve Freides <[EMAIL PROTECTED]> wrote: 1. Can anyone give ballpark numbers of what valve compression percentages feel like, e.g., I know that 90% is considered good. Is, e.g., a horn completely unplayable with 50% compression? Do new valves test out at 100% or very close to that? I'd love to see a link to the actual equipment used to test valve compression. 2. I understand that Yamaha's 668, the horn that came after the 666, is quite similar to the 666 I'm now playing. Does anyone know anything about the 662, which is the horn that came before the 666, in terms of how similar or not it is? There's a used one on one of the horn web sites I'm considering. Many thanks in advance, everyone, and wishing you a good weekend as well - the weather here in the Northeastern United States promises to be beautiful. -S- ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/fbaucom%40sbcglobal.net ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
Different horns react in different ways. Some are quite insensitive. Tightening the bearings theoretically cuts the valve spacing in half, if the bearings were loose to start with. The problem with predicting leak behavior is because the critical factor is the gap being large enough to break down the oil film. That's why serious leaking seems to start suddenly. Also, leaks between adjacent ports can be substantial, but the valve might still seal to the ouside world. That's why a leak in the valve tubing usually effects both sides of the horn. It allows cross port leaking because the pressure in the unused tube can't build up. ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
Re: [Hornlist] Couple of technical questions
___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
[Hornlist] Couple of technical questions
1. Can anyone give ballpark numbers of what valve compression percentages feel like, e.g., I know that 90% is considered good. Is, e.g., a horn completely unplayable with 50% compression? Do new valves test out at 100% or very close to that? I'd love to see a link to the actual equipment used to test valve compression. 2. I understand that Yamaha's 668, the horn that came after the 666, is quite similar to the 666 I'm now playing. Does anyone know anything about the 662, which is the horn that came before the 666, in terms of how similar or not it is?There's a used one on one of the horn web sites I'm considering. Many thanks in advance, everyone, and wishing you a good weekend as well - the weather here in the Northeastern United States promises to be beautiful. -S- ___ post: horn@music.memphis.edu unsubscribe or set options at http://music.memphis.edu/mailman/options/horn/archive%40jab.org
