BassetHoundTrio wrote: Thu Aug 10, 2023 8:25 pm
I am in awe! I have an EMG Xb Oversize, and am so impressed with your abilities. While I am terrible in areas mathematic, my ears can tell you that Balfour Davey got the math 100% right on his horn designs. Thank you so much for sharing all of the details, and if you are ever near Chicago, I hope you will let me know - would love for you to visit.
Thanks! The math for making a horn isn’t actually all that complicated; I just used the exponential horn radius equation given in
Modern Gramophones and Electrical Reproducers, plus some simple circle-related equations for the bends. (The theory is much more complicated--I make no pretense of understanding the math of that.) I appreciate the offer--please do likewise if you're ever near Pittsburgh!
Inigo wrote: Thu Aug 10, 2023 10:17 pm
Yes... if half a horn already has such a sound, how will be the complete unit? it will blow the roof out!
The full horn doesn’t actually seem much louder than the B-39 (which is plenty loud enough)—much fuller sound and stronger bass, though!
chunnybh wrote: Thu Aug 10, 2023 8:55 pm
Very exciting. I can't wait to see the video of it all assembled.
Voilà!:
"Cryin' for the Carolines" (before adding felt gaskets):
https://youtu.be/BLKksEeJmv8
"Cryin' for the Carolines" (after adding the gaskets):
https://youtu.be/8NOrqyLWsjU
"Nobody But You" (before adding gaskets):
https://youtu.be/DNNFYv4wikg
"Did You Mean It?" (before adding gaskets):
https://youtu.be/xRuMsBcJwc4
"To-Night's My Night With Baby" (before adding gaskets):
https://youtu.be/yIwZCGyKPX8
The bell formers came out only semi-successfully—the mouth former popped out quite nicely after a few whacks with a mallet, but the rear bell former stuck; the foam compacted when struck and the wooden end disc broke after several minutes of unsuccessful hammering. At that point, I figured there wasn’t much point trying to get the rest out intact, seeing as the narrow end was already so smashed up, so I removed the former by breaking it apart from the inside; it seems the glue from the horn had adhered to it in a few spots (again…), and it was apparently enough to prevent the former from coming out. I suspect that I didn't have enough Vaseline on the former, as I used up most of what I had on the larger section, which came out much more easily. I used an old credit card to scrape as much of the remaining Vaseline as possible from the interior of the horn, then scrubbed the surface with alcohol wipes to remove any residue--it seems to have worked quite well; the inner surface isn't tacky at all now.
The paper on the mouth section of the bell is rather wrinkly and doesn’t lie flat everywhere, and there are quite a few places where the innermost layers (the first ones to be applied) delaminated, so it needs at least some regluing, and/or possibly a thin coating of something that would fill in the voids or flatten the raised paper—as it’s only at the largest diameters, it seems as though regluing alone might be sufficient, but smoothing the surface would probably make it easier to apply a decorative paper, which I hope to do over winter break. Either way, fixing the bell will have to wait until fall break at this point, as I'll be going back to college in a couple days.
The paper shrank away from the mouth, the same as it did on the last horn, so I had to trim off about ½” off the length, for a final mouth diameter of about 33.5”, which is about what I planned.
There were some slight gaps between the bell halves between the bolts when I first assembled the horn, so after I made the first tests, I dismantled the whole, added felt gaskets between all three joints, and reassembled it—as there doesn’t seem to be a noticeable difference in sound quality, I would guess that the gaps were small enough and close enough to the mouth not to cause much loss of bass.
Sound-wise, it's a major improvement over the last horn; not every record suddenly has a lot of bass (although some do!), but the sound is generally much fuller, and possibly clearer as well; and surface noise seems slightly less noticeable on some records.
More photos--
The complete horn--the B-39 technically could support itself and the cabinet could hold it up without quite tipping over, but at least with the current neck thickness (~3/16"), the B-43's bell is too heavy for the neck to support safely, and the whole thing is too heavy for the cabinet to hold up, so some sort of external support is necessary--a bridge lamp is currently fulfilling the role:
The wrinkled paper inside the mouth:
Shrinkage of of individual layers of paper at the mouth rim--each layer was initially trimmed right to the edge of the former, not staggered as pictured below after the shrinkage (which also made the horn contour slightly concave right at the rim, hence the need to trim some off):