Paul,

Well it would be silly for me to insist that I'm absolutely correct here, as I too am only basing my analysis only on what I see, and what experience I have been able to amass (some profession-related, a little in horn making, and quite a bit in casting bronze sculptures).

Looking closely at the photos, I would estimate the thinnest part of the Brazilian MF horns to be about 5/8 of an inch thick (at the mouth). By comparison, all Altec MF horns I have been able to find in photos appear to be no more than 3/16 inch thick; what's more, the thickness appears to be fairly constant all the way back to the small end. By contrast, look at the massive block around and under the throat of the Brazilian horns.

Never the less, as unlikely as it would seem to me, it is not impossible that your prediction turns out to be correct...

Because despite what I see as a significant difference in surface to mass ratio, I could be over looking something else which would still cause the Brazilian horns to ring, and which could have been equally present in your Altec horns, and caused them to ring.

Only one sure way to find out...

With regard to "horn doping"... that is an interesting way of seeing it. I've been making horns from steel and natrual fiber-reinforced, hard modeling plaster... they are very heavy and thick enough that they do not ring or resonate, so there is no need to add anything to the outside. I am however currently experimenting with different resins, in which to suspend various small particles, creating a textured and somewhat supple layer on the inside... The horns already sound good in bare plaster, but I want to know what effect various treatments to the inside might have.

By the way... While not wanting to suggest you replicate these Brazilian masterpieces, I can confrim that you've got the perfect amps to dip your toes back into horns....

jd*