Dear all,
It is rather well understood that a finite aperture of a horn/wave-guide causes diffraction effects, [1]. However, neither this reference nor another paper [2], which at least tangentially touches on this issue, gives any insight on computation of a mouth shape that would give an optimal (whatever the criteria) diffraction.
I am also aware of the work of Jean Michel Le Cleac'h [3], but this appears to be concerned with the entire horn contour, and not only the mouth shape. As such, it appears inapplicable to a situations, where a horn contour is pre-determined, e.g., constant directivity.
I would appreciate if anyone, who aware of any theory/papers/software dealing with this issue, could post references.
Thank you,
M
[1] Geddes, E., R.: "Sound Radiation from Acoustic Apertures." JAES., vol. 41, pp. 214-23 (April 1993)
[2] Henwood, D.J.: "The Boundary element method and Horn Design, JAES, vol. 41, pp. 485-496 (June 1993)
[3] http://ndaviden.club.fr/pavillon/lecleach.htm
It is rather well understood that a finite aperture of a horn/wave-guide causes diffraction effects, [1]. However, neither this reference nor another paper [2], which at least tangentially touches on this issue, gives any insight on computation of a mouth shape that would give an optimal (whatever the criteria) diffraction.
I am also aware of the work of Jean Michel Le Cleac'h [3], but this appears to be concerned with the entire horn contour, and not only the mouth shape. As such, it appears inapplicable to a situations, where a horn contour is pre-determined, e.g., constant directivity.
I would appreciate if anyone, who aware of any theory/papers/software dealing with this issue, could post references.
Thank you,
M
[1] Geddes, E., R.: "Sound Radiation from Acoustic Apertures." JAES., vol. 41, pp. 214-23 (April 1993)
[2] Henwood, D.J.: "The Boundary element method and Horn Design, JAES, vol. 41, pp. 485-496 (June 1993)
[3] http://ndaviden.club.fr/pavillon/lecleach.htm
The best reference, in fact the only reference I know of, on this topic is Geddes' book, "Audio Transducers". I strongly recommend it.
It can be ordered directly from his site: www.gedlee.com.
A sample calculation may be seen here:
http://gedlee.com/downloads/Appendix_A.pdf
Hope this helps.
It can be ordered directly from his site: www.gedlee.com.
A sample calculation may be seen here:
http://gedlee.com/downloads/Appendix_A.pdf
Hope this helps.
Dear al2002,
thank you for the reference.
However, it seems to me that we are micommunicating because the link that you have posted treats calculation of a wave propagation throug a wave-guide assumed to be conical; therefore, without mouth flare.
The only comment related to my inquiry is on p. 302: ". . . waves reflected . . . can be reduced by radius'd (flared) mouth treatment as we discussed in Sec. 6.6."
Could you tell me if Sec. 6.6. contains any theoretical derivation of the flare or just states to do so?
M
thank you for the reference.
However, it seems to me that we are micommunicating because the link that you have posted treats calculation of a wave propagation throug a wave-guide assumed to be conical; therefore, without mouth flare.
The only comment related to my inquiry is on p. 302: ". . . waves reflected . . . can be reduced by radius'd (flared) mouth treatment as we discussed in Sec. 6.6."
Could you tell me if Sec. 6.6. contains any theoretical derivation of the flare or just states to do so?
M
Is this (http://www.users.onaustralia.com.au/putland/phd/thes.ps.gz) along the lines of what you're looking for? I haven't read it yet as I haven't been able to grab the printer for long enough.
mefistofelez said:
http://www.nutshellhifi.com/library/speaker-design1.html
Look at the Horn paragraph. In fact, the whole article is a "must read".
Dear Cloth Ears,
thank you for the link.
Dear jomor,
thank you for the article. If I understand the issue of mouth termination, there are two phenomena caused by diffraction. One is standing waves caused by reflection of the wave inside the horn, the other by interference of waves difracted outside the horn. It is the latter, I am interested in.
Dear al2002,
thank you for the reply.
Sorry, does it show a theoretical derivation, or does it just state how to curve the flare?
Thanks to the others who responded.
M
thank you for the link.
Dear jomor,
thank you for the article. If I understand the issue of mouth termination, there are two phenomena caused by diffraction. One is standing waves caused by reflection of the wave inside the horn, the other by interference of waves difracted outside the horn. It is the latter, I am interested in.
Dear al2002,
thank you for the reply.
Sorry, does it show a theoretical derivation, or does it just state how to curve the flare?
Thanks to the others who responded.
M
mefistofelez said:
Sorry for the delay. Have been busy and lost track of this thread.
There is enough theory in Geddes' book for you to derive the flare if you wanted to. However, for DIY construction do you really need to do this?
The quick and dirty rule of thumb, according to Geddes, is that the flare radius should be lambda, but lambda/2 will do if you are constrained by size.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.