Folded horn length
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Don Snyder
diyAudio Member

Join Date: Apr 2007
Folded horn length

Calculating the length of the bends in a folded horn is confusing.
Figures 1, 2 & 3 are the most common bends. For low frequency waves,
they are nearly identical, with a small edge given to figure 3. The
green squiggle in figure 1 represents turbulence.

Figure 4 would seem to be the way to go, until you consider that
the outer part of the bend (the green area) has 3 times the area
that the inner (red) part has. Also, the length of the dividing
line is WAY below (30% below) the experimental data.

In figure 5, the "center" line is moved from 50% of the duct width
to 70%. Now, the green area is equal to the red area, and the
length of the line dividing the red from the green agrees within
a few percent of experimental data.

Figure 6 is nearly as good, and a lot less trouble. Just draw a
diagonal line in each corner, and connect the center points of each
line. The length of that line is within a few percent of the horn
length as calculated using figure 5.
Attached Images
 bend.gif (6.2 KB, 441 views)

Don Snyder
diyAudio Member

Join Date: Apr 2007
Here is an example.
Attached Images
 bend2.gif (6.3 KB, 406 views)

 1st May 2009, 09:23 PM #3 MaVo   diyAudio Member   Join Date: Jan 2006 I used nr.6 in all my horns and it allways worked. But, once the diameter rises, the error of this method rises too. For near the mouth, the something between 4rth and 5th may be better.
 1st May 2009, 11:14 PM #4 Don Snyder   diyAudio Member   Join Date: Apr 2007 Tom Danley said: "A word about folding, one mistake made in horn folding is to make the horn passage significantly less volume that it was when straight. The air in a bend has a rotary motion and so momentarily has rotational properties, the effect of this is that the air has slightly more mass (inertia? DS) than in a straight section. This in turn allows a small reduction in acoustic length for that section but it is small. When I lay out a bend I usually try to keep the total volume close to that of a straight horn. With increasing frequency, a bend's dimension will have an impact on the sound. At the point where the difference in acoustic path length around the inside and outside of the bend reaches 1/2 wavelength, there will be a deep notch in the response. Above this frequency will be a pattern of notches and so on as the dimensions are N 1/2 wavelengths. If you have to make a bend, make it where the dimensions are small, make the angle as small as possible." __________________ Don

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is Off Forum Rules
 Forum Jump User Control Panel Private Messages Subscriptions Who's Online Search Forums Forums Home Site     Site Announcements     Forum Problems Amplifiers     Solid State     Pass Labs     Tubes / Valves     Chip Amps     Class D     Power Supplies     Headphone Systems Source & Line     Analogue Source     Analog Line Level     Digital Source     Digital Line Level     PC Based Loudspeakers     Multi-Way     Full Range     Subwoofers     Planars & Exotics Live Sound     PA Systems     Instruments and Amps Design & Build     Parts     Equipment & Tools     Construction Tips     Software Tools General Interest     Car Audio     diyAudio.com Articles     Music     Everything Else Member Areas     Introductions     The Lounge     Clubs & Events     In Memoriam The Moving Image Commercial Sector     Swap Meet     Group Buys     The diyAudio Store     Vendor Forums         Vendor's Bazaar         Sonic Craft         Apex Jr         Audio Sector         Acoustic Fun         Chipamp         DIY HiFi Supply         Elekit         Elektor         Mains Cables R Us         Parts Connexion         Planet 10 hifi         Quanghao Audio Design         Siliconray Online Electronics Store         Tubelab     Manufacturers         AKSA         Audio Poutine         Musicaltech         Holton Precision Audio         CSS         Dx Classic Amplifiers         exaDevices         Feastrex         GedLee         Head 'n' HiFi - Walter         Heatsink USA         miniDSP         SITO Audio         Twin Audio         Twisted Pear         Wild Burro Audio

 Similar Threads Thread Thread Starter Forum Replies Last Post gjeff80 Multi-Way 34 5th September 2011 11:49 PM paulspencer Subwoofers 8 4th November 2005 10:44 PM eRiCdWoNg Subwoofers 7 19th October 2003 11:19 PM slicemaster101 Multi-Way 9 3rd October 2002 02:56 PM

 New To Site? Need Help?

All times are GMT. The time now is 05:24 AM.